Drug-eluting stent: Difference between revisions
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[[Image:Taxus stent FDA.jpg|thumb|right|250px|An example of a drug-eluting stent. This is the TAXUS™ Express<sup>2</sup>™ Paclitaxel-Eluting Coronary Stent System, which releases [[paclitaxel]].]] |
[[Image:Taxus stent FDA.jpg|thumb|right|250px|An example of a drug-eluting stent. This is the TAXUS™ Express<sup>2</sup>™ Paclitaxel-Eluting Coronary Stent System, which releases [[paclitaxel]].]] |
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A '''drug-eluting stent''' is a [[coronary stent]] (a scaffold) placed into narrowed, diseased [[coronary artery|coronary arteries]] that slowly releases a [[drug]] to block [[Hyperplasia|cell proliferation]]. This prevents scar-tissue–like growth that, together with clots ([[thrombus]]), could otherwise block the stented artery, a process called restenosis. The stent is usually placed within the coronary artery by an [[Interventional cardiologist]]. |
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Drug-eluting stents have been shown to be superior to traditional stents ("bare-metal stents") in reducing short-term complications.{{Fact|date=February 2008}} Their long term effectiveness compared to traditional stents or coronary bypass grafting is under scrutiny by the [[Food and Drug Administration|FDA]].<ref>{{cite web |
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Heart attacks, or [[myocardial infarction]]s, are major causes of death and disability; they result when a portion of heart muscle dies from inadequate blood flow. This typically occurs at sites where coronary arteries are already narrowed and damaged. Fat and cholesterol deposition as well as inflammation in the artery wall [[atherogenesis|cause injury]]; excessive tissue growth and additional cholesterol deposition occur, and clots form. These narrowings are prone to being suddenly blocked, or a piece may break off and block a smaller branch downstream. If blood flow can be restored early enough, permanent damage can be prevented, and preemptive restoration can prevent heart attacks from occurring in the first place. |
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|url=http://www.fda.gov/cdrh/news/091406.html+ |
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|title=US FDA/CDRH: FDA Statement on Coronary Drug-Eluting Stents |
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Coronary artery stents, typically a metal framework, can be placed inside the artery to help keep it open. However, the stent is a foreign object (not native to the body), and it incites an immune response. This may cause scar tissue (cell proliferation) to rapidly grow over the stent. In addition, there is a strong tendency for clots to form at the site where the stent damages the arterial wall. Since [[platelet]]s are involved in the clotting process, patients must take [[antiplatelet drug|antiplatelet]] therapy afterwards, usually [[clopidogrel]] for six months and [[aspirin]] indefinitely.<ref name="G&G"> {{cite book |
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|accessdate=2008-02-25 |
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| last = Michel | first = Thomas | editor = Laurence L. Brunton, John S. Lazo, & Keith L. Parker |
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| title = [[Goodman & Gilman's The Pharmacological Basis of Therapeutics]] | origyear = 1941 | edition = 11th ed. | year = 2006 |
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|work= |
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| publisher = McGraw-Hill | location = New York | pages = 842 | chapter = Treatment of Myocardial Ischemia |
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}}</ref> However, the antiplatelet therapy may be insufficient to fully prevent clots; these and the cell proliferation may cause the standard (“bare-metal”) stents to become blocked. Drug-eluting stents were designed to lessen this problem; by releasing an antiproliferative drug (drugs typically used against cancer or as [[immunosuppresant]]s), they can help avoid this ''in-stent restenosis'' (re-narrowing). |
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Drug-eluting stents have been shown to be superior for many of the conditions that traditional stents (“bare-metal stents”) have been used; they have been highly successful at treating coronary heart disease, and offer significant advantages over other therapies, such as surgery. In the few years since their [[FDA]] approval in 2003, the use of drug-eluting stents has become one of the dominant interventions in preventing and treating [[Myocardial infarction|heart attacks]].<ref name="NEJM review">{{cite journal |
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| last = Serruys | first = Patrick W. | coauthors = Michael J.B. Kutryk, and Andrew T.L. Ong | date = [[2006-02-02]] | title = Coronary-Artery Stents |
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| journal = [[New England Journal of Medicine]] | volume = 354 | issue = 5 | pages = 483–495 | url = http://content.nejm.org/cgi/content/extract/354/5/483|id = PMID 16452560 |
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}} (extract)</ref><sup>, </sup><ref name="FDA Cypher">{{cite web |
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| url = http://www.fda.gov/cdrh/mda/docs/p020026.html| title = New Device Approval — Cypher Sirolimus-eluting Coronary Stent| accessdate = 2006-07-22 |
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| publisher = [[Food and Drug Administration]] |
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}}</ref> |
}}</ref> |
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== |
==History== |
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Drug-eluting stents consist of three parts. The stent itself is an expandable framework, usually metal. Added to this is a drug to prevent the artery from being re-occluded, or blocked. These typically have been drugs already in use as anti-cancer drugs or drugs that suppress the immune system, although new drugs are being developed specifically for drug-eluting stents. Finally, there must be a carrier which slowly releases the drug over months. The carrier is typically a [[polymer]], although [[phosphorylcholine]] or ceramics are also being researched.<ref name="NEJM review" /> Different carriers release the loaded drug at different rates. |
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==Placement== |
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A [[catheter]] with a guide wire is used to place the stent; it is loaded in its collapsed form onto a balloon at the end of the catheter. The device is then introduced through a [[peripheral artery]], usually at the groin through one of the [[femoral artery|femoral arteries]]. It is threaded back towards the [[heart]]. In the [[aorta]] just prior to entering the heart, the appropriate coronary artery is entered. The balloon is inflated, cracking and compressing the [[atheroma|plaque]] and expanding the stent. The balloon may be inflated and deflated several times. The balloon and catheter are then withdrawn, leaving the stent in place. The stent releases its drug over the next several months. |
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==Current devices== |
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Currently, two models of drug-eluting stents are used. Both drugs currently in use were previously developed for other purposes; their use to prevent in-stent proliferation is relatively new. |
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===Early interventional cardiology technologies=== |
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The first successful type releases [[sirolimus]] (rapamycin), a powerful immunosuppressive and antiproliferative drug. It is primarily used as an immunosuppressant to prevent organ transplant rejection. Produced by the bacterium ''[[Streptomyces]] hygroscopicus'', it binds to the [[immunophilin]] FKBP-12. The resulting complex inhibits the [[mammalian target of rapamycin]] (mTOR), which has several effects, including preventing the cell from duplicating its genetic material; it blocks the [[cell cycle]] at the G<sub>1</sub>→S transition.<ref name="G&G sirolimus">{{cite book |
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{{Main|History of invasive and interventional cardiology}} |
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| last = Krensky | first = Alan M. | coauthors = Flavio Vincenti, & William M. Bennett |editor = Laurence L. Brunton, John S. Lazo, & Keith L. Parker |
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The first procedural method to treat blocked [[coronary artery|coronary arteries]] was a type of [[open-heart surgery]] called [[coronary artery bypass graft]] (CABG) surgery, which uses a section of vein or artery from elsewhere in the body to bypass the diseased vessel. In 1977, [[Andreas Grüntzig]] introduced [[percutaneous transluminal coronary angioplasty]] (PTCA), also called balloon angioplasty, in which a catheter was introduced through a peripheral artery and a balloon expanded to compress and crack the obstructive plaque.<ref name="NEJM Gruntzig">{{cite journal |
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| title = [[Goodman & Gilman's The Pharmacological Basis of Therapeutics]] | origyear = 1941 | edition = 11th ed. | year = 2006 |
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| publisher = McGraw-Hill | location = New York | pages = 1413 | chapter = Immunosuppressants, Tolerogens, and Immunostimulants |
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}}</ref> A sirolimus-eluting stent is produced by [[Cordis Corporation]] ([[Johnson & Johnson]]), and marketed under the name ''Cypher''. This stent is made of [[stainless steel]] and uses a polymer as the carrier.<ref name="FDA Cypher" /> |
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A second model uses [[paclitaxel]], another antiproliferative drug; it is primarily used against various forms of cancer. Derived from the [[yew]] tree, paclitaxel binds to and stabilizes [[microtubule]]s. Without the dynamic framework provided by these components of the [[cytoskeleton]], the cell cannot undergo [[mitosis]] and so is arrested at the M stage.<ref name="G&G paclitaxel">{{cite book |
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| last = Chabner| first = Bruce A. | coauthors = Philip C. Amrein, Brian J. Druker, M. Dror Michaelson, Constantine S. Mitsiades, Paul E. Goss, David P. Ryan, Sumant Ramachandra, Paul G. Richardson, Jeffrey G. Supko, & Wyndham H. Wilson |editor = Laurence L. Brunton, John S. Lazo, & Keith L. Parker |
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| title = [[Goodman & Gilman's The Pharmacological Basis of Therapeutics]] | origyear = 1941 | edition = 11th ed. | year = 2006 |
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| publisher = McGraw-Hill | location = New York | pages = 1352–1353 | chapter = Antineoplastic Agents |
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}}</ref> The paclitaxel-eluting stent produced by [[Boston Scientific]] is marketed under the name ''Taxus''. Like the Cypher stent, the Taxus stent is made of stainless steel and uses a polymer as drug carrier.<ref name="FDA Taxus">{{cite web |
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| url = http://www.fda.gov/cdrh/mda/docs/p030025.html| title = New Device Approval — P030025 — TAXUS™ Express<sup>2</sup>™ Paclitaxel-Eluting Coronary Stent System |
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| accessdate = 2006-07-22| date = [[2004-09-09]]| publisher = [[Food and Drug Administration]] |
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}}</ref> |
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==History== |
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[[Image:PTCA stent NIH.gif|thumb|right|250px|Diagram of stent placement. In '''A''', the catheter is inserted across the lesion. In '''B''', the balloon is inflated, expanding the stent and compressing the plaque. In '''C''', the catheter and deflated balloon have been removed. Before-and-after cross sections of the artery show the results of the stent placement.]] |
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The first procedural method to treat blocked coronary arteries was a type of open-heart surgery called [[coronary artery bypass graft]] (CABG) surgery, which uses a section of vein or artery from elsewhere in the body to bypass the diseased vessel. In 1977, [[Andreas Grüntzig]] introduced [[percutaneous transluminal coronary angioplasty]] (PTCA), in which a catheter was introduced through a peripheral artery and a balloon expanded to compress and crack the obstructive plaque.<ref name="NEJM Gruntzig">{{cite journal |
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| last = Grüntzig | first = AR | authorlink = Andreas Grüntzig | coauthors = A Senning, & WE Siegenthaler |
| last = Grüntzig | first = AR | authorlink = Andreas Grüntzig | coauthors = A Senning, & WE Siegenthaler |
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| date = [[1979-07-12]] | title = Nonoperative dilatation of coronary-artery stenosis: percutaneous transluminal coronary angioplasty |
| date = [[1979-07-12]] | title = Nonoperative dilatation of coronary-artery stenosis: percutaneous transluminal coronary angioplasty |
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| journal = [[New England Journal of Medicine]] | volume = 301 | issue = 2 | pages = 61–68 |
| journal = [[New England Journal of Medicine]] | volume = 301 | issue = 2 | pages = 61–68 |
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| url = http://content.nejm.org/cgi/content/abstract/301/2/61 | accessdate = 2006-07-22 | id = PMID 449946 |
| url = http://content.nejm.org/cgi/content/abstract/301/2/61 | accessdate = 2006-07-22 | id = PMID 449946 |
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}} |
}}</ref> |
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As equipment and techniques improved, the use of PTCA rapidly increased, and by the mid-1980s, PTCA and CABG were being performed at equivalent rates.<ref name="Harrison's"> {{cite book |
As equipment and techniques improved, the use of PTCA rapidly increased, and by the mid-1980s, PTCA and CABG were being performed at equivalent rates.<ref name="Harrison's"> {{cite book |
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| Line 56: | Line 30: | ||
| title = [[Harrison's Principles of Internal Medicine]] | origyear = 1958 | edition = 16th ed. | year = 2005 | publisher = McGraw-Hill |
| title = [[Harrison's Principles of Internal Medicine]] | origyear = 1958 | edition = 16th ed. | year = 2005 | publisher = McGraw-Hill |
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| location = New York | pages = 1459–1462 | chapter = Percutaneous Coronary Revascularization |
| location = New York | pages = 1459–1462 | chapter = Percutaneous Coronary Revascularization |
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}}</ref> |
}}</ref> PTCA could only be used on limited scenarios, and the vessels had a high rate (30–40% in six months) of [[restenosis]]; additionally, 3% required emergency bypass surgery.<ref name="Harrison's" /> [[Charles Theodore Dotter|Dotter]] and Judkins had suggested using prosthetic devices inside arteries to maintain blood flow (in arteries of the leg) in 1964,<ref name="Dotter">{{cite journal |
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| last = Dotter | first = Charles T. | coauthors = & Melvin P. Judkins | year = 1964 | title = Transluminal Treatment of Arteriosclerotic Obstruction |
| last = Dotter | first = Charles T. | coauthors = & Melvin P. Judkins | year = 1964 | title = Transluminal Treatment of Arteriosclerotic Obstruction |
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| journal = [[Circulation (journal)|Circulation]] | volume = 30 | pages = 654–670 | url = http://circ.ahajournals.org/cgi/content/abstract/30/5/654 |
| journal = [[Circulation (journal)|Circulation]] | volume = 30 | pages = 654–670 | url = http://circ.ahajournals.org/cgi/content/abstract/30/5/654 |
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}} (abstract)</ref> and in 1986, Puel and Sigwart implanted the first stent in humans.<ref name="NEJM review" /> Several trials in the 1990s showed the superiority of stent placement to simple balloon angioplasty, and stent placement became increasingly prevalent, reaching 84% of [[percutaneous]] interventions (those done via needle-puncture rather than incision) by 1999.<ref name="NEJM review" /> |
}} (abstract)</ref> and in 1986, Puel and Sigwart implanted the first stent in humans.<ref name="NEJM review" /> Several trials in the 1990s showed the superiority of stent placement to simple balloon angioplasty, and stent placement became increasingly prevalent, reaching 84% of [[percutaneous]] interventions (those done via needle-puncture rather than incision) by 1999.<ref name="NEJM review" /> |
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Initial difficulties included blood clotting and occluding the stent in the hours or days after placement.<ref name="Harrison's" /> Coating the stent with biologically inert substances like platinum or gold did not help.<ref name="NEJM review" /> Eventually, using high balloon pressures to tightly fix the stent against the vessel and administering aspirin and (usually) clopidogrel as anticoagulants were established; these changes eliminated most of the difficulty with in-stent thrombosis.<ref name="NEJM review" / |
Initial difficulties included blood clotting and occluding the stent in the hours or days after placement.<ref name="Harrison's" /> Coating the stent with biologically inert substances like platinum or gold did not help.<ref name="NEJM review" /> Eventually, using high balloon pressures to tightly fix the stent against the vessel and administering aspirin and (usually) clopidogrel as anticoagulants were established; these changes eliminated most of the difficulty with in-stent thrombosis.<ref name="NEJM review" /><ref name="Harrison's" /> |
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Difficulties still remained, however, with the formation of scar tissue inside the stent (in-stent neointimal hyperplasia) and clotting problems not addressed by the antiplatelet drug regimen. The stent itself was a logical choice for delivering medication. The slow release of drugs from the stent spares the patient the inconvenience of taking yet another medication, and prevents the danger of the patient forgetting to take or losing interest in taking the medicine. But more importantly, a stent that releases a drug can deliver high concentrations directly to the target region, analagous to placing a medicated cream on a skin problem or taking an inhaler to help the lungs or airways. Taking the medication orally or intravenously would require much higher doses to ensure a sufficient concentration at the target; this could cause unacceptable side effects or patient injury. |
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The first successful trials were of sirolimus-eluting stents. A successful trial in 2002 led to approval of the Cypher stent in Europe, followed by FDA approval in the U.S. in 2003.<ref name="NEJM review" /> Soon thereafter, a series of trials of paclitaxel-eluting stents led to FDA approval of the Taxus stent in 2004.<ref name="FDA Taxus" /> |
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==Uses== |
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There has been considerable research showing the benefits of coronary stents. Data specifically on drug-eluting stents are less abundant, though where studied, they have usually been shown to be superior to bare-metal stents, and in some cases, may be used for lesions for which surgery was previously the only option. Drug-eluting stents are used both for restoring blood flow immediately after a heart attack and also electively for improving blood flow in a compromised vessel. Only certain types of blockages are amenable to stent placement, though drug-eluting stents may be successful in lesions for which bare-metal stents were insufficient. Drug-eluting stents are used to reopen grafts from prior CABG surgery that have themselves become blocked, and also can be used for in-stent restenosis in prior stents.<ref name="NEJM review" /> |
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==Current research== |
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Research focuses on establishing the roles for drug-eluting stents and for developing new types of stents. Different materials for all three components—the scaffolding, the carrier, and the drug—are being actively investigated. |
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===Drug elution=== |
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In place of the stainless steel currently used in stents, various biodegradable frameworks are under early phases of investigation. Since metal, as a foreign substance, provokes inflammation, scarring, and thrombosis (clotting), it is hoped that biodegradable or bioabsorbable stents may prevent some of these effects. A [[magnesium]] alloy–based stent has been tested in animals, though there is currently no carrier for drug elution.<ref name="Heart magnesium">{{cite journal |
In place of the stainless steel currently used in stents, various biodegradable frameworks are under early phases of investigation. Since metal, as a foreign substance, provokes inflammation, scarring, and thrombosis (clotting), it is hoped that biodegradable or bioabsorbable stents may prevent some of these effects. A [[magnesium]] alloy–based stent has been tested in animals, though there is currently no carrier for drug elution.<ref name="Heart magnesium">{{cite journal |
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| last = Heublein | first = B. | coauthors = R. Rhode, V. Kaese, N. Niemeyer, W. Hartung, & A. Haverich | year = 2003 |
| last = Heublein | first = B. | coauthors = R. Rhode, V. Kaese, N. Niemeyer, W. Hartung, & A. Haverich | year = 2003 |
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| title = Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology? | journal = [[Heart (journal)|Heart]] |
| title = Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology? | journal = [[Heart (journal)|Heart]] |
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| volume = 89 | pages = 651–656 | url = http://heart.bmjjournals.com/cgi/content/full/89/6/651 | accessdate = 2006-07-23| id = PMID 12748224 |
| volume = 89 | pages = 651–656 | url = http://heart.bmjjournals.com/cgi/content/full/89/6/651 | accessdate = 2006-07-23| id = PMID 12748224 |
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}}</ref> A promising biodegradable framework is made from poly-L-lactide, a polymer of a derivative of L-lactic acid. One of these stents, the Igaki-Tamai stent, has been studied in pigs; [[tranilast]]<ref name="Tsjui">{{cite journal |
}}</ref> A promising biodegradable framework is made from poly-L-lactide, a polymer of a derivative of [[lactic acid|L-lactic acid]]. One of these stents, the Igaki-Tamai stent, has been studied in pigs; [[tranilast]]<ref name="Tsjui">{{cite journal |
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| last = Tsuji | first = T. | coauthors = H. Tamai, K. Igaki, E. Kyo, K. Kosuga, T. Hata, T. Nakamura, S. Fujita, S. Takeda, S. Motohara, & H. Uehata |
| last = Tsuji | first = T. | coauthors = H. Tamai, K. Igaki, E. Kyo, K. Kosuga, T. Hata, T. Nakamura, S. Fujita, S. Takeda, S. Motohara, & H. Uehata |
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| year = 2003 | title = Biodegradable stents as a platform to drug loading. | journal = International Journal of Cardiovascular Interventions |
| year = 2003 | title = Biodegradable stents as a platform to drug loading. | journal = International Journal of Cardiovascular Interventions |
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}}</ref> have been used as eluted drugs. |
}}</ref> have been used as eluted drugs. |
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===Alternative drugs=== |
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There are also several other anti-proliferative drugs under investigationin human clinical trials. In general, these are analogues of sirolimus. Like sirolimus, these block the action of mTOR. [[Abbott]] has developed [[zotarolimus]]; unlike sirolimus and paclitaxel, this sirolimus analogue designed for use in stents with [[phosphorylcholine]] as a carrier. Their ZoMaxx stent is a zotarolimus-eluting, stainless steel and [[tantalum]]–based stent; a modified [[phosphorylcholine]] slowly releases the zotarolimus.<ref name="Abbott ZoMaxx">{{cite web |
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There are also several other anti-proliferative drugs under investigation in human clinical trials. In general, these are analogues of sirolimus. Like sirolimus, these block the action of mTOR. [[Abbott Laboratories|Abbott]] has developed [[zotarolimus]]; unlike sirolimus and paclitaxel, this sirolimus analogue designed for use in stents with [[phosphorylcholine]] as a carrier. Their ZoMaxx stent is a zotarolimus-eluting, stainless steel and [[tantalum]]–based stent; a modified phosphorylcholine slowly releases the zotarolimus.<ref name="Abbott ZoMaxx">{{cite web |
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| url = http://www.abbott.com/global/url/content/en_US/30.20.50:50/general_content/General_Content_00024.htm |
| url = http://www.abbott.com/global/url/content/en_US/30.20.50:50/general_content/General_Content_00024.htm |
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| title = Vascular Devices| accessdate = 2006-07-23| publisher = [[Abbott]]}}</ref> Zotarolimus has been licensed to [[Medtronic]] |
| title = Vascular Devices| accessdate = 2006-07-23| publisher = [[Abbott]]}}</ref> Zotarolimus has been licensed to [[Medtronic]] which is researching the effectiveness in a drug-eluting stent of their own. Their Endeavor stent, which is a [[cobalt]] alloy,<ref name="NEJM review" /> also uses phosphorylcholine to carry the zotarolimus was approved for use in Europe in 2005 is now close to U.S. FDA approval<ref name="StarTribune">{{cite web |
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| url = http://www.startribune.com/535/story/1476560.html |
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| title = FDA advisers OK Medtronic stent| accessdate = 2007-10-10| publisher = [[Star Tribune]]}}</ref> |
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Clinical trials are currently examining two stents carrying [[everolimus]],<ref name="NEJM review" /> an immunosuppressant that like sirolimus is used to prevent organ rejection. |
Clinical trials are currently examining two stents carrying [[everolimus]],<ref name="NEJM review" /> an immunosuppressant that like sirolimus is used to prevent organ rejection.{{Fact|date=February 2008}} [[Guidant]], which has the exclusive license to use everolimus in drug-eluting stents, is the manufacturer of both stents. This Guidant business has subsequently been sold to Abbott Labs.<ref>{{cite web |url=http://www.abbott.com/global/url/pressRelease/en_US/60.5:5/Press_Release_0309.htm |title=Abbott Completes Acquisition of Guidant Vascular Business |accessdate=2007-01-12 |format= |work= }}</ref> The Champion stent uses a bioabsorbable polylactic acid carrier on a stainless steel stent.<ref name="FUTURE">{{cite journal |
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| last = Grube | first = Eberhard | coauthors = Shinjo Sonoda, Fumiaki Ikeno, Yasuhiro Honda, Saibal Kar, Charles Chan, Ulrich Gerckens, Alexandra J. Lansky, & Peter J. Fitzgerald | year = 2004 | title = Six- and Twelve-Month Results From First Human Experience Using Everolimus-Eluting Stents With Bioabsorbable Polymer |
| last = Grube | first = Eberhard | coauthors = Shinjo Sonoda, Fumiaki Ikeno, Yasuhiro Honda, Saibal Kar, Charles Chan, Ulrich Gerckens, Alexandra J. Lansky, & Peter J. Fitzgerald | year = 2004 | title = Six- and Twelve-Month Results From First Human Experience Using Everolimus-Eluting Stents With Bioabsorbable Polymer |
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| journal = [[Circulation (journal)|Circulation]] | volume = 109 | issue = | pages = 2168—2171 | doi = 10.1161/01.CIR.0000128850.84227.FD | id = PMID 15123533 |
| journal = [[Circulation (journal)|Circulation]] | volume = 109 | issue = | pages = 2168—2171 | doi = 10.1161/01.CIR.0000128850.84227.FD | id = PMID 15123533 |
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}}</ref |
}}</ref><ref name="Guidant Champion">{{cite web |
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| url = http://www.guidant.com/news/400/web_release/nr_000459.shtml| title = Guidant News Release — April 5, 2004| accessdate = 2007-07-23| date = [[2004-04-05]] |
| url = http://www.guidant.com/news/400/web_release/nr_000459.shtml| title = Guidant News Release — April 5, 2004| accessdate = 2007-07-23| date = [[2004-04-05]] |
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| publisher = [[Guidant]] |
| publisher = [[Guidant]] |
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}}</ref> In contrast, its Xience stent uses a durable (non- |
}}</ref> In contrast, its Xience stent uses a durable (non-bioabsorbable) polymer on a cobalt stent.<ref name="Guidant Xience">{{cite web |
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| url = http://www.guidant.com/news/500/web_release/nr_000551.shtml| title = Guidant News Release — June 22, 2005| accessdate = 2006-07-23 |
| url = http://www.guidant.com/news/500/web_release/nr_000551.shtml| title = Guidant News Release — June 22, 2005| accessdate = 2006-07-23 |
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| date = [[2005-06-22]]| publisher = [[Guidant]] |
| date = [[2005-06-22]]| publisher = [[Guidant]] |
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}}</ref> |
}}</ref> |
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===The introduction of drug eluting stents=== |
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==Complications and controversy== |
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Difficulties still remained, however, with the formation of scar tissue inside the stent (in-stent neointimal hyperplasia) and clotting problems not addressed by the antiplatelet drug regimen. The stent itself was a logical choice for delivering medication. The slow release of drugs from the stent spares the patient the inconvenience of taking yet another medication, and prevents the danger of the patient forgetting to take or losing interest in taking the medicine. But more importantly, a stent that releases a drug can deliver high concentrations directly to the target region, analogous to placing a medicated cream on a skin problem or taking an inhaler to help the lungs or airways. Taking the medication orally or intravenously would require much higher doses to ensure a sufficient concentration at the target; this could cause unacceptable side effects or patient injury. |
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In the last several years, drug-eluting stent use has become exceedingly popular, both in place of surgery and for lesions not severe enough for surgery. Placing stents is not without risk, however, and the recent development of the drug-eluting stents means that long-term data, especially in comparison to traditional bare-metal stents, are not available. As enthusiasm for the new devices abates, there is some concern about overzealous use of stents in general. |
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The first successful trials were of [[sirolimus]]-eluting stents. A successful trial in 2002 led to approval of the Cypher stent in Europe, followed by FDA approval in the U.S. in 2003.<ref name="NEJM review" /> Soon thereafter, a series of trials of paclitaxel-eluting stents led to FDA approval of the Taxus stent in 2004.<ref name="FDA Taxus">{{cite web |
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As with all cardiac catheterization, there are several risks. Patients may exhibit severe allergic response to the contrast agents used to visualize the coronary arteries, and occasionally, the peripheral entry artery fails to properly heal after the catheter is removed, causing a collection of blood called a [[hematoma]]. Rarely, a coronary artery can be perforated while the catheter is advanced or during stent placement.<ref name="Harrison's" /> |
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|url=http://www.fda.gov/cdrh/mda/docs/p030025.html |
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|title=New Device Approval - P030025 - TAXUS™ Express2™ Paclitaxel-Eluting Coronary Stent System |
|||
|accessdate=2008-02-25 |
|||
|format= |
|||
|work= |
|||
}}</ref> |
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==Indications== |
|||
Finally, stent occlusion can occur. Thrombosis may occur during the procedure, in the following days, or much later. Stents cause damage to the vessel wall, and, as foreign objects, they provoke inflammation and clot formation. And tissue proliferation in the stent can cause the vessel to narrow again. Patients with stents (but not those undergoing isolated balloon angioplasty) must remain on an antiplatelet drug like clopidogrel for at least three to six months; discontinuing it, even for a short time, can cause a clot to form;<ref name="Harrison's" /> aspirin must be taken for life.<ref name="NEJM review" /> Drug-eluting stents have been shown to have significantly lower rates of in-stent proliferation compared to bare-metal stents. However, some studies suggest that the proliferation may be merely delayed; when the drug has been completely eluted, proliferation may occur.<ref name="NEJM review" /> The magnitude and significance of this effect is unclear. Rarely, a type of allergic reaction to the drug may occur; episodes of fatality have been reported.<ref name="hypersensitivity">{{cite journal |
|||
There has been considerable research showing the benefits of coronary stents. Data specifically on drug-eluting stents are less abundant, though where studied, they have usually been shown to be superior to bare-metal stents, and in some cases, may be used for lesions for which surgery was previously the only option. Drug-eluting stents are used both for restoring blood flow immediately after a heart attack and also electively for improving blood flow in a compromised vessel. Only certain types of blockages are amenable to stent placement, though drug-eluting stents may be successful in lesions for which bare-metal stents were insufficient. Drug-eluting stents are used to reopen grafts from prior CABG surgery that have themselves become blocked, and also can be used in cases of in-stent restenosis in prior stents.<ref name="NEJM review" /> |
|||
| last = Virmani | first = Renu | coauthors = Giulio Guagliumi, Andrew Farb, Giuseppe Musumeci, Niccolo Grieco, Teresio Motta, Laurian Mihalcsik, Maurizio Tespili, Orazio Valsecchi, & Frank D. Kolodgie | year = 2004 | title = Localized Hypersensitivity and Late Coronary Thrombosis Secondary to a Sirolimus-Eluting Stent |
|||
| journal = [[Circulation (journal)|Circulation]] | volume = 109 | pages = 701–706 | doi = 10.1161/01.CIR.0000116202.41966.D4 |
|||
==Contraindications== |
|||
| id = PMID 14744976 |
|||
{{Sectstub}} |
|||
==Alternatives== |
|||
[[Coronary artery bypass surgery]] (CABG) is superior to PCI with DES in multivessel (two or more diseased arteries) [[coronary heart disease|coronary artery disease]] (CAD) in terms of death, [[myocardial infarction]] and repeat revascularization.<ref name="Hannan 2008">{{cite journal |author=Hannan EL, Wu C, Walford G, ''et al'' |title=Drug-eluting stents vs. coronary-artery bypass grafting in multivessel coronary disease |journal=N. Engl. J. Med. |volume=358 |issue=4 |pages=331–41 |year=2008 |pmid=18216353 |doi=10.1056/NEJMoa071804}}</ref> |
|||
==Risks== |
|||
In the last several years, drug-eluting stent use has become increasingly popular, both in place of surgery and for lesions not severe enough for surgery. Placing stents is not without risk, however, and the recent development of the drug-eluting stents means that long-term data, especially in comparison to traditional bare-metal stents, are not available. |
|||
===Risks due to cardiac catheterization=== |
|||
As with all cardiac catheterization, there are several risks. Patients may exhibit severe allergic response to the contrast agents used to visualize the coronary arteries, and occasionally, the peripheral entry artery fails to properly heal after the catheter is removed, causing a collection of blood called a [[hematoma]].{{Fact|date=February 2008}} |
|||
===Coronary artery perforation=== |
|||
Rarely, a coronary artery can be perforated while the catheter is advanced or during stent placement.<ref name="Harrison's" /> |
|||
===Stent thrombosis=== |
|||
Stent [[occlusion]] can occur. [[Thrombosis]] may occur during the procedure, in the following days, or much later. Stents cause damage to the vessel wall, and, as foreign objects, they provoke inflammation and clot formation. And tissue proliferation in the stent can cause the vessel to narrow again. Patients with stents (but not those undergoing isolated balloon angioplasty) must remain on an antiplatelet drug like clopidogrel for at least three to six months; discontinuing it, even for a short time, can cause a clot to form;<ref name="Harrison's" /> aspirin must be taken for life.<ref name="NEJM review" /> |
|||
Drug-eluting stents have been shown to have significantly lower rates of in-stent proliferation compared to bare-metal stents. However, some studies suggest that the proliferation may be merely delayed; when the drug has been completely eluted, proliferation may occur.<ref name="NEJM review" /> Both sirolimus and paclitaxel-eluting stents are associated with a small but statistically higher risk of thrombosis after the first year, compared to bare metal stents. Although this risk is still small, fatality results in one-third of patients who develop late thrombosis.<ref name="pmid17145250">{{cite journal |author=Bavry AA, Kumbhani DJ, Helton TJ, Borek PP, Mood GR, Bhatt DL |title=Late thrombosis of drug-eluting stents: a meta-analysis of randomized clinical trials |journal=Am. J. Med. |volume=119 |issue=12 |pages=1056–61 |year=2006 |pmid=17145250 |doi=10.1016/j.amjmed.2006.01.023}}</ref> This risk is offset by drug-eluting stents' markedly reduced risk of restenosis and its complications including myocardial infarction. A [[meta-analysis]] concluded "the risks of mortality associated with drug-eluting and bare-metal stents are similar." The advantage of drug-eluting stents is in reduction of restenosis.{{Fact|date=February 2008}} |
|||
Whether sirolimus or paclitaxel-eluting stents are measurably different in their outcomes is a topic of great interest, including to the marketing departments of the manufacturers themselves. Analyses favoring one or the other stent have been advanced. The differences, if any, between the two devices are small. <ref name="pmid17869634">{{cite journal |
|||
|author=Stettler C, Wandel S, Allemann S, Kastrati A, Morice MC, Schömig A, Pfisterer ME, Stone GW, Leon MB, de Lezo JS, Goy JJ, Park SJ, Sabaté M, Suttorp MJ, Kelbaek H, Spaulding C, Menichelli M, Vermeersch P, Dirksen MT, Cervinka P, Petronio AS, Nordmann AJ, Diem P, Meier B, Zwahlen M, Reichenbach S, Trelle S, Windecker S, Jüni P |
|||
|title=Outcomes associated with drug-eluting and bare-metal stents: a collaborative network meta-analysis |
|||
|journal=Lancet |
|||
|volume=370 |
|||
|issue=9591 |
|||
|pages=937–48 |
|||
|year=2007 |
|||
|pmid=17869634 |
|||
|doi=10.1016/S0140-6736(07)61444-5 |
|||
}}</ref> |
}}</ref> |
||
===Allergic reaction=== |
|||
Nevertheless, coronary stents, and drug-eluting stents in particular, have revolutionized the treatment of coronary heart disease, and new techniques and materials that may ameliorate these problems are being studied. Bioabsorble or biodegradable polymer or stent may help avoid the inflammation and other side effects of long-term foreign objects. Different carriers affect the rate of release of drug, and different antiproliferative drugs may have different clinical effects.<ref name="NEJM review" /> The success of drug-eluting stents in coronary disease has prompted investigation of their use in other narrowed arteries, such as the [[carotid artery|carotid arteries]] leading to the brain.<ref name="carotid">{{cite journal |
|||
| last = Boulos | first = A. S. | coauthors = C. Agner, & E. M. Deshaies | year = 2005 |
|||
Rarely, a type of allergic reaction to the drug may occur; episodes of fatality have been reported.<ref name="hypersensitivity">{{cite journal |
|||
| title = Preliminary evidence supporting the safety of drug-eluting stents in neurovascular disease. |
|||
|author=Virmani R, Guagliumi G, Farb A, Musumeci G, Grieco N, Motta T, Mihalcsik L, Tespili M, Valsecchi O, Kolodgie FD |
|||
| journal = Neurological Research | volume = 27 Suppl 1 | pages = S95–102 |
|||
|title=Localized hypersensitivity and late coronary thrombosis secondary to a sirolimus-eluting stent: should we be cautious? |
|||
| id = PMID 16197833 |
|||
|journal=Circulation |
|||
}}</ref> Such use remains investigational. |
|||
|volume=109 |
|||
|issue=6 |
|||
|pages=701–5 |
|||
|year=2004 |
|||
|pmid=14744976 |
|||
|doi=10.1161/01.CIR.0000116202.41966.D4 |
|||
}}</ref> |
|||
== |
==Design== |
||
Drug-eluting stents consist of three parts. The stent itself is an expandable framework, usually metal. Added to this is a drug to prevent the artery from being re-occluded, or blocked. These typically have been drugs already in use as anti-cancer drugs or drugs that suppress the immune system, although new drugs are being developed specifically for drug-eluting stents. Finally, there must be a carrier which slowly releases the drug over months. The carrier is typically a [[polymer]], although [[phosphorylcholine]] or ceramics are also being researched.<ref name="NEJM review">{{cite journal |
|||
<div class="references-small"> |
|||
|author=Serruys PW, Kutryk MJ, Ong AT |
|||
<references /> |
|||
|title=Coronary-artery stents |
|||
</div> |
|||
|journal=N. Engl. J. Med. |
|||
|volume=354 |
|||
|issue=5 |
|||
|pages=483–95 |
|||
|year=2006 |
|||
|pmid=16452560 |
|||
|doi=10.1056/NEJMra051091 |
|||
}}</ref> Different carriers release the loaded drug at different rates. |
|||
==Mechanism of action== |
|||
{{Sectstub}} |
|||
==Procedure== |
|||
{{Sectstub}} |
|||
==Legal status== |
|||
As enthusiasm for the new devices abates, there is some concern about overzealous use of stents in general. Two studies found that about half of patients received stents for unapproved reasons,<ref name="pmid17488965">{{cite journal |author=Win HK, Caldera AE, Maresh K, ''et al'' |title=Clinical outcomes and stent thrombosis following off-label use of drug-eluting stents |journal=JAMA |volume=297 |issue=18 |pages=2001–9 |year=2007 |pmid=17488965 |doi=10.1001/jama.297.18.2001}}</ref><ref name="pmid17488964">{{cite journal |author=Beohar N, Davidson CJ, Kip KE, ''et al'' |title=Outcomes and complications associated with off-label and untested use of drug-eluting stents |journal=JAMA |volume=297 |issue=18 |pages=1992–2000 |year=2007 |pmid=17488964 |doi=10.1001/jama.297.18.1992}}</ref> with worse outcomes for the patients in both studies. |
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==References== |
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{{reflist|2}} |
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==Further reading== |
==Further reading== |
||
*{{cite journal |
*{{cite journal |
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}} (journal review article, subscription required) |
}} (journal review article, subscription required) |
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==External links== |
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[[Category: Implants]] |
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{{commonscat|Stent}} |
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[[Category: Cardiology]] |
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* [http://www.ptca.org/stent Drug-Eluting Stents — Angioplasty.Org] |
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[[Category: Radiology]] |
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[[Category:Implants]] |
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[[Category:Cardiology]] |
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[[Category:Radiology]] |
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[[Category:Medical equipment]] |
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[[Category:Drug delivery devices]] |
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[[Category:Cardiovascular diseases]] |
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Revision as of 07:58, 11 March 2008
 | This article contains promotional content. (March 2008) |
 |
 | This article needs additional citations for verification. (February 2008) |
A drug-eluting stent is a coronary stent (a scaffold) placed into narrowed, diseased coronary arteries that slowly releases a drug to block cell proliferation. This prevents scar-tissue–like growth that, together with clots (thrombus), could otherwise block the stented artery, a process called restenosis. The stent is usually placed within the coronary artery by an Interventional cardiologist.
Drug-eluting stents have been shown to be superior to traditional stents ("bare-metal stents") in reducing short-term complications.[citation needed] Their long term effectiveness compared to traditional stents or coronary bypass grafting is under scrutiny by the FDA.[1]
History
Early interventional cardiology technologies
The first procedural method to treat blocked coronary arteries was a type of open-heart surgery called coronary artery bypass graft (CABG) surgery, which uses a section of vein or artery from elsewhere in the body to bypass the diseased vessel. In 1977, Andreas Grüntzig introduced percutaneous transluminal coronary angioplasty (PTCA), also called balloon angioplasty, in which a catheter was introduced through a peripheral artery and a balloon expanded to compress and crack the obstructive plaque.[2]
As equipment and techniques improved, the use of PTCA rapidly increased, and by the mid-1980s, PTCA and CABG were being performed at equivalent rates.[3] PTCA could only be used on limited scenarios, and the vessels had a high rate (30–40% in six months) of restenosis; additionally, 3% required emergency bypass surgery.[3] Dotter and Judkins had suggested using prosthetic devices inside arteries to maintain blood flow (in arteries of the leg) in 1964,[4] and in 1986, Puel and Sigwart implanted the first stent in humans.[5] Several trials in the 1990s showed the superiority of stent placement to simple balloon angioplasty, and stent placement became increasingly prevalent, reaching 84% of percutaneous interventions (those done via needle-puncture rather than incision) by 1999.[5]
Initial difficulties included blood clotting and occluding the stent in the hours or days after placement.[3] Coating the stent with biologically inert substances like platinum or gold did not help.[5] Eventually, using high balloon pressures to tightly fix the stent against the vessel and administering aspirin and (usually) clopidogrel as anticoagulants were established; these changes eliminated most of the difficulty with in-stent thrombosis.[5][3]
Drug elution
In place of the stainless steel currently used in stents, various biodegradable frameworks are under early phases of investigation. Since metal, as a foreign substance, provokes inflammation, scarring, and thrombosis (clotting), it is hoped that biodegradable or bioabsorbable stents may prevent some of these effects. A magnesium alloy–based stent has been tested in animals, though there is currently no carrier for drug elution.[6] A promising biodegradable framework is made from poly-L-lactide, a polymer of a derivative of L-lactic acid. One of these stents, the Igaki-Tamai stent, has been studied in pigs; tranilast[7] and paclitaxel[8] have been used as eluted drugs.
Alternative drugs
There are also several other anti-proliferative drugs under investigation in human clinical trials. In general, these are analogues of sirolimus. Like sirolimus, these block the action of mTOR. Abbott has developed zotarolimus; unlike sirolimus and paclitaxel, this sirolimus analogue designed for use in stents with phosphorylcholine as a carrier. Their ZoMaxx stent is a zotarolimus-eluting, stainless steel and tantalum–based stent; a modified phosphorylcholine slowly releases the zotarolimus.[9] Zotarolimus has been licensed to Medtronic which is researching the effectiveness in a drug-eluting stent of their own. Their Endeavor stent, which is a cobalt alloy,[5] also uses phosphorylcholine to carry the zotarolimus was approved for use in Europe in 2005 is now close to U.S. FDA approval[10]
Clinical trials are currently examining two stents carrying everolimus,[5] an immunosuppressant that like sirolimus is used to prevent organ rejection.[citation needed] Guidant, which has the exclusive license to use everolimus in drug-eluting stents, is the manufacturer of both stents. This Guidant business has subsequently been sold to Abbott Labs.[11] The Champion stent uses a bioabsorbable polylactic acid carrier on a stainless steel stent.[12][13] In contrast, its Xience stent uses a durable (non-bioabsorbable) polymer on a cobalt stent.[14]
The introduction of drug eluting stents
Difficulties still remained, however, with the formation of scar tissue inside the stent (in-stent neointimal hyperplasia) and clotting problems not addressed by the antiplatelet drug regimen. The stent itself was a logical choice for delivering medication. The slow release of drugs from the stent spares the patient the inconvenience of taking yet another medication, and prevents the danger of the patient forgetting to take or losing interest in taking the medicine. But more importantly, a stent that releases a drug can deliver high concentrations directly to the target region, analogous to placing a medicated cream on a skin problem or taking an inhaler to help the lungs or airways. Taking the medication orally or intravenously would require much higher doses to ensure a sufficient concentration at the target; this could cause unacceptable side effects or patient injury.
The first successful trials were of sirolimus-eluting stents. A successful trial in 2002 led to approval of the Cypher stent in Europe, followed by FDA approval in the U.S. in 2003.[5] Soon thereafter, a series of trials of paclitaxel-eluting stents led to FDA approval of the Taxus stent in 2004.[15]
Indications
There has been considerable research showing the benefits of coronary stents. Data specifically on drug-eluting stents are less abundant, though where studied, they have usually been shown to be superior to bare-metal stents, and in some cases, may be used for lesions for which surgery was previously the only option. Drug-eluting stents are used both for restoring blood flow immediately after a heart attack and also electively for improving blood flow in a compromised vessel. Only certain types of blockages are amenable to stent placement, though drug-eluting stents may be successful in lesions for which bare-metal stents were insufficient. Drug-eluting stents are used to reopen grafts from prior CABG surgery that have themselves become blocked, and also can be used in cases of in-stent restenosis in prior stents.[5]
Contraindications
![[icon]](/https/en.wikipedia.org/wiki/File:Wiki_letter_w_cropped.svg){kind=small} | This section needs expansion. You can help by adding to it. |
Alternatives
Coronary artery bypass surgery (CABG) is superior to PCI with DES in multivessel (two or more diseased arteries) coronary artery disease (CAD) in terms of death, myocardial infarction and repeat revascularization.[16]
Risks
In the last several years, drug-eluting stent use has become increasingly popular, both in place of surgery and for lesions not severe enough for surgery. Placing stents is not without risk, however, and the recent development of the drug-eluting stents means that long-term data, especially in comparison to traditional bare-metal stents, are not available.
Risks due to cardiac catheterization
As with all cardiac catheterization, there are several risks. Patients may exhibit severe allergic response to the contrast agents used to visualize the coronary arteries, and occasionally, the peripheral entry artery fails to properly heal after the catheter is removed, causing a collection of blood called a hematoma.[citation needed]
Coronary artery perforation
Rarely, a coronary artery can be perforated while the catheter is advanced or during stent placement.[3]
Stent thrombosis
Stent occlusion can occur. Thrombosis may occur during the procedure, in the following days, or much later. Stents cause damage to the vessel wall, and, as foreign objects, they provoke inflammation and clot formation. And tissue proliferation in the stent can cause the vessel to narrow again. Patients with stents (but not those undergoing isolated balloon angioplasty) must remain on an antiplatelet drug like clopidogrel for at least three to six months; discontinuing it, even for a short time, can cause a clot to form;[3] aspirin must be taken for life.[5]
Drug-eluting stents have been shown to have significantly lower rates of in-stent proliferation compared to bare-metal stents. However, some studies suggest that the proliferation may be merely delayed; when the drug has been completely eluted, proliferation may occur.[5] Both sirolimus and paclitaxel-eluting stents are associated with a small but statistically higher risk of thrombosis after the first year, compared to bare metal stents. Although this risk is still small, fatality results in one-third of patients who develop late thrombosis.[17] This risk is offset by drug-eluting stents' markedly reduced risk of restenosis and its complications including myocardial infarction. A meta-analysis concluded "the risks of mortality associated with drug-eluting and bare-metal stents are similar." The advantage of drug-eluting stents is in reduction of restenosis.[citation needed]
Whether sirolimus or paclitaxel-eluting stents are measurably different in their outcomes is a topic of great interest, including to the marketing departments of the manufacturers themselves. Analyses favoring one or the other stent have been advanced. The differences, if any, between the two devices are small. [18]
Allergic reaction
Rarely, a type of allergic reaction to the drug may occur; episodes of fatality have been reported.[19]
Design
Drug-eluting stents consist of three parts. The stent itself is an expandable framework, usually metal. Added to this is a drug to prevent the artery from being re-occluded, or blocked. These typically have been drugs already in use as anti-cancer drugs or drugs that suppress the immune system, although new drugs are being developed specifically for drug-eluting stents. Finally, there must be a carrier which slowly releases the drug over months. The carrier is typically a polymer, although phosphorylcholine or ceramics are also being researched.[5] Different carriers release the loaded drug at different rates.
Mechanism of action
| This section needs expansion. You can help by adding to it. |
Procedure
| This section needs expansion. You can help by adding to it. |
Legal status
As enthusiasm for the new devices abates, there is some concern about overzealous use of stents in general. Two studies found that about half of patients received stents for unapproved reasons,[20][21] with worse outcomes for the patients in both studies.
References
- ^ "US FDA/CDRH: FDA Statement on Coronary Drug-Eluting Stents". Retrieved 2008-02-25.
- ^ Grüntzig, AR (1979-07-12). "Nonoperative dilatation of coronary-artery stenosis: percutaneous transluminal coronary angioplasty". New England Journal of Medicine. 301 (2): 61–68. PMID 449946. Retrieved 2006-07-22.
{{cite journal}}: Check date values in:|date=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d e f Baim, Donald S. (2005) [1958]. "Percutaneous Coronary Revascularization". In Dennis L. Kasper, Anthony S. Fauci, Dan L. Longo, Eugene Braunwald, Stephen L. Hauser, & J. Larry Jameson (ed.). Harrison's Principles of Internal Medicine (16th ed. ed.). New York: McGraw-Hill. pp. 1459–1462.
{{cite book}}:|edition=has extra text (help)CS1 maint: multiple names: editors list (link) - ^ Dotter, Charles T. (1964). "Transluminal Treatment of Arteriosclerotic Obstruction". Circulation. 30: 654–670. PMID 14226164. Retrieved 2006-07-22.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) (abstract) - ^ a b c d e f g h i j k Serruys PW, Kutryk MJ, Ong AT (2006). "Coronary-artery stents". N. Engl. J. Med. 354 (5): 483–95. doi:10.1056/NEJMra051091. PMID 16452560.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Heublein, B. (2003). "Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology?". Heart. 89: 651–656. PMID 12748224. Retrieved 2006-07-23.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Tsuji, T. (2003). "Biodegradable stents as a platform to drug loading". International Journal of Cardiovascular Interventions. 5 (1): 13–6. PMID 12623560.
{{cite journal}}:|access-date=requires|url=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Vogt, Felix (2004). "Long-term assessment of a novel biodegradable paclitaxel-eluting coronary polylactide stent". European Heart Journal. 25: 1330–1340. PMID 15288161. Retrieved 2006-07-22.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Vascular Devices". Abbott. Retrieved 2006-07-23.
- ^ "FDA advisers OK Medtronic stent". Star Tribune. Retrieved 2007-10-10.
- ^ "Abbott Completes Acquisition of Guidant Vascular Business". Retrieved 2007-01-12.
- ^ Grube, Eberhard (2004). "Six- and Twelve-Month Results From First Human Experience Using Everolimus-Eluting Stents With Bioabsorbable Polymer". Circulation. 109: 2168–2171. doi:10.1161/01.CIR.0000128850.84227.FD. PMID 15123533.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Guidant News Release — April 5, 2004". Guidant. 2004-04-05. Retrieved 2007-07-23.
{{cite web}}: Check date values in:|date=(help) - ^ "Guidant News Release — June 22, 2005". Guidant. 2005-06-22. Retrieved 2006-07-23.
{{cite web}}: Check date values in:|date=(help) - ^ "New Device Approval - P030025 - TAXUS™ Express2™ Paclitaxel-Eluting Coronary Stent System". Retrieved 2008-02-25.
- ^ Hannan EL, Wu C, Walford G; et al. (2008). "Drug-eluting stents vs. coronary-artery bypass grafting in multivessel coronary disease". N. Engl. J. Med. 358 (4): 331–41. doi:10.1056/NEJMoa071804. PMID 18216353.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: multiple names: authors list (link) - ^ Bavry AA, Kumbhani DJ, Helton TJ, Borek PP, Mood GR, Bhatt DL (2006). "Late thrombosis of drug-eluting stents: a meta-analysis of randomized clinical trials". Am. J. Med. 119 (12): 1056–61. doi:10.1016/j.amjmed.2006.01.023. PMID 17145250.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Stettler C, Wandel S, Allemann S, Kastrati A, Morice MC, Schömig A, Pfisterer ME, Stone GW, Leon MB, de Lezo JS, Goy JJ, Park SJ, Sabaté M, Suttorp MJ, Kelbaek H, Spaulding C, Menichelli M, Vermeersch P, Dirksen MT, Cervinka P, Petronio AS, Nordmann AJ, Diem P, Meier B, Zwahlen M, Reichenbach S, Trelle S, Windecker S, Jüni P (2007). "Outcomes associated with drug-eluting and bare-metal stents: a collaborative network meta-analysis". Lancet. 370 (9591): 937–48. doi:10.1016/S0140-6736(07)61444-5. PMID 17869634.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Virmani R, Guagliumi G, Farb A, Musumeci G, Grieco N, Motta T, Mihalcsik L, Tespili M, Valsecchi O, Kolodgie FD (2004). "Localized hypersensitivity and late coronary thrombosis secondary to a sirolimus-eluting stent: should we be cautious?". Circulation. 109 (6): 701–5. doi:10.1161/01.CIR.0000116202.41966.D4. PMID 14744976.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Win HK, Caldera AE, Maresh K; et al. (2007). "Clinical outcomes and stent thrombosis following off-label use of drug-eluting stents". JAMA. 297 (18): 2001–9. doi:10.1001/jama.297.18.2001. PMID 17488965.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: multiple names: authors list (link) - ^ Beohar N, Davidson CJ, Kip KE; et al. (2007). "Outcomes and complications associated with off-label and untested use of drug-eluting stents". JAMA. 297 (18): 1992–2000. doi:10.1001/jama.297.18.1992. PMID 17488964.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: multiple names: authors list (link)
Further reading
- Fischetti, Mark (2006). "Vascular Stents: Expanding Use". Scientific American: 94.
{{cite journal}}: Unknown parameter|month=ignored (help) (layperson overview, subscription required) - Serruys, Patrick W. (2006-02-02). "Coronary-Artery Stents". New England Journal of Medicine. 354 (5): 483–495.
{{cite journal}}: Check date values in:|date=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) (journal review article, subscription required)
External links
Wikimedia Commons has media related to Stent.