sábado, 9 de setembro de 2006

Guerra dos stents: perda para os dois lados.

A Boston Cientific e a Johsson & Johnson estão travando há mais de um ano uma guerra para mostrar que tem o melhor stent com medicamento no mercado. Ambas patrocinaram trabalhos que as favorecem, cada uma a seu tempo. Agora, duas apresentações no World Congress of Cardiology recém terminado em Barcelona, Espanha, reduziram as expectativas desse tipo de stent em relação ao tradicional. O melhor texto explicando a confusão é de hoje do The New York Times. Mas, voltaremos ao tema porque essa é uma questão central na organização da assistência ao infartado no Brasil. Interessante, que o estudo citado, o suíco Basket, não nega o uso desses stents, somente limita a sua indicação.
A grosso modo há um aumento considerável no gasto do atendimento ao infartado no mundo todo porque progressivamente os tratamentos mais adequados vão sendo superados por outros mais caros. Muitas aspas em adequados e superados.
Stent Makers Hurt by Reports About Safety By BARNABY J. FEDER Published: September 8, 2006 (copyright NYT) Shareholder qualms about growth prospects for the $5 billion coronary stunt business yesterday shook the stocks of Boston Scientific and Johnson & Johnson, the two leading stent makers. Shares of Boston Scientific fell 3.3 percent, or 57 cents, to $16.70. The stock of Johnson & Johnson, whose overall business is less dependent on stents, fell 46 ceNts, to $63.46. The declines came after a stream of reports about stent safety from a European medical meeting. Those included the disclosure yesterday that Boston Scientific had quietly told federal regulators this summer that new analysis of the company’s accumulating safety data found that patients using its best-selling Taxus stent had a slightly greater but statistically clear risk of developing potentially deadly blood clots compared with older stent designs. Among the earlier reports at the meeting was a Swiss study suggesting that in some patient groups the Cypher stent of Johnson & Johnson posed even higher long-term clotting risks than Taxus. Stents are metal sleeves inserted in arteries to keep them propped open after medical procedures to clear blockages. Although some are used during heart bypass surgery, most coronary stents are inserted as a follow-up to angioplasty, a less invasive procedure in which the blockage is cleared from inside the artery by inflating a balloon. The balloon and stent are delivered to the heart area via a long catheter inserted into a blood vessel in the patient’s thigh. Stents were first used in the 1990’s. The original designs were bare metal devices. Cypher, introduced in the United States in 2003, and Taxus, which was cleared for sale in 2004, are drug-coated devices. The coatings are meant to combat the tendency of arteries to form new blockages, a process called restenosis. Although the drug-coated devices cost more than $2,000 on average, compared with $800 or so for bare metal devices, they rapidly supplanted the older designs in the United States and now account for 85 percent to 90 percent of the market. Analysts said that the stock market reaction reflected fears that growth in the stent market would slow and that more doctors would prescribe the less profitable bare metal products. Word of Boston Scientific’s report to regulators, whom it met with on Aug. 1, and the news that Food and Drug Administration officials then asked Johnson & Johnson for more data on its Cypher stent, was reported yesterday in The Wall Street Journal.

5 comentários:

Anônimo disse...

BASKET-LATE: High cardiac death and MI rates in DES-treated patients fuel late
stent thrombosis debate
March 14, 2006

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Atlanta, GA - Using a drug-eluting stent (DES) in 100 patients may avert five target vessel revascularizations (TVRs), but at the price of three late deaths/MIs related to increased late thrombosis, a new analysis suggests. Outside experts caution that the study, while provocative, was too small to be definitive.




Presenting results of the Basel Stent Cost-effectiveness Trial—Late Thrombotic Events (BASKET-LATE) during a late-breaking clinical-trials session here at the American College of Cardiology 2006 Scientific Sessions, Dr Matthias E Pfisterer (University Hospital Basel, Switzerland) acknowledged that his study was underpowered to detect major differences in thrombosis-related events. Still, he insisted, the indisputably increased thrombosis risk with drug-eluting stents warrants new strategies to prevent late thrombosis.
In the short term, Pfisterer told heartwire, longer dual antiplatelet therapy might be the best temporary solution. In the long term, new stents with bioabsorbable platforms or polymers may solve the late thrombosis problem. Testing for clopidogrel resistance may also help avert stent thrombosis related to drug resistance, he added.
A lethal trade-off
Debate over the true risk of late thrombosis continues to dog drug-eluting stents. As Pfisterer noted in his presentation, delayed endothelialization following stent implantation is the proposed mechanism behind the widely acknowledged increased risk of late thrombosis with DES, although the actual real-world thrombosis rate is hotly disputed.
As Dr William O'Neill observed following Pfisterer's presentation, "The real question that clinicians are going to have is: are you really trading late restenosis, which is not a health hazard, for death or reinfarction? That's obviously a very important and worrisome trade-off."
As previously reported by heartwire, the original BASKET trial enrolled a relatively complex patient group and randomized them to a bare-metal stent, a paclitaxel-eluting stent, or a sirolimus-eluting stent. For BASKET-LATE, Pfisterer and colleagues followed the 746 patients who were MACE free at six months (when the main BASKET cost-effectiveness trial had concluded and clopidogrel was stopped) for an additional 12 months. The aim of BASKET-LATE was to define the incidence of clinical events related to stent thrombosis—and the timing of these events—in patients treated with either a bare-metal stent or a DES. For the purposes of the analysis, sirolimus- and paclitaxel-eluting stent-treated patients were combined in a single group, late stent thrombosis was defined as at least six months after PCI, and "thrombosis-related events" encompassed angiographically confirmed stent thrombosis, sudden cardiac death, or a target vessel MI.
BASKET-LATE results
Somewhat to the surprise of his audience here today, Pfisterer showed that while MACE rates were no different between bare-metal-stent or DES-treated patients, rates of nonfatal MI and cardiac death/nonfatal MI were actually significantly higher in DES-treated patients. By contrast, and as expected, target vessel revascularization was higher in the bare-metal-stent group, although when only restenosis-related TVR was included, this difference was not statistically significant.
Major cardiac events between 7 and 18 months

Outcome Bare-metal stent (%) DES (%) p
Cardiac death 0 1.2 0.09
Nonfatal MI 1.3 4.1 0.04
Cardiac death/nonfatal MI 1.3 4.9 0.01
Restenosis-related TVR 6.7 4.5 0.21
MACE 7.9 9.3 0.53


To download table as a slide, click on slide logo below
When event rates for cardiac death/MI as well as rates of TVR were plotted over the full 18 months after stent implantation, the curves for TVR rates for DES vs bare-metal stents separated at approximately four months, in keeping with observations from the major DES trials (p=0.02). For cardiac death/MI, however, the curves for bare-metal stents and DES were more or less superimposable until approximately eight months, at which time event rates for bare-metal stents appear to plateau, while the rate for DES continue to climb (p=0.06). Timing of thrombotic events appeared to be evenly distributed across the 12 months after clopidogrel discontinuation.
While the stent thrombosis rate was not statistically different between the DES- and bare-metal-stent-treated patients, in absolute numbers, angiographically documented late stent thromboses were twice as high in DES-treated patients, while thrombosis-related clinical events were nearly three times as high. In multivariate analyses, the most important predictors of late cardiac death/MI were prior MI, initial need for GP IIb/III inhibitors (reflecting troponin-positive ACS patients, more complex lesions, or suboptimal revascularization) and DES use, Pfisterer said.
"With currently recommended antiplatelet therapies, one has to balance in real-world DES use the benefit of lower TVR rates with the cost of an increased rate of late cardiac death/MI," Pfisterer concluded. He estimated this cost/benefit to be 3.3 late death/MIs for every five TVRs avoided per 100 patients receiving a DES.
Asked why his findings appeared to depart so dramatically from pivotal trial results, Pfisterer emphasized that BASKET-LATE reflected a much higher-risk-patient cohort, of whom almost 60% were unstable-angina or STEMI patients.
More studies needed
Discussing the results following the presentation, Dr E Murat Tuzcu (Cleveland Clinic, OH) charged Pfisterer of overstating his findings.
"You have not shown a statistically significant difference in late stent thrombosis and thrombosis-related events [between the DES and bare-metal-stent groups], but you make sweeping conclusions in that regard. Moreover, some of the presentation and outcome of late events could be influenced by their definitions as 'thrombosis-related events,' which were not statistically different between the two groups. So do you really think you can make those kind of sweeping conclusions? This is strikingly different from what we have seen in other studies."
Tuzcu also questioned whether nonfatal myocardial infarction at 200 to 300 days after cessation of clopidogrel treatment could "confidently" be attributed to lack of dual antiplatelet therapy.









In response, Pfisterer acknowledged that the major limitation of his study was that it was not powered to look for infrequent events. "In fact, if you wanted to do a study to look at these small differences, you would need a study with tens of thousands of patients, and such a study will most likely never be performed," Pfisterer said. "But we had the unique possibility to look at this phenomenon in our patient group, and in this sense, it is a valuable study. Yes, you can criticize the conclusions for being a little bit stretched, but it's what these data would suggest."
Commenting on the study for heartwire, Dr William Gray (Columbia University, New York, NY) said that the results were intriguing but pointed out that in many centers, physicians are already prescribing clopidogrel for one year.
"The data are interesting," Gray stated. "Late-stent-thrombosis rate is important, and if you looked retrospectively across all the trials with follow-up out to two years, the data are probably there, but it's probably not as profound as this. We're probably going to have to do something larger than this, and probably with longer-duration clopidogrel."
The clopidogrel requirement, however, raises a host of other issues, including clopidogrel resistance and drug cost. In some cases, patients may not be able to afford long-term clopidogrel therapy, and the potential increased risk of late thrombosis following drug-eluting-stent implantation may negate the benefits of drug-eluting stents if patients stop their clopidogrel early.
"The cost of clopidogrel is not insignificant," Gray acknowledged. "It is a problem for some patients who we treat and it can influence our clinical decision-making as to what kind of stents we implant. In some cases, a bare-metal stent may be the better option."

Anônimo disse...

Safety of drug-eluting stents: insights from meta analysis.
A meta-analysis of first generation drug eluting stents - including both first generation drug eluting stent extent of both mortality and Q-wave Myocardial Infarction in comparison to bare metal stents. Here the presenter Edoardo Camenzind (Geneva, Switzerland) and the discussant Alain Nordmann (Basel, Switzerland) provide an overview of the results.
Introduction
First generation drug eluting stents (1stg-DES: sirolimus eluting stent [SES] have been widely accepted and are used for a large spectrum of clinical indications.
Recently case reports and autopsy reports have been published on single cases as well as on series of cases which experienced stent thrombosis more than 30 days after stent deployment, so called late stent thrombosis. Delayed healing and diminished antiplatelet therapy could be demonstrated as relevant precipitating factor.
The global incidence of ‘in-1st g-DES’ thrombosis according to the literature remains uncertain. According to some single center registries and post-marketing surveillance registries as well as meta-analysis the incidence of late angiographic stent thrombosis does not seem to be higher in 1st g-DES as compared to bare metal stents (BMS). However according to the recently presented BASKET-Late trial, a small randomized trial designed to evaluate cost effectiveness of 1st g-DES versus BMS, severe cardio-vascular events were significantly higher in patients with 1st g-DES as compared to BMS in the year following the interruption of dual antiplatelet therapy.
Methods
The current analysis embraced both 1st g-DES clinical programs (SES and PES) and included all available data concerning company supported randomized double-blind clinical trials comparing 1st g-DES to the respective BMS control. Of the SES program the following trials were included: RAVEL, SIRIUS, E-SIRIUS and C-SIRIUS and for the PES program: TAXUS II, IV, V and VI accounting for a total of n=878 SES vs n=870 BMS and n=1685 PES vs n=1675 BMS. Available randomized trials’ data within a specific study program (SES or PES) were stratified by trials and data of the same time-periods of follow-up were pooled as well as data of the latest available follow-up.
The clinically oriented analysis focuses on death, Q-wave MI and death and Q-wave MI combined thought to reflect the incidence of stent thrombosis best instead of using restrictive thrombosis definitions (e.g. late angiographic stent thrombosis).
Results
The incidence - up to the latest available follow-up - of total mortality and Q-wave MI combined were 38% (SES) and 16% (PES) higher in 1st g-DES as compared to control BMS (p-value: SES vs BMS: 0.03 ; PES vs BMS. 0.68).
Conclusion
eath and Q-wave myocardial infarction have a higher incidence in 1st generation drug eluting stents as compared to the bare metal control stents.
Thus the indiscriminated use of 1st g-DES should be avoided and the use of bare metal stent may still be maintained awaiting for safer 2nd g-DES

Anônimo disse...

DES versus BMS: an evidence-based approache to stent selection in real-world" patients -18 month update of BASKET."
The BASKET study, presented in clinical trial update session I, identifies that to achieve optimal benefit drug eluting stents could be restricted to small vessels less than 3mmm and bypass grafts. Here presenter Christoph Kaiser (Basel, Switzerland) and discussant Jean Marco (Toulouse, France)provide an overview of the results.
Background
In order to define patient subgroups with a particularly high versus no or only minimal clinical benefit from DES compared with BMS use we anlayzed our “real-world” experience from BASKET after 18 months.
Methods
BASKET included 826 consecutive patients with PCI and stenting irrespective of indication. Patients were randomized 2:1 to DES versus BMS and followed up for 18 months for the occurrence of major adverse cardiac events (Cardiac death, non-fatal MI and non-MI related TVR). Based on tests for interaction with the different stent types, patient subgroups with high versus low clinical benefit from DES were identified.
Results
Overall, event rates were low (DES vs. BMS: Death/MI: 8.4% vs. 7.5%; (p=0.63); Non-infarct related TVR: 7.5% vs. 11.6% (p=0.05); MACE: 15.8% vs. 18.9% (p=0.26). Overall, only bypass graft interventions and small vessel stenting < 3.0mm showed significant interactions between stent type and non-infarct related TVR as well as Death/ MI or MACE. Therefore, we analyzed outcomes in patients with versus without these two characteristics. Kaplan-Meier survival curves showed a highly significant benefit of patients with small vessel/stent or bypass graft PCI from DES use (Fig. 1). In contrast, for all other patients there was no benefit of DES compared to BMS.
Conclusion
Based on evidence from this long-term follow-up from BASKET, DES may be restricted to small vessels/stents <3mm and to bypass grafts for optimal and long-term benefit. These findings challenge the notion that today every patient should receive DES irrespective of baseline characteristics

Anônimo disse...

Top U.S. cardiologist calls for sweeping stent study
Mon Sep 11, 2006 8:22am ET
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CHICAGO (Reuters) - One of the nation's leading cardiologists is calling for a sweeping study that evaluates the risks of potentially fatal blood clots related to widely used heart devices that treat blocked heart arteries.

Nearly 6 million heart patients worldwide have received a so-called drug-eluting stent, a tiny wire mesh tube that is covered with a drug that reduces scar formation and keeps vessels from reclosing.

But there has been a growing body of evidence that this newer generation of stents, compared with the bare metal variety, may cause blood clots to form long after implantation. Known as late-stent thrombosis, the risks were the center of debate at a cardiology meeting earlier this week in Barcelona.

"This really shakes up the whole cardiology community," Dr. Stephen Nissen, head of cardiovascular medicine at the Cleveland Clinic, said in a telephone interview.

"No one has done the right kind of long-term study," he said, adding that patients should be followed for three or four years instead 9 months. "We need a prospective, randomized trial. That's the gold standard and I'm hoping regulators will mandate it."

He said he will take an active role in initiating such a study. "How else will we answer the question?" Nissen added.

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