COMFORTABLE AMI Published: Biodegradable-Polymer DES Bests BMS in STEMI

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Compared with bare-metal stents (BMS), a novel biolimus-eluting stent equipped with a biodegradable polymer results in fewer adverse events at 1 year in patients with ST-segment elevation myocardial infarction (STEMI). The findings, published in the August 22, 2012, issue of the Journal of the American Medical Association, were originally presented at EuroPCR 2012 in Paris, France.

For the COMFORTABLE AMI (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal Stents in Acute ST-Elevation Myocardial Infarction) trial, Stephan Windecker, MD, of Bern University Hospital (Bern, Switzerland), and colleagues randomized 1,161 STEMI patients at 11 sites in Europe and Israel to either the BioMatrix biolimus-A9-eluting stent (n = 575; Biosensors, Singapore) or the Gazelle BMS (n = 582; Biosensors). Enrollment took place from September 2009 to January 2011 and follow-up was obtained at 1 and 12 months.

Advantage Over BMS

The primary endpoint of 1-year MACE (composite of cardiac death, target vessel-related reinfarction, and ischemia-driven TLR) occurred at a higher rate in BMS-treated patients. The difference was fueled by a lower risk of target vessel-related reinfarction and ischemia-driven TLR in patients receiving the biolimus-eluting stent (table 1).

Table 1. One-Year Results

Abbreviation: ARC, Academic Research Consortium.

Other safety endpoints such as death, stroke, and MI were similar between the 2 groups at 1 year, while there was a trend toward fewer reinfarctions overall (Q-wave or non-Q-wave) with BioMatrix (2.0% vs. 3.7%; P = 0.08). In addition, target-vessel MIs due to restenosis or stent thrombosis were reduced in the BioMatrix group (3 events vs. 14 events; P = 0.01). The number needed to treat to prevent a single MACE event at 1 year with a BioMatrix stent was 24.

Findings were consistent across multiple subgroups defined by diabetes, renal failure, LVEF, LAD disease, thrombus aspiration, time from pain onset to balloon inflation, multivessel disease, small vessel disease, and lesion length.

Focus Switches to Long-term Safety

In an e-mail communication with TCTMD, Dr. Windecker said he expected to see the advantage of BioMatrix with regard to MACE and TLR. However, the fact that the novel stent also proved superior in terms of MI is surprising, he said, and suggests that “DES may be potentially safer than BMS. The findings are reassuring and will increase confidence among physicians to use DES over BMS in STEMI.”

Dr. Windecker referenced 4-year results from the LEADERS trial (Stefanini GG, et al. Lancet.  2011;378;1940-1948) comparing BioMatrix with the sirolimus-eluting Cypher stent (Cordis, Miami Lakes, FL), which showed improved long-term outcome and an 80% lower risk of very late stent thrombosis with the newer device. He noted that patients enrolled in COMFORTABLE AMI will be followed out to 5 years.

Regarding the benefit of new DES over using stents with permanent polymers, Dr. Windecker said that “biodegradable [polymers] render the stent more closely to bare-metal stents after the period of biodegradation, which is appealing. Most future stent platforms use biodegradable polymers, but it remains to be shown whether they are superior.”

Going forward, Dr. Windecker said, it will be necessary for trials comparing DES with BMS to be “powered for safety endpoints rather than efficacy endpoints to determine whether DES offer a safety advantage.” In addition, the authors note, the optimal duration of dual antiplatelet therapy after biolimus-eluting stent implantation remains to be determined.

Comforting Results

COMFORTABLE AMI “is a well-done trial with convincing results regarding its primary endpoint,” Salvatore Cassese, MD, and Adnan Kastrati, MD, both of Deutsches Herzzentrum (Munich, Germany), write in an accompanying editorial. However, they note that the trial has “neither the required sample size nor the sufficient length of follow-up to provide the definitive answer about the long-term safety of the new biodegradable DES in this setting. The trial offers positive signals that . . . these new DES may belong to the ‘first-choice’ devices in patients with STEMI.”

Adding to prior research, the findings “provide several important lessons,” Drs. Cassese and Kastrati write. As DES have already proven more effective than BMS in STEMI, “further studies comparing these interventions might not be needed,” they advise, adding that concerns about very late safety with DES are likely specific to particular devices, especially those that are first-generation. Though noninferiority trials comparing novel BMS to available DES are still expected, they conclude, “until then, recent studies such as the COMFORTABLE AMI trial should make cardiologists feel more comfortable with the use of new generation DES in patients with STEMI.”

Study Details

Baseline characteristics were similar in both groups. The mean age of patients was 60.6 years and 79% were men. At discharge, 43% of patients received prasugrel and 57% received clopidogrel. Use of dual antiplatelet therapy was high and balanced in both treatment groups throughout the entire follow-up period up to 1 year.

 

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Sources:
1. Räber L, Kelbӕk H, Ostoijc M, et al. Effect of biolimus-eluting stents with biodegradable polymer vs bare-metal stents on cardiovascular events among patients with acute myocardial infarction: The COMFORTABLE AMI randomized trial. JAMA. 2012;308:777-787.

2. Cassese S, Kastrati A. New-generation drug-eluting stents for patients with myocardial infarction. JAMA. 2012;308:814-815.

 

 

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