New DES trump BMS for STEMI, but long-term outcomes unclear

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In a randomized clinical trial, biolumis-eluting stents emerged the victor over bare-metal stents (BMS) for treating patients with ST-segment elevation MI (STEMI) undergoing PCI, according to results published Aug. 22 in the Journal of the American Medical Association. The findings should put cardiologists more at ease about using new-generation drug-eluting stents (DES), the writers of an accompanying editorial proposed.

First-generation DES and BMS each had Achilles’ heels. BMS were associated with restenosis; in comparison, early-generation DES reduced the risk of restenosis but showed a higher risk for very late stent thrombosis. New-generation DES have been designed to address that issue using controlled drug release and a biodegradable polymer that leaves the stent surface similar to that of BMS.

Lorenz Räber, MD, of the cardiology department at Bern University Hospital in Switzerland, and colleagues designed the COMFORTABLE AMI trial (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal Stents in Acute ST-Elevation Myocardial Infarction) to compare the efficacy and safety of a newer generation stent—stents that elute biolimus from a biodegradable polymer—with BMS. The study is a prospective, multicenter, randomized, single-blinded controlled trial that enrolled STEMI patients between September 2009 and January 2011.

Patients were randomized 1:1 to either BMS (582 patients, 648 infarct-vessel lesions) or biolimus-eluting stents (575 patients, 629 infarct-vessel lesions) with clinical follow-up at one month and one year. The study’s primary endpoint was the rate of major adverse cardiac events (cardiac death, target vessel-related reinfarction and ischemia-driven target lesion revascularization) at one year. The average age of patients was 60.6 years and 79 percent were men.

Major adverse cardiac events occurred in 4.3 percent of the biolimus-eluting stent group vs. 8.7 percent of the BMS group. There was no significant difference in cardiac death (2.9 percent for the biolimus-eluting stent group vs. 3.5 percent for the BMS group) but the biolimus-eluting stent group had lower risk of target vessel-related reinfarction (0.5 percent vs. 2.7 percent); ischemia-driven target-lesion revascularization (1.6 percent vs. 5.7 percent); and at one year, definite stent thrombosis (0.9 percent vs. 2.1 percent).

“[T]he use of bare-metal stents with a biodegradable polymer was associated with a significant 4.4 percent absolute reduction and 51 percent relative reduction in the risk of major adverse cardiac events at one year, which prevents 42 events per 1,000 patients treated with biolimus-eluting stents compared with bare-metal stents at one year,” Räber and colleagues wrote. “Findings were also robust for the more comprehensive patient-oriented composite of any death, reinfarction, or revascularization. Accordingly, our results suggest better clinical outcomes in terms of major adverse cardiac events of a stent releasing biolimus from a biodegradable polymer compared with a bare-metal stent for the treatment of patients with STEMI.”

The authors observed that their trial compared with other large, randomized trials showed a lower absolute rate of revasculazations in both treatment groups, which may be the result of improvements in lesion preparation using thrombus aspiration and more potent antithrombotics. Polymer coatings on the newer generation DES also may have a thrombo-resistant effect, which they wrote could be important for patients at higher baseline risk of thrombosis.

Their study was powered to test the composite outcome but not individual components for efficacy and safety, they pointed out, and results don’t extend beyond one year. The  biolimus-eluting stent (BioMatrix, Biosensors Europe SA) is not FDA-approved, although it is recommended for clinical use in European guidelines for myocardial revascularization, they wrote.

In an accompanying editorial, Salvatore Cassese, MD, and Adnan Kastrati, MD, of the Technische Universitat in Munich, Germany, described Räber et al’s trial as well done but cautioned that it lacked the sample size and duration to answer questions about the long-term safety of the newer generation DES.

“The trial offers positive signals that, along with previous findings indicating the excellent four-year safety of biodegradable polymer DESs, form a good basis to believe that these new DESs may belong to the ‘first-choice’ devices in patients with STEMI,” they wrote. “Bioabsorption of the drug carrier and even of the entire stent platform may be particularly useful in this setting.”

Cassese and Kastrati argued that there is no need to study the efficacy of DES, based on COMFORTABLE AMI and other trials. They recommended larger randomized trials with longer follow-up periods that provide head-to-head comparisons of DES technologies be conducted to eliminate any concerns about safety. They also called for more intravascular imaging data in trials.

“[A]lthough there is almost no rationale for performing DES vs. BMS studies anymore, it might be conceivable to expect studies that test the hypothesis of noninferiority of new, improved BMSs to available DESs,” Cassese and Kastrati concluded. “Until then, recent studies such as the COMFORTABLE AMI trial should make cardiologists feel more comfortable with the use of new-generation DESs in patients with STEMI.”

COMFORTABLE AMI was supported in part by Biosensors Europe SA.