NEW YORK (Reuters Health) – In patients with ST-segment elevation myocardial infarction (STEMI), most of the benefits of sirolimus-eluting stents over bare-metal stents accrue during the first year following implantation, new research shows.

By the third year, target-vessel outcomes don’t differ much between the two stent types, investigators reported online May 17th in the American Journal of Cardiology.

Data for drug-eluting stents in STEMI patients is relatively scarce, with this population often excluded in studies comparing stent types, the authors note. In the trials that did include STEMI patients, drug-eluting stents proved superior to bare-metal stents at 12-month follow-up, primarily by reducing the need for repeat revascularizations.

In the current article, Dr. Martin J. Schalij and co-investigators at Leiden University Medical Center, the Netherlands present long-term data from the prospective MISSION! Intervention Study. In that trial, 310 patients were kept on aspirin 100 mg/d indefinitely and on clopidogrel 75 mg/d for 12 months, along with beta-blockers, statins, and angiotensin-renin blockers.

In their earlier report on 12-month outcomes, the investigators showed that event-free survival was better in the sirolimus group. In-stent late lumen loss was about one quarter that observed in the bare-metal stent group. (See Reuters Health story of February 13, 2008).

During the next two years, there remained a trend toward better clinical outcomes in the sirolimus group, but differences were no longer significant: death, 4.4% in the bare metal stent group vs 6.6% in the sirolimus-eluting stent group; target vessel-related MI, 2.5% vs 4.6%; target vessel revascularization, 8.9% vs 15.8%; and target vessel failure 12.0% vs 19.7%.

There were three cases of very late, definite stent thrombosis in the sirolimus group but none in the bare metal group.

Thus, there appeared to be “a trend toward a ‘catch-up phenomenon,’” the authors say.

These findings “confirm a consistent pattern of time-dependent benefit of DES over BMS that decreases in magnitude after the first year,” they conclude.

Still, they add, it’s possible that newer stents may have significantly better long-term performance.

Reference:
http://www.ajconline.org/article/S0002-9149(10)00599-0/abstract
Am J Cardiol 2010.