Analysis of GRACE registry data suggests that drug-eluting stents should be used with caution in patients with acute coronary syndrome due to increased all-cause mortality at two years compared with bare metal stents, according to a presentation at the annual meeting of the European Society of Cardiology.

Although drug-eluting stents are extremely effective in preventing restenosis following angioplasty, there has been increasing uncertainty regarding their long-term safety. Specifically, there is concern that some stents may occlude abruptly more than one year after placement due to late stent thrombosis.

Although such thrombosis is rare, probably in the range of less than 1 percent per year, it is extremely severe, with up to 45 percent mortality. Thus, the question is raised whether this rare but life-threatening event may offset the benefit achieved by drug-eluting stents in preventing restenosis.

The risk of late stent thrombosis may be greater in the context of acute coronary syndromes and, in fact, little information is available so far from rigorous randomized clinical trials comparing drug-eluting stents with bare metal stents in these patients, particularly those with acute myocardial infarction. Randomized clinical trials that have compared drug-eluting stents and bare metal stents in the context of acute myocardial infarction are relatively small (totaling fewer than 1,000 patients with drug-eluting stents) and most have only reported one year of follow-up.

The current analysis used the database from the Global Registry of Acute Coronary syndromEs (GRACE), collected in 94 hospitals in 14 countries across 4 continents (Americas, Europe, Australia/NZ) to compare survival at up to two years of patients treated with bare metal stents only or with at least one drug-eluting stent.

Survival appeared similar in at six months after discharge, but thereafter mortality was greater in patients treated with drug-eluting stents. This difference was entirely related to patients treated for acute myocardial infarction and was associated with an increased risk of late reinfarction, suggesting that it may indeed be related to late stent thrombosis.

Although caution should always be exercised when analyzing an observational study such as GRACE (in which patients who received drug-eluting stents and bare metal stents were not similar), this survival difference (which persisted after statistical adjustment for differences in baseline characteristics between the two types of patients) suggests that drug-eluting stents should be used with caution in patients with acute myocardial infarction, at least until more evidence is accumulated of long-term safety from large studies with long-term follow up.