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Acute myocardial infarction: drug eluting stents should be used with caution


Drug-eluting stents ( DES ) are extremely effective devices to prevent restenosis following angioplasty. Yet, since last year, there is some debate and persistent uncertainty regarding the long term safety of these devices. Specifically, there is concern that some of these stents may occlude abruptly more than 1 year after placement, due to late stent thrombosis. Although this is a rare event ( probably in the range of less than 1% per year ) it is extremely severe, with patients dying in up to 45% of those cases. Therefore, there is concern that this rare but life-threatening event may offset the benefit achieved by drug-eluting stents in preventing restenosis.

The risk of such 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 and the more conventional bare metal stents, in the context of acute coronary syndromes, particularly in the context of acute myocardial infarction.
The randomized clinical trials which have compared drug-eluting stent and bare metal stent in the context of acute myocardial infarction are relatively small ( totalling less than 1,000 patients with drug eluting stent ) and most have only reported one year of follow-up.

This 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/New Zealand ) to compare the survival up to 2 years of patients treated with bare metal stents only or receiving at least one drug eluting stent.

Survival appeared similar in the 6-months following 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 analysing 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 persists after statistical adjustment for the differences in baseline characteristics between the two types of patients ) suggests that DES should be used with caution in patients with acute myocardial infarction, at least until more evidence is accumulated of their long term safety from large studies with long term follow up.

Source: European Society of Cardiology ( ESC ) Congress, 2007

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