Conflicting Evidence on Drug-Eluting Stents: GRACE vs SCAAR

Internal Medicine World Report, November 2007, Volume 0, Issue 0

VIENNA, Austria—Caution is in order when using drug-eluting stents (DES) for patients with ST-elevation myocardial infarction (MI), based on new findings from an international registry known as GRACE (Global Registry of Acute Coronary Events).

The data showed a more than 4-fold increase in late deaths among patients with ST-elevation MI who were using DES compared with bare-metal stents (BMS), reported Gabriel Steg, MD, at the Congress of the European Society of Cardiology.

However, follow-up from another registry, the Swedish Coronary Angiography and Angioplasty Registry (SCAAR), showed that the reduction in early events with DES compared with BMS in patients with acute coronary syndromes (ACS) offsets the increase in late events.

It was 1 year ago in Barcelona, at the society's previous meeting, that the controversy over DES erupted, with the presentation of 2 meta-analyses showing an increase in late stent thrombosis and death with DES.

At this year's meeting, Dr Steg presented 2-year follow-up data from GRACE, an ongoing observational registry of patients with ACS hospitalized in 14 countries across 4 continents. Data have been collected at the index admission, and at 6 months and 2 years.

Among the 1729 stents implanted for ST-elevation MI, 24.8% were DES and 75.2% were BMS. Postdischarge survival was virtually identical between patients receiving DES or BMS during the first 6 months.

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However, mortality between 6 months and 2 years was more than 4 times greater in the DES than the BMS group (8.6% vs 1.6%; = .001).

"This survival difference, which persists after statistical adjustment for the differences in baseline characteristics between the 2 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," said Dr Steg, director of the coronary care unit, Hôpital Bichat-Claude Bernard, Paris.

Implanting DES appears to be much riskier in patients with acute MI for several reasons. One is that the frequency of stent malapposition is far greater with DES than with BMS. Interventionalists may not fully expand the stent because of vasoconstriction during the acute phase of the MI, and delayed reendothelialization that occurs with DES may predispose to malapposition and late stent thrombosis, Dr Steg explained. In contrast, undersizing the stent is less of a problem with elective procedures and with BMS, because reendothelialization occurs early.

The data from GRACE contrast with the reassuring results from the 4-year follow-up from SCAAR.

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A 3-year analysis of the SCAAR registry ( 2007;356:1009-1019) showed higher mortality among DES patients, but this difference disappeared by 4 years.

"The results are very positive for the 8 million patients worldwide who have received DES," said lead investigator Stefan James, MD, PhD, Uppsala Clinical Research Center.

The SCAAR registry included 13,786 patients who received DES and 21,480 who received BMS. The 4-year data from patients who received only 1 stent at the index revascularization showed a 52% lower risk of restenosis and no difference in the adjusted risk of death or MI with DES compared with BMS.

A significantly lower event rate in the first 6 months in the patients who received DES offset the significantly higher event rate observed after 6 months in this group. "The risk of late events in DES is counterbalanced by early gains," said Dr James.

He noted that greater awareness of late stent thrombosis might have led to a longer duration of dual antiplatelet therapy in patients who received DES later, which might have accounted for the lack of difference in mortality between the 2 stents at 4 years.

Patient selection may be important to optimal results with stents, both presenters agreed. DES is appropriate in elective percutaneous coronary interventions, in patients at high risk of restenosis, and in those with a low risk of bleeding, according to Dr Steg.

Dr James said that patients with bifurcation lesions, lesions longer than 8 mm, and with diabetes are candidates for DES, whereas BMS would be more appropriate in patients with large vessels, who are at an increased risk of bleeding and who may not comply with their antiplatelet drug regimen.