Patients who were diabetic and diagnosed with acute coronary syndromes were 40 percent less likely to suffer a myocardial infarction if they were treated with prasugrel vs. clopidogrel, according to a sub-group analysis of the TRITON-TIMI 38 trial (8.2 percent vs. 13.2 percent, p<0.001). In addition, according to this same analysis, the combined rate of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke was reduced by 30 percent in diabetes patients treated with prasugrel compared to those treated with clopidogrel (12.2 percent vs. 17.0 percent, p<0.001). In patients without diabetes, there was also improvement in outcomes with prasugrel, with the primary endpoint occurring in 9.2 percent of patients treated with prasugrel and 10.6 percent of patients treated with clopidogrel (p=0.02).

The diabetic sub-group analysis was presented by Stephen Wiviott, M.D., Assistant Professor of Medicine at Harvard Medical School and investigator with the Thrombolysis in Myocardial Infarction (TIMI) Study Group, Brigham & Women's Hospital, Boston, USA, at the Congress of the European Society of Cardiology (ESC) in Munich, Germany. In addition, the manuscript was simultaneously published online in Circulation, the medical journal of the American Heart Association.

"The results observed from this sub-group analysis showed that antiplatelet therapy with prasugrel resulted in significantly greater reduction of cardiovascular events among patients with diabetes when compared to those who were treated with clopidogrel," said Wiviott.

The reduction of cardiovascular events was consistent across the sub-group of diabetes patients regardless of diabetic therapies (insulin versus no insulin). The study showed a significant relative risk reduction in the primary endpoint of cardiovascular death, non-fatal heart attack and non-fatal stroke with prasugrel, 37 percent for insulin treated and 26 percent (p=0.001) for non-insulin treated diabetics. There was also a significantly lower rate of stent thrombosis among diabetes patients treated with prasugrel, resulting in a 48 percent relative risk reduction in stent thrombosis compared with clopidogrel (3.6 percent vs. 2.0 percent, p=0.007).

"These findings are interesting in view of previous studies that showed higher levels of platelet aggregation in insulin-treated diabetes patients after dual antiplatelet therapy compared to diabetes patients not treated with insulin," said Dr. Wiviott.

The main TRITON-TIMI 38 clinical trial, previously published in the New England Journal of Medicine in November 2007 (Vol. 357, No. 20), compared prasugrel with clopidogrel in patients with ACS undergoing percutaneous coronary intervention (PCI). In the primary analysis of the trial, prasugrel reduced the risk of the composite endpoint of cardiovascular death, heart attack or stroke by 19 percent, with an increased risk of major bleeding compared with clopidogrel (2.4 percent vs. 1.8 percent).

In this sub analysis, the rates of major bleeding events were similar for prasugrel (2.5 percent) and clopidogrel (2.6 percent) among patients with diabetes, regardless of diabetes therapies (insulin versus no insulin).