Extending DAPT for more than 1 year shows benefit in diabetic patients

Extended dual antiplatelet therapy (DAPT) was associated with lower rates of death and myocardial infarction (MI) in patients with diabetes who received first-generation drug-eluting stents (DES), but not those without diabetes, a study found.

Researchers conducted an observational study within the Veterans Administration and compared rates of death and MI in diabetic and nondiabetic cohorts who received clopidogrel for more or less than 12 months with aspirin after a stent.

The 28,849 patients undergoing stenting between 2002 and 2006 were categorized into 3 groups: 16,332 without diabetes, 9,905 with diabetes treated with oral medications or diet, and 2,612 with diabetes treated with insulin. Results appeared in the September Journal of the American College of Cardiology.

Among diabetic patients treated with insulin, prolonged clopidogrel treatment was associated with a decreased risk of death (hazard ratio [HR], 0.59; 95% CI, 0.42 to 0.82) and death or MI (HR, 0.67; 95% CI, 0.49 to 0.92). Among patients with noninsulin-treated diabetes, prolonged clopidogrel treatment was also associated with lower mortality (HR, 0.61; 95% CI, 0.48 to 0.77) and combined death or MI (HR, 0.61; 95% CI, 0.5 to 0.75). Prolonged clopidogrel treatment was not associated with a lower risk in patients without diabetes or in any group receiving bare-metal stents.

The authors wrote, “Importantly, this analysis identified the interaction of DM [diabetes mellitus] and stent type as factors that may guide long-term DAPT duration.” They noted that the study's results conflicted with some other recent studies of DAPT, perhaps due to differences in the patient population. They called for future studies of DAPT with first- and second-generation DES to conduct subgroup analyses on patients with diabetes.

An editorial comment noted that several randomized, controlled trials have failed to show a benefit from prolonged DAPT after implantation of bare-metal or newer-generation stents, weakening the support for this study's findings. The editorialist pointed out that despite this study being rigorously performed, the observational design has inherent weaknesses. “Before prolonged DAPT can be routinely recommended for diabetic patients undergoing stent implantation, additional investigation is needed to define the pathogenetic links between the metabolic changes and clinical manifestations of diabetes mellitus, and dedicated clinical trials are needed to identify best practices,” the editorial said.