Impact of Optimal Medical Therapy in the Dual Antiplatelet Therapy Study

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Abstract

Background:

Continued dual antiplatelet therapy and optimal medical therapy (OMT) improve outcomes in selected patient populations with established coronary heart disease, but whether OMT modifies the treatment effect of dual antiplatelet therapy is unknown.

Methods:

The DAPT (Dual Antiplatelet Therapy) Study, a double-blind trial, randomly assigned 11 648 patients who had undergone coronary stenting and completed 1 year of dual antiplatelet therapy without major bleeding or ischemic events to an additional 18 months of continued thienopyridine or placebo. OMT was defined as a combination of statin, β-blocker, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use in patients with an American College of Cardiology/American Heart Association class I indication for each medication. Per protocol, all patients were treated with 75 to 325 mg aspirin daily. End points included myocardial infarction, major adverse cardiovascular and cerebrovascular events, and Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Arteries moderate or severe bleeding events.

Results:

Of 11 643 randomly assigned patients with complete medication data, 63% were on OMT. Between 12 and 30 months, continued thienopyridine reduced myocardial infarction in comparison with placebo in both groups (on OMT 2.1% versus 3.3%, hazard ratio [HR], 0.64; 95% confidence interval [CI], 0.48–0.86; P=0.003; off OMT 2.2% versus 5.2%, HR, 0.41; CI, 0.29–0.58; P<0.001; interaction P=0.103). Comparing continued thienopyridine versus placebo, rates of major adverse cardiovascular and cerebrovascular events were 4.2% versus 5.0% among patients on OMT (HR, 0.82; CI, 0.66–1.02; P=0.077) and 4.5% versus 7.0% among those off OMT (HR, 0.63; CI, 0.49–0.82; P<0.001; interaction P=0.250); rates of bleeding for thienopyridine versus placebo in patients on OMT were 2.2% versus 1.0% (HR, 2.13; CI, 1.43–3.17; P<0.001), and in patients off OMT were 2.8% versus 2.2% (HR, 1.30; CI, 0.88–1.92; P=0.189; interaction P=0.073). Overall, patients on OMT had lower rates of myocardial infarction (2.7% versus 3.7%, P=0.003), major adverse cardiovascular and cerebrovascular events (4.6% versus 5.7%, P=0.007), and bleeding (1.6% versus 2.5%, P<0.001) in comparison with patients off OMT. Rates of stent thrombosis (0.8% versus 1.0%, P=0.171) and death (1.6% versus 1.9%, P=0.155) did not differ.

Conclusions:

Continued thienopyridine therapy reduced the rate of myocardial infarction regardless of OMT status and had consistent effects on reduction in major adverse cardiovascular and cerebrovascular events and increased bleeding.

Clinical Trial Registration:

URL: http://clinicaltrials.gov. Unique identifier: NCT00977938.

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