Benefits and Risks of Extended Duration Dual Antiplatelet Therapy After PCI in Patients With and Without Acute Myocardial Infarction

Background: The benefits and risks of prolonged dual antiplatelet therapy may be different for patients with acute myocardial infarction (MI) compared with more stable presentations.

Objectives: This study sought to assess the benefits and risks of 30 versus 12 months of dual antiplatelet therapy among patients undergoing coronary stent implantation with and without MI.

Methods: The Dual Antiplatelet Therapy Study, a randomized double-blind, placebo-controlled trial, compared 30 versus 12 months of dual antiplatelet therapy after coronary stenting. The effect of continued thienopyridine on ischemic and bleeding events among patients initially presenting with versus without MI was assessed. The coprimary endpoints were definite or probable stent thrombosis and major adverse cardiovascular and cerebrovascular events (MACCE). The primary safety endpoint was GUSTO (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Arteries) moderate or severe bleeding.

Results: Of 11,648 randomized patients (9,961 treated with drug-eluting stents, 1,687 with bare-metal stents), 30.7% presented with MI. Between 12 and 30 months, continued thienopyridine reduced stent thrombosis compared with placebo in patients with and without MI at presentation (MI group, 0.5% vs. 1.9%, p < 0.001; no MI group, 0.4% vs. 1.1%, p < 0.001; interaction p = 0.69). The reduction in MACCE for continued thienopyridine was greater for patients with MI (3.9% vs. 6.8%; p < 0.001) compared with those with no MI (4.4% vs. 5.3%; p = 0.08; interaction p = 0.03). In both groups, continued thienopyridine reduced MI (2.2% vs. 5.2%, p < 0.001 for MI; 2.1% vs. 3.5%, p < 0.001 for no MI; interaction p = 0.15) but increased bleeding (1.9% vs. 0.8%, p = 0.005 for MI; 2.6% vs. 1.7%, p = 0.007 for no MI; interaction p = 0.21).

Conclusions: Compared with 12 months of therapy, 30 months of dual antiplatelet therapy reduced the risk of stent thrombosis and MI in patients with and without MI, and increased bleeding. (The Dual Antiplatelet Therapy Study [The DAPT Study]; NCT00977938).