DAPT Study Compares 12- and 30-Month Treatment in Patients With and Without MI

March 15, 2015—Robert W. Yeh, MD, et al have published findings from the DAPT study online ahead of print in the Journal of the American College of Cardiology simultaneously with the presentation of the study at the American College of Cardiology’s 64th annual scientific session in San Diego, California.

The study evaluated the benefits and risks of extended-duration dual-antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) in patients with and without acute myocardial infarction (MI). The benefits and risks may be different for patients with acute MI patients compared with more stable patients, noted the investigators.

As summarized in JACC, the DAPT study was a randomized double-blind, placebo-controlled trial comparing 30 versus 12 months of DAPT after coronary stenting. The investigators assessed the effect of continued thienopyridine on ischemic and bleeding events among patients initially presenting with MI versus those without MI. The coprimary endpoints were definite or probable stent thrombosis and major adverse cardiovascular and cerebrovascular events (MACCE; a composite of death, myocardial infarction, or stroke). The primary safety endpoint was GUSTO moderate or severe bleeding.

The DAPT investigators reported that of 11,648 randomized patients (9,961 treated with drug-eluting stents and 1,687 treated with bare-metal stents), 3,576 (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%; hazard ratio [HR], 0.27; P < .001; no MI group, 0.4% vs 1.1%; HR, 0.33; P < .001; interaction P = .69). 

The reduction in MACCE for continued thienopyridine was greater for patients with MI (3.9% vs 6.8%; HR, 0.56; P < .001) compared to those with no MI (4.4% vs 5.3%; HR, 0.83; P = .08; interaction P = .03). In both groups, continued thienopyridine reduced MI (2.2% vs 5.2%; HR, 0.42; P < .001 for MI; 2.1% vs 3.5%; HR, 0.6; P < .001 for no MI; interaction P = .15) but increased bleeding (1.9% vs 0.8%; P = .005 for MI; 2.6% vs 1.7%; P = .007 for no MI; interaction P = .21).

Compared with 12 months of therapy, 30 months of DAPT reduced the risk of stent thrombosis and MI in patients with and without MI and increased bleeding, concluded the investigators.