Dual antiplatelet therapy may be safer than triple therapy in older patients with acute MI, afib after PCI
Older patients with acute myocardial infarction and atrial fibrillation who have undergone percutaneous coronary intervention appear to have a higher risk for major bleeding, both early and long-term, with triple therapy versus dual antiplatelet therapy.
Treatment with dual antiplatelet therapy (DAPT) appears to be safer than DAPT plus warfarin (triple therapy) in older patients with acute myocardial infarction (MI) and atrial fibrillation, according to a new observational study.
Researchers used linked data from the National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry-Get with the Guidelines and Medicare administrative claims to examine patients 65 years of age or older who had acute MI and afib and underwent percutaneous coronary intervention (PCI). The goal of the study was to determine appropriate antithrombotic therapy in this population by comparing those taking DAPT with those taking triple therapy. Major cardiac events (MACE) at 2 years, defined as death or readmission for MI or stroke, was the primary effectiveness outcome, while readmission for bleeding was the primary safety outcome.
In addition, in a sensitivity analysis, the authors looked at data from a Medicare Part D prescription claims database to determine persistence of warfarin and P2Y12 inhibitors at 90 days after discharge, as well as warfarin initiation after discharge. The study results were published online Aug. 3 by the Journal of the American College of Cardiology and will appear in the Aug. 11 print issue.
Of the 4,959 patients included in the study, 1,370 (27.6%) were discharged from the hospital on triple therapy and 3,589 (72.4%) were discharged on DAPT. Patients prescribed triple therapy at discharge were more likely to be men and to have a history of PCI or coronary artery bypass grafting, prior stroke, and recent afib or atrial flutter. In addition, they were often taking warfarin before admission. Patients discharged on DAPT, meanwhile, were more likely to have had a major bleeding event during their hospitalization.
Two years after discharge, unadjusted cumulative incidence rates of MACE were 32.6% in the triple therapy group and 32.7% in the DAPT group (P=0.99), and rates for individual MACE components were also similar between groups. The adjusted hazard ratio for MACE in those receiving triple therapy versus DAPT was 0.99 (95% CI, 0.86 to 1.16), but risks for bleeding and intracranial hemorrhage were significantly higher in the triple therapy group (adjusted hazard ratios, 1.61 [95% CI, 1.31 to 1.97] and 2.04 [95% CI, 1.25 to 3.34], respectively). Among the 1,591 patients in the sensitivity analysis who were covered by Medicare Part D, 442 (27.8%) were discharged on warfarin and 1,149 (72.2%) were discharged on DAPT only. At 90 days, 93.2% of those discharged on warfarin continued to take warfarin and 94.7% of those discharged on DAPT continued to take a P2Y12 inhibitor, according to prescription claims data.
The authors noted that their study was observational, that their primary analysis was intention-to-treat, and that they had no data on novel oral anticoagulants due to the study time frame, among other limitations. However, they concluded that older patients with acute MI and afib who have undergone PCI appear to have a higher risk for major bleeding, both early and long-term, with triple therapy versus DAPT.
The authors of an accompanying editorial comment noted that the study found a lack of association between triple therapy and MACE risk but a significant association between triple therapy and bleeding risk. “Although the question of whether triple therapy is beneficial for MACE remains troublingly uncertain, the data are convincing for bleeding,” the editorialists wrote. They noted that while the idea of less therapy has appeal, recent investigations have focused instead on which new agents can be incorporated into triple therapy.
“Thus, the clinical dilemma remains: what do we do with patients who have concurrent indications for [oral anticoagulation] and DAPT?” the editorialists asked. Although the data are not perfect, “they do paint a convincing picture of uncertain benefit for MACE and convincing harm with bleeding,” they wrote. “Can we replace ‘more’ with a better alternative? Unfortunately, the answer to date is ‘not yet.’”