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Triple antiplatelet therapy proved no better than dual therapy for preventing strokes and other cardiovascular events in older patients with atrial fibrillation (AF) who had a heart attack and underwent percutaneous coronary intervention (PCI), according to a large observational study.

However, triple therapy was associated with an approximately 60% increase in risk for hospital readmission due to bleeding and twice the risk for intracranial hemorrhage compared with dual therapy, the investigators, led by , of Duke University, reported in the .

"Therapeutic decisions for older patients with AF and coronary artery disease may be especially challenging. Older patients in particular are at greater risk for AF-related strokes and recurrent events after acute MI but also have higher risk for bleeding events," Hess and colleagues wrote.

"Importantly, the older population has been excluded from or underrepresented in clinical trials and, therefore, remains understudied," the investigators said.

The investigators examined data from the , a national quality improvement registry capturing data on MI patients treated at more than 500 hospitals in the United States. From this registry, they obtained information on nearly 5,000 patients 65 or older with a history of AF who presented with a MI and were treated with PCI.

Slightly more than one-quarter of these patients (27.6%) were discharged on triple antiplatelet therapy and about three-quarters (72.4%) were discharged on dual antiplatelet therapy.

Patients at increased risk for stroke were more likely to receive triple therapy, but predicted bleeding risk did not appear to affect doctors' choice of antiplatelet regimen, "lending insight into how U.S. providers decide between triple therapy versus DAPT [dual antiplatelet therapy] for these patients," the researchers noted.

To assess 2-year outcomes in these patients, the investigators used Medicare administrative claims data. The primary effectiveness outcome was major adverse cardiac events (MACE) at two years. The primary safety outcome was hospital readmission for bleeding or intracranial hemorrhage within 2 years of the index hospitalization.

Compared with patients on dual antiplatelet therapy, those on triple therapy had a similar risk for MACE (HR 0.99; 95% CI 0.86-1.61).

However, patients on triple therapy had a significantly greater risk of hospital readmission for bleeding (HR 1.61; 95% CI 1.31-1.97) and intracranial hemorrhage (HR 2.04; 95% CI 1.25-3.34).

"These associations were robust among various patient subgroups assessed according to age, sex, predicted stroke and bleeding risk groups, stent type, and MI type," the investigators said.

"The increased risk of bleeding without apparent benefit of triple therapy observed in this study suggests that clinicians should carefully consider the risk-to-benefit ratio of triple therapy use in older atrial fibrillation patients who have had a heart attack treated with angioplasty," lead investigator Hess said in a press release.

"Further prospective studies of different combinations of anti-clotting agents are needed to define the optimal treatment regimen for this population," Hess said.

, and , both from the University of Colorado School of Medicine, wrote in an editorial that "Although the question of whether triple therapy is beneficial for MACE remains troublingly uncertain, the data are convincing for bleeding. Regarding MACE, the effects of 'more' remain enigmatic. When it comes to bleeding events, however, 'more' appears to be significantly worse."

Ongoing clinical trials will provide more information on dual versus triple antiplatelet therapy in various patient populations as well as evaluate the role of novel anticoagulants in preventing MACE and bleeding risk. However, to date the evidence is incomplete, Valle and Messenger said.

"Can we replace 'more' with a better alternative? Unfortunately, the answer to date is 'not yet,'" they concluded.

From the American Heart Association: