NEW YORK (Reuters Health) – In patients undergoing percutaneous coronary intervention for ST-segment elevation myocardial infarction (STEMI), triple antithrombotic therapy significantly increases the risk of major bleeding compared to dual antiplatelet therapy, researchers report.

“Most hemorrhagic events occurred within the first 30 days and resulted in frequent discontinuation of VKA (vitamin K antagonist), which might have contributed to the fairly high 1-year rates of stroke in the triple therapy group in the present study,” they comment in their report in the American Journal of Cardiology online December 26.

Dr. Roxana Mehran, at Mount Sinai Medical Center, New York, New York, and colleagues explain that PCI patients who are at high risk of systemic emboli require triple antithrombotic therapy — aspirin, a thienopyridine, and a vitamin K antagonist.  However, the risks and benefits of this triple therapy in STEMI patients undergoing primary PCI are not clear.

To look into that issue, the team assessed outcomes in the HORIZONS-AMI trial involving 3320 patients undergoing primary PCI; 3194 patients received dual antiplatelet therapy and 126 were prescribed triple antithrombotic therapy.  Indications for triple therapy in most cases were very low LV ejection fraction, atrial fibrillation, or mural thrombus.

Rates of ischemic events such as reinfarction and target-vessel revascularization at 30 days and 1 year were similar in the two groups, the researchers report.

However, rates of major bleeding during hospitalization were 17.1% in the triple therapy group compared with 6.5% in the dual therapy arm (p<0.001), the data indicate.  VKA was discontinued in 14.3% of patients in the triple therapy group

Furthermore, the 1-year incidence of stroke was 3.3% in the triple therapy group versus 0.9% in the dual therapy group, Dr. Mehran and colleagues report.

“Consistent with previous studies, the present analysis found a threefold increase in major bleeding with triple therapy,” they conclude.

They also point out that newer, potent oral anticoagulants and antiplatelet agents have been introduced, “posing new questions of whether these therapies can be safely combined in certain clinical scenarios, including patients with STEMI who are at high risk of systemic thromboembolism.”

SOURCE:

Outcomes of Patients Treated With Triple Antithrombotic Therapy After Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction (from the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction [HORIZONS-AMI] Trial)

Am J Cardiol 2012