High platelet reactivity on aspirin in patients with acute ST elevation myocardial infarction.

Background: Despite dual antiplatelet treatment, major ischemic events are common following ST elevation myocardial infarction (STEMI). We aimed to assess high platelet reactivity on aspirin (HPR-aspirin) and its association with P2Y12i (HPR-P2Y12i) during the acute phase of STEMI.

Methods: We included all consecutive patients admitted for STEMI treated by primary angioplasty in our center for 1year. All patients received a loading dose followed by a maintenance dose of aspirin (75mg/day) and prasugrel (ticagrelor or clopidogrel if contraindicated). Platelet reactivity was assessed 4±1days and 75±15days after admission using light transmission aggregometry with arachidonic acid (LTA-AA-HPR-aspirin) and VASP (HPR-P2Y12i) to define HPR as well as serum Thromboxane-B2 and LTA-ADP. Major cardiac and cerebrovascular events were recorded for 1year.

Results: We included 106 patients - mean age was 61y.o., 76% were male and 20% had diabetes. STEMI was anterior in 52% and LV ejection fraction at discharge was 51±9%. 50% of patients were treated with prasugrel and 34% with ticagrelor. At day 4 after STEMI, HPR-aspirin was found in 26% patients and HPR-P2Y12i in 7%. HPR- both aspirin and P2Y12i was found in 4%. Diabetes and age were predictors of HPR-aspirin. HPR-aspirin was persistent 75days later in 36% patients. At 1year, 7.9% patients had experienced major adverse cardiovascular and cerebrovascular events (MACCE). HPR-aspirin and HPR on both aspirin and P2Y12i were significantly associated with MACCE.

Conclusion: HPR-aspirin is frequent just after STEMI and associated with MACCE especially when associated with HPR-P2Y12i.