Increased Platelet FcɣRIIa Identifies Patients at Greater Risk of Multiple Cardiovascular Events After Myocardial Infarction

BACKGROUND: After myocardial infarction (MI), quantifying platelet FcɣRIIa (pFCG) stratifies ischemic risk. OBJECTIVES: This study aimed to assess a prognostic biomarker, pFCG, in patients with and without subsequent ischemic and bleeding events. METHODS: Patients (n = 765) with type 1 MI were enrolled in a prospective noninterventional trial. Inclusion criteria included at least 2 of the following: age ≥65 years, multivessel coronary artery disease, prior MI, chronic kidney disease, and diabetes. Flow cytometry quantified pFCG at a core laboratory. Ischemic endpoints (n = 158) were MI, stroke, and death. Bleeding endpoints (n = 74) were Bleeding Academic Research Consortium 2, 3, and 5. RESULTS: Patients were categorized as no events (n = 562), bleeding events alone (n = 45), single ischemic event (n = 101), bleeding + ischemic events (n = 29), multiple ischemic events (n = 23), and fatal MI (defined as MI combined with death within 2 days, n = 5). Average pFCG (molecules/platelet) in patient groups was 1,491 ± 655 (no events), 1700 ± 740 (single ischemic), 1850 ± 625 (multiple ischemic), and 1880 ± 440 (fatal MI, P < 0.001 for trend). Early ischemic events associated with high pFCG were driven by first ischemic endpoints and were accentuated between 6 months and 1 year by additional ischemic endpoints (HR: 2.7; 95% CI: 1.82-4.02; P < 0.0001). The average expression (molecules/platelet) in patients with bleeding (without ischemia) 1,491 ± 517 was similar to that in patients without ischemia or bleeding. CONCLUSIONS: High pFCG is associated with a greater risk of both first and additional ischemic endpoints. The strong association of pFCG with a greater risk of recurrent ischemic events may be useful to inform clinical decision-making. CLINICAL TRIAL REGISTRATION INFORMATION: NCT05175261.