Platelet FcɣRIIa Expression Refines Clinical Risk Assessment After Myocardial Infarction

BACKGROUND: In patients with myocardial infarction (MI), quantifying expression of platelet FcɣRIIa (pFCG) stratifies risk of subsequent MI, stroke, and death. AIMS: Assess the prognostic implications of clinical risk alone and in combination with the pFCG test. METHODS: Patients (n = 749) were enrolled in a prospective non-interventional trial during hospitalization with type 1 MI (ST elevation and non-ST elevation). Inclusion criteria included ≥ 2 of the following clinical risk factors: age ≥ 65, multi-vessel coronary artery disease, prior MI, chronic kidney disease, or diabetes mellitus. High and low pFCG (quantified by flow cytometry at a core laboratory) were defined by a prespecified threshold. The primary endpoint was the composite of MI, stroke, and death. RESULTS: Distribution of clinical risk factors was 346 patients (45%) with 2 factors, 272 patients (36%) with 3 factors, and 131 patients (17%) with 4 or 5 factors. A greater number of risk factors was associated with a greater risk of the composite of MI, stroke, and death after 1 year. The event rate with 2 risk factors was 10.2%, with 3 factors it was 14.4%, and with 4/5 factors it was 35.6%. Across all cohorts of clinical risk, the pFCG test identified a higher-risk and a lower-risk cohort. CONCLUSIONS: Both clinical risk and the pFCG test assess prognosis. Results of the pFCG test refine the prognosis defined by clinical risk. The prognostic implications suggest that the pFCG test may be a useful tool to balance ischemic risk with that of bleeding to define treatment strategy. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/study/NCT05175261.