Erythrocyte and Platelet Indices at Admission and Discharge Stratify Long-Term Cardiovascular Risk After Invasive Treatment of Myocardial Infarction.

Background/Objectives: Cardiovascular risk remains substantial after myocardial infarction (MI) despite established clinical risk markers. Erythrocyte and platelet indices are routinely available, but their long-term prognostic relevance remains insufficiently studied. Methods: This retrospective cohort study was based on the Styrian Registry on Genuine Myocardial Infarction (STRONG-MI) and included patients with MI undergoing invasive coronary angiography in Styria, Austria, between January 2007 and March 2016. Multivariable Cox regression models were used to assess the associations of admission and discharge erythrocyte and platelet indices with 3-point major adverse cardiovascular events (MACE) during follow-up extending to 175 months. Results: Among 10,920 patients, admission hemoglobin showed a U-shaped association with MACE. Median hemoglobin decreased from admission to discharge (14.2 g/dL vs. 13.1 g/dL) and the lowest discharge tertile showed the highest association with MACE compared with the middle tertile (AHR 1.27, 95% CI 1.18-1.38). Lower mean corpuscular hemoglobin concentration (MCHC) was independently linked to adverse outcomes at both admission and discharge (AHR 1.17, 95% CI 1.08-1.27, and 1.14, 95% CI 1.05-1.23, respectively). Higher platelet count and mean platelet volume (MPV) were also associated with increased risk, particularly at discharge (AHR 1.15, 95% CI 1.06-1.24, and 1.19, 95% CI 1.10-1.29, respectively). Conclusions: Routine erythrocyte and platelet indices were independently associated with long-term cardiovascular outcomes after invasively treated MI and reflect residual biological risk after discharge.