Seasonal variation in outcomes of diabetic patients with acute myocardial infarction: A retrospective cohort study

Abstract

Backgrounds Acute myocardial infarction (AMI) is associated with substantial mortality risk. Diabetes mellitus, a leading cause of disability, has become increasingly prevalent in developing countries. Beyond established lifestyle-related risk factors, seasonal variation has been implicated in both the incidence and prognosis of AMI and diabetes. This study aimed to investigate the association between season of admission, diabetes status, and long-term outcomes in patients with AMI. Methods The study recruited patients admitted for AMI who successfully received percutaneous coronary intervention (PCI). In this retrospective cohort study, diabetic patients with AMI admitted at a single center, the median follow-up was 36.7 months (interquartile range: 36.3–37.2 months). The association between season of admission and outcomes was assessed using multivariable Cox regression, adjusting for sex, age, Triglyceride (TG), left ventricular ejection fraction (LVEF), hypertension, left anterior descending branch (LAD), current smoking, current drinking, stroke, post-PCI TIMI 3 flow, Low-density lipoprotein cholesterol (LDL-C), and Peripheral artery disease (PAD). Patients were classified based on diabetes and seasons. The endpoint of interest was cardiovascular (CV) death, all-cause death, myocardial infarction (MI), stroke, unplanned revascularization, and cardiac hospitalization. Results A total of 3838 patients with AMI were enrolled. The proportion of patients suffering from AMI in spring was higher than that in the other three seasons. Among the population with myocardial infarction and diabetes, the hospitalization rate in summer was 33.4%, and in autumn it was 31.2%. After multivariate adjustment, patients without diabetes and hospitalized in summer (HR: 0.61, 95% CI: 0.39–0.97), fall (HR: 0.60, 95% CI: 0.37–0.97), and winter (HR: 0.61, 95% CI: 0.39–0.96) remained significantly at lower risk of death compared to diabetic patients hospitalized in winter. Conclusion Winter admission is associated with the highest long-term mortality risk in diabetic patients with AMI, particularly among elderly males. These results underscore the importance of incorporating seasonal vulnerability into risk stratification for this population. Enhanced cardiovascular and glycemic monitoring during colder months may represent a pragmatic approach to reducing the seasonal excess in adverse outcomes.