Characteristics of Coronary Artery Lesions in Patients with Acute Myocardial Infarction Under 45 Years of Age

Background: Acute myocardial infarction (AMI) remains a leading cause of cardiovascular mortality worldwide. Although traditionally considered a disease of middle-aged and elderly individuals, an increasing incidence has been observed among younger patients. Differences in coronary artery lesion characteristics between age groups may have important implications for clinical management and prognosis. Objective: To describe and compare the characteristics of coronary artery lesions in patients with acute myocardial infarction aged ≤ 45 years and those aged > 45 years. Methods: A cross-sectional descriptive study was conducted in patients diagnosed with AMI who underwent coronary angiography and/or percutaneous coronary intervention. Patients were stratified into two groups according to age (≤ 45 years and > 45 years). The analyzed variables included the number of diseased vessels, lesion length, and lesion morphology according to the A, B, and C classification. Results: Single-vessel disease was significantly more common in patients ≤ 45 years (42.1%) compared with those > 45 years (24.6%; p < 0.05). In contrast, three-vessel disease was more frequent in the older group (36.8% vs 22.8%; p < 0.05). When combined two- and three-vessel disease were analyzed, the proportion remained significantly higher in patients > 45 years (75.4% vs 57.9%; p < 0.05), indicating more diffuse coronary involvement with advancing age. Additionally, younger patients tended to have shorter and more localized lesions, whereas older patients more often presented with longer and more complex lesions, with a higher prevalence of B and C-type lesions. Conclusions: Older patients with AMI are more likely to exhibit multivessel, diffuse, and complex coronary artery disease compared with younger patients, reflecting the progressive nature of atherosclerosis over time and underscoring the need for age-specific therapeutic considerations.