Acute myocardial infarction (AMI) in young adults, though less common than in older populations, is an emerging clinical concern with increasing incidence and diverse etiologies. Unlike classic atherosclerotic presentations, a significant proportion of AMI cases in individuals under 45 years are due to nonatherothrombotic mechanisms such as coronary vasospasm, spontaneous coronary artery dissection (SCAD), vasculitis, hypercoagulable states, and drug-induced coronary injury. This manuscript aims to explore the multifactorial nature of AMI in young adults through a focused review of current evidence and a series of illustrative clinical cases. We present and analyze four distinct cases of young patients with AMI, each demonstrating different pathophysiological mechanisms and risk profiles-including premature atherosclerosis, substance use, human immunodeficiency virus (HIV)-related coronary disease, and SCAD. Despite the heterogeneity of underlying causes, early diagnosis, individualized management, and aggressive secondary prevention were key to favorable outcomes. Advanced imaging, lipid profiling, and risk factor modification played a central role in guiding therapy. AMI in young adults requires heightened clinical suspicion and a comprehensive, multidisciplinary approach. Early intervention and recognition of nontraditional risk factors are essential to improving outcomes and preventing recurrent events in this vulnerable population.