Alcohol's impact on cardiovascular health is biphasic: low-to-moderate intake may appear protective, but excessive or binge drinking causes significant harm. This review examines mechanisms linking overconsumption to cardiovascular disease. Acute heavy drinking can trigger "Holiday Heart Syndrome," a transient atrial arrhythmia from electrophysiological instability, autonomic imbalance, and electrolyte shifts. Chronic excess contributes to alcoholic cardiomyopathy via oxidative stress, mitochondrial dysfunction, and impaired calcium handling. Alcohol also promotes atrial fibrillation and hypertension by inducing atrial fibrosis, neurohormonal dysregulation, and endothelial injury. Excessive intake accelerates coronary artery disease and type 2 diabetes through dyslipidemia, vascular inflammation, and insulin resistance, raising risks of stroke, heart failure, and myocardial infarction. While moderate consumption was once thought cardioprotective, emerging evidence-especially for atrial fibrillation-suggests risks may outweigh benefits. In conclusion, public health guidance increasingly emphasizes moderation, individualized assessment, and avoiding binge patterns, particularly for those with underlying cardiovascular vulnerabilities.