An estimated 6 to 10% of myocardial infarctions occur in patients under the age of 45. Usually this applies to men, but an increasing prevalence is being observed among women. Atherosclerosis, often one vessel disease, is the main cause. The presence of classic risk factors affects the dynamics of coronary artery disease: the strongest risk factor is smoking, regardless of gender. Environmental influence is also possible. No atherosclerosis is found in 20% of young patients. In such cases, the most frequent mechanisms of ischemia are: coronary artery embolism (5%), thrombosis (5%), anomalies (4%) and inflammation or spasm of the vessel. Age is an independent prognostic factor. Thus the clinical outcome after myocardial infarction is better in younger than in older patients.