A myocardial infarction happens when a vessel (coronary arteries) irriguating the cardiac muscle is narrowed by a plaque of atheroma of which fragment breaks away (atherosclerosis), and/or obstructed by a clot or thrombus (thrombosis), or still momentarily closed by a spasm (spontaneous contraction). The coronary arteries not irrigating sufficiently the cardiac muscle, the latter not receiving the oxygen it needs (ischemia), it then necrotizes in a more or less important way (death of the myocytes).
Certain factors ncrease the risk of infarction such as obesity (mainly abdominal), sedentarity, high blood pressure, diabetes, hypercholesterolemia (factors gathered under the name metabolic syndrome), the excessive consumption of alcohol, smoking or stress. In addition,
heredity as well as the age and the sex affect the cardiac risk : myocardial infarction mainly concern men over 65 years old.