A minor heart attack affects only a small portion of heart muscle, while a major or massive heart attack affects a larger portion of heart muscle or results in significant heart damage, according to Healthgrades. Heart attacks occur when oxygenated blood cannot flow to the heart muscle, according to the National Heart, Lung and Blood Institute, and heart muscle in the area cut off from oxygenated blood begins to die if the blood flow isn't restored rapidly.
One type of severe heart attack is a ST-segment elevation myocardial infarction, according to SecondsCount.org. In this type of heart attack, a coronary artery is entirely blocked and cuts off a large segment of heart muscle from bloodflow. In contrast, a non-ST segment elevation myocardial infarction is a heart attack in which patients have the protein troponin in their blood, indicating damage to heart muscle but not necessarily a blockage on an electrocardiogram. Doctors may treat heart attacks with medications alone or with surgery and medication together.
Men age 50 and older who have heart disease in their family history and post-menopausal women are at a higher risk of heart attack, according to WebMD. Heart attacks most often occur when a blood clot forms suddenly on an already clogged coronary artery. Risk factors for heart attacks include smoking, obesity and high cholesterol, and other lifestyle factors, such as inactivity, high stress and overexertion, may contribute to these risk factors.