Myocardial ischemia occurs when blood flow to the heart muscle (myocardium) is obstructed by a partial or complete blockage of a coronary artery by a buildup of plaques (atherosclerosis). If the plaques rupture, you can have a heart attack (myocardial infarction).Damage or disease in the heart's major blood vessels.The usual cause is the build-up of plaque. This causes coronary arteries to narrow, limiting blood flow to the heart.Coronary artery disease can range from no symptoms, to chest pain, to a heart attack.Treatments include lifestyle changes, medication, angioplasty and surgery.