HEART DOCTORS NEAR ME Angina Angina occurs when the heart must do extra work but does not receive enough oxygen for its needs because a coronary artery is narrowed due to arteriosclerosis. angina may occur not only in the case of physical exertion but also during an episode of mental stress or the digestion of a large meal. Angina pain generally disappears quickly once the activity has stopped or with nitroglycerin. Someone has stable angina when the angina pain occurs and can be reproduced during specific activities and remains of short duration. Unstable angina , which is also called acute coronary syndrome, refers to prolonged pain that generally occurs when patients are at rest and that can be a sign of myocardial infarction (heart attack). These symptoms are described in the Acute Coronary Syndrome section