Angina pectoris is defined as cardiac-induced pain arising from a lack of myocardial oxygen. "Angina" is used to describe clinical symptoms such as discomfort in the chest, jaw, shoulder, back, or arms that are induced by physical exertion or emotional stress and subside with rest or treatment with nitroglycerin. Angina is clinically classified into stable angina (SA) and unstable angina (UA). SA is a chronic medical condition while UA is an acute coronary syndrome. Among the causes of angina pectoris, the most common is coronary artery disease (CAD). At the cellular level, angina pectoris is a result of increased myocardial oxygen demand or decreased myocardial oxygen supply.