What is the primary cause of angina pectoris?

Angina pectoris is primarily caused by decreased blood supply to the myocardium, which leads to ischemia and associated pain. This reduction in blood flow typically occurs due to the narrowing of coronary arteries, often as a result of atherosclerosis. When the myocardium is not receiving sufficient oxygenated blood, it cannot function properly, resulting in the chest pain that characterizes angina.

Factors such as increased heart rate can exacerbate angina symptoms because a faster heart rate demands more oxygen from the heart muscle. However, this is more of a contributing factor rather than the primary cause. Low blood pressure and valve abnormalities also can affect heart function, but they are not direct causes of angina pectoris. The essence of angina is the mismatch between the myocardial oxygen demand and the oxygen supply, highlighting the critical nature of blood flow to the heart muscle in preventing ischemia.