What is the primary cause of ischemic heart disease?

The primary cause of ischemic heart disease is the narrowing of the coronary arteries, which leads to reduced blood flow to the heart muscle itself. This condition is often a result of atherosclerosis, where plaque builds up in the coronary arteries, narrowing their passage and restricting blood supply. When the heart does not receive enough oxygenated blood, it can lead to chest pain (angina) or even heart attacks.

The other choices, while they can affect heart function, do not directly cause ischemic heart disease. Valvular regurgitation relates to issues with heart valves, arrhythmias involve the electrical system of the heart leading to irregular heartbeats, and heart chamber dilation indicates structural changes in the heart that can arise from various conditions but are not the root cause of ischemic heart disease. Therefore, the narrowing of the coronary arteries is fundamental to the pathophysiology of ischemic heart disease, making it the correct answer.