Which antianginal agent primarily works through venodilation?

Nitrates are the antianginal agents that primarily work through venodilation. This means they cause the veins to dilate, which decreases the amount of blood returning to the heart (preload). By reducing preload, nitrates lower the heart's workload and oxygen demand, which is particularly beneficial in the treatment of angina pectoris, a condition characterized by chest pain due to reduced blood flow to the heart muscle.

Nitrates, such as nitroglycerin, directly relax smooth muscle in the blood vessels, leading to this venous dilation. This mechanism is especially important in conditions where reducing myocardial oxygen consumption helps alleviate symptoms of angina.

Other classes of antianginal agents have different mechanisms of action. For instance, beta-blockers reduce heart rate and contractility, which lowers oxygen demand but does not primarily focus on venous dilation. Calcium channel blockers can both dilate arteries and reduce heart workload but are not primarily venodilators. Ranolazine, a newer antianginal agent, works primarily by altering cardiac metabolism and reducing sodium influx during ischemic episodes, which is distinct from the venodilatory effects of nitrates.