What is a primary role of nitrates in treating angina?

Nitrates are primarily used in the treatment of angina due to their ability to reduce myocardial oxygen demand. They achieve this effect primarily by causing vasodilation, which reduces the preload (the volume of blood returning to the heart). When the preload is decreased, the heart does not have to work as hard to pump blood, thus lowering the overall oxygen requirement of the myocardial tissue.

In addition to decreasing preload, nitrates also have a role in dilating coronary arteries, which can help improve blood flow to the heart muscle, though the primary mechanism for alleviating angina is through the reduction of the heart's oxygen demand. This alleviation helps to prevent or relieve angina symptoms, making nitrates an effective first-line treatment for episodes of chest pain associated with coronary artery disease. Other options, such as improving contractility or enhancing heart rhythm, are not the main goals of nitrate therapy in the context of treating angina.