What class of medications is the treatment of choice for variant or Prinzmetal's angina?

Calcium channel blockers are the treatment of choice for variant angina, also known as Prinzmetal's angina, because they effectively relieve coronary vasospasm, which is the primary cause of this form of chest pain. Unlike typical angina, where the pain arises from increased myocardial oxygen demand, variant angina occurs due to transient spasms in the coronary arteries that lead to decreased blood flow.

These medications work by inhibiting the influx of calcium into the vascular smooth muscle and myocardial cells, leading to vasodilation and decreased myocardial contractility. The resulting relaxation of the coronary arteries helps to alleviate the episodes of angina and improve blood flow to the heart muscle.

In contrast, ACE inhibitors, beta blockers, and angiotensin II receptor blockers do not have the same direct effect on coronary vasospasm. While they may be useful in the management of other cardiovascular conditions, such as hypertension and heart failure, they are less effective in treating the specific pathophysiology of variant angina.