Prinzmetal's angina

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Overview
Prinzmetal's angina, also known as variant angina or angina inversa, is a syndrome typically consisting of angina (cardiac chest pain) at rest that occurs in periodic cycles. Prinzmetal's angina is caused by vasospasm, a narrowing of the coronary arteries caused by contraction of the smooth muscle tissue in the vessel walls rather than fixed narrowings of the coronary arteries due to atherosclerosis (buildup of fatty plaque and hardening of the arteries).

History and Eponym
It was first described as a variant form in 1959 by the American cardiologist Dr. Myron Prinzmetal (1908-1987).

Signs and Symptoms
While the symptoms of chronic stable angina occur with exertion, the symptoms of Prinzmetal's angina typically occur at rest. The symptoms may occur reproducibly at certain times of the day or night. In the classic description, the symptoms often come on at night.

Electrocardiographic Changes
Prinzmetal's angina is associated with transmural injury and ST segment elevation rather than ST segment depression.

Diagnosis
Patients who develop cardiac chest pain are generally treated empirically as an "acute coronary syndrome" patient, and are generally evaluated with serial testing of cardiac enzymes such as creatine kinase isoenzymes or troponin I or T. These may in some cases be abnormal or  positive, as coronary spasm can lead to  myocardial necrosis in severe cases.

The gold standard test is coronary angiography including the administration of provocative agents via the intracoronary route. It should be noted that two-thirds of patients with Prinzmetal's angina have concurrent atherosclerosis of a major coronary artery, but the extent of the atherosclerosis is generally  mild, and the symptoms are out of proportion to the extent of disease. Depending on the local protocol, provocative testing may utilize either ergonovine, methylergonovine or acetylcholine. Exaggerated spasm is diagnostic of Prinzmetal's angina. Care should be taken to have nitrates and calcium channel agents readily available to reverse the spasm.

EKG findings during spasm include ST segment elevation rather than ST depression.

Treatment
Prinzmetal angina typically responds to nitrates and calcium channel blockers. Patients with multivessel spasm, refractory spasm, spasm that results in sudden death may benefit from dual calcium channel blocker therapy.