Diagnosis and treatment of Prinzmetal's variant angina.

The presentation, diagnosis (including provocative testing), and therapy of Prinzmetal's variant angina are reviewed. Prinzmetal's variant angina (PVA) is a form of angina caused by coronary-artery vasospasm (CAS) and is not associated with exertion. It is diagnosed by history, electrocardiogram, or coronary-artery angiography. Provocative tests, such as the cold-pressor test or intravenous ergonovine maleate, are sometimes used to aid diagnosis of PVA. Nitrates, adrenergic - blocking agents, and calcium-channel blocking agents can be used in treating PVA. Nitroglycerin and isosorbide dinitrate effectively relieve CAS. However, long-term prospective studies on the use of these drugs for PVA are lacking in the literature. Studies on treating PVA with adrenergic-blocking agents have been equivocol, with some studies reporting improvement and some reporting worsening. Calcium-channel blocking agents are promising drugs for PVA. Nifedipine is generally considered the prototype of this class for antianginal activity. It is administered orally in PVA patients and is effective. Side effects are mild and do not usually require termination of therapy. Verapamil hydrochloride, the prototype calcium-channel blocking agent for arrhythmias, is effective for PVA, but only 10-20% of an orally administered dose reaches systemic circulation because of the first-pass effect. Other calcium-channel blockers, including perhexilene maleate, diltiazem hydrochloride, prenylamine, and lidoflazine, have been tested in a few CAS patients with some success; adverse effects and toxicities limit the use of some of them, especially perhexilene. Therapy, using combinations of nitrates, adrenergic-blocking agents, and calcium-channel blocking agents, is needed in some patients. Dosing guidelines for all drugs are given in the paper. Treatment of PVA should begin with oral nitrates. Calcium-channel blocking agents are indicated in the patient who has failed to respond or is intolerant to maximum doses of nitrates given in various forms.