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.