Calcium antagonists in the treatment of Prinzmetal's angina and unstable angina pectoris.

Calcium antagonists block the entry of calcium into vascular smooth muscle cells, producing pharmacological vasodilation. Thus, it is not surprising that these drugs are effective in treating unstable angina that is often characterized by increased vasomotion and dynamic obstruction at the site of atheromatous plaques. Nifedipine, diltiazem, and verapamil are all highly and equally effective in reducing painful and painless ischemic episodes in Prinzmetal's variant angina. In patients with unstable angina who have known or suspected significant underlying coronary artery disease, a multipharmacological approach to therapy is warranted. Nifedipine used with beta-blocker drugs is more effective than nifedipine as monotherapy. Diltiazem and verapamil have been shown to be effective when given without beta-blockers in unstable angina patients. In many patients, thrombus formation rather than vasospasm is the major pathophysiological event resulting in progression of the syndrome to infarction or sudden death. In these patients, antiplatelet, antithrombotic, or antiplatelet and antithrombotic therapy is of utmost importance to maintain adequate coronary flow. Nonresponders to medical therapy with unstable angina have a high prevalence of eccentric and multiple coronary stenoses with a high incidence of thrombi. The best responders to calcium antagonist therapy are patients with concentric coronary stenoses. In summary, calcium antagonists are highly effective in reducing ischemic episodes in patients with Prinzmetal's angina and effective for therapy for unstable angina when used in conjunction with other forms of medical treatment aimed at the processes of platelet activation and thrombus formation.