RATIONALE FOR THE USE OF CALCIUM-ANTAGONISTS IN THE TREATMENT OF SILENT-MYOCARDIAL-ISCHEMIA

Silent myocardial ischemia, whether it occurs at rest or during exerci se, is associated with an unfavorable prognosis and may lead to sudden cardiac death. Agents used to treat silent myocardial ischemia have i ncluded nitrates, beta-blockers, and calcium antagonists (CAs). Despit e treatment with traditional anti-ischemic agents, studies have shown that up to 40% of patients who receive what is considered to be clinic ally optimal antianginal therapy continue to have daily episodes of si lent myocardial ischemia. The use of nitrates and beta-blockers is som etimes confounded by issues of tolerance and tolerability. Although th e CAs have been found to be effective in decreasing the duration and f requency of episodes of silent ischemia, in general beta-blockers prod uce a greater reduction in these variables. Thus a need for effective and tolerable antiischemic agents persists. A new class of CAs, the te tralol derivatives, may show promise in this regard. The first of this new class, mibefradil, is characterized by selective blockade of T-ty pe calcium-ion channels and has been shown in a few studies to reduce the frequency and duration of asymptomatic ischemic episodes in patien ts with stable exertional angina pectoris. Large-scale clinical trials are necessary before the efficacy and tolerability of this new CA can be compared fully with those of the beta-blockers and currently avail able CAs.