At present, the use of
calcium antagonists for the
secondary prevention of
cardiac events following an acute
myocardial infarction (MI) is not recommended. This advice is based on several large mortality studies using short-acting
calcium antagonists in the absence of coronary reperfusion
therapy. Even in these studies, discrepancies between the different pharmacological classes of
calcium antagonists were recognised. When separated from the
dihydropyridine calcium antagonists, the rate-lowering
calcium antagonists,
verapamil and
diltiazem, do appear to provide some benefit in reduction of recurrent MI. Three large trials using
verapamil post-MI demonstrated a significant reduction in reinfarction with a favourable trend towards reducing death as well. Similarly, the effects of
diltiazem post-MI have been evaluated in 3 large trials. In 2 earlier trials,
diltiazem lessened
cardiac events in patients with nonQ-wave
infarctions and those without pulmonary congestion upon presentation. Overall, there was a significant benefit in lessening reinfarction with no effect on mortality. The recently completed Incomplete
Infarction Trial of European Research Collaborators Evaluating Prognosis Post-
Infarction (INTERCEPT) trial found that sustained-release
diltiazem given after
thrombolytic therapy for acute MI lessened
cardiac events by 23% (a nonsignificant difference) without worsening congestive symptoms. Overall, there is adequate data to support the use of heart-rate-lowering
calcium antagonists for
secondary prevention post-MI provided the patient is intolerant of beta-blocker
therapy. These trials are reviewed in detail, and suggestions for clinical practice are provided in this article.