Calcium antagonists and myocardial infarction

Summary

In vitro and in vivo studies have demonstrated many similarities between the three calcium antagonists verapamil, nifedipine, and diltiazem in relation to protection of the myocardium during hypoxia. Important clinical differences exist between the three drugs when they are used during or after an acute myocardial infarction with the purpose of preventing death and reinfarction. The balance between the negative inotropic and the vasodilator properties and concomitant treatment with beta blockers may explain the results of clinical trials with the three calcium antagonists.Patients not treated with beta blockers. Nifedipine has been demonstrated to be no better than placebo both during and after an acute myocardial infarction. No placebo-controlled studies exist with diltiazem. Verapamil had no effect during the acute phase of a myocardial infarction. After a myocardial infarction, verapamil improved survival and reduced the reinfarction rate, an effect primarily found in patients without heart failure in the coronary care unit.Patients also treated with beta blockers. Nifedipine prevents the development of myocardial infarcts in patients with unstable angina. Diltiazem probably prevents reinfarction in the first two weeks after non-Q-wave infarction. Secondary prevention with diltiazem after an acute myocardial infarction had no overall effect on death or cardiac events (i.e., reinfarction or cardiac death). Subgroup analysis demonstrated in diltiazem-treated patients, compared with placebo-treated patients, a significant reduction of cardiac events in patients without and a significant increase of cardiac events in patients with heart failure. At present no indications exist for nifedipine during or after a myocardial infarction; further studies are needed with diltiazem, and verapamil may be used in secondary prevention of death and reinfarction.