Calcium Channel Blockers and Ischemia: A Review

Abstract

This paper is primarily concerned with the use of calcium channel blockers for the long-term management of patients with ischemic heart disease. The topic is timely, because whereas the recent clinical trials with beta adrenoceptor antagonists (1) and platelet inhibitors (2) have shown them to be effective under these conditions, comparable clinical trials with calcium channel blockers have, with one recent exception (3), yielded disappointing results (4–7). The exception is the recently completed trial in which diltiazem was used (3). At the outset it is important to note the essential differences between the diltiazem trial and the other calcium channel blocker trials, which involved either verapamil or nifedipine. Firstly, the diltiazem study relates to a particular subset of patients - those with non-Q wave or non-transmural infarcts. Secondly, treatment was not initiated until 24–72 hours after the onset of severe chest pain. Thirdly, the trial lasted for only fourteen days, and used re-infarction as its end-point. The most remarkable finding of this study was that whilst mortality was unchanged, the rate of re-infarction was reduced (p < 0.03). Even though this trial involved a relatively small population of selected patients (3) and the period of follow up was limited, the results are important in that they show that in this particular subset of patients who are a high risk group for recurrent infarction (8–10), prophylactic therapy with this particular calcium channel blocker can slow, or prevent, the progression of damage caused by inadequate perfusion. The results of this trial, therefore, substantiate the idea that calcium channel blockers (11–14) can protect the potentially jeopardized myocardium, provided that the appropriate therapy is initiated at the appropriate time, at the appropriate dose level, and to the appropriate patients.