Mechanisms whereby calcium channel antagonists may protect patients with coronary artery disease.

Calcium antagonists have multiple mechanisms whereby they are able to protect against myocardial ischaemia. Recently questions have been posed about the long-term safety of this group of agents. This article is a selective rather than a complete review of the problems. Fears have largely centred around rapidly acting nifedipine when inappropriately used. This agent remains useful in Prinzmetal's angina, a condition in which there are no long-term comparative outcome studies. Current evidence is that verapamil is as safe and as effective as the beta-blocker in effort angina and that non-dihydropyridines (verapamil and diltiazem) are efficacious in the follow up of non-Q wave infarct. Verapamil post-infarct is safe and reduces reinfarction, provided that clinical heart failure is first excluded.