Calcium antagonists in coronary artery disease

The introduction of calcium antagonists has had a significant influence on the management of angina pectoris. Whereas, a beta blocker functions by reducing oxygen demand, the calcium antagonists increase oxygen supply and also decrease oxygen demand. The calcium ion is a vital link in excitation-contraction coupling; the regulation of intracellular calcium levels directly modulates cardiac and smooth muscle function. The three agents currently in use are verapamil, nifedipine, and diltiazem; ony the first two are available by prescription at this time. Although all three are calcium channel blocking agents, they differ in their electrophysiologic effects. Verapamil and, to a lesser extent, diltiazem slow AV nodal transmission and are thus helpful in controlling the ventricular rate in atrial fibrillation. All have a negative inotropic property which may limit their use in patients with advanced left ventricular dysfunction.