[Calcium inhibitors and myocardial ischemia]

Calcium antagonists share common property of blocking calcium influx and decreasing intracellular calcium in cardiac and vascular smooth muscle cells. They however differ from each other by their pharmacological properties. All calcium antagonist induce coronary and systemic vascular relaxation, thus increasing myocardial oxygen supply and decreasing myocardial oxygen demand, respectively. Only subgroups of diltiazem and verapamil, however, can exert negative chronotropic and/or inotropic effect which contribute to a further decrease in myocardial oxygen demand. In this pharmacological context, long term clinical studies in large groups of patients show that vasospastic angina is the first choice therapeutic indication of calcium antagonists. Furthermore, stable angina is a good indication only for subgroups of diltiazem and verapamil, and unstable angina is a contra-indication for the actually known phenyldihydropyridines, thus confirming the heterogeneity of this class of drugs and probably the major role of myocardial tropism in their antiischemic properties.