Prevention of coronary vasoconstriction by diltiazem during dynamic exercise in patients with coronary artery disease

AbstractWhether exercise-induced vasoconstriction of coronary artery stenoses is modified by the administration of calcium antagonists was examined in 14 patients with classic angina pectoris. In this group the effect of intracoronary diltiazem (2 to 3 mg) on luminal area was evaluated in normal and stenotic segments of epicardial coronary arteries during symptom-limited supine exercise. The luminal area of a normal and a stenotic coronary artery segment was determined by quantitative coronary arteriography with a computer-assisted system. Patients were studied at rest, 6 min after 2 to 3 mg of intracoronary diltiazem, during supine bicycle exercise (96 W) and 5 min after sublingual administration of 1.6 mg nitroglycerin. Heart rate, mean pulmonary and aortic pressure as well as the percent change of both normal and stenotic luminal area were determined.Intracoronary administration of diltiazem was associated with mild dilation of both normal (19%, p < 0.01) and stenotic coronary luminal area (11%, p < 0.05). During subsequent exercise, luminal area of the stenotic vessel segment increased by 23% (p < 0.001) and that of the normal vessel segment by 24% (p < 0.001), whereas in a previously reported control group, luminal area of the stenotic vessel segment decreased by 29% during exercise. After sublingual administration of nitroglycerin, the luminal area of both the normal and the stenotic vessel segment increased further by 19% (p < 0.01) and 22% (p < 0.01), respectively, compared with the values after intracoronary administration of diltiazem.Thus, intracoronary administration of diltiazem prevents exercise-induced vasoconstriction of stenotic coronary arteries, suggesting a direct vasodilating effect on the coronary artery. Diltiazem and nitroglycerin seem to have an additive effect on coronary vasodilation of stenotic vessel segments probably as a result of restoration of endothelial function of the diseased coronary vessel by diltiazem