Comparison of effect between nitrates and calcium channel antagonist on vascular function in patients with normal or mildly diseased coronary arteries

Abstract

The comparative long-term antianginal efficacy of long-acting nitrates versus calcium channel antagonists remains unclear. The goal of the present study was to compare the coronary endothelial cell function and coronary artery vasoconstriction between patients with normal or mildly diseased coronary arteries treated with long-acting nitrates or calcium channel antagonists. Forty-two patients suspected to have angina pectoris and with normal or mildly diseased coronary arteries underwent Doppler flow study of the left anterior descending coronary artery. All patients were suspected to have angina pectoris and were receiving either long-acting nitrates (n = 18; Nitrates group) or calcium channel antagonists (n = 24; Ca-antagonists group) for at least 1 year. Vascular reactivity was assessed by intracoronary administration of papaverine, acetylcholine (Ach), and nitroglycerin using a Doppler guidewire. Segments that showed the greatest constrictive response to Ach were used for assessment of vasoconstriction. The percent increase in coronary blood flow (CBF) and coronary artery diameter (CAD) induced by Ach was significantly smaller in the Nitrates group than in the Ca-antagonists group (33% +/- 74% vs 83% +/- 77%, P < 0.05; -3% +/- 16% vs 11% +/- 12%, P < 0.01, respectively). The percent diameter reduction in the region of greatest constrictive response to Ach was significantly greater in the Nitrates group than in the Ca-antagonists group (44% +/- 39% vs 15% +/- 32%, P < 0.02). Long-term treatment with long-acting nitrates may produce less favorable effects on coronary endothelial function and the constrictive response to Ach when compared with long-acting calcium channel antagonists in patients with normal or mildly diseased coronary arteries.