Preserved endothelial function in the spastic segment of the human epicardial coronary artery in patients with variant angina--role of substance P in evaluating endothelial function.

This study aimed to determine whether or not endothelium-dependent vasodilation is preserved in spastic segments of human epicardial coronary arteries. Segmental responses of coronary arteries to substance P were examined in 30 patients with variant angina and in 10 patients with atypical chest pain using a quantitative angiographic technique. Coronary diameter at the basal state was matched between spastic and non-spastic segments in patients with variant angina, normal coronary arteries and with atypical chest pain (2.3 +/- 0.2 mm, 2.3 +/- 0.4 mm, 2.4 +/- 0.3 mm, respectively). In segments where vasospasm was induced by ergonovine and/or acetylcholine, changes in diameter in response to substance P did not differ from those in non-spastic segments; maximal dilation averaged 27.1 +/- 9.5% in the spastic segments and 24.4 +/- 9.6% in the non-spastic segments (expressed as a percent increase over the value before drug administration). It would appear that the potential of the endothelium to release endothelium-dependent relaxant factor (EDRF) and the vasodilator response to EDRF are preserved, even in spastic segments.