METHODS AND RESULTS: Using computerized quantitative coronary angiography, we studied the effects of intracoronary infusion of
serotonin on 38
coronary stenoses of different morphologies (concentric, eccentric, complicated) in 11 patients with
stable angina and 4 with variant angina. In response to the maximum infused concentration of
serotonin, 100% of complicated
stenoses and 50% of concentric
stenoses constricted by > or = 20% (P < .05). The magnitude of constriction was greater at eccentric
stenoses (32.08 +/- 4.1%) than concentric
stenoses (15.68 +/- 2.8%, P < .05) and greater in complicated
stenoses (57.69 +/- 7.6%, P < .05) than eccentric
stenoses. At complicated
stenoses, the constriction was greater (0.85 +/- 0.16 mm, P < .05) than at the adjacent reference segments (0.42 +/- 0.12 mm). It was similar to the reference segment for both concentric and eccentric
stenoses. The constriction at the
stenosis was greater for irregular (complicated) lesions than for smooth (concentric and eccentric) lesions in both patients with stable (51.8 +/- 7.3% versus 22.5 +/- 4.1%, P < .001) and those with variant (77 +/- 17% versus 28.2 +/- 8.1%, P < .05) angina. There was a weak correlation (r = .39) of magnitude of constriction with
stenosis length but not with baseline
stenosis severity (minimum diameter).
CONCLUSIONS: In these patients, the magnitude of the
vasoconstrictor response to
serotonin at the site of an atheromatous coronary plaque depends on the morphological characteristics of the plaque and is more closely related to irregular contour than
stenosis severity or length. This relation suggests that variations in receptor type or density or in the smooth muscle cell response to stimulation may determine the response to locally released
serotonin in patients with
coronary disease.