REACTIVITY OF ECCENTRIC AND CONCENTRIC CORONARY STENOSES IN PATIENTS WITH CHRONIC STABLE ANGINA

Dynamic coronary stenoses may be the cause of a variable angina threshold and rest angina in patients with chronic stable angina. It has been suggested that eccentric but not concentric coronary artery stenoses have the potential for dynamic changes of caliber in response to vasoactive stimuli. The vasomotor response of eccentric (asymmetric narrowing) and concentric (symmetric narrowing) coronary stenoses to ergonovine (20-mu-g intracoronary or 300-mu-g intravenous) and isosorbide dinitrate (1 mg intracoronary) was studied in 51 patients with chronic stable angina. Diameter of reference segments (angiographically normal segments proximal to the stenoses) and that of eccentric (n = 30) and concentric (n = 35) coronary stenoses that ranged from 50% to 90% luminal diameter reduction were measured by computerized quantitative angiography before and after ergonovine and isosorbide dinitrate. Ergonovine reduced stenosis diameter (by greater-than-or-equal-to 10%) in 80% of eccentric stenoses and 42% of concentric stenoses (p < 0.05). Mean (+/- SEM) diameter reduction with ergonovine was 19 +/- 3% and 9.5 +/- 2% for eccentric and concentric stenoses, respectively (p < 0.05). Isosorbide dinitrate increased coronary diameter (by greater-than-or-equal-to 10%) in 70% of eccentric and 43% of concentric stenoses (p < 0.05). Mean diameter of eccentric stenoses increased from 1.15 +/- 0.05 to 1.35 +/- 0.06 mm after nitrate (18.6 +/- 2.5%), whereas diameter of concentric stenoses increased from 1.05 +/- 0.05 to 1.14 +/- 0.05 mm (10 +/- 2.5%) (p < 0.05). Average dilation of reference segments with administration of isosorbide dinitrate and constriction with ergonovine were not significantly different in patients with concentric and eccentric stenoses. Thus, in patients with chronic stable angina, both eccentric and concentric stenoses have the potential for dynamic changes of caliber in response to vasoactive stimuli. However, a significantly larger proportion of eccentric stenoses exhibit this potential. The magnitude of dynamic changes of caliber is also larger in eccentric than in concentric stenoses.