PATTERNS OF CORONARY-ARTERY STENOSIS VASOMOTION - OBSERVED VERSUS PREDICTED STENOSIS REACTIVITY IN PATIENTS WITH CHRONIC STABLE ANGINA

Background: Patterns of constriction and dilatation of angiographicall y normal coronary artery segments and coronary stenoses, in response t o vasoactive stimuli, remain speculative. Methods: We compared the vas omotor response of angiographically normal and stenotic coronary segme nts and assessed the effects of stenosis location and morphology on co ronary stenosis vasomotion in 52 patients with chronic stable angina ( 40 men and 12 women) who underwent intracoronary ergonovine or isosorb ide dinitrate administration or both. Changes in coronary diameter in response to nitrate and ergonovine were assessed by computed arteriogr aphy. The ''predicted'' change in stenosis diameter was calculated acc ording to the ''geometric theory'' (based on the vasomotor response of angiographically normal segments adjacent to the lesion and on stenos is severity). Coronary diameter was assessed at baseline and after nit rate administration in 58 stenoses (34 concentric and 24 eccentric), o f which 40 were located proximally and 18 distally, and also after erg onovine administration (23 stenoses: 14 proximal and 9 distal, 14 conc entric and 9 eccentric). Results: Significant (greater-than-or-equal-t o 10% lumen diameter change) vasoconstriction was observed after ergon ovine administration in 14 of the 23 stenoses (61%), and significant v asodilation was noted after nitrate administration in 29 of 58 stenose s (50%). A larger proportion of distal (89%) and eccentric (89%) compa red with proximal (43%) and concentric (43%) stenoses showed a greater than 10% vasoconstriction after ergonovine administration (P<0.05). V asodilatation after nitrate administration was also observed in a larg er proportion of distal (78%) and eccentric (67%) than in proximal (38 %) and concentric (38%) stenoses (P<0.05). On average, the ''observed' ' changes in coronary diameter in response to nitrate and ergonovine a dministration were of significantly less magnitude than those ''predic ted'' by the geometric theory in both proximal and distal stenoses and in concentric and eccentric stenoses. In only 17% of stenoses were ob served and predicted vasoconstriction similar. Conclusions: Our result s suggest that in patients with chronic stable angina, calculations ba sed on the ''geometric theory'' cannot predict the actual vasomotor re sponse of a stenosis. Factors other than severity, such as baseline co ronary tone, stenosis location, and stenosis morphology, appear to mod ulate stenosis vasomotion in vivo.