Elevated endothelin concentrations are associated with reduced coronary vasomotor responses in patients with chest pain and normal coronary arteriograms

OBJECTIVES The purpose of this study was to investigate the relationship between arterial and coronary sinus endothelin (ET) concentrations and coronary vasomotor responses during rapid atrial pacing in patients with chest pain and normal coronary arteriograms (CPNA). BACKGROUND Plasm ET concentrations are significantly higher in CPN patients than in healthy control subjects. METHODS We investigated 19 carefully characterized CPN patients (14 women; mean age 53 ± 9 years) of whom 10 had positive electrocardiographic responses to exercise. The percentage fall in coronary vascular resistance (%d.CVR) after 10 min of rapid atrial pacing was determined using thermodilution pacing catheter. Plasm ET concentrations were measured by radioimmunoassay on simultaneously drawn arterial and coronary sinus samples. RESULTS No significant differences in ET concentrations were observed between men and women, but strong statistical trend suggested that %d.CVR was lower in women than men (27[23 to 31]% vs. 34[29 to 45]%—median[interquartile range]; p = 0.07). Simple regression analysis including only the women (n = 14) suggested significant relationship between baseline arterial ET concentrations and %d.CVR (R2 = 0.34; p = 0.06). Furthermore, stepwise multivariate regression analysis of the group as whole indicated that both gender (p = 0.03) and baseline arterial ET concentration (p = 0.02) were independently predictive of %d.CVR (R2 = 0.44; overall p = 0.02); this relationship predicts that women with high ET levels would have the lowest %d.CVR during pacing. CONCLUSIONS These dat support the hypothesis that elevated ET activity may be associated with reduced coronary flow responses during rapid atrial pacing in CPN patients.