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 be tween arterial and coronary sinus endothelin (ET) concentrations and corona ry vasomotor responses during rapid atrial pacing in patients with chest pa in and normal coronary arteriograms (CPNA). BACKGROUND Plasma ET concentrations are significantly higher in CPNA patien ts than in healthy control subjects. METHODS We investigated 19 carefully characterized CPNA patients (14 women; mean age 53 +/- 9 years) of whom 10 had positive electrocardiographic resp onses to exercise. The percentage fall in coronary vascular resistance (%d. CVR) after 10 min of rapid atrial pacing was determined using a thermodilut ion pacing catheter. Plasma ET concentrations were measured by radioimmunoa ssay on simultaneously drawn arterial and coronary sinus samples. RESULTS No significant differences in ET concentrations were observed betwe en men and women, but a strong statistical trend suggested that %d.CVR was lower in women than men (27[23 to 31]% vs. 34[29 to 45]%-median[interquarti le range]; p = 0.07). Simple regression analysis including only the women ( n = 14) suggested a significant relationship between baseline arterial ET c oncentrations and %d.CVR (R-2 = 0.34; p = 0.06). Furthermore, stepwise mult ivariate regression analysis of the group as a whole indicated that both ge nder (p = 0.03) and baseline arterial ET concentration (p = 0.02) were inde pendently predictive of %d.CVR (R-2 = 0.44; overall p = 0.02); this relatio nship predicts that women with high ET levels would have the lowest %d.CVR during pacing. CONCLUSIONS These data support the hypothesis that elevated ET activity may be associated with reduced coronary flow responses during rapid atrial pac ing in CPNA patients. (C) 1999 by the American College of Cardiology.