DIFFERENTIAL PLASMA ENDOTHELIN LEVELS IN SUBGROUPS OF PATIENTS WITH ANGINA AND ANGIOGRAPHICALLY NORMAL CORONARY-ARTERIES

Background Raised plasma endothelin concentrations have previously bee n reported in patients with cardiac syndrome X, but it is not known wh ether these levels vary between clinically distinct subgroups in this heterogeneous condition.Methods and Results We compared plasma immunor eactive endothelin levels in 54 patients with angina pectoris and norm al coronary angiograms and 21 healthy control subjects. The patient gr oup was divided into 4 clinically distinct subgroups: 7 with left bund le branch block (group A); 7 with previous myocardial infarction (grou p B); 24 with positive exercise electrocardiography (group C); and 16 with negative exercise electrocardiography (group D). The plasma endot helin concentration was significantly higher in Patients compared with control subjects (3.7 [2.9 to 4.3] vs 2.96 [2.4 to 3.4] pg/mL, respec tively, median [interquartile range]; P = 0.002). Endothelin concentra tions were most significantly elevated in group A and group B (4.5 [3. 6 to 5.2] pg/mL; P = 0.005 and 4.1 [3.9 to 4.5] pg/mL; P = 0.001, resp ectively). Plasma endothelin concentrations were also significantly el evated in group C (3.7 [2.8 to 4.1] pg/mL; P = 0.02) but not in group D (3.0 [2.5 to 3.8] pg/mL; P = 0.3). Conclusions Plasma endothelin con centration is elevated in patients with angina pectoris and angiograph ically normal coronary arteries, particularly those with left bundle b ranch block or previous myocardial infarction.