Endogenous plasma endothelin concentrations and coronary circulation in patients with mild dilated cardiomyopathy
- Division of Cardiology, Pneumology and Angiology, School of Medicine, Heinrich Heine University, Moorenstraβe 5, 40225 Düsseldorf, Germany
- Dr Schwartzkopff. email: schwartk{at}uni-duesseldorf.de
- Accepted 26 October 1998
Abstract
OBJECTIVE To determine whether increased plasma concentrations of endothelin-1 (ET-1) and big endothelin (BET) play a role in the regulation of coronary circulation in patients with idiopathic dilated cardiomyopathy (IDCM).
SETTING Tertiary referral centre for cardiac diseases.
PATIENTS Fourteen patients (eight male/six female; mean (SD) age 59 (9) years) with IDCM (ejection fraction 36 (9)%) and five normotensive subjects (two male/three female; age 52 (7) years) serving as controls were studied.
METHODS Functional status was classified according to New York Heart Association (NYHA) class. Endogenous ET-1 and BET plasma concentrations from the aorta and the coronary sinus were determined by radioimmunoassay. Coronary blood flow, using the inert chromatographic argon method, myocardial oxygen consumption, and coronary sinus oxygen content under basal conditions were determined.
RESULTS In the aorta, mean (SD) concentrations of ET-1 (IDCM 0.76 (0.25) v controls 0.31 (0.06) fmol/ml; p = 0.002) and BET (IDCM 3.58 (1.06) vcontrols 2.11 (0.58) fmol/ml; p = 0.014) were increased in patients with IDCM. Aortic ET-1 concentrations correlated positively with NYHA class (r = 0.731; p < 0.001), myocardial oxygen consumption (r = 0.749; p < 0.001), and coronary blood flow (r = 0.645; p = 0.003), but inversely with coronary sinus oxygen content (r = −0.633; p = 0.004), which was significantly decreased in IDCM patients (IDCM 4.68 (1.05)v controls 6.70 (1.06) vol%; p = 0.003).
CONCLUSIONS The coronary circulation in patients with IDCM is exposed to an increased endothelin load. ET-1 concentrations correlate with functional deterioration. A decrease of the coronary sinus content of oxygen suggests a mismatch between coronary blood flow and metabolic demand. Thus, ET-1 might be a marker of a disequilibrium between myocardial oxygen demand and coronary blood flow in IDCM.
