Endothelin-1 as a predictor of positive ischemic diagnosis during dobutamine stress echocardiography

Endothelin is a naturally occurring polypeptide substance with potent vasoconstrictive actions. Plasma endothelin-1 (ET-1) level was a predictor of prognosis during early stages of acute myocardial infarction. The aim of this study was to test the hypothesis that plasma ET-1 levels in patients with ischemic heart disease are related either to myocardial ischemia or left ventricular (LV) dysfunction during dobutamine stress echocardiography. Plasma levels of ET-1 were measured in 37 patients against normal controls (group I, n = 11), positive stress echocardiography with resting ejection fraction (EF) more than 50% (group II, n = 16), and positive stress test with resting EF less than 50% (group III, n = 10). All 3 patient groups were subjected to Thallium 201 scintigraphy and coronary angiography studies. There was no significant difference among patients in these 3 groups with respect to age, gender, blood pressure, and heart rate. The resting LV end-diastolic pressure were higher significantly in group III (26±6 mmHg) and group II (19±6 mmHg) as compared to group I (14±3 mmHg). The EF of LV decreased significantly in group III as compared to group I and group II (43±12 vs 68±1%, and vs 67±7%, respectively). The cardiac output during stressed state was higher significantly in group I patients as compared to group III. In the resting state, there were higher ET-1 concentrations in group II and group III patients compared to group I (289±183 vs 151±54 pg/ml, p<0.05 and 301±167 vs 151±54 pg/ml, p<0.05). During the peak dose of dobutamine infusion, the ET-1 increased 59.6% of baseline in group I. However, there levels were reduced in group II (-0.02%) and group III (-10.3%). In conclusion, patients with suspected ischemic heart disease, the concentration of ET-1 may predict significant anatomical and functional coronary artery disease. However, ET-1 does not play a pathophysiological role during an ischemic attack.