Endothelin Levels in Patients with Cardiac Syndrome X at Rest and Exercise

We aimed to determine plasma endothelin levels in patients with cardiac syndrome X at rest and exercise, as compared to healthy subjects. Plasma endothelin-1 concentrations were measured in 30 patients with cardiac syndrome X (group A) at rest and after peak exercise, as compared to 14 healthy control subjects (group B) who were in a similar age group. ELISA method was used for the measurement of ET-1 levels. Coronary angiograms were normal in all patients and the control group. Symptom-limited maximal treadmill exercise tests with Bruce protocol were found positive in all patients with syndrome X. Exercise tests were normal in the control group.
RESULTS
In patients with cardiac syndrome X, plasma endothelin-1 levels were found significantly elevated either during rest or after peak exercise when compared with the control group (2.52±1.6 pg/ml, 1.38±1.8 pg/ml, p<0.001, 3.68±1.1 pg/ml, 1.37±0.2 pg/ml, p<0.001 respectively). In patients with cardiac syndrome X, plasma endothelin-1 levels after peak exercise were found significantly higher than at rest (3.68±1.1 pg/ml 2.52±1.6 pg/ml, p<0.001). No significant difference (p=0.17) existed between plasma endothelin-1 levels during rest and after peak exercise in the control group. It may be concluded that ET-1 increase has an important role in the pathogenesis of the cardiac syndrome X. ECG changes and exertional angina in these patients can be related to increase in plasma ET-1 levels.