Effect of Xamoterol on Exercise Capacity and Left Ventricular Function in Angina Pectoris and in Dilated Cardiomyopathy

The present study evaluates the effect of the beta 1 partial agonist xamoterol in patients with coronary artery disease compared to the effect in patients with dilated cardiomyopathy. Nineteen patients with angina pectoris and nine patients with dilated cardiomyopathy received xamoterol 200 mg b.i.d. for 4 weeks in a placebo-controlled double-blind study. The effect was evaluated with a standardized exercise test and radionuclide angiocardiography with determination of global and regional ejection fraction. At rest xamoterol caused no significant changes among the angina patients while global and regional ejection fraction increased among the cardiomyopathy patients. During exercise, when the drug exerts a beta 1-antagonist effect, xamoterol increased the exercise performance among the angina pectoris patients. Fourteen out of 19 patients with angina pectoris were unable to increase their ejection fraction from rest to work due to coronary ischaemia. These 14 patients improved their global ejection fraction during work after xamoterol treatment.