Left ventricular function and beta-blockade in chronic ischaemic heart failure. Double-blind, cross-over study of propranolol and penbutolol using non-invasive techniques

Abstract

From an original group of 32 male post-infarction patients treated with digoxin for presumed cardiac failure 8 patients were recruited for the present study by means of a single-blind evaluation of the patients' clinical need for continued treatment with digoxin. Dyspnoea on effort as recorded on a standardised questionnaire was used to define failure of the left ventricle. In order to be recruited to the present study the functional class (NYHA) of the patients had to deteriorate at least one full class while on placebo instead of digoxin. During a subsequent double-blind, cross-over phase digoxin was kept constant and additional treatment with 160 mg propranolol or 40 mg penbutolol twice daily was given. Each patient received the 2 beta-blockers for periods of 2 weeks each separated by an intermediate 4-week placebo period. Cardiac function was investigated using electrocardiography, apexcardiography, phonocardiography, echocardiography, and pulse curves from the carotid artery, jugular bulb, and liver before and at the end of each treatment period. The findings indicated well-preserved systolic function before beta-blockade despite the history and symptoms, and despite several indices of cardiac damage such as pronounced ischaemic electrocardiographic abnormalities, and large and hypertrophied hearts (x-ray and echo). Instead, many variables reflected impaired diastolic function. During beta-blockade no signs of impaired cardiac function emerged. On the contrary, enhanced diastolic filling properties were found; these also contributed to the performance of the left ventricle during systole. No differences between propranolol and penbutolol could be shown.