Comparative effects of atenolol and cicloprolol on cardiac performance in coronary heart disease.

Cicloprolol is a new cardioselective beta-blocking agent with partial agonist activity (intrinsic sympathomimetic activity, ISA). Its haemodynamic profile was compared with that of atenolol (cardioselective; no ISA) in a comparative dose-response study of 24 ischaemic patients with diminished cardiac reserve. Following a stable control period, equivalent intravenous (i.v.) beta-blocking boluses of atenolol (1, 1, 2, and 4 mg) or cicloprolol (0.025, 0.025, 0.05, and 0.1 mg/kg) were randomly administered and haemodynamics and left ventricular ejection fraction were determined at rest and during bicycle exercise. At rest, atenolol reduced heart rate (HR) and cardiac index; diastolic blood pressure (DBP), systemic vascular resistance index (SVRI), and pulmonary artery occluded pressure (PAOP) increased without change in mean arterial pressure (MAP). Cicloprolol increased left ventricular ejection fraction, reduced its end-diastolic volume, and tended to reduce filling pressure without change in other variables. During exercise, atenolol reduced ejection fraction and increased SVRI; in contrast, cicloprolol did not significantly alter these parameters. Attenuation of exercise tachycardia and cardiac index increase was similar after each agent. Thus, the cardiac performance assessed from left ventricular stroke index or ejection fraction/filling pressure relationships was less depressed after cicloprolol as compared with atenolol. The relevance of such haemodynamic differences to exercise ability or quality of life during sustained therapy warrants examination.