Hemodynamic and energetic comparison of bucindolol and metoprolol for the treatment of congestive heart failure

Although β blockers have demonstrated a salutary effect on ventricular function in patients with heart failure, it is unclear whether a nonselective third-generation β blocker produces different hemodynamic and energetic effects than a second-generation β1 selective agent. In 30 male patients with heart failure, we retrospectively analyzed hemodynamic data from 2 protocols examining the effects of a nonselective β antagonist bucindolol [n = 15), and a highly selective β1 antagonist metoprolol (n = 15). Both studies were conducted in a similar fashion with patients undergoing cardiac catheterization before and after receiving 3 months of β blockade. Both groups were matched at baseline in terms of ventricular function, β blockade resulted in similar reductions in heart rate and similar improvements in ejection fraction, ventricular volumes, stroke and minute work, peak +dP/dt, and isovolumic relaxation in both groups. Only patients faking bucindolol had a significant within-group decrease in resting left ventricular end-diastolic pressure. The metoprolol group had a greater decrease in coronary sinus blood flow and myocardial oxygen consumption. Bucindolol increased cardiac index more than metoprolol, but did not increase stroke volume index more than metoprolol. The bucindolol group had an increase in systolic elastance, whereas the metoprolol group had a parallel left shift in this relation, thus, metoprolol reduces coronary blood flow and myocardial oxygen consumption more than bucindolol, whereas bucindolol produces slightly more favorable improvements in resting cardiac index and end-diastolic pressure. Otherwise, these 2 agents produced similar hemodynamic changes.