Background: It is still uncertain whether or not there is a difference between metoprolol and carvedilol for the treatment of congestive heart failure. We attempted to determine the difference between the two beta-blockers in terms of their antiadrenergic effect during exercise in patients with heart failure and their efficacy based on the baseline plasma brain natriuretic peptide concentration.
Methods: Fifty-three patients with mild to moderate heart failure with a radionuclide left ventricular ejection fraction <40% received open label metoprolol or carvedilol in a randomized fashion. The increase in the heart rate normalized to the increase in the plasma norepinephrine concentration during exercise, was calculated as an index of adrenergic responsiveness during exercise.
Results: The increase in heart rate normalized by the increase in plasma norepinephrine concentration, decreased after the initiation of beta-blockers in the carvedilol group, but not in the metoprolol group. The change in cardiac function was more favorable for carvedilol than metoprolol in patients who exhibited a higher baseline brain natriuretic peptide concentration.
Conclusions: Carvedilol exerts a more potent antiadrenergic effect than metoprolol during stress in patients with mild to moderate heart failure. Carvedilol appears to be more efficacious than metoprolol in patients who exhibit higher baseline brain natriuretic peptide concentrations. These differences should be kept in mind when selecting appropriate pharmacologic agents in the treatment of heart failure.