Principal Findings:

The carvedilol (n=37) and metoprolol (n=30) groups were well-matched at baseline with no significant difference in percent of patients achieving target dose or in required alteration of diuretic dose during uptitration. Twenty participants did not complete the 12-month study, with these patients equally divided between the 2 groups.

Both groups demonstrated significant parallel clinical and exercise benefits over 1 year with no discernible difference between the two β-blockers in any of the measured parameters, including blood pressure, symptom score, QOL measures, clinical status, ejection fraction, or exercise parameters. Heart rate declined significantly with both drugs, but the decline with carvedilol (17 bpm) was greater than with metoprolol (10 bpm, p=0.05). This probably reflects the greater degree of beta blockade achieved with the relatively higher equivalent dose of carvedilol compared with metoprolol. TBARS, as a measure of antioxidant activity, declined significantly over time. This occurred as functional status improved, with no difference shown between the two groups.

As heart failure improved, dry weight tended to increase without any deterioration in renal function. This weight increase without edema may reflect an increase in mean muscle mass or beneficial effects of chronic β-blockade on cytokines and/or a reduction in oxidative stress.