The effect of beta-blocker therapy on left ventricular systolic functions and functional capacity in patients with heart failure: a comparison between metoprolol succinate and carvedilol

Objectives: We evaluated the effect of metoprolol succinate or carvedilol given in addition to conventional treatment on left ventricular systolic functions and effort capacity in patients with heart failure. Study design: The study included 33 patients (6 females, 27 males; mean age 60 +/- 10 years) with mild to moderate heart failure (NYHA functional class II-III). Following six weeks of standard treatment, the patients were randomized to receive carvedilol or metoprolol succinate, whose initial doses were 3.125 mg twice daily and 25 mg daily, with weekly increments to target doses of 50 mg/day and 100 mg/day, respectively. The patients were assessed by the six-minute walk test and transthoracic echocardiography prior to, and after three months of, beta-blocker treatment. Results: Compared with pretreatment values, resting heart rate and systolic blood pressure showed significant decreases after beta-blocker treatment (carvedilol, p<0.001; metoprolol, p<0.05). Decrease in diastolic pressure was significant only in the metoprolol group (p<0.01). In both groups, systolic and diastolic diameters and end volumes showed significant decreases, and ejection fraction showed a significant increase. There was a dramatic increase in the walking distance in both groups (p<0.001) associated with significantly decreased heart rate and symptom scores which were more notable in the carvedilol group. However, none of the improvements obtained by beta-blocker treatment differed significantly between the two groups (p>0.05). Conclusion: Our findings show that metoprolol succinate and carvedilol provide similar but significant improvements in left ventricular systolic functions and effort capacity of patients with mild to moderate heart failure.