Recent studies have demonstrated the benefits of beta-blocker therapy in some patients with congestive heart failure (CHF). Studies have suggested that metoprolol, a selective beta blocker, improves left ventricular function and reduces mortality rates. The Randomized Evaluation of Strategies for Left Ventricular Dysfunction (RESOLVD) Pilot Study represents one of the largest studies conducted on the use of metoprolol in patients with CHF of mixed causes who were already receiving angiotensin receptor blockers, angiotensin-converting enzyme (ACE) inhibitors or a combination.
The RESOLVD Pilot Study was a randomized, double-blinded trial of various therapeutic options in patients with CHF that included the initial use of angiotensin receptor blockers or ACE inhibitors for approximately four months. In the second phase of the study patients were randomized to receive controlled-release metoprolol at 200 mg per day for six months. Eligible subjects were those who had symptomatic CHF (New York Heart Association class II to IV) with an ejection fraction of less than 40 percent. For those given metoprolol, the dosage was titrated upward from 12.5 mg per day to the maximum of 200 mg per day. Baseline studies included the following: evaluation of vital signs, quality-of-life questionnaires, measurement of distance during a six-minute walk and quantitative radionuclide ventriculographic studies. These were repeated at the end of the study period.
The study enrolled 426 patients (placebo group: 212; metoprolol group: 214). Patients tended to be white men with CHF of more than 12 months' duration and a previous history of myocardial infarction. The mean ejection fraction of the study participants was approximately 29 percent. Notable findings included the following: metoprolol did not affect six-minute walking distance, NYHA functional class or quality of life. However, there were significant though small (2.4 percent) improvements in measures of left ventricular function. Most importantly, there were fewer deaths in the group receiving metoprolol (placebo group: 8.1 percent; metoprolol group: 3.4 percent).
The authors concluded that six months of metoprolol therapy was well tolerated in patients with moderately severe CHF, regardless of the cause. Metoprolol appeared to improve left ventricular function and reduce mortality rates in these patients.
editor's note: This study confirms the potential beneficial effects of beta-blocker therapy in select patients with CHF. While not presented by the authors, the calculated number needed to treat in this study was 23. This means that 23 patients with CHF would need to be treated for six months in order to prevent one death. Given the relatively low cost of metoprolol, its favorable side effect profile in selected patients and its effect on mortality, clinicians should consider the use of beta blockade in patients with CHF. Patients with mild to moderate compensated CHF from ischemic and nonischemic dilated cardiomyopathies with New York Heart Association class II to III symptoms on standard treatment, including diuretics and ACE inhibitors, who do not have a contraindication for beta blockers, are candidates for this therapy.—j.n.