Effect of metoprolol on myocardial function and energetics in patients with nonischemic dilated cardiomyopathy: a randomized, double-blind, placebo-controlled study

Effects of carvedilol on systolic and diastolic left ventricular performance in idiopathic dilated cardiomyopathy or ischemic cardiomyopathy

Recent evidence has shown that improvement in left ventricular (LV) systolic function in patients with New York Heart Association class II to III heart failure occurs with beta-adrenergic blocking agents. However the specific effects on LV diastolic function have been subjected to only limited examination. This study investigated the effects of the combined beta blocker/vasodilator, carvedilol, on systolic and diastolic LV performance in dilated cardiomyopathy. Thirty-six patients with New York Heart Association II to III heart failure and LV ejection fraction < or = 0.35 were entered into either arm of this placebo-controlled, double-blind 4-month trial. Twenty-one subjects were entered into the carvedilol treatment arm and 15 patients were entered into the placebo arm in a 3:2 ratio. Carvedilol therapy resulted in a significant improvement in LV ejection fraction, from 0.22 +/- 0.02 to 0.30 +/- 0.02 when compared with the placebo group (0.19 +/- 0.02 to 0.21 +/- 0.02 at baseline and after 4 months of therapy, respectively; p = 0.0001). However, no significant change in radionuclide parameters of LV diastolic function, including peak filling rate or time to peak filling rate, was observed. LV end-diastolic volume index did not change with carvedilol therapy, whereas end-diastolic volume index increased in the placebo group, although the difference between groups at 4 months was significant (p = 0.02). In conjunction with these changes, end-systolic volume index was smaller at 4 months after carvedilol treatment compared with that of the placebo group (p = 0.04). Thus, these results demonstrate that in moderate chronic heart failure, systolic LV performance improves but diastolic LV function does not improve when compared with placebo after treatment with carvedilol.

Changes in early and late diastolic filling patterns induced by long-term adrenergic beta-blockade in patients with idiopathic dilated cardiomyopathy

BACKGROUND

beta-Blockers have been used in patients with idiopathic dilated cardiomyopathy to improve cardiac performance and theoretically would be beneficial to diastolic function. However, there are few reports on changes in diastolic function during chronic pharmacological treatment of congestive heart failure.

METHODS AND RESULTS

The present study was a substudy in the international Metoprolol in Dilated Cardiomyopathy Trial. Transmitral Doppler echocardiography was used to evaluate diastolic function in 77 patients randomly assigned to placebo (n = 37) or metoprolol (n = 40). The patients were treated for 12 months. Changes in Doppler flow variables in the metoprolol group implied a less restrictive filling pattern, expressed as an increase in E-wave deceleration time (placebo, 185 +/- 126 to 181 +/- 64 ms; metoprolol, 152 +/- 63 to 216 +/- 78 ms; P = .01, placebo versus metoprolol). Maximal increase in deceleration time had occurred by 3 months, whereas systolic recovery was achieved gradually and maximal effect was seen by 12 months of treatment. Although deceleration time was correlated to heart rate at baseline, changes in deceleration time were not significantly correlated to changes in heart rate during treatment.

CONCLUSIONS

During the first 3 months of treatment, maximal effects on diastolic variables were reached, whereas the most prominent effect on systolic function was seen late in the study. It is suggested that effects on diastolic filling account for subsequent later myocardial systolic recovery. The E-wave deceleration time, which in recent studies has been shown to be a powerful predictor of survival, was significantly improved in the metoprolol-treated patients.

Acute effects of beta 1-selective and nonselective beta-adrenergic receptor blockade on cardiac sympathetic activity in congestive heart failure

BACKGROUND

beta-Blockers may reduce cardiac sympathetic activity in patients with heart failure by antagonizing beta-adrenergic receptors that facilitate sympathetic outflow to the heart. To explore this possible effect of beta-blockade, we measured cardiac norepinephrine spillover responses in patients with heart failure after the acute administration of either propranolol, a nonselective beta-blocker, or metoprolol, a beta 1-selective agent.

METHODS AND RESULTS

Eighteen patients were studied. Repeated intravenous doses of propranolol (0.5 mg; nine patients; left ventricular ejection fraction, 14 +/- 2%) or metoprolol (1.0 mg; nine patients; left ventricular ejection fraction, 18 +/- 2%) were administered until one of the following end points was reached: a 15% decrease in heart rate, left ventricular +dP/dt, or mean arterial blood pressure or a 5 mm Hg increase in left ventricular end-diastolic pressure. Propranolol (mean dose, 2.0 mg) and metoprolol (mean dose, 3.6 mg) caused similar reductions in heart rate, +dP/dt, and coronary sinus plasma flow. Cardiac norepinephrine spillover was reduced after propranolol (277 +/- 55 to 262 +/- 53 pmol/min, P < .05) but was increased after metoprolol (233 +/- 57 to 296 +/- 82 pmol/min, P < .05). In a comparison of the two groups, the decrease in spillover after propranolol was significantly different than the increase seen after metoprolol (P < .01).

CONCLUSIONS

The administration of a beta 1-selective antagonist was associated with increased cardiac norepinephrine spillover. In contrast, the administration of a nonselective beta-blocker until similar hemodynamic end points were reached caused a reduction in norepinephrine spillover. This suggests that in patients with heart failure, nonselective beta-blockade may have favorable inhibitory effects on cardiac sympathetic activity.

Negative chronotropic effect of beta-blockade therapy reduces myocardial oxygen expenditure for nonmechanical work

BACKGROUND

The negative chronotropic effect of beta-blocking agents is likely to provide hemodynamic and energetic advantages. However, the negative chronotropic effect on cardiac energetics observed on the initiation of beta-blockade therapy has not been fully elucidated.

METHODS AND RESULTS

In 18 patients with heart failure, left ventricular pressure and volume, external work (EW), myocardial oxygen consumption per beat (total Vo2), mechanical efficiency (EW/total Vo2), and Vo2 for nonmechanical work (total Vo2-2.EW) were measured with the use of conductance catheter and Webster catheter at the following three states: under control conditions and after beta-blockade (0.15 +/- 0.07 mg/kg propranolol IV) with and without atrial pacing to keep the heart rate at control levels. Heart rate decreased after atrial pacing was stopped. EW decreased during beta-blockade with pacing and returned to the control level after pacing was stopped. Total Vo2 did not change during beta-blockade with or without pacing, whereas Vo2 for nonmechanical work increased with pacing and returned to the control level after pacing was stopped. As a result, mechanical efficiency decreased during beta-blockade with pacing and returned to the control level after pacing was stopped.

CONCLUSIONS

The negative chronotropic effect of a beta-blocking agent may offset the mechanoenergetical deterioration resulting from its negative inotropic effect through a reduction in oxygen expenditure for nonmechanical work. These findings suggest that the negative chronotropic effect is an important aspect of beta-blockade therapy.

Metoprolol in dilated cardiomyopathy: is it possible to identify factors predictive of improvement? The Heart Muscle Disease Study Group

BACKGROUND

Some controlled clinical trials showed a beneficial effect of beta-blockers on symptoms, exercise tolerance, and left ventricular function in dilated cardiomyopathy. The purpose of this study was to investigate if there are clinical variables at baseline that could predict a favorable response to long-term metoprolol therapy.

METHODS AND RESULTS

Since November 1987, 94 consecutive patients with dilated cardiomyopathy and left ventricular ejection fraction less than 0.40 were treated with metoprolol (mean final dosage, 136 +/- 32 mg) associated with tailored medical therapy with digitalis, diuretics, and angiotensin-converting enzyme inhibitors. Eighty-four surviving patients had a complete 2-year noninvasive follow-up period. Ten patients died or were transplanted before the final assessment. Improvement was defined according to a clinical score based on left ventricular ejection fraction (increase > or = 10 U), left ventricular end-diastolic diameter (decrease > or = 10%), regression of restrictive filling pattern, New York Heart Association functional class, exercise tolerance (increase > or = 2 minutes), and cardiothoracic ratio (decrease > or = 10%). According to these criteria, 48 patients (51.1%) were classified as improved. Multivariate analysis identified a group of patients with a history of mild hypertension (blood pressure between 140/90 and 170/100 mmHg) and significantly higher probability of improvement with longterm metoprolol (odds ratio [OR], 2.22; 95% confidence interval, 1.25-3.94; P = .007). Among the 71 patients with normal blood pressure (< 140/90 mmHg), heart rate in upright position (100 vs 75 beats/min: OR, 2; 95% confidence interval, 1.38-4.94; P = .003), left ventricular ejection fraction 0.20-0.33 versus less than 0.20 (OR, 4.72; 95% confidence interval, 1.06-21.04; P = .042), and New York Heart Association class I-II versus III-IV (OR, 2.74; 95% confidence interval, 0.97-7.75; P = .05) were significantly associated with a positive response to metoprolol. At baseline, both supine and upright heart rate were significantly higher in patients who improved, but heart rate in the upright position was the most significant predictor of improvement in patients with normal blood pressure at multivariate analysis.

CONCLUSIONS

According to the authors' logit model, patients with a history of mild hypertension or with a higher resting heart rate, associated with controlled symptoms of heart failure (New York Heart Association class I-II) or moderate to severe left ventricular ejection fraction (range, 0.20-0.33) showed a remarkable probability of long-term (2-year) improvement on metoprolol.

The effect of carvedilol on morbidity and mortality in patients with chronic heart failure. U.S. Carvedilol Heart Failure Study Group

BACKGROUND

Controlled clinical trials have shown that beta-blockers can produce hemodynamic and symptomatic improvement in chronic heart failure, but the effect of these drugs on survival has not been determined.

METHODS

We enrolled 1094 patients with chronic heart failure in a double-blind, placebo-controlled, stratified program, in which patients were assigned to one of the four treatment protocols on the basis of their exercise capacity. Within each of the four protocols patients with mild, moderate, or severe heart failure with left ventricular ejection fractions < or = 0.35 were randomly assigned to receive either placebo (n = 398) or the beta-blocker carvedilol (n = 696); background therapy with digoxin, diuretics, and an angiotensin-converting-enzyme inhibitor remained constant. Patient were observed for the occurrence death or hospitalization for cardiovascular reasons during the following 6 months, after the beginning (12 months for the group with mild heart failure).

RESULTS

The overall mortality rate was 7.8 percent in the placebo group and 3.2 percent in the carvedilol group; the reduction in risk attributable to carvedilol was 65 percent (95 percent confidence interval, 39 to 80 percent; P < 0.001). This finding led the Data and Safety Monitoring Board to recommend termination of the study before its scheduled completion. In addition, as compared with placebo, carvedilol therapy was accompanied by a 27 percent reduction in the risk of hospitalization for cardiovascular causes (19.6 percent vs. 14.1 percent, P = 0.036), as well as a 38 percent reduction in the combined risk of hospitalization or death (24.6 percent vs, 15.8 percent, P < 0.001). Worsening heart failure as an adverse reaction during treatment was less frequent in the carvedilol than in the placebo group.

CONCLUSIONS

Carvedilol reduces the risk or death as well as the risk of hospitalization for cardiovascular causes in patients with heart failure who are receiving treatment with digoxin, diuretics, and an angiotensin-converting-enzyme inhibitor.

Medium-term effects of beta-blockade on left ventricular mechanics: a double-blind, placebo-controlled comparison of nebivolol and atenolol in patients with ischemic left ventricular dysfunction

The aim of this study was to compare the effects on left ventricular function and exercise tolerance of a selective beta-antagonist (atenolol) with those of another selective beta 1-antagonist with vasodilator properties (nebivolol) in patients with ischemic left ventricular dysfunction but no overt congestive heart failure. Beta blockers are widely used in ischemic heart disease, but their effects on left ventricular mechanics and exercise tolerance are poorly defined in the subgroup of patients with significant systolic dysfunction but without clinical evidence of ischemia or congestive heart failure. Angiographic and symptom-limited exercise data were obtained at baseline and after an 8-10-week double-blind treatment with placebo (n = 10), 50 mg atenolol daily (n = 10), or 2.5 mg (n = 10) or 5 mg (n = 10) nebivolol daily. When compared to placebo, both atenolol and nebivolol reduced resting heart rate and improved left ventricular ejection fraction (from 33.9 to 39.2% with atenolol and from 36.5 to 40.8% with nebivolol, both P < .05) while lowering mean systolic wall stress. Only nebivolol, however, produced a parallel downward shift of the pressure-volume relationship during early diastolic filling and improved the early peak filling rate when compared to placebo (+ 10%, P < .05). When compared to baseline, maximal exercise duration increased by 7 and 13 seconds with placebo and atenolol, respectively (both NS vs baseline), and increased by 44 seconds with nebivolol (P = .0077 vs baseline). Both atenolol and nebivolol decreased maximal exercise heart rate; the reduction was more pronounced with atenolol. Prolonged beta 1-adrenoceptor blockade leads to a significant increase in left ventricular ejection fraction in patients with ischemic left ventricular dysfunction. The dissociation between the changes in resting left ventricular function and the changes in exercise duration suggests that in this clinical setting, the changes in systolic function may have less impact on functional capacity than an improvement in diastolic distensibility during the rapid filling phase.

Early reduction of neurohumoral factors plays a key role in mediating the efficacy of beta-blocker therapy for congestive heart failure

This study examined the role played by neurohumoral factors in mediating the effects of beta-blocker therapy for congestive heart failure. Fifteen patients with congestive heart failure underwent beta-blocker therapy. Plasma norepinephrine and alpha-atrial natriuretic peptide concentrations decreased 2 weeks after initiation of beta-blocker therapy. Decrease in plasma norepinephrine level persisted for 6 months. Lymphocyte beta-adrenoceptor density increased 2 weeks after therapy but was not increased 6 months later. Left ventricular ejection fraction was unchanged 2 weeks after therapy, but it increased 6 months after introduction of beta-blockers. Plasma norepinephrine level decreased 2 weeks after the therapy in the responders (increase in ejection fraction > 0.10) but not in the nonresponders. Thus early reduction of neurohumoral factor levels preceded the late improvement of left ventricular contractile function and may therefore be partly responsible for the efficacy of beta-blocker therapy for congestive heart failure.

Design of the Beta-Blocker Evaluation Survival Trial (BEST). The BEST Steering Committee

Central to our current understanding of heart failure is the concept that compensatory mechanisms that maintain blood pressure and perfusion ultimately contribute to worsening of ventricular function. Studies of the effect of angiotensin-converting enzyme inhibitors in patients with heart failure are consistent with this paradigm. This manuscript describes a 2,800-patient randomized trial that will definitively determine whether sympathetic nervous system antagonism with a beta blocker prolongs the life of patients with moderate to severe heart failure.

Time course of improvement in left ventricular function, mass and geometry in patients with congestive heart failure treated with beta-adrenergic blockade

OBJECTIVES

We examined the time course of ventricular functional improvement in patients with dilated cardiomyopathy who received beta-blockade and the long-term effects of beta-blockade on ventricular mass and geometry in these patients.

BACKGROUND

Previous studies have shown that beta-adrenergic blocking agents when administered long term improve ventricular function in patients with heart failure. However, the time course of improvement in ventricular function and the long-term effects of beta-blockade on ventricular mass and geometry are not known.

METHODS

Twenty-six men with dilated cardiomyopathy underwent serial echocardiography on days 0 and 1 and months 1 and 3 of either metoprolol (n = 16) or standard therapy (n = 10). At 3 months all patients on standard therapy were crossed over to metoprolol, and late echocardiograms were obtained after 18 +/- 5 (mean +/- SD) months of metoprolol therapy. All echocardiograms were read in blinded manner.

RESULTS

Patients treated with metoprolol had an initial decline (day 1 vs. day 0) in ventricular function (increase in end-systolic volume and decrease in ejection fraction). Ventricular function improved between months 1 and 3 (p = 0.013, metoprolol vs. standard therapy). Left ventricular mass regressed at 18 months (333 +/- 85 to 275 +/- 53 g, p = 0.011) but not at 3 months. Left ventricular shape became less spherical and assumed a more normal elliptical shape by 18 months (major/minor axis ratio 1.5 +/- 0.2 to 1.7 +/- 0.2, p = 0.0001).

CONCLUSIONS

Patients with heart failure treated with metoprolol do not demonstrate an improvement in systolic performance until after 1 month of therapy and may have a mild reduction in function initially. Long-term therapy with metoprolol results in a reversal of maladaptive remodeling with reduction in left ventricular volumes, regression of left ventricular mass and improved ventricular geometry by 18 months.

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

Although beta blockers have demonstrated a salutary effect on ventricular function in patients with heart failure, it is unclear whether a nonselective third-generation beta blocker produces different hemodynamic and energetic effects than a second-generation beta 1 selective agent. In 30 male patients with heart failure, we retrospectively analyzed hemodynamic data from 2 protocols examining the effects of a nonselective beta antagonist bucindolol (n = 15), and a highly selective beta 1 antagonist metoprolol (n = 15). Both studies were conducted in a similar fashion with patients undergoing cardiac catheterization before and after receiving 3 months of beta blockade. Both groups were matched at baseline in terms of ventricular function. beta 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 taking 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.

Predictors of systolic and diastolic improvement in patients with dilated cardiomyopathy treated with metoprolol

OBJECTIVES

The aim of this study was to determine which patients will have systolic and diastolic improvement after beta-blockade with metoprolol.

BACKGROUND

Beta-adrenergic blocking agents improve systolic and diastolic function in patients with heart failure. However, it is unclear which patients will respond best to therapy.

METHODS

We retrospectively examined baseline characteristics of 24 patients who underwent double-blind then open-label treatment with metoprolol to determine which characteristic predicted improvement in systolic and diastolic function. Degree of improvement in systolic function (22 patients) was defined by the change in left ventricular ejection fraction after 3 months of therapy. Degree of improvement in diastolic function (15 patients) was defined as the change in left ventricular end-diastolic pressure and change in the slope of the isovolumetric relaxation rate-end-systolic pressure relation.

RESULTS

Both systolic blood pressure at baseline (r = 0.54, p = 0.009) and the maximal positive value of the first derivative of left ventricular pressure with respect to time (peak +dP/dt) at baseline (r = 0.39, p = 0.07) correlated with improvement in ejection fraction after metoprolol treatment. Stepwise logistic regression demonstrated that only peak systolic pressure was an independent predictor of systolic improvement. Baseline heart rate, ventricular volumes, ejection fraction and adrenergic activation, as reflected by coronary sinus norepinephrine, did not predict response. Patients with the most diastolic impairment at baseline had the most favorable diastolic improvement. Those with the lowest myocardial respiratory quotient (most fatty acid utilization) at baseline also had the most marked reduction in left ventricular end-diastolic pressure.

CONCLUSIONS

These data suggest that those patients with the highest peak systolic pressure, highest left ventricular end-diastolic pressure and most prolonged isovolumetric relaxation at baseline will respond best to therapy with metoprolol. However, other patients without these characteristics may also benefit.

Functional importance of myocardial relaxation in patients with congestive heart failure

The factors that determine left ventricular end-diastolic pressure (LVEDP) are not completely understood. While many investigators measure relaxation in patients with heart failure, its relative functional importance remains unclear. The authors studied 22 patients with cardiomyopathy before and after 3 months of therapy with metoprolol or placebo. At catheterization, LVEDP, isovolumic relaxation rates not normalized for load (tau), the slope of the tau-end-systolic pressure relation (R), the constant of chamber stiffness (k), left ventricular ejection fraction, stroke volume, and coronary sinus norepinephrine levels were measured using micromanometer pressure measurements and digital ventriculography. The myocardial respiratory quotient was measured using blood gas analysis of the coronary sinus and left ventricular blood. Univariate analysis demonstrated that changes in LVEDP correlated with changes in relaxation rates, R, and the myocardial respiratory quotient. However, multivariate stepwise regression analysis demonstrated that only changes in R independently correlated with changes in LVEDP. These data suggest that relaxation may play some role in the determination of LVEDP in patients with heart failure. Changes in glycolytic activity may also play a role in the determination of LVEDP in patients with congestive heart failure.