Therapeutic controversies with use of beta-adrenoceptor blockade in heart failure

Vidarabine, an Anti-Herpes Virus Agent, Protects Against the Development of Heart Failure With Relatively Mild Side-Effects on Cardiac Function in a Canine Model of Pacing-Induced Dilated Cardiomyopathy

BACKGROUND

In heart failure patients, chronic hyperactivation of sympathetic signaling is known to exacerbate cardiac dysfunction. In this study, the cardioprotective effect of vidarabine, an anti-herpes virus agent, which we identified as a cardiac adenylyl cyclase inhibitor, in dogs with pacing-induced dilated cardiomyopathy (DCM) was evaluated. In addition, the adverse effects of vidarabine on basal cardiac function was compared to those of the β-blocker, carvedilol.Methods and Results:Vidarabine and carvedilol attenuated the development of pacing-induced systolic dysfunction significantly and with equal effectiveness. Both agents also inhibited the development of cardiac apoptosis and fibrosis and reduced the Na⁺-Ca²⁺exchanger-1 protein level in the heart. Importantly, carvedilol significantly enlarged the left ventricle and atrium; vidarabine, in contrast, did not. Vidarabine-treated dogs maintained cardiac response to β-AR stimulation better than carvedilol-treated dogs did.

CONCLUSIONS

Vidarabine may protect against pacing-induced DCM with less suppression of basal cardiac function than carvedilol in a dog model. (Circ J 2016; 80: 2496-2505).

Impact of β-Blocker Dosage Changes during Heart Failure Exacerbation

Background:

Although β-blockers are important life-saving medications in heart failure patients, studies evaluating β-blocker dosing in decompensated heart failure are limited.

Objective:

To determine the clinical outcomes in patients with severe decompensated heart failure receiving the same dose of β-blockers as well as those whose outpatient regimen was altered.

Methods:

A retrospective chart analysis was conducted in patients with severe decompensated heart failure receiving chronic β-blocker therapy who were admitted to the hospital for decompensated heart failure. Of 245 patients identified, 76 were included in the study: same dose (n = 26), decreased dose (n = 19), discontinued dose (n = 21), or increased dose (n = 10). χ2 Analysis for K-independent samples evaluated the incidence of proarrhythmic events, mortality, and the number of recurrent hospitalizations after the index admission. Stepwise forward linear regression analysis determined the variables correlated with morbidity and mortality in these patients.

Results:

New arrhythmias during hospital admission occurred in 19 (25%) patients. The discontinued dose group had the most proarrhythmic events (47.6%; n = 10) and the most deaths (50%) in 6 months. Arrhythmias developed 1.8 and 3 days following β-blocker discontinuation or dosage reduction, respectively.

Conclusions:

Patients who remained on their outpatient β-blocker dose upon admission for decompensated heart failure had better clinical outcomes than others whose β-blocker dose was changed. A prospective, randomized, controlled clinical trial is warranted to further explore the implications of this drug–disease state interaction.

Beta-blocker treatment of dilated cardiomyopathy with congestive heart failure in children: a multi-institutional experience

BACKGROUND

Dilated cardiomyopathy is the primary indication for heart transplantation in children beyond infancy. Although beta-blockers improve symptoms, ejection fraction, and survival in adults with congestive heart failure, little is known of their effects in children.

METHODS

This study reviews our pediatric experience with the beta-blocker, metoprolol, at 3 institutions. We gave metoprolol to 15 children, age 8.6 +/- 1.3 years (range 2.5 to 15 years), with idiopathic dilated cardiomyopathy (n = 9), anthracycline cardiomyopathy (n = 3), and Duchenne muscular dystrophy cardiomyopathy, postmyocarditis cardiomyopathy, and post-surgical cardiomyopathy (n = 1 each). All had been treated with conventional medications (digoxin, diuretics, and ACE inhibitors) for 22.5 +/- 9 months before starting metoprolol. Metoprolol was started at 0.1 to 0.2 mg/kg/ dose given twice daily and slowly increased over a period of weeks to a dose of 1.1 +/- 0.1 mg/kg/day (range 0.5 to 2.3 mg/kg/day).

RESULTS

Between the time point of stabilization on conventional medications and the initiation of metoprolol therapy, there was no significant change in fractional shortening (13.1 +/- 1.2% vs 15.0 +/- 1.2%) or ejection fraction (25.6 +/- 2.1% vs 27.0 +/- 3.4%). However, after metoprolol therapy for 23.2 +/- 7 months, there was a significant increase in fractional shortening(23.3 +/- 2.6%) and ejection fraction (41.1 +/- 4.3%) (p < 0.05).

CONCLUSIONS

Metoprolol improves ventricular function in some children with dilated cardiomyopathy and congestive heart failure. Further study is warranted to better define which children may benefit most from beta-blocker therapy and which beta-blockers are most efficacious.

Cardiac and hemodynamic effects of TZC-5665, a novel pyridazinone derivative, and its metabolite in humans and dogs

1. TZC-5665 is a novel pyridazinone derivative with vasodilatory and beta-adrenergic blocking activities and type III phosphodiesterase inhibitory action. 2. In healthy volunteers, TZC-5665 was rapidly absorbed and immediately metabolized. Its main metabolite, M-2, remained at a higher concentration in plasma. Orally administered TZC-5665 reduced end-diastolic left ventricular volume (20.16 ml) and exhibited a tendency to increase ejection fraction (0.04). 3. In dogs, M-2 dose-dependently increased cardiac contractility and reduced both preload and afterload. These effects appeared more potent in the failed heart than in the normal heart. At the same dose (30 micrograms/kg), the effects of M-2 seem to be more potent than those of milrinone. 4. We concluded that TZC-5665 is a useful medication for treating patients with chronic congestive heart failure (CHF) because of the positive inotropic and vasodilating effects due to its active metabolite in addition to its own beta-adrenergic blocking actions.

Hemodynamic predictors of early intolerance and long-term effects of propranolol in dilated cardiomyopathy

BACKGROUND

Fifty-six patients with dilated cardiomyopathy (DCM) (aged 14-68 years) and background therapy of angiotensin-converting enzyme inhibitors, diuretics, and digoxin were given an initial challenge of propranolol in gradually increasing doses. These patients were studied noninvasively and hemodynamically and subjected to right ventricle biopsy.

METHODS AND RESULTS

Forty-four patients tolerated propranolol and received the drug for 6 months; 12 patients deteriorated after starting the drug with worsening of congestive heart failure and/or hypotension. The patients who did not tolerate propranolol had higher left ventricular end-diastolic dimension (73 +/- 8 vs 66 +/- 8 mm, P < .05), and severe mitral regurgitation was more common. Hemodynamically these patients had higher heart rate, right ventricular end-diastolic pressure, mean pulmonary artery pressure, mean pulmonary artery wedge pressure, and left ventricular end-diastolic pressure (102 +/- 16 vs 89 +/- 12 beats/min, 15 +/- 7 vs 9 +/- 4, 39 +/- 16 vs 31 +/- 12, 28 +/- 8 vs 21 +/- 8, 28 +/- 8 vs 22 +/- 8 mmHg, respectively, P < .01). These patients had a significantly lower cardiac index (1.9 +/- 0.6 vs 2.5 +/- 0.6 L/min/m2, P < .01). Forty patients completed 6 months follow-up evaluation and were further subjected to repeat noninvasive and hemodynamic study. There was a significant improvement in New York Heart Association class, cardiothoracic ratio, and left ventricular end-diastolic dimension (68% vs 62%, 66 +/- 8 vs 62 +/- 7 mm, respectively, P < .01), while the ejection fraction (EF) rose from 23 to 35% (P < .001). Hemodynamically, there was a significant decrease in heart rate, right ventricular end-diastolic pressure, mean pulmonary artery pressure, mean pulmonary artery wedge pressure, and left ventricular end-diastolic pressure (91 +/- 14 vs 71 +/- 5 beats/min, 9 +/- 4 vs 5 +/- 3, 32 +/- 11 vs 22 +/- 7, 25 +/- 9 vs 17 +/- 8, 21 +/- 7 vs 14 +/- 4 mmHg, P < .05). The cardiac index rose from 2.3 +/- 0.6 to 3.2 +/- 0.7 L/min/m2 (P < .01).

CONCLUSIONS

Propranolol in dilated cardiomyopathy is associated with significant intolerance. Those who tolerate propranolol seem to have long-term beneficial effects. This study is limited as it is uncontrolled and nonrandomized.

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.

Effect of low dose beta blockers on atrial and ventricular (B type) natriuretic factor in heart failure: a double blind, randomised comparison of metoprolol and a third generation vasodilating beta blocker

OBJECTIVES

This study examines the acute effects of two differing beta adrenergic blocking agents (metoprolol and a third generation vasodilating beta blocker) on plasma concentrations of atrial natriuretic factor (ANF), brain (ventricular) natriuretic factor (BNF), and haemodynamic variables in patients with heart failure.

SETTING

University teaching hospital.

METHODS

20 patients with impaired left ventricular systolic function [ejection fraction 32 (SEM 2.3)%] were randomised in a double blind manner to receive either oral metoprolol 6.25 mg twice daily or celiprolol 25 mg daily. Haemodynamic variables were evaluated by Swan-Ganz pulmonary artery catheter over 24 hours. ANF and BNF concentrations were measured at baseline, 5 h, and 24 h by radioimmunoassay.

RESULTS

At baseline ANF and BNF concentrations were considerably raised compared to the normal range. Treatment with metoprolol caused ANF to rise further to 147% of the basal level at 5 h (P = 0.017) and 112% at 24 h (P = 0.029). This was associated with a small but non-significant rise in pulmonary capillary wedge pressure. Cardiac output and systemic vascular resistance were unchanged at 24 h. In contrast, after celiprolol ANF fell to 90% of basal levels at 5 h and to 74% of basal level at 24 h (P = 0.019), associated with a small but non-significant fall in pulmonary capillary wedge pressure [-3.3 (2.7) mm Hg] and systemic vascular resistance, and rise in cardiac output from 3.2 (0.2) to 4.0 (0.4) l/min (P = 0.04). BNF concentrations rose to 112% of baseline at 5 h (P = 0.09) after metoprolol but fell slightly, to 91% of baseline values, after celiprolol (NS).

CONCLUSIONS

Metoprolol, even in very low doses (6.25 mg), produced a rise in ANF and BNF, although minimal haemodynamic changes were detected. In contrast, a vasodilating beta blocker was associated with a significant fall in ANF and BNF and a small rise in cardiac output. This study confirms both the advantages of vasodilating beta blockers over metoprolol for initial treatment of heart failure and the usefulness of ANF and BNF measurements for the assessment of drug effects in heart failure compared to traditional haemodynamic measurements.

Use of beta-adrenoceptor blockers in patients with congestive heart failure

The beneficial effect of chronic beta-blockade in patients with congestive heart failure has been repeatedly shown since its introduction into treatment for this condition in 1975. Still this kind of therapy remains controversial, it is sometimes regarded as a therapeutic paradox, and its use is mainly limited to specialist centers. Various favorable effects of beta-blockers in patients with heart failure due to idiopathic dilated cardiomyopathy and ischemic heart disease have been demonstrated, the principal among them being reduction in energy requirements and ischemia, antiarrhythmogenic effect, improvement of diastolic function, protection of myocytes against catecholamine overload, centrally mediated increase in vagal tone, upregulation of beta-adrenergic receptors, and possible blockade of autoantibodies against beta 1-receptors. Although most of the studies used metoprolol, these effects may be relevant to certain other beta-blockers. Despite very solid pathophysiological and pharmacological rationales for the use of beta-blockade, a major obstacle for a general acceptance of this therapeutic concept is the striking contrast between hemodynamic changes during the acute effect and long-term treatment. When titrated carefully from very low doses and used with a true commitment to long-term treatment, beta-blockers have been shown to prevent further deterioration of heart failure and to improve hemodynamics, exercise tolerance, quality of life, and prognosis.

Effects of short- and long-term carvedilol administration on rest and exercise hemodynamic variables, exercise capacity and clinical conditions in patients with idiopathic dilated cardiomyopathy

OBJECTIVES

The study evaluated the effects of short- and long-term administration of carvedilol in patients with idiopathic dilated cardiomyopathy.

BACKGROUND

Carvedilol is a beta-adrenergic blocking agent with vasodilator activity that might be well tolerated in patients with heart failure.

METHODS

Forty patients with idiopathic dilated cardiomyopathy treated with digoxin, furosemide and angiotensin-converting enzyme inhibitors were randomized in a double-blind manner to receive either placebo or carvedilol. Right heart hemodynamic variables were evaluated up to 8 h after short-term drug administration and, on the next day, during cardiopulmonary exercise testing before and 3 h after drug ingestion. Placebo or carvedilol was added to standard therapy, starting with a dose of 6.25 mg twice a day with weekly increments up to the maximum of 25 mg twice a day. Patients were reevaluated after 4 months by cardiopulmonary exercise testing and measurement of right heart hemodynamic variables 12 h after last drug ingestion and 3 h after drug readministration. Left ventricular ejection fraction and volume, measured by equilibrium radionuclide ventriculography, quality of life and submaximal exercise duration were assessed before and after long-term therapy.

RESULTS

Compared with placebo, carvedilol produced a short-term reduction in heart rate and pulmonary artery and pulmonary wedge pressures and, after long-term administration, increased both rest and peak exercise cardiac, stroke volume and stroke work indexes, with a further reduction in right atrial, pulmonary artery and pulmonary wedge pressures. Long-term carvedilol administration also improved rest left ventricular ejection fraction (from 20 +/- 7% to 30 +/- 12%, p < 0.001), submaximal exercise capacity, quality of life and New York Heart Association functional class. No baseline variable was predictive of the response to therapy.

CONCLUSIONS

Short-term carvedilol administration reduces heart rate and mean pulmonary artery and pulmonary wedge pressures, whereas it improves both long-term rest and exercise left ventricular systolic function, reduces heart failure symptoms and improves submaximal exercise tolerance in patients with idiopathic cardiomyopathy.