Beta-blockers: new standard therapy for heart failure

The effect of biofeedback on function in patients with heart failure

Decreased HRV has been consistently associated with increased cardiac mortality and morbidity in HF patients. The aim of this study is to determine if a 6-week course of heart rate variability (HRV) biofeedback and breathing retraining could increase exercise tolerance, HRV, and quality of life in patients with New York Heart Association Class I-III heart failure (HF). Participants (N = 29) were randomly assigned to either the treatment group consisting of six sessions of breathing retraining, HRV biofeedback and daily practice, or the comparison group consisting of six sessions of quasi-false alpha-theta biofeedback and daily practice. Exercise tolerance, measured by the 6-min walk test (6MWT), HRV, measured by the standard deviation of normal of normal beats (SDNN), and quality of life, measured by the Minnesota Living with Congestive Heart Failure Questionnaire, were measured baseline (week 0), post (week 6), and follow-up (week 18). Cardiorespiratory biofeedback significantly increased exercise tolerance (p = .05) for the treatment group in the high (>or=31%) left ventricular ejection fraction (LVEF) category between baseline and follow-up. Neither a significant difference in SDNN (p = .09) nor quality of life (p = .08), was found between baseline and follow-up. A combination of HRV biofeedback and breathing retraining may improve exercise tolerance in patients with HF with an LVEF of 31% or higher. Because exercise tolerance is considered a strong prognostic indicator, cardiorespiratory biofeedback has the potential to improve cardiac mortality and morbidity in HF patients.

Molecular genetics and genomics of heart failure

Heart failure is a major disease burden worldwide, and its incidence continues to increase as premature deaths from other cardiovascular conditions decline. Although the overall molecular portrait of this multifactorial disease remains incomplete, molecular and genetic studies have implicated, in recent decades, various pathways and genes that participate in the pathophysiology of heart failure. Here, we highlight the current understanding of the molecular and genetic basis of heart failure and show how recently developed genomic tools are providing a new perspective on this complex disease.

Cardiac metaiodobenzylguanidine activity can predict the long-term efficacy of angiotensin-converting enzyme inhibitors and/or beta-adrenoceptor blockers in patients with heart failure

PURPOSE

Although the benefits of treatment with angiotensin-converting enzyme (ACE) inhibitors and beta-blockers are well known, no method has as yet been established to predict the efficacy of drug therapy. This study tested whether cardiac 123I-metaiodobenzylguanidine (MIBG) activity is of prognostic value and can predict the improvement in heart failure patients resulting from treatment with ACE inhibitors and/or beta-blockers.

METHODS

Following quantification of the heart-to-mediastinum ratio (HMR) of MIBG activity, 88 patients with heart failure who were treated with ACE inhibitors and/or beta-blockers (treated group) and 79 patients with heart failure who were treated conventionally without the aforementioned agents, and who served as controls, were followed up for 43 months with a primary endpoint of cardiac death.

RESULTS

The treated group had a significantly lower prevalence of cardiac death and a significantly lower mortality at 5 years compared with the control group (15% vs 37% and 21% vs 42%, p<0.05, respectively). Multivariate analysis revealed that significant predictors were HMR, age, nitrate use and ventricular tachycardia for the treated group, and HMR, nitrate use and NYHA class for the control group. The drug treatment significantly reduced mortality from 36% to 12% when HMR was 1.53 or more and from 53% to 37% when HMR was less than 1.53. The reduction in risk of mortality within 5 years in patients without a severe MIBG defect (67%) was twice that in patients with such a defect (32%) (p<0.05).

CONCLUSION

The reduction in mortality risk achieved by using ACE inhibitors and/or beta-blockers is associated with the severity of impairment of cardiac MIBG uptake. Cardiac MIBG activity can consequently be of long-term prognostic value in predicting the effectiveness of such treatment in patients with heart failure.

Predicted 3D structure for the human beta 2 adrenergic receptor and its binding site for agonists and antagonists

We report the 3D structure of human beta2 adrenergic receptor (AR) predicted by using the MembStruk first principles method. To validate this structure, we use the HierDock first principles method to predict the ligand-binding sites for epinephrine and norepinephrine and for eight other ligands, including agonists and antagonists to beta 2 AR and ligands not observed to bind to beta 2 AR. The binding sites agree well with available mutagenesis data, and the calculated relative binding energies correlate reasonably with measured binding affinities. In addition, we find characteristic differences in the predicted binding sites of known agonists and antagonists that allow us to infer the likely activity of other ligands. The predicted ligand-binding properties validate the methods used to predict the 3D structure and function. This validation is a successful step toward applying these procedures to predict the 3D structures and function of the other eight subtypes of ARs, which should enable the development of subtype-specific antagonists and agonists with reduced side effects.

An unusual death in an asthmatic patient

A 35-year-old black woman with a history of bronchial asthma collapsed and died after ingestion of three 20-mg tablets of propranolol. She was recently treated in the emergency department at a local hospital for an acute asthma exacerbation and was given a written prescription for prednisone. The prescription was filled and the medication was taken as prescribed. Within minutes after ingestion of the medication, she became acutely short of breath and was witnessed to collapse. Paramedics responded to the scene and initiated resuscitative efforts while en route to the local emergency department. The decedent was unable to be resuscitated and was pronounced dead shortly after reaching the hospital. It was later discovered that the medication she was given by the pharmacy was 20-mg propranolol tablets instead of 20-mg prednisone tablets.

Empleo de bisoprolol en la insuficiencia cardíaca. Resultados del estudio BISOCOR

INTRODUCTION AND OBJECTIVES

The benefits of beta blockers in heart failure are highly dependent on dosage. This study aimed to analyze the degree of concordance between targeted (CIBIS II) and achieved doses of bisoprolol in a group of patients with stable heart failure on conventional treatment. We also evaluated functional parameters, adverse effects and the reasons for withdrawal or drop-out.

PATIENTS AND METHOD

The study group consisted of 334 patients with stable systolic heart failure who were receiving conventional treatment. Treatment with bisoprolol was initiated according to current guidelines (starting dose 1.25 mg/day, with weekly increments to 5 mg/day, and then increments every four weeks to a targeted dosis of 10 mg/day). The main endpoint was the comparison between targeted dose and dose reached at each follow-up. Secondary endpoints were quality of life assessment (Minnesota Living with Heart Failure Questionnaire), functional status (New York Heart Association), ejection fraction change, and side effects during the 9-month follow-up period.

RESULTS

Thirty-four (10%) patients did not finish the study: 1 because of sudden death, 2 because of surgery, and 31 because of side effects. 63% of the patients attained the maximum targeted dose; the mean dose at the end of follow-up was 8.5 mg. Functional status, quality of life and ejection fraction improved significantly between the beginning and the end of the study. Only 4 patients had severe adverse effects.

CONCLUSIONS

This is the first study in Spain to show that bisoprolol can be used effectively at the maximum recommended doses, for the outpatient treatment of heart failure.