Role of beta adrenergic receptor polymorphisms in heart failure: systematic review and meta-analysis

RAAS and adrenergic genes in heart failure: Function, predisposition and survival implications

It is well appreciated that several neurohormones and signaling cascades are activated that promote long-term deterioration of cardiac function and structure. Activation of the renin-angiotensin-aldosterone system (RAAS) and the adrenergic system is closely related to heart failure. Common gene variants that encode neurohormonal, adrenergic and intracellular proteins have been demonstrated to modulate the course and consequences of heart failure. However, the literature is replete with conflicting results and it remains uncertain as to whether particular gene variants predispose heart failure. Therefore, the main purpose of this review was to discuss the effects of single nucleotide polymorphisms (SNPs) that are located in genes encoding elements of the RAAS and the adrenergic system on the predisposition to and survival from heart failure. Most studies indicate that common SNPs encoding elements of the RAAS and the adrenergic system do not predispose individuals to heart failure. Conversely, it has been demonstrated that ARB1 Arg389Gly, GRK5 Gln41Leu, ACE I/D, CYP11B2 C-344T and AGTR1 A+1166C modulate pharmacological responses and have a considerable impact on cardiac-related survival. It should not be expected, however, that a single polymorphism determines survival, given that multiple gene products and environmental factors contribute to the pathogenesis of heart failure. Therefore, future studies should consider the interaction effects of multiple genes in populations that are as homogeneous as possible with respect to environmental characteristics.

Nebivolol in chronic heart failure: current evidence and future perspectives

IMPORTANCE OF THE FIELD

Chronic activation of the sympathetic nervous system leads to deterioration of cardiovascular function in heart failure patients. In systolic heart failure, beta-blockers were proven to be effective in decreasing the number of deaths and improving morbidity. However, beta-blockers are a heterogeneous drug group, consisting of agents with different selectivity for adrenergic receptors and/or additional effects in heart or peripheral circulation.

AREAS COVERED IN THE REVIEW

We describe the role of the sympathetic nervous system, beta-blockers and specifically nebivolol in chronic heart failure.

WHAT THE READER WILL GAIN

Nebivolol is a third-generation beta-blocker, with high beta(1)/beta(2) selectivity. Moreover, it has important vasodilating properties, by stimulating the production of nitric oxide. Smaller studies have already shown beneficial effects of nebivolol treatment on surrogate end points in heart failure patients. The recently published SENIORS (Phase III) study in an elderly heart failure population demonstrated a decreased number of clinical events in patients treated with nebivolol. Importantly, this effect was observed in patients with both impaired and preserved left ventricular systolic function.

TAKE HOME MESSAGE

Specific beta-blockers may have distinct effects in various subgroups of heart failure patients. So far, nebivolol is the only beta-blocker to have been shown effective in elderly heart failure patients, regardless of their left ventricular ejection fraction.

Cardiovascular nursing on human genomics: what do cardiovascular nurses need to know about congestive heart failure?

This paper presents the main causes of heart failure (HF) and an update on the genetics studies on each cause. The review includes a delineation of the etiology and fundamental pathophysiology of HF and provides rational for treatment for the patient and family. Various cardiomyopathies are discussed, including primary cardiomyopathies, mixed cardiomyopathies, cardiomyopathies that involve altered cardiac muscle along with generalized multiorgan disorders, and various cardiovascular conditions, such as coronary artery disease (ischemic cardiomyopathy) and hypertension (hypertensive cardiomyopathy). A brief review of pharmacogenetics and HF is presented. The application of the genetic components of cardiomyopathy and pharmacogenetics is included to enhance cardiovascular nursing care.

Beta 1- and beta 2-adrenoceptor polymorphisms and cardiovascular diseases

Beta(1)- and beta(2)-adrenoceptors (AR) play a pivotal role in the regulation of cardiovascular function. Both beta-AR subtypes are polymorphic: two single nucleotide polymorphisms (SNPs) have been described for the beta(1)- (Ser49Gly, Arg389Gly) and four for the beta(2)-AR (Arg-19Cys, Arg16Gly, Gln27Glu, Thr164Ile), and they are possibly of functional relevance. In recombinant cell systems, Gly49-beta(1)-AR are more susceptible to agonist-promoted down-regulation than Ser49-beta(1)-AR, whereas Arg389-beta(1)-AR are three to four times more responsive to agonist-evoked stimulation than Gly389-beta(1)-AR. With respect to beta(2)-AR, the Cys-19 variant is associated with greater beta(2)-AR expression than the Arg-19 variant; Gly16-beta(2)-AR are more susceptible, whereas Glu27-beta(2)-AR are almost resistant to agonist-promoted down-regulation; Thr164-beta(2)-AR are three to four times more responsive to agonist-evoked stimulation than Ile164-beta(2)-AR. Several studies addressed potential phenotypic consequences of these SNPs in vivo by influencing and/or contributing to the pathophysiology of cardiovascular/pulmonary diseases such as hypertension, congestive heart failure, arrhythmias or asthma. At present, it appears that these beta-AR SNPs are very likely not disease-causing genes but possibly predictive for the responsiveness to agonists and antagonists. Patients carrying one or two alleles of the Gly389-beta(1)-AR are poor or non-responders to agonists and antagonists, whereas patients homozygous for the Arg389-beta(1)-AR are good responders. Subjects carrying the Ile164-beta(2)-AR exhibit blunted responses to beta(2)-AR stimulation. Asthma patients carrying the Arg16-Gln27-Thr164-beta(2)-AR haplotype who receive regularly short- or long-acting beta(2)-AR agonists are rather susceptible to agonist-induced desensitization and in consequence exhibit reduced bronchodilating and -protective effects and/or increased asthma exacerbations. The clinical relevance of these findings is still under debate.

Future directions in cardiocerebral resuscitation

Outcomes from pediatric cardiac arrest and cardiopulmonary resuscitation (CPR) seem to be incrementally improving. The past 2 decades have brought advances in the understanding of the pathophysiology of cardiac arrest and ventricular fibrillation, better treatment strategies, and a more robust standard for CPR epidemiology and research reporting. The evolution of practice based on an improved understanding of the pathophysiology and timing, intensity, duration, and variability of the hypoxic-ischemic insult should lead to goal-directed therapy gated to the phase of cardiac arrest and the postarrest period encountered. By strategically focusing therapies to specific phases of cardiac arrest and resuscitation and to the evolving pathophysiology and by implementing evidence-based practice, there is great promise that critical care interventions can lead the way to more successful cardiopulmonary and cerebral resuscitation in children.

Common beta-adrenergic receptor polymorphisms are not associated with risk of sudden cardiac death in patients with coronary artery disease

BACKGROUND

Previous studies suggest that beta-adrenergic receptor (betaAR) single nucleotide polymorphisms (SNPs) are associated with out-of-hospital sudden cardiac death (SCD) and overall mortality, but did not specifically examine risk of ventricular arrhythmias (VA).

OBJECTIVE

This study examined the effects of functional SNPs of beta1AR and beta2AR on the risk of VA and SCD in patients with coronary artery disease (CAD).

METHODS

beta1AR (Ser49Gly, Arg389Gly) and beta2AR (Gly16Arg, Gln27Glu) SNPs were genotyped in a case-control study comparing 107 patients with CAD and aborted SCD due to VA with 287 CAD control subjects and 101 healthy control subjects. These variants were also examined in the Heart and Estrogen Replacement Study (HERS) cohort of women with CAD followed for SCD (n = 66) and nonfatal VA (NFVA) (n = 33) over 6.8 years.

RESULTS

In the case-control study, no statistically significant association was observed for the odds of SCD with any of the SNPs or haplotypes tested. Similarly, HERS revealed null effects for these SNPs and haplotypes in relation to risk of SCD, SCD + NFVA, and all-cause mortality. Point estimates and confidence intervals for risk of SCD associated with beta2AR27 were similar in both populations (Glu27 carriers vs Gln27 homozygotes: adjusted odds ratio 1.23 [95% confidence interval 0.75 to 2.03, P = .41] in the case-control study, and adjusted relative risk (RR) 1.18 [95% confidence interval 0.69 to 2.00, P = .55] in HERS). These null findings trend in the opposite direction and differ from previous published estimates (P = .01 and .07, respectively).

CONCLUSION

We did not find an increase in risk of SCD associated with any of these common betaAR polymorphisms.