Tolerability, safety, and efficacy of beta-blockade in black patients with heart failure in the community setting: insights from a large prospective beta-blocker registry

Race and Beta-Blocker Survival Benefit in Patients With Heart Failure: An Investigation of Self-Reported Race and Proportion of African Genetic Ancestry

Background

It remains unclear whether beta‐blockade is similarly effective in black patients with heart failure and reduced ejection fraction as in white patients, but self‐reported race is a complex social construct with both biological and environmental components. The objective of this study was to compare the reduction in mortality associated with beta‐blocker exposure in heart failure and reduced ejection fraction patients by both self‐reported race and by proportion African genetic ancestry.

Methods and Results

Insured patients with heart failure and reduced ejection fraction (n=1122) were included in a prospective registry at Henry Ford Health System. This included 575 self‐reported blacks (129 deaths, 22%) and 547 self‐reported whites (126 deaths, 23%) followed for a median 3.0 years. Beta‐blocker exposure (BBexp) was calculated from pharmacy claims, and the proportion of African genetic ancestry was determined from genome‐wide array data. Time‐dependent Cox proportional hazards regression was used to separately test the association of BBexp with all‐cause mortality by self‐reported race or by proportion of African genetic ancestry. Both sets of models were evaluated unadjusted and then adjusted for baseline risk factors and beta‐blocker propensity score. BBexp effect estimates were protective and of similar magnitude both by self‐reported race and by African genetic ancestry (adjusted hazard ratio=0.56 in blacks and adjusted hazard ratio=0.48 in whites). The tests for interactions with BBexp for both self‐reported race and for African genetic ancestry were not statistically significant in any model (P>0.1 for all).

Conclusions

Among black and white patients with heart failure and reduced ejection fraction, reduction in all‐cause mortality associated with BBexp was similar, regardless of self‐reported race or proportion African genetic ancestry.

A Review of the External Validity of Clinical Trials with Beta-Blockers in Heart Failure

BACKGROUND

Beta-blockers (BBs) are the mainstay prognostic medication for all stages of chronic heart failure (CHF). There are many classes of BBs, each of which has varying levels of evidence to support its efficacy in CHF. However, most CHF patients have one or more comorbid conditions such as diabetes, renal impairment, and/or atrial fibrillation. Patient enrollment to randomized controlled trials (RCTs) often excludes those with certain comorbidities, particularly if the symptoms are severe. Consequently, the extent to which evidence drawn from RCTs is generalizable to CHF patients has not been well described. Clinical guidelines also underrepresent this point by providing generic advice for all patients. The aim of this review is to examine the evidence to support the use of BBs in CHF patients with common comorbid conditions.

METHODS

We searched MEDLINE, PubMed, and the reference lists of reviews for RCTs, post hoc analyses, systematic reviews, and meta-analyses that report on use of BBs in CHF along with patient demographics and comorbidities.

RESULTS

In total, 38 studies from 28 RCTs were identified, which provided data on six BBs against placebo or head to head with another BB agent in ischemic and nonischemic cardiomyopathies. Several studies explored BBs in older patients. Female patients and non-Caucasian race were underrepresented in trials. End points were cardiovascular hospitalization and mortality. Comorbid diabetes, renal impairment, or atrial fibrillation was detailed; however, no reference to disease spectrum or management goals as a focus could be seen in any of the studies. In this sense, enrollment may have limited more severe grades of these comorbidities.

CONCLUSIONS

RCTs provide authoritative information for a spectrum of CHF presentations that support guidelines. RCTs may provide inadequate information for more heterogeneous CHF patient cohorts. Greater Phase IV research may be needed to fill this gap and inform guidelines for a more global patient population.

Association of β-blocker exposure with outcomes in heart failure differs between African American and white patients

BACKGROUND

β-Blockers (BB) are a mainstay of heart failure (HF) treatment, yet there are inconclusive data regarding their efficacy in African American individuals.

METHODS AND RESULTS

We performed a retrospective study of insured patients who received care from a large health system who were hospitalized for HF between January 2000 and June 2008 and had a documented ejection fraction <50%. BB exposure was estimated over 6-month rolling windows, using pharmacy claims data. Proportional hazards regression was used to test the association between BB exposure and all-cause hospitalization or death with adjustment for baseline covariates and other HF medication exposure. We performed analyses stratified by race and overall with a BB exposure×race interaction term. A total of 1094 patients met inclusion criteria (476 white and 618 African American individuals). Median follow-up was 2.1 years. In adjusted models, BB exposure was associated with lower risk of death or hospitalization in both groups, but more so in white individuals (hazard ratio, 0.40; 95% confidence interval, 0.27, 0.60; P<0.001) compared with African American individuals (hazard ratio, 0.67; 95% confidence interval, 0.48, 0.94; P=0.024). A formal test for interaction indicated that the protection association for BB exposure differed by race (P=0.098, β=0.40). Reanalysis restricted to BBs approved for HF or HF-specific hospitalizations did not substantively alter the findings.

CONCLUSIONS

BB appears to be 40-50% less effective in preventing death or hospitalization among African American patients with HF as compared with white individuals. Further study is needed to better understand BB effectiveness in African Americans with HF.

Are tolerability concerns a class effect of beta-blockers in treating patients with hypertension?

Beta-blockers (beta-blockers) have demonstrated their value across the cardiovascular disease spectrum. Beta-blockers effectively lower blood pressure in patients with hypertension and provide symptomatic or mortality benefits in patients with heart failure and in post-myocardial infarction patients. However, despite their utility, beta-blockers remain underused. There have been recent concerns that beta-blockers as a class are not as effective as once thought in uncomplicated hypertension due to a relatively weak effect on reduction of stroke and the absence of an effect on coronary heart disease when compared with placebo or no treatment. Underuse can, in part, be related to tolerability concerns. Beta-blockers have been traditionally associated with side effects including depression, fatigue, sexual dysfunction, and cold extremities, which limit their acceptance by patients and physicians and may lead to discontinuation of therapy. Because of inherent heterogeneity of the beta-blocker class in terms of adrenergic receptor selectivity, intrinsic sympathomimetic activity, and vasodilatory activity, these agents vary in tolerability profile. Recently, more attention has been focused on the third-generation vasodilatory beta-blockers (ie, carvedilol, labetalol, and nebivolol), with the recognition that these agents may diverge in meaningful ways from the traditional beta-blockers. By examining the differences among members of the beta-blocker class, it may be possible to determine whether and which tolerability issues are indeed a class effect of beta-blockers or whether these agents should be evaluated on a case-by-case basis.

Race-based therapeutics

The issue of race in medicine is problematic. Race is not a physiologic grouping, and all persons of a given race do not necessarily share the same clinical phenotype or genetic substrate. Despite clear signals that certain risk factors and diseases vary as a function of race, translating those differences into race-based therapeutics has been awkward and has done little to change the natural history of cardiovascular disease as it affects special populations. Among the varied special populations, the African American population appears to have the most significant and adverse variances for cardiovascular disease as well as worrisome signals that drug responsiveness varies. Recent guideline statements have now acknowledged certain treatment options that are most appropriate for African Americans with cardiovascular disease, especially hypertension and heart failure. As more physiologic markers of disease and drug responsiveness become available, the need for racial designations in medicine may lessen, and therapies can be optimized for all patients without regard to race or ethnicity.