A population-based analysis of the class effect of beta-blockers after myocardial infarction

Class effect of beta-blockers in survivors of ST-elevation myocardial infarction: A nationwide cohort study using an insurance claims database

Beta-blockers can help reduce mortality following acute myocardial infarction (MI); however, whether beta-blockers exert a class effect remains controversial. This study identified all patients with first ST-elevation MI for the period of 2003 to 2010 from the National Health Insurance claims database, Taiwan. We compared patients prescribed carvedilol, bisoprolol, and propranolol. Study outcomes included all-cause death, cardiovascular death, and recurrence of MI. The propensity scores were constructed using multinomial logistic regression to model the receipt of different beta-blockers. Treating carvedilol group as a reference, we employed a simultaneous three-group comparison approach using the Cox regression model with adjustment for the propensity scores to compare the relative risks of various outcomes. Among the 16836 patients, 7591 were prescribed carvedilol, 5934 bisoprolol, and 3311 propranolol. Mean follow-up time was one year. After accounting for baseline differences, patients treated with bisoprolol (HR 0.87, 95% CI 0.72–1.05, p = 0.14) or propranolol (HR 1.07, 95% CI 0.84–1.36, p = 0.58) had a similar risk of all-cause death in comparison with carvedilol. No significant differences were observed among three beta-blocker groups with regard to the risks of cardiovascular death and recurrence of MI. Our results suggest that beta-blockers exert a possible class effect in the treatment of acute MI.

Beta-Blockers in the Management of Hypertension and/or Chronic Kidney Disease

This minireview provides current summaries of beta-blocker use in the management of hypertension and/or chronic kidney disease. Accumulated evidence suggests that atenolol is not sufficiently effective as a primary tool to treat hypertension. The less-than-adequate effect of beta-blockers in lowering the blood pressure and on vascular protection, and the unfavorable effects of these drugs, as compared to other antihypertensive agents, on the metabolic profile have been pointed out. On the other hand, in patients with chronic kidney disease, renin-angiotensin system blockers are the drugs of first choice for achieving the goal of renal protection. Recent studies have reported that vasodilatory beta-blockers have adequate antihypertensive efficacy and less harmful effects on the metabolic profile, and also exert beneficial effects on endothelial function and renal protection. However, there is still not sufficient evidence on the beneficial effects of the new beta-blockers.

Population-based analysis of class effect of β blockers in heart failure

The long-term use of β blockers has been shown to improve the outcomes of patients with heart failure (HF). However, it is still disputed whether this is a class effect, and, specifically, whether carvedilol or bisoprolol are superior to metoprolol. The present study was a comparative effectiveness study of β blockers for patients with HF in a population-based setting. We conducted an observational cohort study using the Quebec administrative databases to identify patients with HF who were prescribed a β blocker after the diagnosis of HF. We used descriptive statistics to characterize the patients by the type of β blocker prescribed at discharge. The unadjusted mortality for users of each β blocker was calculated using Kaplan-Meier curves and compared using the log-rank test. To account for differences in follow-up and to control for differences among patient characteristics, a multivariate Cox proportional hazards model was used to compare the mortality. Of the 26,787 patients with HF, with a median follow-up of 1.8 years per patient, the crude incidence of death was 47% with metoprolol, 40% with atenolol, 41% with carvedilol, 36% with bisoprolol, and 43% with acebutolol. After controlling for several different covariates, we found that carvedilol (hazard ratio [HR] 1.04, 95% confidence interval [CI] 0.97 to 1.12, p = 0.22) and bisoprolol (HR 0.96, 95% CI 0.91 to 1.01, p = 0.16) were not superior to metoprolol in improving survival. Atenolol (HR 0.82, 95% CI 0.77 to 0.87, p <0.0001) and acebutolol (HR 0.86, 95% CI 0.78 to 0.95, p = 0.004) were superior to metoprolol. In conclusion, we did not find evidence of a class effect for β blockers in patients with HF.

[Perioperative beta-receptor blockade. For and against]

Results from recent studies have questioned the application of beta-receptor blockers for reduction of morbidity and mortality during the perioperative period. This holds true especially for patients with no or only low cardiac risk. Although beta-receptor blockade was a form of standard therapy at the end of the 1990s, data today show no clear evidence for such a therapy not even in patients at risk for cardiac events. At least in patients with low risk the initiation of beta-receptor blockade during the perioperative period might lead to side-effects, thereby increasing morbidity and mortality.

Survival among patients with left ventricular systolic dysfunction treated with atenolol

Metoprolol succinate, carvedilol, and bisoprolol are approved for use in heart failure. Other beta-blockers have been found to be inferior (metoprolol tartrate) or have not been studied (atenolol). The authors compared all-cause mortality following treatment with either atenolol, carvedilol, or metoprolol tartrate for 974 patients with left ventricular function < or =40%. The unadjusted mortality at 6 months was lower with atenolol (3.2%) and carvedilol (4.2%) when compared with metoprolol tartrate (7.5%, P< or =.039). However, patients with atenolol were older but had less prior heart failure. After adjustment for the propensity to be treated with atenolol, patients actually treated with atenolol had a significantly lower risk of death compared with treatment with metoprolol tartrate and comparable outcome to those treated with carvedilol. These results suggest that atenolol may be useful for patients with heart failure treatment and highlight the need for a randomized trial comparing atenolol with established beta-blockers.

Comparative analysis of beta-blockers with other antihypertensive agents on cardiovascular outcomes in hypertensive patients with diabetes mellitus: a systematic review and meta-analysis

OBJECTIVES

To analyze the effects of beta-blockers (BBs) on cardiovascular (CV) outcomes in diabetic patients with hypertension.

DATA SOURCE

Literature search was performed with relevant search words using PubMed and Ovid Gateway search engines for trials published in English from June 1996 to July 2007.

REVIEW METHODS

Systematic reviews of randomized control trials that used BBs as treatment or control therapy in diabetic patients with hypertension were included for the analysis. All the included studies use intention-to-treat analysis. Two individual authors procured the data. Myocardial infarction, stroke, CV mortality, and total mortality were the outcomes analyzed. Relative risk across the different groups was calculated using Mantel-Haenszel random- and fixed-effects model. Interstudy heterogeneity was computed by chi(2) test. Results were calculated with 95%confidence intervals (CIs) and were considered significant with double-sided alpha error less than 0.05. Funnel plot was used to assess for publication bias.

RESULTS

Eight trials (N = 130,270) met the inclusion criteria for the analysis. The relative risks for myocardial infarction, stroke, CV mortality, and total mortality were 1.08 (95% CI 0.82-1.42; P = 0.6), 1.13 (95% CI 0.95-1.36; P = 0.1), 1.15 (95% CI 0.83-1.6; P = 0.3), and 1.16 (95% CI 0.92-1.47; P = 0.2), respectively. BBs were associated with increased risk for CV mortality 1.39 (95% CI 1.07-1.804; P ,0.01) when compared with renin angiotensin blockade (RAS) therapy.

CONCLUSION

BBs have increased risk for CV mortality when compared with RAS blockade therapy in diabetic patients with hypertension. BBs do not have increased risk for myocardial infarction, stroke, CV mortality, and total mortality when compared with control antihypertensive therapy in diabetic patients with hypertension.

The unresolved issues with risk stratification and management of patients with coronary artery disease undergoing major vascular surgery

PURPOSE

The purpose of this article, with a specific focus on patients undergoing vascular surgery, is to review controversial issues related to mechanisms of perioperative myocardial infarction (MI), coronary artery disease detection, and strategies to reduce perioperative complications. We propose explanations for the many conflicting results that have recently emerged in the literature.Source documents: We searched MEDLINE and reviewed all relevant manuscripts and scientific statements regarding management of patients undergoing non-cardiac surgery.

PRINCIPAL FINDINGS

Identification and prevention of ischemia in patients undergoing vascular surgery remains controversial. While the identification of preoperative ischemia is a marker of a higher perioperative risk, the value of identifying such ischemia has been questioned. We believe this may be, at least in part, due to our limited understanding of perioperative MI. Appropriate management of patients, based on the results of such testing, is likely the key to improving outcomes, and deserves further investigation. Efforts aimed at reducing the ischemic consequences of severe coronary plaques (by revascularization or beta-blocker therapy) have yielded conflicting results. The use of high doses of preoperative beta-blocker therapy may be harmful. Some studies suggest a promising role for statin therapy. Benefits of acetylsalicylic acid must be weighted against the risk of bleeding.

CONCLUSION

Many questions remain unanswered about the impact of detecting inducible ischemia, and the role of revascularization or beta-blockers in patients undergoing vascular surgery. A better understanding of the pathophysiology of perioperative MI is critical, in order to identify the best approach to improve cardiac outcomes in these patients.