Common Beta-Blockers Show Similar CV Risk

Beta-blockers atenolol and metoprolol tartrate had no statistically significant effect on the risk of cardiovascular (CV) events in patients with hypertension, according to an analysis from the Cardiovascular Research Network (CVRN) Hypertension Data Registry and reported online in Archives of Internal Medicine [doi:10.1001/archinternmed.2012.4276].

The findings suggest that the potentially unfavorable characteristics of atenolol do not support recent results from hypertension trials demonstrating higher CV rates in patients treated with atenolol compared with other classes of antihypertensive medications.

Safety and efficacy concerns of atenolol arose after 2 large trials found that the atenolol-based regimens were less effective than other antihypertensive regimens for preventing CV events in patients with hypertension. A subsequent meta-analysis found that beta-blockers were inferior to other agents, primarily regarding hypertension.

To investigate the lingering concerns about atenolol’s safety and efficacy, the researchers conducted a retrospective cohort study comparing patients initiating beta-blocker treatment with either atenolol or metoprolol tartrate on the rate of myocardial infarction (MI), heart failure (HF), and stroke. The researchers used data from the CVRN Hypertension Data Registry from 3 large integrated healthcare delivery systems to identify all patients ≥18 years of age with hypertension from 2000 through 2009.

The patients were started on therapy with either atenolol or metoprolol tartrate after the first date of diagnosis with no prior use of any beta-blocker for at least 12 months. The investigators performed 2 analyses: one employing standard covariate adjustment (n=120,978) and the other with propensity score-matching methodology (n=22,352).

During a median follow-up of 5.2 years, CV events consisted of 3517 MIs, 3272 HF hospitalizations, and 3664 strokes. Comparing metroprolol tartrate to atenolol resulted in hazard ratios (HRs) of 0.99 (95% confidence interval [CI], 0.97-1.01) for all 3 outcomes. Analysis of any CV event (n=9353) resulted in a HR of 0.98 (95% CI, 0.99-1.00). The propensity score-matched analysis results for MI (n=712 events), HF, (n=831 events), and stroke (n=773) were nearly identical to the multivariable results in HRs of 0.99 (95% CI, 0.97-1.02), 0.99 (95% CI, 0.96-1.01), and 0.99 (0.97-1.02), respectively. Any CV event (n=2064) resulted in a HR of 0.98 (95% CI, 0.95-1.00).

In the multivariable analysis of beta-blocker users, baseline blood pressure (BP) values were significantly higher in the atenolol group compared with the metoprolol tartrate group (148.5 and 84.2 mm Hg vs 145.4 and 82.5 mm Hg, respectively; P<.001) for systolic and diastolic BP. At the 6-month follow-up, systolic BP did not differ significantly between the atenolol and metoprolol tartrate groups (137.4 vs 137.5 mm Hg, respectively). Although diastolic BP was statistically higher in the metoprolol tartrate group versus the atenolol group (77.7 vs
77.3 mm Hg, respectively; P=.005), the difference was small.