It’s known beta-blockers reduce morbidity and mortality in those with heart failure with reduce left ventricular ejection fraction (HFrEF) in sinus rhythm. But questions remain about the roles baseline and achieved heart rates play in patients on beta-blockers and those with concomitant atrial fibrillation (AFib).

An international research team performed a meta-analysis on data from 11 trials to try and answer three questions:

1. Does baseline heart rate predict mortality?

2. Do mortality rates differ according to baseline heart rates for those taking beta-blockers?

3. What are the associations between heart rate, achieved dose and mortality?

Individual patient data was collected 18,637 patients, with the final cohort including 14,313 with sinus rhythm and 3,065 with AFib. The median age was 62 years old, and women made up 24 percent. The median baseline heart rate was 80 beats/min for the sinus rhythm group and 81 beats/min for the AFib.

The findings were published in the June issue of the Journal of the American College of Cardiology.

“Beta-blockers reduce mortality at all studied heart rates in patients with HFrEF in sinus rhythm, and those who achieved lower resting heart rates in dose-titrated trials had lower mortality,” wrote lead author Dipak Kotecha, PhD, MBBS, from the University of Birmingham Institute of Cardiovascular Sciences, and colleagues. “This did not hold true for patients with concomitant AFib, for whom there was no mortality benefit from beta-blockade, nor a relationship between heart rate and mortality.”

In the sinus rhythm group, there were 2,141 deaths among 14,166 patients (15.1 percent) over a mean follow-up period of 1.5 years. Baseline heart rate was associated with all-cause mortality, with a heart rate of 1.11 per 10 beats/min, adjusted for baseline variables and treatment allocation.

For the AFib group, there were 609 deaths among 3,034 patients (20.1 percent), but there was no association between baseline heart rate and mortality.

“For patients in sinus rhythm, resting heart rate is an important prognostic indicator, both before and after the initiation of beta-blockers,” wrote Kotecha et al. “A lower achieved heart rate is associated with lower subsequent mortality and is more likely to occur in patients initiated on beta-blockers. In patients with concomitant AFib, heart rate was not associated with mortality, and beta-blockers did not reduce mortality at any observed heart rate.”