Clinical

Atrial fibrillation blunts beta-blockers for HFrEF

 

Key clinical point: Patients with heart failure with reduced ejection fraction and atrial fibrillation showed no mortality benefit from beta-blocker treatment or from a heart rate reduced from baseline levels.

Major finding: All-cause mortality was similar in patients with HFrEF and atrial fibrillation regardless of whether they received a beta-blocker or placebo.

Data source: BB-META-HF, a meta-analysis of 11 beta-blocker treatment trials with 17,378 HFrEF patients.

Disclosures: BB-META-HF received funding from Menarini and GlaxoSmithKline. Dr. Cleland has received research funding and honoraria from GlaxoSmithKline.

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New insights gained on beta-blockers for HFrEF

 

The findings from this analysis have several implications. First, the association of reduced mortality with reduced heart rate occurred only in patients in sinus rhythm. The irregular heart rhythms in patients with atrial fibrillation may counterbalance any reverse remodeling effects that come from reducing heart rate.

Also, the beneficial effect of beta-blocker treatment was roughly similar regardless of whether baseline heart rate was high or low. This distinguishes beta-blockers from ivabradine, a drug that only reduces heart rate. The magnitude of benefit from ivabradine treatment depends on a patient’s baseline heart rate. The observation that beta-blockers do not have the same limitation suggests that the mechanism of action of beta-blockers may go beyond their heart rate effect. It may also result from the effect of beta-blockers on antagonizing toxic effects from beta-adrenergic stimulation.

The pooled analysis also showed that many patients with HFrEF in sinus rhythm continued to have a high heart rate despite beta-blocker treatment. These patients may get additional benefit from further treatment to reduce their heart rate, with an agent like ivabradine.

But we must be cautious in interpreting the findings because they represent a secondary analysis, and the endpoint studied does not take into account quality of life, exercise tolerance, heart rate control, and tachyarrhythmias. We need prospective, randomized trials of HFrEF patients in sinus rhythm and with atrial fibrillation to better understand how to optimally treat these different types of patients.

The findings highlight that beta-blockers remain a mainstay of treatment for patients with HFrEF in sinus rhythm, and that we have more limited treatment options for HFrEF patients with atrial fibrillation.

Michael Böhm, MD, is professor and director of the cardiology clinic at Saarland University Hospital in Homburg, Germany. He has received honoraria from Bayer, Medtronic, Servier, and Pfizer, and he was a coauthor on the report presented by Dr. Cleland. He made these comments as designated discussant for the study.


 

AT HEART FAILURE 2017

 

– Maximal beta-blocker treatment and lower heart rates are effective at cutting all-cause mortality in patients with heart failure with reduced ejection fraction (HFrEF) who are also in sinus rhythm, but it’s a totally different story for patients with similar heart failure plus atrial fibrillation. In the atrial fibrillation subgroup, treatment with a beta-blocker linked with no mortality benefit, and lower heart rates – below 70 beats per minute – appeared to actually link with worse patient survival, based on a meta-analysis of data from 11 beta-blocker trials with a total of more than 17,000 patients.

“Beta blockers may be doing good in heart failure patients with atrial fibrillation, but they also are doing harm that neutralizes any good they do.” In patients with HFrEF and atrial fibrillation, “I don’t like to see the heart rate below 80 beats per minute,” John G.F. Cleland, MD, said at a meeting held by the Heart Failure Association of the ESC.

Dr. John G.F. Cleland Mitchel L. Zoler/Frontline Medical News
Dr. John G.F. Cleland
For HFrEF patients in sinus rhythm “it is not only important to achieve the target beta-blocker dosage, but also important to insure an adequately reduced heart rate” which might also mean adding treatment with ivabradine (Corlaner). But for HFrEF patients with atrial fibrillation “more and more data suggest that the optimal heart rate may be 80-90 beats per minutes [bpm] at rest, and we do a disservice to these patients by any additional control of their ventricular rate,” said Dr. Cleland, professor of cardiology at the University of Glasgow.

“We’ve perhaps been too aggressive with heart-rate control in HFrEF patients with atrial fibrillation,” he added in an interview. In these patients “in the range of 60-100 bpm it doesn’t seem to make a lot of difference what the heart rate is, and, if it is less than 70 bpm, patients seem to do a little worse. When we treat these patients with a beta-blocker we don’t see benefit in any way that we’ve looked at the data.”

In contrast, among HFrEF patients in sinus rhythm “beta-blocker treatment is similarly effective regardless of what the baseline heart rate was. The benefit was as great when the baseline rate was 70 bpm or 90 bpm, so heart rate is not a great predictor of beta-blocker benefit in these patients. Patients who tolerated the full beta-blocker dosage had the greatest benefit, and patients who achieved the slowest heart rates also had the greatest benefit.”

In the multivariate models that Dr. Cleland and his associates tested in their meta-analysis, in HFrEF patients in sinus rhythm, the relationship between reduced heart rate and mortality benefit was stronger statistically than between beta-blocker dosage and reduced mortality, he said. “This suggests to me that, while we should use the targeted beta-blocker dosages when we can, it’s more important to achieve a target heart rate in these patients of 55-65 bpm.”

Dr. Cleland hypothesized, based on a report presented at the same meeting by a different research group, that reduced heart rate is not beneficial in HFrEF patients with atrial fibrillation because in this subgroup slower heart rates linked with an increased number of brief pauses in left ventricular pumping. These pauses may result in ventricular arrhythmias, he speculated. “It may be that beta-blockers are equally effective at slowing heart rate in patients with or without atrial fibrillation, but there is also harm from beta-blockers because they’re causing pauses in patients with atrial fibrillation,” he said.

These days, if he has a HFrEF patient with atrial fibrillation whose heart rate slows to 60 bpm, he will stop digoxin treatment if the patient is on that drug, and he will also reduce the beta-blocker dosage but not discontinue it.

The findings came from the Collaborative Systematic Overview of Randomized Controlled Trials of Beta-Blockers in the Treatment of Heart Failure (BB-META-HF), which included data from 11 large beta-blocker randomized trials in heart failure that had been published during 1993-2005. The analysis included data from 17,378 HFrEF patients, with 14,313 (82%) in sinus rhythm and 3,065 (18%) with atrial fibrillation. Follow-up data of patients on treatment was available for 15,007 of these patients.

Dr. Cleland and his associates showed in multivariate analyses that, when they controlled for several baseline demographic and clinical variables among patients in sinus rhythm who received a beta-blocker, the follow-up all-cause mortality fell by 36%, compared with placebo, in patients with a resting baseline heart rate of less than 70 bpm; by 21%, compared with placebo, in patients with a baseline heart rate of 70-90 bpm; and by 38%, compared with placebo, in patients with a baseline heart rate of more than 90 bpm. All three reductions were statistically significant. In contrast, among patients who also had atrial fibrillation beta-blocker treatment linked with no significant mortality reduction, compared with placebo, for patients with any baseline heart rate.
Concurrently with Dr. Cleland’s report at the meeting the results appeared online (J Amer Coll Cardiol. 2017 Apr 30. doi: 10.1016/j.jacc.2017.04.001).
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