Evidence supporting medications that slow the heart rate (HR), notably beta-blockers, is overwhelming in heart failure (HF) with reduced ejection fraction. Underwhelming, however, is clinical trial support for such agents in patients with HF with preserved ejection fraction (HFpEF).
Indeed, at least for some such patients, a treatment that modestly accelerates resting HR may be a more promising strategy, suggests an early line of research that challenges prevalent thinking about HFpEF therapy.
In a small, randomized test of the idea, patients with HFpEF and standard pacemakers set to a backup resting HR a bit higher than a standard of care 60 bpm, usually to about 75 bpm, reaped important quality of life benefits.
More strikingly, their natriuretic peptide levels and burden of atrial fibrillation (AFib) fell significantly, the latter by 27% over 1 year.
The trial enrolled only HFpEF patients with pacemakers previously implanted for sick sinus syndrome or atrioventricular block. But researchers say their 107-patient study called myPACE – if confirmed in larger, multicenter trials – lays the groundwork for a device therapy that is broadly useful, potentially, in patients with “preclinical or overt” HFpEF.
Indeed, some of the intervention’s “quite substantial” benefits rivaled or surpassed what his group has observed with available HFpEF drug therapies, including the sodium-glucose cotransporter 2 inhibitors, observed Markus Meyer, MD, PhD, University of Minnesota, Minneapolis.
Moreover, the study may be “the first to show that, with this approach, we can actually also reduce atrial fibrillation,” he said in an interview.
Dr. Meyer said his group is “confident” that the HR-modulation strategy will be successful in appropriate clinical trials and that “pacemakers, in the end, will become a treatment modality for HFpEF.”
Meyer is senior author on the trial’s publication in JAMA Cardiology in JAMA Cardiology (2023 Feb 1. doi: 10.1001/jamacardio.2022.5320), with lead author Margaret Infeld, MD, University of Vermont, Burlington.
The trial entered pacemaker patients with HFpEF of stage B or C – that is, either asymptomatic with structural disease or fully symptomatic. But, Dr. Meyer said, “we saw that the treatment effect was much more pronounced in the patients who had overt heart failure with preserved ejection fraction.”
Challenging beta-blocker dogma
The study, the report states, “contradicts canonical thinking” by suggesting HFpEF patients may benefit from a higher resting heart rate, which would presumably shorten diastolic filling time. It also “may help reduce the overprescription of beta-blockers to allow higher heart rates in this population.”
Indeed, Dr. Meyer observed, no one really knows whether beta-blockers work in HFpEF, “because they really have never been studied in a sufficiently powered randomized controlled trial.”
The current study “basically rewrites what we know about the pathophysiology of this form of clinical heart failure,” said Michael R. Zile, MD, Medical University of South Carolina and Veterans Affairs Medical Center, both in Charleston, who was not part of the trial or report.
Previously in HFpEF, Dr. Zile said in an interview, “everybody thought you needed to make diastole longer to give the ventricle a longer time to fill. And none of that really made any sense. It was just sort of accepted as dogma.”
The idea led to widespread use of beta-blockers in HFpEF but “turned out just not to be true.” Indeed, European and North American guidelines, Dr. Zile observed, “have all taken beta-blockers out of the equation for HFpEF” except for treating comorbidities that can be associated with HFpEF, like hypertension or AFib.
Many patients with HFpEF and chronotropic incompetence could be provided with standard pacemakers with primarily conduction-system pacing but are not getting them, he observed.
The current study might help change that. No one is suggesting, based on the current study, “that we start putting pacemakers in every single patient with HFpEF,” Dr. Zile said. Still, for HFpEF patients already with a pacemaker, the study provides “reasonable assurance” that its criteria for elevated resting HR may well improve symptoms.
Moreover, it suggests such pacemakers, programmed as in the study, might potentially give a boost to HFpEF patients without chronotropic incompetence but with persisting symptoms despite guideline-directed drug therapy. That’s certainly worth exploring in further trials, Dr. Zile said.