Women Thrive on Baroreflex Activation for
Heart Failure

Bruce Jancin

June 26, 2020

The striking gains in functional capacity and quality of life conferred by baroreflex activation therapy in patients with heart failure, as shown in the pivotal phase 3 clinical trial for this novel intervention, were at least as great in women as in men, JoAnn Lindenfeld, MD, said at the European Society of Cardiology Heart Failure Discoveries virtual meeting.

The results of the multicenter, prospective, randomized BeAT-HF trial led to marketing approval of the BaroStim Neo system for improvement in symptoms of heart failure with reduced ejection fraction (HFrEF) by the Food and Drug Administration in August 2019. Dr. Lindenfeld presented a fresh breakdown of the results by gender which showed, intriguingly, that the improvement in all study endpoints was consistently numerically greater in the women — sometimes startlingly so — although these gender differences in response didn't achieve statistical significance. The 6-month randomized trial was underpowered for drawing definitive conclusions on that score, with a study population of only 53 women and 211 men. So the investigator remained circumspect.

"We think that what this study shows us is that women have at least equivalent improvement as men in this population. I don't think we can conclude from this study yet that it's better, but it's certainly in all these parameters as least as good. And I think this is a population in which we've seen that improving symptoms and functional capacity is very important," said Dr. Lindenfeld, professor of medicine and director of advanced heart failure/cardiac transplantation at Vanderbilt University, Nashville, Tenn.

The FDA approval was restricted to patients like those enrolled in BeAT-HF: that is, individuals with New York Heart Association functional class III heart failure, a left ventricular ejection fraction of 35% or less while on stable optimal medical therapy, and ineligibility for cardiac resynchronization therapy according to current guidelines. Seventy-eight percent of BeAT-HF participants had an implantable cardioverter-defibrillator.

Participants were randomized to baroreflex activation therapy (BAT) plus optimal medical therapy or to optimal medical therapy alone. The three coprimary endpoints were change from baseline to 6 months in 6-minute hall walk distance (6MHW), scores on the Minnesota Living with Heart Failure Questionnaire (MLHF), and N-terminal pro-B-type natriuretic peptide (NT-proBNP).

In the overall study population, 6MHW increased by 60 m in the BAT group and decreased by 8 m in controls; MLHF scores dropped by 14 and 6 points, respectively; and NT-proBNP fell by an average of 25% with BAT while rising by 3% in controls.

Very often, just a 5-point reduction in MLHF score is considered a clinically meaningful improvement in quality of life, the cardiologist noted.

The gender-based analysis is where things got particularly interesting.

The investigators defined a clinically relevant response as a greater than 10% increase from baseline on the 6MHW, at least a one-class improvement in NYHA class, or a reduction of 5 points or more on the MLHF. Among subjects in the BAT group, 70% of women and 60% of men met the clinically relevant response standard in terms of 6MHW, as did 70% of women and 64% of men for improvement in NYHA class, and 78% of women and 66% of men for MLHF score.

Eighty-seven percent of women and 68% of men on BAT had a clinically relevant response on at least one of these endpoints, as did about 28% of controls. Moreover, 31% of women in the BAT group were clinically relevant responders on at least two endpoints, compared with 19% of BAT men and 4% and 9% of controls.

Women Dominate Super-Responder Category

In order to be classified as a super responder, a patient had to demonstrate a greater than 20% increase in 6MHW, improvement in NYHA class I status, or at least a 10-point improvement in MLHF score. Ninety-one percent of women on BAT achieved super-responder status for at least one of these endpoints, compared with 76% of men. Forty-three percent of women and 24% of men in the BAT group were super responders in at least two domains, as were 8% and 11% of female and male controls, Dr. Lindenfeld continued.

Discussant Ewa Anita Jankowska, MD, PhD, deemed the BeAT-HF results on the therapeutic benefits of this autonomic modulation strategy "quite convincing."

"We need to acknowledge that in recent years we have been spoiled a bit by the huge trials in heart failure where the ultimate goal was a reduction in mortality. But I think this is the time when we should think about the patients who want to live — here, now — with a better life. Patients expect symptomatic benefits. There is a substantial group of patients who are symptomatic even though they receive quite extensive neurohormonal blockage and who are not suitable for CRT. This study demonstrates that, for this group of patients, BAT can bring really significant symptomatic benefits," she said.

"If you think about a treatment that provides patients who are NYHA class III an increase in 6MHW of 60 meters, that's really something. And 20% of patients went from NYHA class III to class I — that's really something, too," added Dr. Jankowska, professor of medicine and head of the laboratory of applied research on the cardiovascular system at Wroclaw (Poland) University.

How Baroreflex Activation Therapy Works

The BaroStim system consists of a 2-mm unipolar electrode on a 7-mm backer that is placed over the carotid sinus. It is supported by a small generator with a 4- to 5-year battery life implanted under the collarbone, along with radiofrequency telemetry capability and programming flexibility.

Stimulation of the carotid baroreceptor promotes an integrated autonomic nervous system response which enhances parasympathetic activity and inhibits sympathetic nervous system activity. The result, as shown in numerous earlier proof-of-concept studies, is a reduced heart rate, decreased ventricular remodeling, enhanced diuresis, increased vasodilation, a drop in elevated blood pressure, and decreased renin secretion — all achieved nonpharmacologically.

The study was sponsored by CVRx. Dr. Lindenfeld reported serving as a consultant to CVRx, Abbott, AstraZeneca, Boehringer Ingelheim, Edwards Lifesciences, Impulse Dynamics, and VWave.

This story originally appeared on MDedge.com.

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