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Baroreflex activation therapy may benefit HF patients without CRT
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BOSTON — For patients with HF who underwent baroreflex activation therapy, the magnitude of effect was greater in those without a chronic resynchronization therapy device, according to findings presented at the Heart Rhythm Society Annual Scientific Sessions.
The baroreflex activation therapy device (Barostim neo, CVRx Inc.) is a 2 mm electrode surgically implanted on the carotid sinus connected to a surgically implanted subcutaneous power unit. It works by stimulation of the carotid baroreceptor to reduce sympathetic activity and increase parasympathetic activity to stave off worsening symptoms and disease progression in patients with HF, according to the study background.
Researchers conducted a phase 2 study to assess the safety and efficacy of baroreflex activation therapy. They randomly assigned 146 patients with HF to receive guideline-directed medical therapy alone or guideline-directed medical therapy plus baroreflex activation therapy; six patients died or withdrew before activation date. All patients were NYHA class III, had left ventricular ejection fraction of 35% or less and had a 6-minute walking distance of 120 m to 400 m. “These were well-treated patients who continued to be symptomatic despite that treatment,” Michael R. Zile, MD, of the Medical University of South Carolina and the Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, South Carolina, said during a press conference.
Michael R. Zile
According to the main findings, presented at the American College of Cardiology Scientific Sessions in March and published in JACC: Heart Failure, patients in the baroreflex activation therapy group had greater improvement in 6-minute walk distance (P = .004), Minnesota Living with Heart Failure Questionnaire (MLHFQ) quality-of-life score (P < .001) and NYHA class ranking (P = .002) compared with controls, and the overall rate of freedom from major neurological and CV events was 97.2%.
At the HRS scientific sessions, Zile presented results of a prespecified analysis comparing the patients from the study who had a CRT device at baseline (n = 45) with those who did not (n = 95).
Freedom from major neurological and CV events at 6 months occurred in 100% of those in the baroreflex arm with CRT and in 96% of those in the baroreflex arm without CRT, Zile said.
Among those without CRT, those in the baroreflex arm had an improvement in MLHFQ score of –21.6 vs. a worsening of 3.5 for controls (P < .001), whereas among those with CRT, the baroreflex arm had an improvement of –9.3 compared with –0.9 for controls (P = .23; P for interaction = .04), Zile said.
For those without CRT, change from baseline in 6-minute walk distance was 85.5 m for the baroreflex arm vs. 3.6 m for controls (P = .003), whereas for those with CRT, it was 16.4 m for the baroreflex arm vs. –3.5 m (P = .38; P for interaction = .01), he said.
Change in N-terminal pro–B type natriuretic peptide levels were –97 pg/mL in the baroreflex arm vs. 116 pg/mL in controls among those without CRT (P = .03), and 79.8 pg/mL in the baroreflex arm vs. 433 pg/mL in controls among those with CRT (P = .16; P for interaction = .59), Zile said.
LVEF improved 4.3% from baseline in the baroreflex arm but decreased 0.1% in controls among those without CRT (P < .03), whereas it decreased 1.2% in the baroreflex arm and 0.1% in controls among those with CRT (P = .71; P for interaction = .02), according to the researchers.
HF hospitalization days declined by 8.9 between baseline and 6 months for those in the baroreflex arm but increased by 0.18 in controls among those without CRT (P = .05), whereas they declined by 1.05 in the baroreflex arm and 0.13 in controls among those with CRT (P = .75; P for interaction = .09), Zile said.
Based on these results, the phase 3 pivotal trial for the device, which is scheduled to start in September and has a planned enrollment of 480 patients, will be conducted in those without CRT, Zile said during the press conference.
“We don’t mean to suggest that CRT patients aren’t responsive, we just are noting the fact that the no-CRT group seemed to have a little more pronounced response,” Zile said. “This represents a therapy which can be applied to those patients in which you’ve exhausted all other therapies, and it can be applied to patients who are not candidates for CRT. It will fit into a unique position of therapy for this group of symptomatic patients.”– by Erik Swain
References:
Abraham WT, et al. JACC Heart Fail. 2015;doi:10.1016/j.jchf.2015.02.006.
Zile MR, et al. Abstract LBCT02-02. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 13-16, 2015; Boston.
Disclosure: The study was funded by CVRx. Zile reports receiving consulting fees and speaking honoraria from CVRx and serving on its HF executive steering committee.
Perspective
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Michael R. Gold, MD, PhD, FHRS
There is a lot of excitement for autonomic modulation. We know that HF is associated with a dysautonomia, where we see an imbalance with increased sympathetic tone and decreased parasympathetic tone. We have largely directed our therapy toward inhibiting sympathetic activity through pharmacologic therapies such as beta-blockers, ACE inhibitors and aldosterone antagonists. We have not had treatments for the parasympathetic aspect. There is now a whole family of device approaches to try to address that. We have spinal-cord stimulation, vagal-nerve stimulation, baroreceptor stimulation and renal denervation. This was the first study on baroreceptor activation, which was a very intriguing, encouraging study. It wasn’t powered to be an outcome or pivotal study, but it showed that the response is somewhat attenuated in patients who are getting CRT, which is a very effective therapy already. The device appears to work better in patients who have a narrower QRS or who aren’t getting CRT, but that certainly doesn’t detract from the findings because those are the patients for whom we don’t have a lot of options in terms of device therapy.
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