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NEW ORLEANS -- Using an adaptive pacemaker in patients diagnosed with heart failure with preserved ejection fraction (HFpEF) failed to improve exercise performance, the RAPID-HF trial showed.

In the 29-patient crossover trial, oxygen consumption at the anaerobic threshold was the same between groups, at 10.4 mL/kg/minute when pacing was turned off compared with 10.7 mL/kg/minute when the adaptive pacemaker was active (P=0.46), reported Barry Borlaug, MD, of the Mayo Clinic in Rochester, Minnesota.

Those primary endpoint findings were presented in a featured science session at the annual scientific sessions of the American College of Cardiology and in .

"Although this study had a small number of patients, I think we can scratch this from the list of remedies for patients with heart failure and preserved ejection fraction," said Ileana Piña, MD, MPH, of Thomas Jefferson University in Philadelphia and a spokesperson for the American Heart Association.

Borlaug agreed: "In addition to lack of efficacy, pacemaker implantation was associated with increased risk of significant, clinically important adverse events, even when implanted by highly experienced operators."

"Current guideline recommendations for pacing for chronotropic incompetence are largely based on expert opinion, including consideration of pacing in patients with HFpEF and a phenotype with chronotropic incompetence," he added. "The present data do not support this recommendation."

In commenting on the study, Piña told 番茄社区app that the rationale made sense, that increasing the heart rate when the pacemaker detects activity would help in HFpEF, "because these people have a lot of exercise intolerance, and we think they can't mount the right heart rate to get their cardiac output up to match the activity."

However, she added, "In this case, when the heart rate increased, the heart adjusted and dropped the stroke volume, which was not expected. So nothing really changed."

Piña also noted that the study had a high percentage of women, so the reason the trial failed was not because there weren't enough women in the study. HFpEF is found more often in women with heart failure, she said.

"This was a very well done study. They checked all the bases, and it was a crossover trial," she said. "And it didn't work, so we aren't going to use this device in this population of heart failure patients."

Borlaug and colleagues recruited 32 patients who underwent pacemaker implantation, of whom 29 completed the RAPID-HF study. They were randomized to atrial rate responsive pacing or no pacing for 4 weeks, followed by a 4-week washout period, and then crossover for an additional 4 weeks.

The patients in the study averaged age 66 years, 45% were women, and all participants had ejection fractions over 50%.

Pacemaker implantation was associated with an increase in adverse events. Adverse events judged to be related to the pacemaker device were observed in six of 29 participants (21%), Borlaug noted. Those adverse events included one upper-extremity deep vein thrombosis, one pericardial effusion requiring drainage, one potential case of pacemaker lead-induced tricuspid regurgitation, and three local skin reactions at the pacemaker pocket site.

There was a serious adverse event that was judged related to pacemaker implantation (a case of pericardial effusion). Minor adverse events during the pacing-on phase occurred in eight patients during the control phase and seven during pacing. Chest discomfort or palpitations occurred in five patients during the pacing-on phase compared with one during the pacing-off phase.

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