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BOSTON -- For older syncope patients found to have bifascicular block, heading straight to pacing without watching for actionable findings with an implantable loop recorder appears to give better outcomes, the pragmatic trial showed.

An empiric pacemaker-first strategy lowered the combined rate of syncope, symptomatic or asymptomatic bradycardia, acute or chronic device complications, or cardiovascular death compared with an implantable cardiac monitoring strategy (19 of 57 versus 44 of 58, P<0.001).

For every 10 such patients implanted with a loop recorder, there were six with bradycardia leading to pacemaker implantation, two vasodepressor syncope occurrences, one death, and one case of dementia or withdrawal, Robert Sheldon, MD, PhD, of the University of Calgary Health Sciences Centre in Alberta, reported here at the Heart Rhythm Society (HRS) meeting.

Because so many patients cross over to pacemaker therapy, it's a practical strategy, he said.

"You don't need to rush to admit these patients, you just need to get on with treating them if you chose to treat them," Sheldon concluded, noting that these are patients who have lost one bundle branch and have their heart's electrical activity dependent on just one of the two fascicles of the other bundle branch.

This was "a study that is long overdue. While it hasn't ended the discussion, it has at least moved us to re-examine these patients that we haven't examined in a long time, and I think that's a good step," commented Sanjeev Saksena, MD, of Rutgers University Robert Wood Johnson Medical School in New Brunswick, New Jersey, and a past president of the HRS.

If an electrocardiogram (ECG) shows atrioventricular block after a syncope event, physicians can now tell patients that if they chose a loop recorder "they should know that they will probably move over to the other side," he said.

The 2017 syncope guidelines from the American College of Cardiology, the American Heart Association, and the HRS do recommend an ECG when patients present with unexplained syncope.

However, session discussant Win-Kuang Shen, MD, of the Mayo Clinic in Phoenix, cautioned that while the study could say these two practical strategies are both safe, it might not have been large enough to assess death or malignant arrhythmias.

The trial included 115 patients ages 50 and older with at least one syncope episode in the prior year and bifascicular block on a 12-lead ECG seen as usual in device clinics and followed for at least 2 years (average 33 months). Crossover between arms was at physician discretion.

Also, there will be the question of whether this pacing strategy can get reimbursed in this population in the U.S., Shen noted. "It's going to take further discussion."

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