Clinical variables do not predict syncope in pacemaker patients with bifascicular block: a SPRITELY substudy.

Background: The SPRITELY study showed no differences in the recurrence of syncope in patients with bifascicular block (BFB) and syncope, regardless of whether patients received an empiric pacemaker (PM) or an implantable cardiac monitor (ICM). Whether syncope resistant to pacing can be predicted by baseline clinical variables is unknown.

Objectives: To determine whether baseline clinical characteristics predict syncope recurrence in patients with bifascicular block and a permanent pacemaker.

Methods: This was a retrospective analysis of the SPIRITELY trial, a randomized clinical trial in which patients with syncope and bifascicular block were assigned randomly to receive either a pacemaker or implantable loop recorder as an initial management strategy. In 60 patients who received a pacemaker, we tested the ability of 38 baseline clinical variables to predict a syncope recurrence. These included demographics, comorbidities, medications, and syncopal history and symptoms. Univariable and multivariate statistics were performed and a p < 0.05 was accepted as significant.

Results: In the 60 patients who received a pacemaker, 12 (20%) had recurrent syncope. Only the use of angiotensin receptor blockers (ARB) and a history of a composite of one or more of asystole, supraventricular tachycardia (SVT), or diabetes were univariable significant predictors of recurrent syncope (p = 0.042). In the multivariate analysis only a history of a composite of one or more of asystole, SVT, or diabetes significantly predicted syncope (p = 0.03). Neither SVT nor diabetes alone predicted syncope recurrence.

Conclusions: In older patients with syncope and bifascicular heart block, only a history of one or more of asystole, SVT, or diabetes significantly predicted syncope.