Predictors of pacemaker requirement in patients receiving implantable loop recorders for unexplained syncope: A systematic review and meta-analysis

Jeremy William; Shane Nanayakkara; David Chieng; Hariharan Sugumar; Liang-Han Ling; Hitesh Patel; Justin Mariani; Sandeep Prabhu; Peter M Kistler; Aleksandr Voskoboinik

doi:10.1016/j.hrthm.2024.03.038

Predictors of pacemaker requirement in patients receiving implantable loop recorders for unexplained syncope: A systematic review and meta-analysis

Heart Rhythm. 2024 Mar 18:S1547-5271(24)00284-4. doi: 10.1016/j.hrthm.2024.03.038. Online ahead of print.

Affiliations

¹ The Alfred Hospital, Melbourne, Victoria, Australia; Monash University, Melbourne, Victoria, Australia; The Baker Heart and Diabetes Research Institute, Melbourne, Victoria, Australia.
² The Alfred Hospital, Melbourne, Victoria, Australia; The Baker Heart and Diabetes Research Institute, Melbourne, Victoria, Australia.
³ The Alfred Hospital, Melbourne, Victoria, Australia.
⁴ The Alfred Hospital, Melbourne, Victoria, Australia; Monash University, Melbourne, Victoria, Australia; The Baker Heart and Diabetes Research Institute, Melbourne, Victoria, Australia; University of Melbourne, Melbourne, Victoria, Australia.
⁵ The Alfred Hospital, Melbourne, Victoria, Australia; Monash University, Melbourne, Victoria, Australia; The Baker Heart and Diabetes Research Institute, Melbourne, Victoria, Australia. Electronic address: a.voskoboinik@alfred.org.au.

PMID: 38508296
DOI: 10.1016/j.hrthm.2024.03.038

Abstract

Background: Implantable loop recorders (ILRs) are increasingly used to evaluate patients with unexplained syncope. Identification of all predictors of bradycardic syncope and consequent permanent pacemaker (PPM) insertion is of substantial clinical interest as patients in the highest risk category may benefit from upfront pacemaker insertion.

Objective: We performed a systematic review and meta-analysis to identify risk predictors for PPM insertion in ILR recipients with unexplained syncope.

Methods: An electronic database search (MEDLINE, Embase, Scopus, Cochrane) was performed in June 2023. Studies evaluating ILR recipients with unexplained syncope and recording risk factors for eventual PPM insertion were included. A random effects model was used to calculate the pooled odds ratio (OR) for clinical and electrocardiographic characteristics with respect to future PPM requirement.

Results: Eight studies evaluating 1007 ILR recipients were included; 268 patients (26.6%) underwent PPM insertion during study follow-up. PPM recipients were older (mean age, 70.2 ± 15.4 years vs 61.6 ± 19.7 years; P < .001). PR prolongation on baseline electrocardiography was a significant predictor of PPM requirement (pooled OR, 2.91; 95% confidence interval, 1.63-5.20). The presence of distal conduction system disease, encompassing any bundle branch or fascicular block, yielded a pooled OR of 2.88 for PPM insertion (95% confidence interval, 1.53-5.41). Injurious syncope and lack of syncopal prodrome were not significant predictors of PPM insertion. Sinus node dysfunction accounted for 62% of PPM insertions, whereas atrioventricular block accounted for 26%.

Conclusion: Approximately one-quarter of ILR recipients for unexplained syncope require eventual PPM insertion. Advancing age, PR prolongation, and distal conduction disease are the strongest predictors for PPM requirement.

Keywords: Bradycardia; Heart block; Implantable loop recorder; Permanent pacemaker; Sinus node dysfunction; Syncope.