Interatrial Block Association With Adverse Cardiovascular Outcomes in Patients Without a History of Atrial Fibrillation.

Background: Interatrial block (IAB) is associated with thromboembolism and atrial arrhythmias. However, prior studies included small patient cohorts so it remains unclear whether IAB predicts adverse outcomes particularly in context of atrial fibrillation (AF)/atrial flutter (AFL).
Objectives: This study sought to determine whether IAB portends increased stroke risk in a large cohort in the presence or absence of AFAF/AFL.
Methods: We performed a 5-center retrospective analysis of 4,837,989 electrocardiograms (ECGs) from 1,228,291 patients. IAB was defined as P-wave duration ≥120 ms in leads II, III, or aVF. Measurements were extracted as .XML files. After excluding patients with prior AF/AFL, 1,825,958 ECGs from 458,994 patients remained. Outcomes were analyzed using restricted mean survival time analysis and restricted mean time lost.
Results: There were 86,317 patients with IAB and 355,032 patients without IAB. IAB prevalence in the cohort was 19.6% and was most common in Black (26.1%), White (20.9%), and Hispanic (18.5%) patients and least prevalent in Native Americans (9.2%). IAB was independently associated with increased stroke probability (restricted mean time lost ratio coefficient [RMTLRC]: 1.43; 95% CI: 1.35-1.51; tau = 1,895), mortality (RMTLRC: 1.14; 95% CI: 1.07-1.21; tau = 1,924), heart failure (RMTLRC: 1.94; 95% CI: 1.83-2.04; tau = 1,921), systemic thromboembolism (RMTLRC: 1.62; 95% CI: 1.53-1.71; tau = 1,897), and incident AF/AFL (RMTLRC: 1.16; 95% CI: 1.10-1.22; tau = 1,888). IAB was not associated with stroke in patients with pre-existing AF/AFL.
Conclusions: IAB is independently associated with stroke in patients with no history of AF/AFL even after adjustment for incident AF/AFL and CHA ₂ DS ₂ -VASc score. Patients are at increased risk of stroke even when AF/AFL is not identified.
Competing Interests: Funding Support and Author Disclosures This project was internally funded. Dr Reddy has served as a consultant to Kardium Inc (including Equity); is a consultant to Abbott, Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, APN Health, Aquaheart, Atacor, AtiAN, Autonomix, Axon Therapies, Backbeat, BioSig, Biosense-Webster, BioTel Heart, Biotronik, Boston Scientific, Cairdac, CardiaCare, Cardiofocus, Cardionomic, CardioNXT / AFTx, Circa Scientific, CoreMap, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EBR, EPD-Philips, EP Frontiers, Epix Therapeutics, EpiEP, Eximo, Farapulse-Boston Scientific, Fire1, Focused Therapeutics, Gore & Associates, HRT, Impulse Dynamics, Intershunt, Javelin, Keystone Heart, LuxMed, Medlumics, Medtronic, Middlepeak, Neutrace, Nuvera-Biosense Webster, Oracle Health, Philips, Pulse Biosciences, Restore Medical, Sirona Medical, SoundCath, and Valcare; and has equity from Ablacon, Acutus Medical, Affera-Medtronic, Apama Medical-Boston Scientific, APN Health, Aquaheart, Atacor, Autonomix, Axon Therapies, Backbeat, BioSig, CardiaCare, CardioNXT / AFTx, Circa Scientific, CoRISMA, Corvia Medical, Dinova-Hangzhou DiNovA EP Technology, East End Medical, EPD-Philips, EP Frontiers, Epix Therapeutics, EpiEP, Eximo, Farapulse-Boston Scientific, Focused Therapeutics, HRT, Intershunt, Javelin, Keystone Heart, LuxMed, Manual Surgical Sciences, Medlumics, Middlepeak, Neutrace, Newpace, Nuvera-Biosense Webster, Nyra Medical, Oracle Health, Restore Medical, Sirona Medical, SoundCath, Surecor, Valcare, and Vizaramed. Dr Fuster serves as the Editor-in-Chief of JACC. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
(Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)