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Association of the Interatrial Block and Left Atrial Fibrosis in the Patients Without History of Atrial Fibrillation

Arintaya Phrommintikul, Natnicha Pongbangli, Siriluck Gunaparn, Narawudt Prasertwitayakij, Teerapat Nantsupawat, Wanwarang Wongcharoen

Presence of left atrial (LA) fibrosis reflects underlying atrial cardiomyopathy. Interatrial block (IAB) is associated with LA fibrosis in patients with atrial fibrillation (AF). The association of IAB and LA fibrosis in the patients without history of AF is unknown. We examined association of IAB and LA fibrosis in the patients without AF history. This is a retrospective analysis of 229 patients undergoing cardiac magnetic resonance imaging (CMR). 

LA fibrosis was reported from spatial extent of late gadolinium enhancement of CMR. IAB was measured from 12-lead electrocardiography using digital caliper. Of 229 patients undergoing CMR, prevalence of IAB was 50.2%. Patients with IAB were older (56.9±13.9 years vs. 45.9±19.2 years, p<0.001) and had higher prevalence of co-morbidities. Left ventricular ejection fraction was lower in IAB group.

Atrial cardiomyopathy is defined by a complex of structural, architectural, contractile or electrophysiological changes affecting the atrium with the potential to produce clinically relevant manifestations [1]. It is related to an increased risk of thromboembolism independent of the presence of atrial fibrillation (AF) [2]. Left atrial (LA) fibrosis is the hallmark of LA structural remodeling [3] and serves as a substrate for slow conduction, intra-atrial re-entry, predisposing to future atrial arrhythmia [4, 5].

This is a retrospective analysis of patients who presented at Maharaj Nakhon Chiang Mai hospital for CMR during the specified study periods. The inclusion criteria comprised individuals who were (1) aged over 18 years; (2) undergoing CMR for various indications between April 1, 2013 to December 1, 2021; (3) had a standard 12-lead electrocardiogram (ECG) conducted within 6 months before or after of the CMR. Patients with history of AF, sinus arrest or those in whom P wave could not be identified from the standard 12-lead ECG were excluded. Demographic characteristics were collected.

A total of 229 patients who underwent CMR imaging were included in the study. The most common reason for CMR scanning was to assess myocardial ischemia in patients with known or suspected coronary artery disease (45%). The other indications included known or suspected cardiomyopathy (26%), suspected myocarditis (12%), congenital heart disease (11%), ventricular arrhythmia/ premature ventricular complex (5%) and cardiac mass (1%).

Atrial fibrosis and myofibril disorganization constitute the characteristic phenotype of atrial cardiomyopathy [1]. Previous studies have demonstrated the association of atrial fibrosis with an increased risk of stroke, heart failure, and the prediction of new-onset AF and AF recurrence after ablation [3, 6, 7]. CMR-LGE is considered the gold standard in imaging fibrosis [8]. However, the widespread adoption of CMR is limited due to its cost, requirement for higher technical expertise, and relatively long time for image acquisition [7]. In contrast, 12-lead ECG is inexpensive test, more widely available and does not require technical expertise. The utility of 12-lead ECG in predicting LA fibrosis is valuable in clinical practice for identifying patients at risk.

The prevalence of IAB in patients without a history of AF who had undergone CMR was relatively high. We demonstrated a strong association between the presence of IAB and LA fibrosis in patients without a history of AF.

Citation: Phrommintikul A, Pongbangli N, Gunaparn S, Prasertwitayakij N, Nantsupawat T, Wongcharoen W (2024) Association of the interatrial block and left atrial fibrosis in the patients without history of atrial fibrillation. PLoS ONE 19(2): e0297920.

Editor: Roberto Magalhães Saraiva, Oswaldo Cruz Foundation, BRAZIL

Received: October 12, 2023; Accepted: January 14, 2024; Published: February 8, 2024

Copyright: © 2024 Phrommintikul et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: Association of the interatrial block and LA fibrosis in the patients without history of AF does not cover data posting in public databases. However, data are available upon request should be sent to the ethics committee of Faculty of Medicine, Chiang Mai University (

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.