Interatrial block predicts left atrial appendage thrombus in nonvalvular atrial fibrillation.

BACKGROUND

Interatrial block (IAB) is an electrocardiographic manifestation of atrial conduction delay and structural remodeling. While it has been linked to atrial fibrillation (AF) and thromboembolic events, its potential role in predicting left atrial appendage (LAA) thrombus formation remains underexplored. This study aimed to investigate the association between IAB and the presence of LAA thrombus in patients with nonvalvular AF (NVAF) or atrial flutter referred for rhythm control procedures.

METHODS

In this retrospective observational study, 750 patients with NVAF who underwent transesophageal echocardiography (TEE) prior to catheter ablation or cardioversion were evaluated. P-wave parameters were measured from digitally amplified 12‑lead ECGs, and IAB was defined according to current consensus criteria. Patients were stratified by the presence of LAA thrombus, and multivariate logistic regression was used to identify independent predictors.

RESULTS

LAA thrombus was detected in 10.8 % of patients. Those with thrombus were older and had higher thromboembolic risk scores, more frequent history of stroke, and lower left ventricular ejection fraction (LVEF). Interatrial block was observed in 85.2 % and advanced IAB in 44.4 % of patients with thrombus. In multivariate analysis, IAB (OR: 2.698; p = 0.008), larger LA diameter, lower LVEF, and greater P-wave dispersion were independently associated with thrombus presence.

CONCLUSION

IAB is independently associated with LAA thrombus in NVAF patients and may serve as a noninvasive marker to identify individuals at higher thromboembolic risk, potentially guiding the need for TEE before rhythm control.