Predictive value of interatrial block on electrocardiogram among obese patients undergoing atrial fibrillation ablation.

BACKGROUND: Determine a predictive value of interatrial block (IAB) on atrial fibrillation (AF) ablation outcomes in obese patients.

METHODS: Medical records were retrospectively reviewed for 205 consecutive patients with body mass indices (BMI) ≥ 30 kg/m2 who underwent initial AF ablation. Evidence of partial IAB defined as P-wave duration (PWD) ≥ 120 ms and advanced IAB with PWD ≥ 120 ms and biphasic or negative P-wave in inferior leads was examined from sinus electrocardiograms (ECGs) within 1-year pre-ablation. The primary outcome was recurrent atrial arrhythmia after 3-month blanking period post-ablation.

RESULTS: The mean BMI was 36.9 ± 5.7 kg/m2 . Partial IAB and advanced IAB were observed in 155 (75.61%) and 42 (20.49%) patients, respectively. During the median follow-up of 1.35 (interquartile range 0.74, 2.74) years, 115 (56.1%) patients had recurrent atrial arrhythmias. In multivariable analysis adjusting for age, gender, persistent AF, use of antiarrhythmic drugs (AADs), left atrial volume index (LAVI), partial IAB, and advanced IAB were independent predictors of recurrent arrhythmia with hazard ratio (HR) of 2.80 (95% confidence interval [CI] 1.47-6.05; p = 0.001) and HR 1.79 (95% CI 1.11-2.82; p = 0.017), respectively. The results were similar in a subgroup analysis of patients who had no severe left atrial enlargement and a subgroup analysis of patients who were not on AADs.

CONCLUSIONS: IAB is highly prevalent in patients with obesity and AF. Partial IAB, defined as PWD ≥ 120 ms, and advanced IAB with evidence of biphasic P-wave in inferior leads were independently associated with increased risk of recurrent arrhythmia after AF ablation. Its predictive value is independent of other traditional risk factors, LAVI, or use of AADs.