Automatically Derived Unipolar Low-Voltage-Area Burden for Predicting Atrial Fibrillation Ablation Outcomes.

Background: Unipolar voltage mapping has shown value in delineating comprehensive atrial substrates. However, the clinical application of unipolar low-voltage areas (Uni-LVAs) in atrial fibrillation (AF) ablation is limited, largely because of the absence of a well established voltage threshold. In this study we aimed to: (1) define the threshold for Uni-LVA in the left atrium (LA); and (2) investigate the association between Uni-LVA burden and ablation outcomes in a prospective AF cohort.

Methods: The Uni-LVA threshold was defined as the average of the 6 cutoff values, representing the voltage at 95% of all electrograms from a reference cohort who underwent left-sided accessory pathway ablation and concomitant LA mapping. In a single-centre, prospective AF ablation cohort, LA mapping was conducted and the Uni-LVA burden was automatically calculated.

Results: Uni-LVA was defined as an area with an amplitude of < 1.6 mV. In 145 patients, the Uni-LVA burden was automatically obtained using customized software. During a follow-up period of 16 ± 4 months, 44 patients experienced recurrence. Uni-LVA burden was significantly associated with recurrence rates. Compared with group 1 (< 1%), the recurrence rates for group 2 (1%-10%) and group 3 (> 10%) were significantly higher (hazard ratio, 5.08 [P<0.001] and hazard ratio, 24.07 [P < 0.001]). Receiver operator curve analysis showed significantly higher predictive efficiency for Uni-LVA burden (area under the curve, 0.880 vs 0.762; P < 0.001) compared with the bipolar low voltage burden.

Conclusions: Using a unipolar voltage threshold of < 1.6 mV, Uni-LVA burden was independently associated with long-term AF recurrence after ablation and outperformed bipolar assessment. This finding suggests Uni-LVA could serve as a valuable tool for prognostic evaluation.