Left atrial voltage mapping using a new impedance-based algorithm in patients with paroxysmal atrial fibrillation

Atrial fibrosis is associated with the pathogenesis and progression of atrial fibrillation (AF). We sought to evaluate the extent of left atrial (LA) scarring in patients with paroxysmal AF (PAF) undergoing catheter ablation using a new impedance-based algorithm.

We prospectively enrolled 73 consecutive patients (43 males, 58 years) with PAF who underwent pulmonary vein antral isolation. We first performed high-density bipolar voltage mapping during sinus rhythm using Tissue Proximity Indicator (TPI), one of the features of the ConfiDense mapping module integrated in the electroanatomic mapping system. A dense LA shell was created initially without TPI (mean points 2,411) and subsequently activating TPI (mean points 1,167). Each point was classified according to the peak-to-peak bipolar voltage electrogram based on two criteria (criterion A: healthy >0.8 mV, border zone: 0.4-0.8 mV, scarred: <0.4 mV; criterion B: healthy: >0.5 mV, border zone: 0.25-0.5 mV, scarred: <0.25 mV).

LA voltage analysis represented significantly smaller scarred areas when mapping was performed with TPI-ON compared with TPI-OFF in both voltage criteria (average LA voltage area: 3.02 ± 5.28 cm2 vs 9.15 ± 13.11 cm2 vs in criterion A and 1.19 ± 2.54 cm2 vs 5.61 ± 9.56 cm2 in criterion B). A statistically significant voltage difference was observed in all segments of the left atrium between the two mapping protocols, particularly on the inferior wall.

A more specific delineation of LA fibrosis may be produced using the TPI feature of the ConfiDense mapping module, through elimination of false-positive annotated mapping points due to low contact.