Low-voltage areas have been used as atrial structural substrates in estimating fibrotic degeneration in patients with atrial fibrillation (AF). The high-resolution maps obtained by recently developed mapping catheters allow the visualization of several functional abnormalities. We investigated the association between left atrial (LA) functional abnormal findings on a high-resolution substrate map and AF recurrence in patients who underwent pulmonary vein isolation without any additional LA substrate ablation. This observational study included 100 consecutive patients who underwent second ablation for AF (paroxysmal, 48%; persistent, 52%). Patients with extra-pulmonary-vein LA substrate ablation during the initial and second ablation were excluded. LA mapping was performed using a 64-pole mini-basket catheter on the RHYTHMIA mapping system (Boston Scientific, Marlborough [Cambridge] Massachusetts). Patients were followed for 2 years. AF recurrence developed in 39 (39%) patients. On the high-resolution substrate map, AF recurrence was associated with the presence of the following findings: low-voltage areas (<1.0 mV, >5 cm²; hazard ratio [HR] = 2.53; 95% confidence interval [CI] = 1.30 to 4.93; p <0.006), fractionated-electrogram areas (≥5 peaks, >5 cm²; HR = 2.15, 95% CI = 1.10 to 4.19; p = 0.025), LA conduction time of >130 ms (HR = 3.11, 95% CI = 1.65 to 5.88, p <0.0001), deceleration zone (≥5 isochrones/cm²; HR = 1.97, 95% CI = 1.04 to 3.37, p = 0.039), and multiple septal break-out points (HR = 3.27, 95% CI = 1.50 to 7.16, p = 0.003). Accumulation of these risk factors increased AF recurrence in a stepwise manner, with an HR = 1.90, 95% CI = 1.44 to 2.52, p <0.00001 for each additional risk factor. In conclusion, a high-resolution map revealed new LA functional substrates associated with AF recurrence. Implementation of functional substrates may improve the prediction of AF recurrence after ablation, and possibly aid the development of tailored AF ablation strategies.

Abnormal left atrial substrates and accumulation of risk factors

Study design, representative maps demonstrating abnormal substrates, and atrial fibrillation recurrence rates stratified by the number of risk factors are shown. Accumulation of these risk factors increased atrial fibrillation recurrence rates in a stepwise manner with a hazard ratio = 1.90, 95% confidence interval = 1.44 to 2.52, p <0.00001, for 1 risk increase.