Influence of the left atrial contact areas on fixed low-voltage zones during atrial fibrillation and sinus rhythm in persistent atrial fibrillation.

BACKGROUND

Atrial low-voltage zones (LVZ) are suggested as important factors for maintaining persistent atrial fibrillation (PsAF). The relationship between LVZs and left atrial (LA) contact areas (CoAs) is still unclear.

OBJECTIVE

To assess whether CoA regions were involved in atrial substrate properties maintaining PsAF.

METHODS

A total of 50 patients with PsAF (36 long-lasting) were analyzed. Three representative CoA detection areas (ascending aorta-anterior-LA, descending aorta-left pulmonary vein antrum, and vertebrae-posterior-LA) were registered on the mapping geometry. Electrograms during AF and sinus rhythm (SR) were acquired, and the fractionated electrograms (CFE; < 80milliseconds) and voltages were analyzed regarding the CoAs.

RESULTS

After SR conversion, 76% (38/50) had a significant LVZ (>5% of the total LA surface area). Patients with long-lasting PsAF versus PsAF had larger CoA areas (7.7 ± 3.0 vs. 4.5 ± 2.5cm2 , P < 0.05) and overlapped-LVZs (8.2 [3.2-11.0] vs. 2.1 [0.7-3.7] cm2 , P = 0.0126) between the SR-LVZs (<0.5 mV) and AF-LVZs (<0.2 mV). Overlapped-LVZs were frequently observed in CoA regions (anterior 76.4%; LIPV antrum 78.8%, and vertebrae 39.2%), and those LVZs had smaller unipolar voltages than those distant from the CoA regions (0.64 ± 0.16 vs. 2.5 ± 1.5 mV, P < 0.0001). SR-LVZ targeted ablation, including of CoA regions, rendered AF termination (n = 8, 21%), and 88% of the sites were not located immediately above, but adjacent to, the overlapped-LVZs. Significant AF slowing (6.0 ± 0.6 to 5.6 ± 0.6 Hz; P < 0.05) accompanied by unintentional CFE elimination (9.8-1.8 cm2 ; P < .0001) was achieved in patients without termination.

CONCLUSION

Our data suggested that external structures in contact with the LA are involved in the creation of localized diseased myocardium necessary for PsAF maintenance.