Does the extent of left atrial arrhythmogenic substrate depend on the electroanatomical mapping technique: impact of pulmonary vein mapping catheter vs. ablation catheter.

Aims: In persistent atrial fibrillation (AF), left atrial low-voltage areas and complex fractionated atrial electrograms (CFAEs) have been thoroughly discussed as critical substrate points for AF perpetuation. Thus, in patients undergoing pulmonary vein isolation, these sites are often considered additional ablation targets. Currently, mapping techniques for these substrate indicators are still under discussion. The aim of this study was to evaluate the impact of different mapping catheters on the detection of low-voltage areas and CFAE.

Methods and results: Two bipolar voltage maps and two CFAE left atrial maps were obtained each in 30 patients undergoing catheter ablation of AF using the following two different catheters: A four-pole ablation catheter (MAP, mapping and ablation catheter) (electrode size: tip: 4 mm, band: 1 mm; inter-electrode spacing: 0.5-5-2 mm) and a 10-pole circular pulmonary vein mapping catheter (CMC) (electrode size: 1 mm; inter-electrode spacing: 7-7-7 mm). Successively, low-voltage and CFAE area sizes were then compared between the two catheters. Areas with a bipolar voltage of <0.5 mV were significantly smaller when obtained with the CMC compared with the MAP (8.9 ± 8.9 vs. 17.4 ± 11.7 cm², P < 0.001). This was also significantly different for a bipolar voltage of <0.2 mV (2.3 ± 4.6 vs. 6.2 ± 9.6 cm², P < 0.001). Complex fractionated atrial electrogram area sizes were significantly larger when obtained with the CMC compared with the MAP group (14.6 ± 10.9 vs. 19.4 ± 9.4 cm², P = 0.011).

Conclusion: Low-voltage and CFAE area size varies significantly between different mapping catheters. Mapping electrode settings have to be taken into consideration for the assessment of electroanatomical substrate of AF.