Correlation Between Voltage and Impedance Mapping in Patients with Atrial Fibrillation

Background. Pulmonary vein isolation (PVI) represents the cornerstone of paroxysmal (PAF) and persistent atrial fibrillation (PsAF) ablation. Impedance values provide insights on tissue conductive properties. Methods. Consecutive patients undergoing PAF and PsAF ablation were prospectively enrolled. All the patients underwent a preprocedural multidetector computed tomography (MDCT) to evaluate left atrial wall thickness (LAWT). Electroanatomic maps were acquired with the ablation catheter, and impedance values (Ω) and voltage amplitude (mV) of bipolar electrograms were collected. Results. A total of 60 patients (40 with PAF and 20 with PsAF) were included in the study. In all PAF cases, no voltage value lower than 0.5 mV was found at LA mapping; the corresponding mean impedance value was 151.5 ± 5.4 Ω. In PsAF cases, voltage values inferior to 0.05 mV have been reported in 19/20 patients. PsAF patients showed a mean impedance value of 129.1 ± 3.8 Ω. The correlation analysis between bipolar voltage and impedance reported an r_s value of 0.4166 (p < 0.001), showing a positive correlation between the two variables. On the contrary, no direct correlation was found between voltage and LAWT and between impedance and LAWT (rsv-t = 0.1838; rsi-t = 0.1133, respectively). Conclusions. This research study suggests a correlation between voltage amplitude and impedance values, so that impedance might be used for arrhythmogenic substrate characterization.