Opposite evolution on voltage and thickness from paroxysmal to persistent AF

Abstract Funding Acknowledgements Type of funding sources: None. Background There is a controversy about correlation between voltage and thickness in the atrial myocardium and their evolution from paroxysmal to persistent atrial fibrillation (AF). Purpose This is an observational study to compare voltage and thickness of different areas on the left atrium in paroxysmal and persistent atrial fibrillation. Methods 43 patients underwent first procedure atrial fibrillation ablation. Points with electrical information from an electroanatiomical map in sinus rhythym were acquiered during the ablation procedure covering the whole atrial surface. CT was acquired in all patients before the procedure and endo- and epicardium from the atrium was segmented for the atrial thickness calculation. All the points from the electromecanical map were projected on the thickness map to have both information on the same location. 3D atrium was segmented in 5 areas for the analysis: Lateral, Anterior, Septal, Posterior and Roof (Figure 1). Voltage and thickness values among different areas and between AF type were compared. Results 30 paroxysmal and 13 persistent AF patients were analyzed acquiring 435±192 points per patient and 87±55 points per patient/area (20884 points in total). There was no linear correlation between voltage and thickness comparing all the patients nor among different areas nor between AF type (R<0.2 in all cases). Regarding paroxysmal AF patients, septum showed significatly lower voltage compared with the other segments, posterior, lateral, anterior and roof (1.4±1.3mV*, P<0.001). The roof showed the highest voltage (2.3±1.7mV). The thickness analysis showed the septal segment as thinner segment and lateral as thicker segment (1.4±0.6mm,1.7±0.9mm, P<0.001) (Figure 2). Regarding persistent AF patients: septum showed significatly lower voltage (1±0,9mV*)compared with the other segments. Roof showed higher voltage(2±1.7mV) (Figure 2). The thickness analysis showed the anterior segment as thinner segment and lateral as the thickest segment (1.6±0.8mm, 1.9±0.9mm, (P<0.001) different like on paroxysmal AF population. Comparing voltage and thicknes between paroxysmal and persistent AF, all the segments on persistent population showed lower voltage values, with significant differences on all segmentes but the lateral one. On the other hand, all segments on persistent population showed statisticaly signignificant thicker myocardium in camparison with paroxysmal population (Figure 2). Conclusions According to our findings, there is no linear correlation between voltage and thickness. Persistent AF atria show thicker walls but with lower voltages in comparison with paroxysmal AF atria.