Abstract 4651: Local Bipolar Electrogram-Based Criteria to Evaluate the Transmurality of the Atrial Ablation Lesion
It is important to recognize whether a transmural lesion (TL) was created by ablation in each ablation site during atrial ablation procedures. The local bipolar atrial electrogram (LBAE)-based criteria to diagnose TL formation, however, remain to be established. This study was performed to define LBAE-based criteria for local TL formation. In 13 anesthetized adult porcines, point-by-point radiofrequency energy applications (30W/55°C/30sec) were performed using a conventional 4-mm tip ablation catheter in the atria (right/left3150/91 sites) during sinus rhythm. After the ablation procedure, the hearts were extracted and the ablation lesions were macroscopically identified. The hearts were fixed with formalin, and each section (0.5 mm interval) was stained with Masson’s trichrome stain and examined under light microscopy. Histopathological examination revealed TLs in 111 and non-transmural lesions (NTLs) in the remaining 130 sites. The LBAEs recorded from the TLs exhibited predominant attenuation in the positive deflection with a morphological change to the QS, Qr or rS pattern, while those recorded from the NTLs exhibited the RS or QR pattern without an abbreviation of the positive deflection (ratio of the amplitude of the positive (Ap) and negative deflection (An) after ablation (=Ap/An) in the TL vs NTL: 0.2±0.3 vs 0.9±1.0; P<0.0001, the Ap after ablation in the TL vs NTL: 0.07±0.6 mV vs 0.5±0.4 mV; P <0.0001). The percent reduction in the Ap (Rp), An (Rn) and total amplitude (Rt) after ablation was significantly larger in the TLs than in the NTLs (Rp:94±6% vs 48±30%; P<0.0001, Rn: 25±48% vs 14±41%; P=0.04, Rt:65±24% vs 35±25%; P<0.0001). A cut-off value of Rp≥80% best discriminated the TL from the NTL with a sensitivity, specificity and positive and negative predictive values of 100%, 85%, 84% and 100%, respectively. The cut-off value of the Rp≥80% with the morphological change of the LBAE to the QS, Qr or rS pattern could discriminate the TLs from the NTLs with high accuracy. This criterion can be one of the practical endpoints for energy delivery at each ablation site during ablation procedures.