Yong Wang1,2, Genqing Zhou3, Songwen Chen3, Yong Wei3, Xiaofeng Lu3, Juan Xu3, Xiaoyu Wu3, Shaowen Liu1. 1. Department of Cardiology, Shanghai General Hospital of Nanjing Medical University, Shanghai, China. 2. Department of Cardiology, The Second People's Hospital of Wuhu, Anhui, China. 3. Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Abstract
BACKGROUND: Ablation index (AI), a novel lesion quality marker, includes contact force, time, and power of radiofrequency (RF) application, but not regional variation in wall thickness within the wide antral catheter ablation (WACA) circle. This study explored the relationships among AI target value, atrial wall thickness, and gap formation within the WACA circle in patients with paroxysmal atrial fibrillation (PAF). METHODS: We evaluated 102 consecutive patients (mean age, 65 ± 9 years) with PAF who underwent AI-guided WACA for ipsilateral pulmonary vein isolation (PVI). Each WACA circle was subdivided into eight segments, and overall 7143 RF applications were delivered, including 125 gaps in PVI ablation lines. For each RF tag within the ablation circle, we collected data on ablation lesion depth surrogates (time of application, delivery power, impedance drop, average contact force, force-time integral [FTI], and AI) and left atrial wall thickness measured by multidetector computer tomography scanning. RESULTS: The anterior and roof walls were the thickest segments of the ablation circle, in which 85.8% of gaps concentrated, while the posterior and inferior walls were the thinnest. Gap formation was significantly associated with FTI, AI, wall thickness, FTI/wall thickness, and AI/wall thickness. AI/wall thickness had the highest predictive value for gap formation, with a cutoff of 195.6 au/mm for effective ablation. CONCLUSIONS: In AI-guided PVI of PAF, AI/wall thickness by normalizing myocardial thickness variation along the WACA circle was a strong predictor of gap formation, with a target of 195.6 au/mm appearing suitable for effective ablation.
BACKGROUND: Ablation index (AI), a novel lesion quality marker, includes contact force, time, and power of radiofrequency (RF) application, but not regional variation in wall thickness within the wide antral catheter ablation (WACA) circle. This study explored the relationships among AI target value, atrial wall thickness, and gap formation within the WACA circle in patients with paroxysmal atrial fibrillation (PAF). METHODS: We evaluated 102 consecutive patients (mean age, 65 ± 9 years) with PAF who underwent AI-guided WACA for ipsilateral pulmonary vein isolation (PVI). Each WACA circle was subdivided into eight segments, and overall 7143 RF applications were delivered, including 125 gaps in PVI ablation lines. For each RF tag within the ablation circle, we collected data on ablation lesion depth surrogates (time of application, delivery power, impedance drop, average contact force, force-time integral [FTI], and AI) and left atrial wall thickness measured by multidetector computer tomography scanning. RESULTS: The anterior and roof walls were the thickest segments of the ablation circle, in which 85.8% of gaps concentrated, while the posterior and inferior walls were the thinnest. Gap formation was significantly associated with FTI, AI, wall thickness, FTI/wall thickness, and AI/wall thickness. AI/wall thickness had the highest predictive value for gap formation, with a cutoff of 195.6 au/mm for effective ablation. CONCLUSIONS: In AI-guided PVI of PAF, AI/wall thickness by normalizing myocardial thickness variation along the WACA circle was a strong predictor of gap formation, with a target of 195.6 au/mm appearing suitable for effective ablation.
Authors: Caroline H Roney; Charles Sillett; John Whitaker; Jose Alonso Solis Lemus; Iain Sim; Irum Kotadia; Mark O'Neill; Steven E Williams; Steven A Niederer Journal: Eur Heart J Cardiovasc Imaging Date: 2021-12-18 Impact factor: 6.875