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Background: Left atrial (LA) fibrosis is thought to be a substrate for atrial fibrillation (AF) and can be quantified by late gadolinium enhancement magnetic resonance imaging (LGE‐MRI). Fibrosis formation in LA is a dynamic process and may either progress or regress following AF ablation. We examined the impact of postablation progression in LA fibrosis on AF recurrence. Methods: LA enhancement in LGE‐MRI was quantified in 127 consecutive patients who underwent first time AF ablation. Serial LGE‐MRIs were done prior to AF ablation, 3 months postablation and at least 12 months after second LGE‐MRI. Transient postablation lesion (TL) was defined as atrial enhancement caused by ablation lesions that was detected on the first (3 month) but not on the second postablation LGE‐MRI. New fibrosis (NF) was defined as atrial enhancement detected on the most recent LGE‐MRI, at least 15 months after the ablation procedure. AF recurrence and its correlation with TL and NF was assessed in all patients during the follow‐up period. Results: An increase of 1% NF increased the chance of postablation AF recurrence by 3% (hazard ratio [HR] 1.03, 95% CI 1‐1.06, P =.05). TL had no significant impact on recurrence (P =.057). After adjusting for cardiovascular risk factors, HR increased as NF became greater. Greater volume of NF (≥21%) corresponded with lower arrhythmia‐free survival (37% vs 62%, P =.01). Conclusion: NF formation postablation of AF is a novel marker of long‐term procedural outcome. Extensive NF is associated with significantly higher risk of atrial arrhythmia recurrence. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Adequate catheter/atrial tissue contact is critical for lesion formation during radiofrequency (RF) ablation of atrial fibrillation (AF). Late gadolinium enhancement magnetic resonance imaging (LGE‐MRI) is a unique tool for the evaluation of lesion formation and detection of acute esophageal injury. Methods: LGE‐MRIs were obtained prior, within 24 hours of, and at 115 ± 62 days after first AF ablation in 36 patients. The Visitag module of CARTO3 was used to collect contact force (CF) and duration from a CF sensing ablation catheter for each registered ablation point. The minimum CF resulting in permanent lesions was determined. Esophageal enhancement detected by acute LGE‐MRI was classified as mild, moderate, and severe. The CF resulting in esophageal enhancement was determined. Results: A total of 4,642 registered ablation tags at 50 W power were analyzed. The mean RF duration (5.9 ± 3.7 vs. 5.6 ± 3.2 seconds, P < 0.05), CF (11.5 ± 5.6 vs. 10.9 ± 5.4 g, P < 0.001), and force time integral (FTI) (67.3 ± 54.5 vs. 62.2 ± 52.7 gs, P < 0.01) were significantly higher between ablation tags with and without associated LGE‐MRI detected scar. The mean CF (15.7 ± 6.1 vs. 12.6 ± 5.9 g, P < 0.05, n  =  17 patients) in areas of esophageal enhancement was greater than areas without. Conclusion: Left atrial short duration ablation lesions with a CF greater than 12 g are more likely to be associated with permanent lesion formation. Ablating on top of the esophagus, CF less than 15 g would help minimize esophageal wall injury. [ABSTRACT FROM AUTHOR]

The article discusses an analysis of gaps in atrial ablation lesions using a real-time magnetic resonance imaging (RT-MRI) system which causes a full and transmural ablation in the atrium. The study used a swine model, with ablation lesions with a gap created in the atrium using fluoroscopy and an electroanatomic system in the first group. Results show RT-MRI system can identify and acutely target gaps in atrial ablation lesion sets.

Background: Esophageal wall thermal injury after atrial fibrillation ablation is a potentially serious complication. However, no noninvasive modality has been used to describe and screen patients to examine whether esophageal wall injury has occurred. We describe a noninvasive method of using delayed-enhancement MRI to detect esophageal wall injury and subsequent recovery after atrial fibrillation ablation.Methods and Results: We analyzed the delayed-enhancement MRI scans of 41 patients before ablation and at 24 hours and 3 months after ablation to determine whether there was evidence of contrast enhancement in the esophagus after atrial fibrillation ablation. In patients with contrast enhancement, 3D segmentation of the esophagus was performed using a novel image processing method. Upper gastrointestinal endoscopy was then performed. Repeat delayed-enhancement MRI and upper gastrointestinal endoscopy was performed 1 week later to track changes in lesions. The wall thickness of the anterior and posterior wall of the esophagus was measured at 3 time points: before ablation, 24 hours after ablation, and 3 months after ablation. Evaluation of preablation MRI scans demonstrated no cases of esophageal enhancement. At 24 hours, 5 patients showed contrast enhancement. Three of these patients underwent upper gastrointestinal endoscopy, which demonstrated esophageal lesions. Repeat upper gastrointestinal endoscopy and MRI 1 week later demonstrated resolution of the lesions. All 5 patients had confirmed resolution of enhancement at 3 months. All patients with esophageal tissue enhancement demonstrated left atrial wall enhancement directly adjacent to the regions of anterior wall esophageal enhancement.Conclusions: Our preliminary results indicate delayed-enhancement MRI can assess the extent and follow progression of esophageal wall injury after catheter ablation of atrial fibrillation. It appears that acute esophageal injury recovers within 1 week of the procedure. [ABSTRACT FROM AUTHOR]

Left atrial (LA) volumes are related to success of atrial fibrillation (AF) ablation, but the relation to other functional and structural parameters is less well understood. Our goal was to detect potential functional and structural predictors of arrhythmia recurrence after ablation using cardiac magnetic resonance imaging (CMRi) and to non-invasively assess the relation between LA functional and structural remodeling pre- and post-ablation. A total of 55 patients (38 male, age 67 ± 10 years) underwent CMRi prior to and then within 24-h and 3-months after ablation. LA volumes (LAV) and function (as assessed by ejection fraction and peak longitudinal atrial strain (PLAS)) were measured by feature-tracking CMRi, and LA fibrosis/scarring was quantified using late‑gadolinium enhancement (LGE) imaging. Atrial function was lower acutely in patients with recurrence versus those with non-recurrence: [R vs NR: EF Total 27.8 ± 10.3% vs 38.1 ± 11% p = 0.002; EF Active 10.5 ± 8% vs 19.1 ± 12% p = 0.007; EF Passive 19.4 ± 8 vs 25.8 ± 10 p = 0.021; PLAS 13 ± 5.9% vs 20.2 ± 7% p = 0.004]. With univariate analysis, baseline minimum volume (MinLAV, MinLAVi), several baseline functional parameters (EF Total , EF Passive , EF Active , PLAS), and LA-LGE were predictors of recurrence [all p < 0.05]. Acute function (EF Total , EF Passive , EF Active , PLAS) also predicted recurrence (p < 0.01). Lower pre-ablation EF Total , EF Passive , and PLAS correlated with higher amount of pre-ablation LA-LGE (p < 0.05). In a multivariate model including MinLAV, EF Active and LA-LGE (all at baseline), LA-LGE was the only independent predictor of recurrence (p = 0.0322). Pre-ablation function inversely correlated with LA-LGE and was related to success of AF ablation. Multi-parametric and longitudinal assessment of LA function and structure could be helpful in selection of optimal treatment strategies for AF patients by predicting outcomes. • This longitudinal CMRi study reports left atrial (LA) function and structure pre-ablation, acutely (< 24-h) and at follow-up • Lower LA strain (measured in sinus rhythm) correlated with higher fibrosis • Besides baseline LA function and fibrosis, acute functional impairment also associated with AF recurrence • Acute functional impairment was more severe in patients with high baseline LA fibrosis • Poor functional recovery was detected in patients with poor baseline function regardless of the amount of ablation scar [ABSTRACT FROM AUTHOR]