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Background Esophageal thermal injury (ETI) is a byproduct of atrial fibrillation (AF) ablation using thermal sources. The most severe form of ETI is represented by atrioesophageal fistula, which has a high mortality rate. Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows identification of ETI. Hence, we sought to evaluate the utility of LGE-MRI as a method to identify ETI across the entire spectrum of severity. Methods and Results All AF radiofrequency ablations performed at the University of Utah between January 2009 and December 2017 were reviewed. Patients with LGE-MRI within 24 hours following AF ablation as well as patients who had esophagogastroduodenoscopy in addition to LGE-MRI were identified. An additional patient with atrioesophageal fistula who had AF ablation at a different institution and had MRI and esophagogastroduodenoscopy at the University of Utah was identified. A total of 1269 AF radiofrequency ablations were identified. ETI severity was classified on the basis of esophageal LGE pattern (none, 60.9%; mild, 27.5%; moderate, 9.9%; severe, 1.7%). ETI resolved in most patients who underwent repeat LGE-MRI at 3 months. All patients with esophagogastroduodenoscopy-confirmed ETI had moderate-to-severe LGE 24 hours after ablation MRI. Moderate-to-severe LGE had 100% sensitivity and 58.1% specificity in detecting ETI, and a negative predictive value of 100%. Atrioesophageal fistula was visualized by both computed tomography and LGE-MRI in one patient. Conclusions LGE-MRI is useful in detecting and characterizing ETI across the entire severity spectrum. LGE-MRI exhibits an extremely high sensitivity and negative predictive value in screening for ETI after AF ablation.

Introduction: Endurance athletes are at higher risk for developing atrial fibrillation as compared to the general population. The exact mechanism to explain this observation is incompletely understood. Our study aimed to determine whether degree of left atrial fibrosis detected by late gadolinium-enhancement magnetic resonance imaging (LGE-MRI) differed between Masters athletes and non-athlete controls., Methods: We recruited 20 endurance healthy Masters athletes and 20 healthy control subjects who underwent cardiac MRI. Healthy controls were recruited during screening colonoscopies and Masters athletes were recruited through word of mouth and at competitions. The two groups were age and gender matched. None of the participants were known to have an arrhythmia. Fibrosis, as measured by late gadolinium-enhancement, was measured in each participant by blinded readers. The degree of left atrial fibrosis was compared between the two groups. All participants were recruited from the Salt Lake City region and scanned at the University of Utah healthcare complex., Results: Left ventricular function was normal in all study participants. Left atrial volumes were significantly larger in the athletes (74.2 ml ± 14.4) as compared to the healthy control subjects (60.8 mL ± 21.4) (P = .02). Mean left atrial fibrosis score, reported as a percentage of the LA, was 15.5% ± 5.9 in the athlete cohort compared to 9.6% ± 4.9 in the controls (P = .002)., Conclusions: To our knowledge this is the first study that describes, characterizes and specifically quantifies fibrotic changes within the left atrium of highly trained endurance athletes. Increased atrial fibrosis seen in this population may be an early indicator for endurance athletes at risk of developing atrial arrhythmias., Competing Interests: Declaration of competing interest There are no pertinent relationships with industry., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Cryoballoon ablation (CBA) for pulmonary vein isolation (PVI) is an established modality for the treatment of atrial fibrillation (AF). We report feasibility of left atrial (LA) substrate modification in addition to PVI both using the cryoballoon., Methods: LA substrates and CBA-induced scar were assessed at baseline and 3 months after ablation using late gadolinium enhancement magnetic resonance imaging (LGE-MRI). Common periprocedural data including postablation LGE-MRI for evaluation of esophageal thermal injury, and CBA-associated complications were collected. Freedom from AF recurrence at 12 months was assessed using Holter and 30-day rhythm monitors., Results: In 26 patients (64 ± 11 years, 69% male; 27% persistent AF, CHADSVASC score: 2.3 ± 1.5; left ventricular ejection fraction: 56 ± 10%, oral anticoagulation with warfarin/direct oral anticoagulants: n = 11/15), referred for first-time AF ablation, CBA of the pulmonary veins and extrapulmonary LA substrates was performed (median: 12 [interquartile range {IQR}: 7-14] freezes over 1675 seconds [IQR: 1168-2160]). On LGE-MRI, significant postablation cryoballoon-induced LA scar (median: 19.4% [IQR: 13.4-24.7] in comparison to baseline preablation LA-LGE (median: 10.6% [IQR 3.1-13.1]; P = .01) was found. Freedom from AF recurrence at 12 months was 74.5% with median time-to-recurrence of 242 days (IQR: 172-298). In 15 of 26 (58%) patients, esophageal enhancement on the postablation MRI was present with full recovery after 3 months. No major periprocedural complications were observed., Conclusion: LA substrate modification in addition to PVI using LGE-MRI-guided CBA is feasible but still experimental. The efficacy and safety have to be investigated in a prospective randomized trial., (© 2020 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

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., (© 2019 Wiley Periodicals, Inc.)

Left atrial fibrosis plays an important role in the pathophysiology of atrial fibrillation. Left atrial ablation is an effective and increasingly used strategy to restore and maintain sinus rhythm in patients with atrial fibrillation. Late gadolinium enhancement (LGE) MRI and custom image analysis software have been used to visualize and quantify preablation atrial fibrosis and postablation scar and new fibrosis formation. This article reviews technical aspects of imaging atrial fibrosis/scar by LGE-MRI; use of atrial fibrosis and scar in predicting outcomes; applications of LGE-MRI to assess ablation lesions and optimize ablation parameters while avoiding collateral damage., (Published by Elsevier Inc.)

Objectives: This study retrospectively evaluated the feasibility and esophageal thermal injury (ETI) patterns of high-power short-duration (HPSD) radiofrequency atrial fibrillation (AF) ablation., Background: ETI following AF ablation can lead to serious complications. Little consensus exists on the optimal radiofrequency power setting or on the optimal strategy to assess ETI., Methods: A total of 687 patients undergoing first-time AF ablation with either HPSD ablation (50 W for 5 s, n = 574) or low-power long-duration ablation (LPLD, ≤35 W for 10 to 30 s, n = 113) were analyzed. ETI was assessed by late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) within 24 h post-ablation. Patients with moderate or severe esophageal LGE had a follow-up MRI within 24 h to 1 week, and esophagogastroduodenoscopies were performed when significant gastrointestinal symptoms or persistent LGE on repeat MRI was present. AF recurrence adjusted for potential confounders was analyzed., Results: The average age was 69.0 ± 11.8 years in the group undergoing HPSD ablation versus 68.3 ± 11.6 years in the LPLD group (p = 0.554), with 67.1% versus 59.3% male (p = 0.111). Esophageal LGE patterns were similar (64.8% vs. 57.5% none, 21.0% vs. 28.3% mild, 11.5% vs. 11.5% moderate, 2.8% vs. 2.7% severe for HPSD vs. LPLD, respectively; p = 0.370) with no atrioesophageal fistulas. Mean procedure length was significantly shorter in the HPSD group (149 ± 65 min vs. 251 ± 101 min; p < 0.001). AF recurrence rates were similar in the 2 groups for the mean 2.5-year follow-up period (adjusted, 42% vs. 41%; p = 0.571)., Conclusions: HPSD ablation results in similar ETI patterns, as assessed by same-day LGE MRI, compared with the LPLD setting but with significantly shorter procedure times. Recurrence rates at 2.5-year follow-up are similar., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

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., (© 2018 Wiley Periodicals, Inc.)

Objectives: The purpose of this study is to evaluate the spatial distribution of late gadolinium enhancement (LGE) of the left atrium (LA) by LGE-magnetic resonance imaging in an atrial fibrillation (AF) population., Background: LGE of the LA can be a surrogate of pre-existing structural remodeling of LA., Methods: LGE-magnetic resonance imaging scans were used for 160 patients with AF (mean age 66 ± 11 years) before AF ablation. To know the spatial distribution of LGE, the extent of LGE in 6 LA subregions was examined. Overall LGE distribution was also summarized as a spatial frequency histogram using an atlas of LA shape. These data were also compared between paroxysmal AF (87 patients) and persistent AF (73 patients)., Results: LGE coverage (%) in each subregion was as follows: 41.8 ± 18.9% in the left pulmonary vein (PV) antrum, 27.1 ± 16.7% in the left lateral wall, 25.8 ± 15.3% in the posterior wall, 19.7 ± 15.3% in the anterior wall, 17.1 ± 15.0% in the right PV antrum, and 12.0 ± 13.2% in the septum wall. LGE was heterogeneously distributed in the LA and was found with the highest frequency in the posterior wall near the inferior left PV antrum by the LGE histogram. A comparison of paroxysmal AF with persistent AF suggests that LGE was more expected in persistent AF compared with paroxysmal AF, particularly with a spread on the posterior and the anterior wall., Conclusions: LGE in the LA was heterogeneously distributed. LGE was highly distributed in the inferior left PV antrum near the posterior wall side, and spread on the posterior and anterior wall with AF progression., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Macroreentrant atrial tachycardia (AT) accounts for 40% to 60% of recurrent atrial arrhythmias after atrial fibrillation (AF) ablation. To describe late gadolinium enhancement magnetic resonance imaging (LGE-MRI)-detected scar-based dechanneling as new ablation strategy to treat ATs after AF ablation.Methods: Data from 102 patients who underwent initial AF ablation and repeat ablation for recurrent atrial arrhythmia within 1-year follow-up were analyzed. All patients underwent LGE-MRI before initial and repeat ablation. Depending on the recurrent rhythm, patients with AF and AT recurrence were assigned to group 1 or 2, respectively. Group 1 underwent fibrosis homogenization as second procedure. Group 2 underwent LGE-MRI-detected scar-based dechanneling. Both groups underwent reisolation of pulmonary veins if necessary.Results: Forty-six patients (45%) presented with AF, and 56 patients (55%) presented with AT recurrence during follow-up after initial ablation. In the first 25 patients from group 2, the AT was electroanatomically mapped, and a critical isthmus was defined. It was found that those isthmi were located in the regions with nontransmural scarring detected by LGE-MRI. In the last 31 patients from group 2, an empirical LGE-MRI-based dechanneling was performed solely based on the LGE-MRI results. During 1-year follow-up after second ablation, 67% patients in group 1 and 64% patients in group 2 were free from recurrence (log-rank, P=1.000). In group 2, 64% in the electroanatomically guided and 65% in the LGE-MRI dechanneling group were free from recurrence (log-rank, P=0.900).Conclusions: Anatomic targeting of LGE-MRI-detected gaps and superficial atrial scar is feasible and effective to treat recurrent arrhythmias post-AF ablation. Homogenization of existing scar is the appropriate treatment for recurrent AF, whereas dechanneling of existing isthmi seems the right approach for patients recurring with AT. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Multiple markers left atrium (LA) remodeling, including LA shape, correlate with outcomes in atrial fibrillation (AF). Catheter ablation is an important treatment of AF, but better tools are needed to determine which patients will benefit. In this study, we use particle‐based modeling to quantitatively assess LA shape, and determine to what degree it predicts AF recurrence after catheter ablation. Methods and results: There were 254 patients enrolled in the DECAAF study who underwent cardiac magnetic resonance imaging of the LA prior to AF ablation and were followed for recurrence for up to 475 days. We performed particle‐based shape modeling on each patient's LA shape. We selected shape parameters using the LASSO method and factor analysis, and then added them to a Cox regression model, which included multiple clinical parameters and LA fibrosis. We computed Harrell's C‐statistic with and without shape in the model. We used the model to stratify patients into recurrence risk classes by both shape and shape and fibrosis combined. Three shape parameters were selected for inclusion. The C‐statistic increased from 0.68 to 0.72 when shape was added to the model (P < 0.05). Visualized shapes showed that a more round LA shape with a shorter, more laterally rotated appendage was predictive of recurrence. Conclusion: LA shape is an independent predictor of recurrence after AF ablation. When combined with LA fibrosis, shape analysis using PBM may improve patient selection for ablation. [ABSTRACT FROM AUTHOR]

Background: Severity of left atrial (LA) fibrosis is a strong predictor of atrial fibrillation (AF) ablation success and has been associated with a history of stroke, hypertension, and heart failure (HF). However, it is unclear whether more severe LA fibrosis independently increases the risk of major adverse cardiovascular and cerebrovascular events (MACCE) among those with AF.Objectives: The goal of this study was to evaluate the occurrence and frequency of MACCE by strata of LA fibrosis severity in patients with AF.Methods: This was a retrospective cohort study of 1,228 patients with AF who underwent late gadolinium enhancement (LGE)-cardiac magnetic resonance imaging to quantify LA fibrosis severity between January 2007 and June 2015. Patients were stratified according to Utah stage of LA LGE criteria, and observed for the occurrence of MACCE, which included a composite of stroke or transient ischemic attack (TIA), myocardial infarction, acute decompensated HF, or cardiovascular death. Disease risk score (DRS) stratification was used to control for between-group differences in baseline characteristics and risk.Results: During follow-up, 62 strokes or TIAs, 42 myocardial infarctions, 156 HF events, and 38 cardiovascular deaths occurred. In DRS stratified analysis, the hazard ratio comparing patients with stage IV versus stage I LA LGE was 1.67 (95% confidence interval: 1.01 to 2.76) for the composite MACCE outcome. The only individual component of the MACCE outcome to remain significantly associated with advanced LGE following DRS stratification was stroke or TIA (hazard ratio: 3.94; 95% confidence interval: 1.72 to 8.98).Conclusions: This retrospective analysis demonstrated that more severe LA LGE is associated with increased MACCE risk, driven primarily by increased risk of stroke or TIA. [ABSTRACT FROM AUTHOR]

Introduction: Left atrial (LA) volume and function are related to success of atrial fibrillation (AF) ablation. However, the relationship between LA structure and function is not well understood. Magnetic resonance imaging (MRI) is a non-invasive method to assess LA fibrosis and LA function. Hypothesis: Our goal is to evaluate the left atrial functional recovery after successful atrial fibrillation ablation procedure focusing on the ablation lesion sets. Methods: CMR scans were performed in 55 AF patients (66.1±10.5 years) without AF recurrence, at three time points: prior to ablation procedure, in the acute post-ablation period (<48 hours) and at 3 months follow-up. We categorized patients into three groups according to the ablation lesion sets: Gr1{n=11} pulmonary vein isolation only (PVI); Gr2{n=33} PVI, roof line (RL) and posterior wall homogenisation (PH), Gr3{n=11} PVI, RL, PH and additional anterior wall fibrosis homogenization (AH). Maximum (maxLAV), minimum (minLAV) and pre-atrial contraction LA volumes (pre-aLAV) were measured according to the biplane area-length method with CMR. Total, passive and active LA ejection fractions (LAEF) were calculated, and LA fibrosis was quantified using late-gadolinium enhancement images. Results: Comparing the three groups, baseline pre-ablation atrial volumes and function were not significantly different among groups, but Gr3 had higher pre-ablation LA fibrosis% (Gr1 vs Gr2 vs Gr3 11.5±5.1% vs 11.7±4.1% vs 14.8±5.9% p<0.05). In the acute phase, the lowest total LA-EF was identified in Gr3 (Gr1 vs Gr3 total LAEF: 56.9±16.0% vs 37.2±14.9 p<0.05), but during follow-up no significant difference was identified. After 3 months Gr2 showed functional recovery, and total and also active LAEF was significantly higher compared to the baseline function (Gr3 pre-ablation vs follow-up LAEF: 42.5±12.5 vs 51.1±16.5% p<0.005) (Figure). Conclusions: In patient with posterior wall ablation LA function recovered, and additional left atrial fibrosis homogenization did not decrease LA function significantly at follow-up. [ABSTRACT FROM AUTHOR]