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Background: The low-voltage area detected by electroanatomic mapping (EAM) is a surrogate marker of left atrial fibrosis. However, the correlation between the EAM and late gadolinium enhancement magnetic resonance imaging (LGE-MRI) has been inconsistent among studies. This study aimed to investigate how LA size affects the correlation between EAM and LGE-MRI., Methods: High-density EAMs of the LA during sinus rhythm were collected in 22 patients undergoing AF ablation. The EAMs were co-registered with pre-ablation LGE-MRI models. Voltages in the areas with and without LGE were recorded. Left atrial volume index (LAVI) was calculated from MRI, and LAVI > 62 ml/m 2 was defined as significant LA enlargement (LAE)., Results: Atrial bipolar voltage negatively correlates with the left atrial volume index. The median voltages in areas without LGE were 1.1 mV vs 2.0 mV in patients with vs without significant LAE (p = 0.002). In areas of LGE, median voltages were 0.4 mV vs 0.8 mV in patients with vs without significant LAE (p = 0.02). A voltage threshold of 1.7 mV predicted atrial LGE in patients with normal or mildly enlarged LA (sensitivity and specificity of 74% and 59%, respectively). In contrast, areas of voltage less than 0.75 mV correlated with LGE in patients with significant LA enlargement (sensitivity 68% and specificity 66%)., Conclusions: LAVI affects left atrial bipolar voltage, and the correlation between low-voltage areas and LGE-MRI. Distinct voltage thresholds according to the LAVI value might be considered to identify atrial scar by EAM., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Left atrial (LA) enlargement is prevalent among atrial fibrillation (AF) patients and constitutes an important marker of atrial myopathy. Several studies have described reduction in LA volume post-catheter ablation (CA) of AF, however, none have investigated differences related to additional ablation outside the pulmonary veins (PVs)., Objectives: The authors sought to study early LA remodeling following CA of persistent AF and the impact of additional, fibrosis-guided extra-PV ablation., Methods: In this DECAAF II (Effect of MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation on Atrial Arrhythmia Recurrence in Patients With Persistent Atrial Fibrillation) trial subanalysis, patients with persistent AF were randomized to receive pulmonary vein isolation (PVI) only or PVI + fibrosis-guided ablation. Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) was performed before and 3 months after CA. Patients were followed up with single-lead electrocardiogram devices for 12 to18 months. AF burden was calculated as days with AF divided by days monitored., Results: This analysis included 733 patients. The mean LA volume index (LAVI) before ablation was 62.0 mm 3 /m 2 and after ablation was 51.3 mm 3 /m 2 , with a mean reduction of 10.7 mm 3 /m 2 (P < 0.001). Patients in the fibrosis-guided ablation arm had more volume reduction than did those in the PVI-only group (12.1 mm 3 /m 2 vs 9.3 mm 3 /m 2 ; P = 0.02). LAVI reduction was greater in patients with heart failure (15.7 vs 8.9; P = 0.001) and was associated with improved left ventricular ejection fraction (LVEF) (r = 0.23; P < 0.001), reduced AF burden (r = -0.173; P < 0.001), improved LVEF, and improved quality of life (r = 0.146; P < 0.001)., Conclusions: We confirmed the presence of LA remodeling within 3 months after ablation for persistent AF. Importantly, we saw more LA volume reductions in patients in the PVI + fibrosis-guided ablation arm in comparison with PVI only, and in patients with LV dysfunction. LA volume reduction in response to CA is associated with decreased arrhythmia recurrence, reduced AF burden, and improved LVEF and quality of life., Competing Interests: Funding Support and Author Disclosures The DECAAF II trial was funded by Medtronic, GE, Siemens, Boston Scientific, Biosense Webster, and Abbott. Dr Marrouche has received consulting fees from Biosense Webster, Boston Scientific and AtriCure; is a speaker for Abbott, Biosense Webster, AtriCure and Sanofi; has received research support from Abbott, Medtronic, Biosense Webster, Siemens, GE, Boston Scientific, Sanofi and Samsung; is the founder of Marrek, being named in a patent issued for MRI fibrosis imaging; and has a family member who is the CEO of Cardiac Designs. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023. Published by Elsevier Inc.)

Objectives: Magnetic resonance angiography (MRA) has been established as an important imaging method in cardiac ablation procedures. In pulmonary vein (PV) isolation procedures, MRA has the potential to minimize the risk of severe complications, such as atrio-esophageal fistula, by providing detailed information on esophageal position relatively to cardiac structures. However, traditional non-gated, first-pass (FP) MRA approaches have several limitations, such as long breath-holds, non-uniform signal intensity throughout the left atrium (LA), and poor esophageal visualization. The aim of this observational study was to validate a respiratory-navigated, ECG-gated (EC), saturation recovery-prepared MRA technique for simultaneous imaging of LA, LA appendage, PVs, esophagus, and adjacent anatomical structures., Methods: Before PVI, 106 consecutive patients with a history of AF underwent either conventional FP-MRA ( n = 53 patients) or our new EC-MRA ( n = 53 patients). Five quality scores (QS) of LA and esophagus visibility were assessed by two experienced readers. The non-parametric Mann-Whitney U-test was used to compare QS between FP-MRA and EC-MRA groups, and linear regression was applied to assess clinical contributors to image quality., Results: EC-MRA demonstrated significantly better image quality than FP-MRA in every quality category. Esophageal visibility using the new MRA technique was markedly better than with the conventional FP-MRA technique (median 3.5 [IQR 1] vs median 1.0, p < 0.001). In contrast to FP-MRA, overall image quality of EC-MRA was not influenced by heart rate., Conclusion: Our ECG-gated, respiratory-navigated, saturation recovery-prepared MRA technique provides significantly better image quality and esophageal visibility than the established non-gated, breath-holding FP-MRA. Image quality of EC-MRA technique has the additional advantage of being unaffected by heart rate., Advances in Knowledge: Detailed information of cardiac anatomy has the potential to minimize the risk of severe complications and improve success rates in invasive electrophysiological studies. Our novel ECG-gated, respiratory-navigated, saturation recovery-prepared MRA technique provides significantly better image quality of LA and esophageal structures than the traditional first-pass algorithm. This new MRA technique is robust to arrhythmia (tachycardic, irregular heart rates) frequently observed in AF patients.

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: Success rates of catheter ablation in persistent atrial fibrillation (AF) remain suboptimal. A better and more targeted ablation strategy is urgently needed to optimize outcomes of AF treatment. We sought to assess the safety and efficacy of targeting atrial fibrosis during ablation of persistent AF patients in improving procedural outcomes., Methods: The DECAAF II trial (ClinicalTrials. gov identifier number NCT02529319) is a prospective, randomized, multicenter trial of patients with persistent AF. Patients with persistent AF undergoing a first-time ablation procedure were randomized in a 1:1 fashion to receive conventional pulmonary vein isolation (PVI) ablation (Group 1) or PVI + fibrosis-guided ablation (Group 2). Left atrial fibrosis and ablation induced scarring were defined by late gadolinium enhancement magnetic resonance imaging at baseline and at 3-12 months postablation, respectively. The primary endpoint is the recurrence of atrial arrhythmia postablation, including atrial fibrillation, atrial flutter, or atrial tachycardia after the 90-day postablation blanking period. Patients were followed for a period of 12-18 months with a smartphone ECG Device (ECG Check Device, Cardiac Designs Inc.). With an anticipated enrollment of 900 patients, this study has an 80% power to detect a 26% reduction in the hazard ratio of the primary endpoint., Results and Conclusion: The DECAAF II trial is the first prospective, randomized, multicenter trial of patients with persistent AF using imaging defined atrial fibrosis as a treatment target. The trial will help define an optimal approach to catheter ablation of persistent AF, further our understanding of influencers of ablation lesion formation, and refine selection criteria for ablation based on atrial myopathy burden., (© 2021 Wiley Periodicals LLC.)

Introduction: 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., Methods: 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., Results: 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)., Conclusion: 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., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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.)

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.

Background Late gadolinium enhancement magnetic resonance imaging is an effective tool for assessment of atrial fibrosis. The degree of left atrial fibrosis is a good predictor of atrial fibrillation ( AF ) ablation success at 1 year, but the association between left atrial fibrosis and long-term ablation success has not been studied. Methods and Results Late gadolinium enhancement magnetic resonance images of sufficient quality to quantify atrial fibrosis were obtained before the first AF ablation in 308 consecutive patients. Left atrial fibrosis was classified in 4 Utah stages (I, 0-10%; II , 10-20%; III , 20-30%; and IV , >30%). Patients were followed up for up to 5 years until the time of first arrhythmia recurrence or second ablation. A total of 308 patients were included; the mean age was 64.5±12.1 years, and 63.4% were men. During follow-up, 157 patients experienced an arrhythmia recurrence and 106 patients underwent a repeated ablation. A graded effect was observed in which patients with more advanced atrial fibrosis were more likely to experience recurrent AF (hazard ratio for stage IV versus stage I, 2.73; 95% confidence interval, 1.57-4.75) and undergo a repeated ablation (proportional odds ratio for stage IV versus stage I, 5.19; 95% confidence interval, 2.12-12.69). Conclusions The degree of left atrial fibrosis predicts the success of AF ablation at up to 5 years follow-up. In patients with advanced atrial fibrosis, AF ablation is associated with a high procedural failure rate.

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.)

Aim: Age and female sex are associated with a higher risk of stroke in atrial fibrillation (AF). We sought to determine whether advancing age and female sex are associated with higher atrial fibrosis., Methods and Results: We conducted an observational cohort study of patients with AF enrolled in the University of Utah AF Database and a non-AF control group who underwent late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) for atrial fibrosis quantification. Participants with contra-indications for contrast MRI scanning were excluded. Nine hundred and eight consecutive men and women with AF and 15 non-AF controls were included in this study. Left atrial fibrosis increased with age in both men and women with AF. Women with AF (n = 316) were older than men (n = 592): mean age 68.7±11.6 vs. 64.9±11.7 years; P < 0.01, and had higher left atrial fibrosis compared with men 17.5 ± 10.1% vs. 15.3 ± 8.9%; P < 0.001. Women also had a higher prevalence of prior stroke compared with men (15.8% vs. 6.5%; P < 0.001). Age and sex relationships with atrial fibrosis remained significant in multivariate analysis. Compared with the non-AF control group, patients with AF had significantly higher atrial fibrosis: 16.0 ± 9.4 vs. 5.5 ± 5.8%; P < 0.001., Conclusions: Advancing age and female sex are associated with a higher burden of atrial fibrosis in patients with AF. Women with a prior history of stroke also have higher fibrosis compared with both women and men without history of stroke. Advanced fibrosis may explain the female and age association with stroke in AF.

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.)

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., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Left ventricular (LV) scar identified by late gadolinium enhanced (LGE) cardiac magnetic resonance (CMR) is associated with adverse outcomes in coronary artery disease and cardiomyopathies. We sought to determine the prognostic significance of LV-LGE in atrial fibrillation (AF). We studied 778 consecutive patients referred for radiofrequency ablation of AF who underwent CMR. Patients with coronary artery disease, previous myocardial infarction, or hypertrophic or dilated cardiomyopathy were excluded. The end points of interest were major adverse cardiac and cerebrovascular events (MACCE), defined as a composite of cardiovascular death, myocardial infarction, and ischemic stroke/transient ischemic attack. Of the 754 patients who met the inclusion criteria, 60% were men with an average age of 64 years. Most (87%) had a normal LV ejection fraction of ≥55%. LV-LGE was found in 46 patients (6%). There were 32 MACCE over the mean follow-up period of 55 months. The MACCE rate was higher for patients with LV-LGE (13.0% vs 3.7%; p = 0.002). In multivariate analysis, CHA2DS2-VASc score (hazard ratio [HR] 1.36, 95% CI 1.05 to 1.76), the presence of LV-LGE (HR 3.21, 95% CI 1.31 to 7.88), and the LV-LGE extent (HR 1.43, 95% CI 1.15 to 1.78) were independent predictors of MACCE. In addition, the presence of LV-LGE was an independent predictor for ischemic stroke/transient ischemic attack (HR 3.61, 95% CI 1.18 to 11.01) after adjusting for CHA2DS2-VASc score. In conclusion, the presence and extent of LV scar identified by LGE-CMR were independent predictors of MACCE in patients with AF., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: Patients routinely undergo ablation for atrial fibrillation (AF) but the recurrence rate remains high. We explored in this study whether poor scar formation as seen on late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) correlates with AF recurrence following ablation., Methods: We retrospectively identified 94 consecutive patients who underwent their initial ablation for AF at our institution and had pre-procedural magnetic resonance angiography (MRA) merged with left atrial (LA) anatomy in an electroanatomic mapping (EAM) system, ablated areas marked intraprocedurally in EAM, 3-month post-ablation LGE-MRI for assessment of scar, and minimum of 3-months of clinical follow-up. Ablated area was quantified retrospectively in EAM and scarred area was quantified in the 3-month post-ablation LGE-MRI., Results: With the mean follow-up of 336 days, 26 out of 94 patients had AF recurrence. Age, hypertension, and heart failure were not associated with AF recurrence, but LA size and difference between EAM ablated area and LGE-MRI scar area was associated with higher AF recurrence. For each percent higher difference between EAM ablated area and LGE-MRI scar area, there was a 7-9% higher AF recurrence (p values 0.001-0.003) depending on the multivariate analysis., Conclusions: In AF ablation, poor scar formation as seen on LGE-MRI was associated with AF recurrence. Improved mapping and ablation techniques are necessary to achieve the desired LA scar and reduce AF recurrence.

Objectives: This study sought to evaluate the prognostic significance of left ventricular late gadolinium enhancement (LV-LGE) incidentally found in atrial fibrillation (AF) patients who undergo ablation therapy., Background: LV-LGE provides prognostic information in patients with ischemic and nonischemic cardiomyopathies. However, data on the clinical significance of incidental LV-LGE in the AF population are limited., Methods: A total of 778 patients who were referred for radiofrequency ablation of AF underwent cardiac magnetic resonance examinations between June 2006 and January 2013. Patients with a history of myocardial infarction or ablation therapy were excluded. The presence of LV-LGE was assessed by experienced imaging physicians. Patients were followed for arrhythmia recurrence after the radiofrequency ablation procedure., Results: Of 598 patients included in the study, 60% were men with a mean age of 64 years and a median AF duration of 25 months. LV-LGE was detected in 39 patients (6.5%). There were 240 arrhythmia recurrences observed involving 40% of patients over a median follow-up period of 52 months. On univariate analysis, age (hazard ratio [HR]: 1.02; 95% confidence interval [CI]: 1.00 to 1.03), male sex (HR: 0.63; 95% CI: 0.47 to 0.86), diabetes (HR: 1.53; 95% CI: 1.03 to 2.27), CHADS2 score (HR: 1.19; 95% CI: 1.04 to 1.36), CHA2DS2-VASc score (HR: 1.18; 95% CI: 1.08 to 1.30), left atrial (LA) fibrosis (HR: 1.66; 95% CI: 1.41 to 1.96), LV-LGE (HR: 1.83; 95% CI: 1.11 to 3.03), persistent AF (HR: 1.52; 95% CI: 1.11 to 2.09), and LA area (HR: 1.03; 95% CI: 1.01 to 1.05) were significantly associated with arrhythmia recurrence. The recurrence rate was 69% in patients with LV-LGE compared with 38% in patients without LV-LGE (p < 0.001). In a multivariate model, LA fibrosis and LV-LGE were independent predictors of arrhythmia recurrence., Conclusions: In AF patients without history of myocardial infarction, LV-LGE is a significant independent predictor of arrhythmia recurrence after ablation therapy., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Three-dimensional electroanatomic mapping (EAM) is routinely used to mark ablated areas during radiofrequency ablation. We hypothesized that, in atrial fibrillation (AF) ablation, EAM overestimates scar formation in the left atrium (LA) when compared to the scar seen on late-gadolinium enhancement magnetic resonance imaging (LGE-MRI)., Methods and Results: Of the 235 patients who underwent initial ablation for AF at our institution between August 2011 and December 2012, we retrospectively identified 70 patients who had preprocedural magnetic resonance angiography merged with LA anatomy in EAM software and had a 3-month postablation LGE-MRI for assessment of scar. Ablated area was marked intraprocedurally using EAM software and quantified retrospectively. Scarred area was quantified in 3-month postablation LGE-MRI. The mean ablated area in EAM was 30.5 ± 7.5% of the LA endocardial surface and the mean scarred area in LGE-MRI was 13.9 ± 5.9% (P < 0.001). This significant difference in the ablated area marked in the EAM and scar area in the LGE-MRI was present for each of the 3 independent operators. Complete pulmonary vein (PV) encirclement representing electrical isolation was observed in 87.8% of the PVs in EAM as compared to only 37.4% in LGE-MRI (P < 0.001)., Conclusions: In AF ablation, EAM significantly overestimates the resultant scar as assessed with a follow-up LGE-MRI., (© 2014 Wiley Periodicals, Inc.)

Background: Atrial fibrillation (AF) is a progressive condition that begins with hemodynamic and/or structural changes in the left atrium (LA) and evolves through paroxysmal and persistent stages. Because of limitations with current noninvasive imaging techniques, the relationship between LA structure and function is not well understood., Methods and Results: Sixty-five patients (age, 61.2+/-14.2 years; 67% men) with paroxysmal (44%) or persistent (56%) AF underwent 3D delayed-enhancement MRI. Segmentation of the LA wall was performed and degree of enhancement (fibrosis) was determined using a semiautomated quantification algorithm. Two-dimensional echocardiography and longitudinal LA strain and strain rate during ventricular systole with velocity vector imaging were obtained. Mean fibrosis was 17.8+/-14.5%. Log-transformed fibrosis values correlated inversely with LA midlateral strain (r=-0.5, P=0.003) and strain rate (r=-0.4, P<0.005). Patients with persistent AF as compared with paroxysmal AF had more fibrosis (22+/-17% versus 14+/-9%, P=0.04) and lower midseptal (27+/-14% versus 38+/-16%, P=0.01) and midlateral (35+/-16% versus 45+/-14% P=0.03) strains. Multivariable stepwise regression showed that midlateral strain (r=-0.5, P=0.006) and strain rate (r=-0.4, P=0.01) inversely predicted the extent of fibrosis independent of other echocardiographic parameters and the rhythm during imaging., Conclusions: LA wall fibrosis by delayed-enhancement MRI is inversely related to LA strain and strain rate, and these are related to the AF burden. Echocardiographic assessment of LA structural and functional remodeling is quick and feasible and may be helpful in predicting outcomes in AF.

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.

Background: Atrial fibrillation (AF) is associated with diffuse left atrial fibrosis and a reduction in endocardial voltage. These changes are indicators of AF severity and appear to be predictors of treatment outcome. In this study, we report the utility of delayed-enhancement magnetic resonance imaging (DE-MRI) in detecting abnormal atrial tissue before radiofrequency ablation and in predicting procedural outcome., Methods and Results: Eighty-one patients presenting for pulmonary vein antrum isolation for treatment of AF underwent 3-dimensional DE-MRI of the left atrium before the ablation. Six healthy volunteers also were scanned. DE-MRI images were manually segmented to isolate the left atrium, and custom software was implemented to quantify the spatial extent of delayed enhancement, which was then compared with the regions of low voltage from electroanatomic maps from the pulmonary vein antrum isolation procedure. Patients were assessed for AF recurrence at least 6 months after pulmonary vein antrum isolation, with an average follow-up of 9.6+/-3.7 months (range, 6 to 19 months). On the basis of the extent of preablation enhancement, 43 patients were classified as having minimal enhancement (average enhancement, 8.0+/-4.2%), 30 as having moderate enhancement (21.3+/-5.8%), and 8 as having extensive enhancement (50.1+/-15.4%). The rate of AF recurrence was 6 patients (14.0%) with minimal enhancement, 13 (43.3%) with moderate enhancement, and 6 (75%) with extensive enhancement (P<0.001)., Conclusions: DE-MRI provides a noninvasive means of assessing left atrial myocardial tissue in patients suffering from AF and might provide insight into the progress of the disease. Preablation DE-MRI holds promise for predicting responders to AF ablation and may provide a metric of overall disease progression.

Background: Atrial fibrillation (AF) ablation uses radiofrequency (RF) energy to induce thermal damage to the left atrium (LA) in an attempt to isolate AF circuits. This injury can be seen using delayed enhancement magnetic resonance imaging (DE-MRI)., Objective: The purpose of this study was to describe DE-MRI findings of the LA in the acute and chronic stages postablation., Methods: Twenty-five patients were scanned at two time points postablation. The first group (n = 10) underwent DE-MRI at 24 hours and at 3 months. The second group (n = 16) was scanned at 3 months and at 6 or 9 months. One patient had three scans (24 hours, 3 months, 9 months) and was included in both groups. The location and extent of enhancement were then analyzed between both groups., Results: The median change in LA wall injury between 24 hours and 3 months was -6.38% (range -11.7% to 12.58%). The median change in LA wall injury between 3 months and later follow-up was +2.0% (range -4.0% to 6.58%). There appears to be little relationship between the enhancement at 24 hours and 3 months (R(2) = 0.004). In contrast, a strong correlation is seen at 3 months and later follow-up (R(2) = 0.966). Qualitative comparison revealed a stronger qualitative relationship between MRI findings at 3 months and later follow-up than at 24 hours and 3 months., Conclusion: RF-induced scar appears to have formed by 3 months postablation. At 24 hours postablation, DE-MRI enhancement appears consistent with a transient inflammatory response rather than stable LA scar formation.

Objectives: We describe a noninvasive method of detecting and quantifying left atrial (LA) wall injury after pulmonary vein antrum isolation (PVAI) in patients with atrial fibrillation (AF). Using a 3-dimensional (3D) delayed-enhancement magnetic resonance imaging (MRI) sequence and novel processing methods, LA wall scarring is visualized at high resolution after radiofrequency ablation (RFA)., Background: Radiofrequency ablation to achieve PVAI is a promising approach to curing AF. Controlled lesion delivery and scar formation within the LA are indicators of procedural success, but the assessment of these factors is limited to invasive methods. Noninvasive evaluation of LA wall injury to assess permanent tissue injury may be an important step in improving procedural success., Methods: Imaging of the LA wall with a 3D delayed-enhanced cardiac MRI sequence was performed before and 3 months after ablation in 46 patients undergoing PVAI for AF. Our 3D respiratory-navigated MRI sequence using parallel imaging resulted in 1.25 x 1.25 x 2.5 mm (reconstructed to 0.6 x 0.6 x 1.25 mm) spatial resolution with imaging times ranging 8 to 12 min., Results: Radiofrequency ablation resulted in hyperenhancement of the LA wall in all patients post-PVAI and may represent tissue scarring. New methods of reconstructing the LA in 3D allowed quantification of LA scarring using automated methods. Arrhythmia recurrence at 3 months correlated with the degree of wall enhancement with >13% injury predicting freedom from AF (odds ratio: 18.5, 95% confidence interval: 1.27 to 268, p = 0.032)., Conclusions: We define noninvasive MRI methods that allow for the detection and quantification of LA wall scarring after RF ablation in patients with AF. Moreover, there seems to be a correlation between the extent of LA wall injury and short-term procedural outcome.

Both post-contrast myocardial T1 and extracellular volume (ECV) measurements have been associated with diffuse interstitial fibrosis. The cardiovascular magnetic resonance (CMR) field is migrating towards ECV, because it is largely insensitive to confounders that affect post-contrast myocardial T1 . Despite the theoretical advantages of myocardial ECV over post-contrast myocardial T1 , systematic experimental studies comparing the two measurements are largely lacking. We sought to measure the temporal changes in post-contrast myocardial T1 and ECV in an established canine model with chronic atrial fibrillation. Seventeen mongrel dogs, implanted with a pacemaker to induce chronic atrial fibrillation via rapid atrial pacing, were scanned multiple times for a total of 46 CMR scans at 3T. These dogs with different disease durations (0-22 months) were part of a separate longitudinal study aimed at studying the relationship between AF and pathophysiology. In each animal, we measured native and post-contrast T1 values and hematocrit. Temporal changes in post-contrast myocardial T1 and ECV, as well as other CMR parameters, were modeled with linear mixed effect models to account for repeated measurements over disease duration. In 17 animals, post-contrast myocardial T1 decreased significantly from 872 to 698 ms (p < 0.001), which corresponds to a 24.9% relative reduction. In contrast, ECV increased from 21.0 to 22.0% (p = 0.38), which corresponds to only a 4.5% relative increase. To partially investigate this discrepancy, we quantified collagen volume fraction (CVF) in post-mortem heart tissues of six canines sacrificed at different disease durations (0-22 months). CVF quantified by histology increased from 0.9 to 1.9% (p = 0.56), which agrees better with ECV than with post-contrast myocardial T1 . This study shows that post-contrast myocardial T1 and ECV may disagree in a longitudinal canine study. A more comprehensive study, including histologic, cardiac, and renal functional analyses, is warranted to test rigorously which CMR parameter (ECV or post-contrast myocardial T1 ) agrees better with CVF.

Aim: Age and female sex are associated with a higher risk of stroke in atrial fibrillation (AF). We sought to determine whether advancing age and female sex are associated with higher atrial fibrosis.Methods and results: We conducted an observational cohort study of patients with AF enrolled in the University of Utah AF Database and a non-AF control group who underwent late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) for atrial fibrosis quantification. Participants with contra-indications for contrast MRI scanning were excluded. Nine hundred and eight consecutive men and women with AF and 15 non-AF controls were included in this study. Left atrial fibrosis increased with age in both men and women with AF. Women with AF (n = 316) were older than men (n = 592): mean age 68.7±11.6 vs. 64.9±11.7 years; P < 0.01, and had higher left atrial fibrosis compared with men 17.5 ± 10.1% vs. 15.3 ± 8.9%; P < 0.001. Women also had a higher prevalence of prior stroke compared with men (15.8% vs. 6.5%; P < 0.001). Age and sex relationships with atrial fibrosis remained significant in multivariate analysis. Compared with the non-AF control group, patients with AF had significantly higher atrial fibrosis: 16.0 ± 9.4 vs. 5.5 ± 5.8%; P < 0.001.Conclusions: Advancing age and female sex are associated with a higher burden of atrial fibrosis in patients with AF. Women with a prior history of stroke also have higher fibrosis compared with both women and men without history of stroke. Advanced fibrosis may explain the female and age association with stroke in AF. [ABSTRACT FROM AUTHOR]

Both post-contrast myocardial T1 and extracellular volume (ECV) measurements have been associated with diffuse interstitial fibrosis. The cardiovascular magnetic resonance (CMR) field is migrating towards ECV, because it is largely insensitive to confounders that affect post-contrast myocardial T1. Despite the theoretical advantages of myocardial ECV over post-contrast myocardial T1, systematic experimental studies comparing the two measurements are largely lacking. We sought to measure the temporal changes in post-contrast myocardial T1 and ECV in an established canine model with chronic atrial fibrillation. Seventeen mongrel dogs, implanted with a pacemaker to induce chronic atrial fibrillation via rapid atrial pacing, were scanned multiple times for a total of 46 CMR scans at 3T. These dogs with different disease durations (0-22 months) were part of a separate longitudinal study aimed at studying the relationship between AF and pathophysiology. In each animal, we measured native and post-contrast T1 values and hematocrit. Temporal changes in post-contrast myocardial T1 and ECV, as well as other CMR parameters, were modeled with linear mixed effect models to account for repeated measurements over disease duration. In 17 animals, post-contrast myocardial T1 decreased significantly from 872 to 698 ms ( p < 0.001), which corresponds to a 24.9% relative reduction. In contrast, ECV increased from 21.0 to 22.0% ( p = 0.38), which corresponds to only a 4.5% relative increase. To partially investigate this discrepancy, we quantified collagen volume fraction (CVF) in post-mortem heart tissues of six canines sacrificed at different disease durations (0-22 months). CVF quantified by histology increased from 0.9 to 1.9% ( p = 0.56), which agrees better with ECV than with post-contrast myocardial T1. This study shows that post-contrast myocardial T1 and ECV may disagree in a longitudinal canine study. A more comprehensive study, including histologic, cardiac, and renal functional analyses, is warranted to test rigorously which CMR parameter (ECV or post-contrast myocardial T1) agrees better with CVF. Copyright © 2014 John Wiley & Sons, Ltd. [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: Magnetic resonance imaging (MRI) allows visualization of location and extent of radiofrequency (RF) ablation lesion, myocardial scar formation, and real-time (RT) assessment of lesion formation. In this study, we report a novel 3-Tesla RT -RI based porcine RF ablation model and visualization of lesion formation in the atrium during RF energy delivery. Objective: The purpose of this study was to develop a 3-Tesla RT MRI-based catheter ablation and lesion visualization system. Methods: RF energy was delivered to six pigs under RT MRI guidance. A novel MRI-compatible mapping and ablation catheter was used. Under RT MRI, this catheter was safely guided and positioned within either the left or right atrium. Unipolar and bipolar electrograms were recorded. The catheter tip–tissue interface was visualized with a T1-weighted gradient echo sequence. RF energy was then delivered in a power-controlled fashion. Myocardial changes and lesion formation were visualized with a T2-weighted (T2W) half Fourier acquisition with single-shot turbo spin echo (HASTE) sequence during ablation. Results: RT visualization of lesion formation was achieved in 30% of the ablations performed. In the other cases, either the lesion was formed outside the imaged region (25%) or the lesion was not created (45%) presumably due to poor tissue–catheter tip contact. The presence of lesions was confirmed by late gadolinium enhancement MRI and macroscopic tissue examination. Conclusion: MRI-compatible catheters can be navigated and RF energy safely delivered under 3-Tesla RT MRI guidance. Recording electrograms during RT imaging also is feasible. RT visualization of lesion as it forms during RF energy delivery is possible and was demonstrated using T2W HASTE imaging. [ABSTRACT FROM AUTHOR]