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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

Objectives This study hypothesized that left atrial structural remodeling (LA-TR) correlates with exercise capacity (EC) in a cohort of patients with atrial fibrillation (AF). Background Late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) imaging provides a method of assessing LA-TR in patients with AF. Methods A total of 145 patients (32% female, mean age 63.4 ± 11.6 years of age) with AF (66 paroxysmal, 71 persistent, 8 long-standing persistent) presenting for catheter ablation were included in the study. All patients underwent LGE-CMR imaging as well as maximal exercise test using the Bruce protocol prior to catheter ablation of AF. EC was quantified by minutes of exercise and metabolic equivalent (MET) level achieved. LA-TR was quantified from LGE-CMR imaging and classified according to the Utah classification of LA structural remodeling (Utah stage I: 30%). AF recurrence was assessed at 1 year from the date of ablation. Results The average duration of exercise was 8 ± 3 min, and the mean MET achieved was 9.7 ± 3.2. METs achieved were inversely correlated with LA-TR (R 2 = 0.061; p = 0.003). The duration of exercise was also inversely correlated with LA-TR (R 2 = 0.071; p = 0.001). Both EC and LA-TR were associated with AF recurrence post ablation in univariate analysis, but only LA-TR and age were independently predictive of recurrence in multivariate analysis (p = 0.001). For every additional minute on the treadmill, subjects were 13% more likely to be free of AF 1 year post ablation (p = 0.047). Conclusions EC is inversely associated with LA-TR in patients with AF and is predictive of freedom from AF post-ablation.

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.

Introduction Besides the traditional concept of atrial fibrillation (AF) perpetuating atrial structural remodeling, there is increasing evidence that atrial fibrosis might precede AF, highlighting the need for better characterization of the fibrotic substrate. We aimed to assess atrial fibrosis by use of late gadolinium enhancement magnetic resonance imaging (LGE-MRI) in non-AF individuals and to identify predisposing risk factors. A second aim was to establish a risk score for the prevalence of AF using atrial fibrosis in addition to established clinical variables. Methods and results Non-AF individuals without structural heart disease (n = 91) and matched AF controls (n = 91) underwent MRI for assessment of LGE. According to the established UTAH classification, atrial LGE ≥20% was considered extensive. Mean left atrial (LA) fibrosis in non-AF and AF individuals were 8.8 ± 6.5% and 12.5 ± 5.8%, respectively. Body mass index (BMI) >30 kg/m 2 and LA volume were predictors of atrial fibrosis. Diastolic function was not significantly different with respect to atrial fibrosis. A novel scoring system for the prevalence of AF (2 points for arterial hypertension and/or left ventricular ejection fraction 6%) was derived demonstrating that patients in the intermediate/high-risk group had a significantly increased risk of AF. Conclusion This study reports unexpectedly high atrial fibrosis in non-AF patients without apparent heart disease, highlighting the concept that structural fibrotic alterations may precede AF onset in a significant proportion of individuals. BMI as a predictor of atrial fibrosis suggests that lifestyle and drug intervention, that is, weight reduction, could positively influence fibrosis development. The derived risk score for AF prevalence provides the basis for prospective studies on AF incidence.

Shape change of the left atrium (LA) and LA appendage in atrial fibrillation (AF) patients is hypothesized to be linked to AF pathology and to play a role in thrombogenesis; however, many aspects of shape variation in the heart are poorly understood. To date, studies of the LA shape in AF have been limited to empirical observation and summary metrics, such as volume and its likeness to a sphere. This paper describes a more comprehensive approach to the study of the LA shape through the use of computationally derived statistical shape models. We describe practical approaches that we have developed to extract shape parameters automatically from the three-dimensional MR images of the patient. From these images and our techniques, we can produce a more comprehensive description of LA geometric variability than that has been previously possible. We present the methodology and results from two examples of specific analyses using shape models: (1) we describe statistically significant group differences between the normal control and AF patient populations ( n = 137) and (2) we describe characteristic shapes of the LA appendage that are associated with the risk of thrombogenesis determined by transesophageal echocardiography ( n = 203).

ObjectivesThis 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.BackgroundLV-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.MethodsA 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.ResultsOf 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.ConclusionsIn AF patients without history of myocardial infarction, LV-LGE is a significant independent predictor of arrhythmia recurrence after ablation therapy.

A 63-year-old woman who presented with a 2-week history of fever and fatigue was found to have persistent group B β-hemolytic streptococcal bacteremia. A transesophageal echocardiogram (TEE) showed a mobile mass adhering to the mitral valve (MV). Two- and 3-dimensional TEE revealed a large echodense structure in the left atrium, adhering to the intra-atrial septum and posterior MV leaflet, along with a retrocardiac mass (Fig. 1). The patient was referred for cardiac magnetic resonance imaging. Steady-state free-precession images with T1 weighting showed a thickened posterior MV leaflet with vegetation, severe mitral regurgitation, and a myocardial mass involving the basal inferior wall of the left ventricle (LV) (Fig. 2). Dynamic first-pass perfusion images revealed a hypoperfused mass with no enhancement when compared with normal myocardium (Fig. 3A). Double-inversion-recovery (DIR) images with T1 weighting revealed mild heterogeneity of the mass (Fig. 3B). Pre- and post-contrast DIR and late-gadolinium-enhanced images with T1 weighting showed substantial peripheral enhancement with central hypointensity (Fig. 3C and Fig. 3D). The diagnosis was mitral paravalvular abscess (PA). The patient underwent debridement of the large abscess, along with MV replacement and reconstruction of the MV annulus and portions of the left atrial and LV wall with bovine pericardial patch. Fig. 1 A) Two- and B) 3-dimensional transesophageal echocardiograms show vegetation on the posterior mitral valve leaflet (arrows) and reveal a retrocardiac mass (arrowhead). Fig. 2 Steady-state free-precession magnetic resonance images in A) vertical long-axis and B) short-axis views show a mitral paravalvular mass (arrows). Fig. 3 Cardiac magnetic resonance reveals the mitral paravalvular abscess (arrows) by means of A) dynamic perfusion, B) pre- and C) post-contrast T1-weighted double-inversion recovery, and D) delayed enhancement modes.

Cardiovascular magnetic resonance (CMR) perfusion has been established as a useful imaging modality for the detection of coronary artery disease (CAD). However, there are several limitations when applying standard, ECG-gated stress/rest perfusion CMR to patients with atrial fibrillation (AF). In this study we investigate an approach with no ECG gating and a rapid rest/stress perfusion protocol to determine its accuracy for detection of CAD in patients with AF. 26 patients with AF underwent a rapid rest/regadenoson stress CMR perfusion imaging protocol, and all patients had X-ray coronary angiography. An ungated radial myocardial perfusion sequence was used. Imaging protocol included: rest perfusion image acquisition, followed nearly immediately by administration of regadenoson to induce hyperemia, 60 s wait, and stress image acquisition. CMR perfusion images were interpreted by three blinded readers as normal or abnormal. Diagnostic accuracy was evaluated by comparison to X-ray angiography. 21 of the CMR rest/stress perfusion scans were negative, and 5 were positive by angiography criteria. Majority results of the ungated datasets from all of the readers showed a sensitivity, specificity and accuracy of 80, 100 and 96%, respectively, for detection of CAD. An ungated, rapid rest/stress regadenoson perfusion CMR protocol appears to be useful for the diagnosis of obstructive CAD in patients with AF.

Aim Late gadolinium enhanced (LGE) magnetic resonance imaging (MRI) is a useful tool for facilitating ventricular tachycardia (VT) ablation. Unfortunately, most VT ablation candidates often have prophylactic implantable cardioverter-defibrillator (ICD) and do not undergo cardiac MRI largely due to image artefacts generated by ICD. A prior study has reported success of ‘wideband’ LGE MRI for imaging myocardial scar without image artefacts induced by ICD at 1.5T. The purpose of this study was to widen the availability of wideband LGE MRI to 3T, since it has the potential to achieve higher spatial resolution than 1.5T. Methods and results We compared the performance of standard and wideband LGE MRI pulse sequences in phantoms and canines with myocardial lesions created by radiofrequency ablation. Standard LGE MRI produced image artefacts induced by ICD and 49% accuracy in detecting 97 myocardial scars examined in this study, whereas wideband LGE MRI produced artefact-free images and 94% accuracy in detecting scars. The mean image quality score (1 = nondiagnostic, 2 = poor, 3 = adequate, 4 = good, 5 = excellent) was significantly ( P < 0.001) higher for wideband (3.7 ± 0.8) than for standard LGE MRI (2.1 ± 0.7). The mean artefact level score (1 = minimal, 2 = mild, 3 = moderate, 4 = severe, 5 = nondiagnostic) was significantly ( P < 0.001) lower for wideband (2.1 ± 0.8) than for standard LGE MRI (4.0 ± 0.6). Wideband LGE MRI agreed better with gross pathology than standard LGE MRI. Conclusion This study demonstrates the feasibility of wideband LGE MRI for suppression of image artefacts induced by ICD at 3T.

The extent of left atrial (LA) wall structural remodeling (fibrosis) detected by late gadolinium enhancementmagnetic resonance imaging (LGE-MRI) is correlated with advanced atrial fibrillation (AF). The concomitant occurrence of AF and left ventricular (LV) dysfunction is not uncommon. We studied the effect of LA fibrosis, a confounder of both AF and LV dysfunction, on LV ejection fraction (EF). For the analysis, we identified and included 384 patients from our retrospective AF database who underwent LGE-MRI and transthoracic echocardiography prior to AF ablation. Based on the degree of LA fibrosis, patients were categorized into four stages as: Utah 1 (35% fibrosis). The average pre-ablation LVEF was 60.5%+-8.5% (n=24) in Utah stage 1 patients, 55.7%+-10.3% (n=240) in Utah stage 2 patients, 51.7+-11.5% (n=90) in Utah stage 3 patients, and 48.9%+-11.6% (n=30) in Utah stage 4 patients (p

Introduction Transesophageal echocardiography (TEE) is used to evaluate for left atrial appendage (LAA) thrombi prior to restoration of sinus rhythm in atrial fibrillation (AF). We examined the relationship of atrial fibrosis quantified using late gadolinium enhancement MRI (LGE-MRI) with TEE findings.

LV Systolic Dysfunction is Related to LA-SRM in AF Patients Background Catheter ablation significantly improves the left ventricular (LV) function in patients with atrial fibrillation (AF) and LV systolic dysfunction. In this study, we compared the degree of left atrial structural remodeling (LA-SRM) in patients with normal versus reduced LV ejection fraction (LVEF). We also studied the impact of LA-SRM on LVEF improvement in patients undergoing ablation of AF. Method and Results We categorized 384 patients into 2 groups based on their cardiac function: reduced LVEF group (LVEF ≤50%; n = 105) and normal LVEF group (LVEF > 50%; n = 279). LVEF was determined prior and mean 8 ± 3 months after catheter ablation for AF. Percentage of LA-SRM was quantified using LGE-MRI and patients were classified into 4 groups based on the amount of structural remodeling in their LA wall: minimal ≤ 5%, mild = 5–20%, moderate = 20–35%, and extensive ≥ 35%. The average preablation LA-SRM (21.5 ± 13.2% vs 15.4 ± 10.0%; P < 0.001) was significantly higher in reduced LVEF group than normal LVEF group. Among the 105 patients with reduced LVEF, while there was a modest 11.7 ± 8.4% average increase in LVEF following ablation, the greatest increase was seen in patients with less extensive LA-SRM (minimal = 19.3 ± 5.1%, n = 3, P = 0.02 and mild = 16.6 ± 9.9%, n = 48, P < 0.001). Patients with moderate and extensive fibrosis had an average EF improvement of 8.7 ± 11.1% and 2.8 ± 6.4%, respectively (n = 39, P

The aim of this study was to assess acute ablation injuries seen on late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) immediately post-ablation (IPA) and the association with permanent scar 3 months post-ablation (3moPA).Success rates for atrial fibrillation catheter ablation vary significantly, in part because of limited information about the location, extent, and permanence of ablation injury at the time of procedure. Although the amount of scar on LGE MRI months after ablation correlates with procedure outcomes, early imaging predictors of scar remain elusive.Thirty-seven patients presenting for atrial fibrillation ablation underwent high-resolution MRI with a 3-dimensional LGE sequence before ablation, IPA, and 3moPA using a 3-T scanner. The acute left atrial wall injuries on IPA scans were categorized as hyperenhancing (HE) or nonenhancing (NE) and compared with scar 3moPA.Heterogeneous injuries with HE and NE regions were identified in all patients. Dark NE regions in the left atrial wall on LGE MRI demonstrate findings similar to the "no-reflow" phenomenon. Although the left atrial wall showed similar amounts of HE, NE, and normal tissue IPA (37.7 ± 13%, 34.3 ± 14%, and 28.0 ± 11%, respectively; p = NS), registration of IPA injuries with 3moPA scarring demonstrated that 59.0 ± 19% of scar resulted from NE tissue, 30.6 ± 15% from HE tissue, and 10.4 ± 5% from tissue identified as normal. Paired t-test comparisons were all statistically significant among NE, HE, and normal tissue types (p0.001). Arrhythmia recurrence at 1-year follow-up correlated with the degree of wall enhancement 3moPA (p = 0.02).Radiofrequency ablation results in heterogeneous injury on LGE MRI with both HE and NE wall lesions. The NE lesions demonstrate no-reflow characteristics and reveal a better predictor of final scar at 3 months. Scar correlates with procedure outcomes, further highlighting the importance of early scar prediction.

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.

BACKGROUND Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease. OBJECTIVE This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities. METHODS Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (5% LA wall enhancement), Utah II (5% to 20%), Utah III (20% to 35%), or Utah IV (35%). RESULTS Distribution in Utah I to IV was comparable in patients with lone AF and non‐lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 8.94 vs. 16.94 11.37) was not significantly different between the 2 groups (P .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non‐lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P .001). CONCLUSION The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.

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 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.

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 × 1.25 × 2.5 mm (reconstructed to 0.6 × 0.6 × 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.

Atrial fibrillation (AF) is common in the setting of abnormal ventricular relaxation. We evaluated the association between ventricular relaxation grade and atrial fibrosis and examined the change in left ventricular filling parameters following catheter ablation. AF patients undergoing catheter ablation who had cardiac late gadolinium enhancement MRI (LGE-MRI) and echocardiographic examinations were included in the study. Left atrial (LA) tissue fibrosis and volume were quantified using LGE-MRI. Echocardiograms were performed at baseline and 3 months following catheter ablation to assess left ventricular (LV) filling. Two hundred and ninety three patients (60.8 % male) met the inclusion criteria. In patients in sinus rhythm at baseline (n = 115), ventricular relaxation pattern was identified as normal in 54 patients (47.0 %), impaired in 35 (30.4 %), pseudo-normal in 18 (15.7 %), and restrictive in 8 (7.0 %). Restrictive LV filling was associated with higher LA volume index (61.2 ± 30.5 vs 46.0 ± 18.5 ml/m2; p

Introduction: Atrial fibrillation (AF) is associated with diffuse myocardial fibrosis as quantified by cardiac magnetic resonance (CMR) using T1 mapping methods. Radiofrequency catheter ablation (RFCA) is evolving, and the role in rhythm control may be ideal for reversing left ventricular (LV) remodeling. Hypothesis: We aimed to study the impact of RFCA on diffuse myocardial fibrosis in AF patients. Methods: We retrospectively collected data from consecutive AF patients who underwent RFCA with modified Look-Locker Inversion recovery T1 mapping sequences on pre/post procedural CMR at 3.0-Tesla. Precontrast T1 relaxation time of the mid-LV short-axis view was used as an index of diffuse LV fibrosis. Primary outcome was the change in diffuse LV fibrosis after RFCA. Results: A total of 11 patients (mean age 67 years, 72% male, 67% paroxysmal AF) were enrolled. Median AF duration was 24.6 months [Interquartile range (IQR): 13.3-45.3)] and median CHA2DS2-VASc was 2 [IQR: 1-3]. Post RFCA CMR was obtained 99.5±18.1 days after the RFCA procedure. Mean precontrast T1 time was significantly lower after RFCA (1182ms vs 1158ms; p=0.0157). Conclusions: Based on our preliminary results, RFCA in AF reduces diffuse myocardial fibrosis and may play a role in reverse LV remodeling.

Current methods for prediction of recurrence after atrial fibrillation (AF) ablation are limited. Recently, left atrial (LA) fibrosis and the single shape measure of sphericity have been shown to predict recurrence. We aim to show that quantitative shape assessment can predict AF recurrence after

Background Cardiac T1 and extracellular volume fraction (ECV), derived from preand post-contrast cardiac and blood T1 measurements, are emerging imaging biomarkers of diffuse cardiac fibrosis. The most frequently used cardiac T1 mapping pulse sequence is MOLLI [1]. However, MOLLI is known to be sensitive to rapid heart rate and irregular rhythm, because it is based on inversion-recovery (IR) of magnetization preparation. In response, we developed an arrhythmia-insensitive-rapid (AIR) cardiac T1 mapping pulse sequence based on B1insensitive saturation-recovery (SR) of magnetization preparation [2]. Our prior study [2] showed that AIR (scan time = 2-3 heart beats) is faster and yields more accurate cardiac T1 measurements than MOLLI (scan time = 17 heart beats). We sought to compare ECV measurements between SR-based AIR and IR-based MOLLI cardiac T1 mapping at 3T.

Background Atrial fibrillation (AF) is associated with increase in size of the left atrium (LA). Recent studies have shown that LA shape may be an earlier and independent marker of atrial remodeling in AF. However, previous studies have been limited to qualitative assessments of shape and parameters that do not fully characterize shape. In this study, we use an entropy-driven particle-based shape modeling technique to investigate the relationship between shape and volume of the LA in AF.

Background— Although catheter ablation therapy for atrial fibrillation (AF) is becoming more common, results vary widely, and patient selection criteria remain poorly defined. We hypothesized that late gadolinium enhancement MRI (LGE-MRI) can identify left atrial (LA) wall structural remodeling (SRM) and stratify patients who are likely or not to benefit from ablation therapy. Methods and Results— LGE-MRI was performed on 426 consecutive patients with AF without contraindications to MRI before undergoing their first ablation procedure and on 21 non-AF control subjects. Patients were categorized by SRM stage (I–IV) based on the percentage of LA wall enhancement for correlation with procedure outcomes. Histological validation of SRM was performed comparing LGE-MRI with surgical biopsy. A total of 386 patients (91%) with adequate LGE-MRI scans were included in the study. After ablation, 123 patients (31.9%) experienced recurrent atrial arrhythmias during the 1-year follow-up. Recurrent arrhythmias (failed ablations) occurred at higher SRM stages with 28 of 133 (21.0%) in stage I, 40 of 140 (29.3%) in stage II, 24 of 71 (33.8%) in stage III, and 30 of 42 (71.4%) in stage IV. In multivariate analysis, ablation outcome was best predicted by advanced SRM stage (hazard ratio, 4.89; P P =0.036), whereas increased LA volume and persistent AF were not significant predictors. LA wall enhancement was significantly greater in patients with AF versus non-AF controls (16.6±11.2% versus 3.1±1.9%; P Conclusions— Atrial SRM is identified on LGE-MRI, and extensive LGE (≥30% LA wall enhancement) predicts poor response to catheter ablation therapy for AF.

Background In patients undergoing atrial fibrillation (AF) procedures, imaging of the left atrium (LA) and pulmonary veins (PV) is important for pre-ablation planning and to identify post ablation complications. Conventional MRA protocols use first-pass, non-gated sequences that require long breathholds. Quality of non-gated MRA’s can be challenging in sick or sedated patients. We developed a novel ECGgated, respiratory navigated MRA sequence less dependent on patient compliance, which yields better clarity of LA anatomy.

Summary Identification of early post-atrial ablation MRI characteristics can help predict the development of significant chronic pulmonary stenosis. Background Pulmonary vein stenosis (PVS) is a rare complication of atrial fibrillation (AF) ablation with a rate of significant stenosis, defined as >50%, of 1.3% in a recent multicenter study. As significant morbidity is associated with PVS, detection and surveillance with non-invasive imaging is routine. In this study, we hypothesized that prediction of PVS can be determined with early MRI to identify patients at risk for this complication. Methods A single-center, retrospective, 1:1 cohort to control matched study including patients with (23) and without (23) significant PVS 3 months post-ablation (3moPA) was performed. Study groups were selected from 925 patients who underwent AF ablation and serial MRI scanning. Inclusion criteria for both groups required a full set of three MRI scans: pre-ablation (pre), 24 hours post-ablation (24hrPA), and 3moPA. MRI scanning was performed on a 1.5T or 3T Siemens magnet. Of the 925 patients, 28 were found with significant stenosis on MRA 3moPA. The final PVS study cohort included 23/ 28 patients as 5 were excluded secondary to incomplete MRI scan sets. The control group was comprised of 23 age and sex-matched patients without significant stenosis 3moPA. PV cross-sectional areas were measured at the ostial/proximal portion of the vessels by 3D MRA (Figure 1). In patients with multiple stenotic PV’s, the most stenotic vein was selected for analysis. Results Out of 925 patients, we found 3% (28/925) incidence of significant PVS 3moPA. Of the 23/28 patients in the PVS study cohort, early PV narrowings of >20% on the 24hrPA scan were found in all (23/23, 100%) compared with significantly fewer in the control group (9/23, 39%) (p 20%) on the 24hrPA MRI scan. In addition, small PV caliber on baseline imaging appears to predispose to PVS with the LIPV involved disproportionately. Overall, MRI image characteristics are useful for predicting PVS and may help determine which patients will benefit from surveillance imaging.

Background Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting more than 5 million people in North America and Europe. Radio-frequency ablation (RFA) is effective in symptomatic, drug refractory AF. Reported success rates of the procedure vary significantly with AF recurrences ranging from 25-40%. The transmural extent of left atrial (LA) wall injury is difficult to assess with conventional electro-physiological (EP) measurements. Late gadolinium enhancement (LGE) and double inversion recovery T2-weighted TSE (DIR-T2w-TSE) and HASTE have been proposed to evaluate acute LA wall injury. In this study, we examine the evolution of acute (< 30 hours after RFA) atrial lesions in LGE and DIR-T2w-TSE MRI with time after the procedure. The main goals of this project are to study changes in acute lesion appearance with time after RF ablation and to determine the time interval after ablation when MRI achieves the best visibility of acute LA lesions.

Background Cardiovascular Magnetic Resonance (CMR) stress perfusion is an effective noninvasive diagnostic clinical tool when combined with late gadolinium enhancement imaging (LGE) for evaluation of ischemia, infarct, and cardiac prognosis. Good ECG-gating is essential to the commonly used perfusion sequences, but ECG-gating is problematic in obese patients, high field magnetic fields, and patients with arrhythmias. We describe a rapid radial-based self-gated (SG) perfusion acquisition for detection of perfusion defects and compare this to LGE and X-ray coronary angiography (XCA) in the detection of infarction or ischemia. Methods

Chemotherapeutic agents reduce mortality and can prevent morbidity in a wide range of malignancies. These agents are, however, associated with toxicities of their own, and the treating physician must remain ever vigilant against the risk outgrowing the benefit of therapy. Thus, pre-treatment evaluation and monitoring for toxicity during and following administration is a fundamental tenet of oncologic practice. Among the most insidious and deadly toxicities of anti-tumor agents is cardiac toxicity, which in some cases may be irreversible. Early detection of cardiotoxicity allows the treating oncologist to redirect therapy or dose modify, taking into account the cost of a reduction in therapy against the potential of further injury to the patient. In these instances, the role of the cardiologist is to assist and advise the oncologist by providing diagnostic and prognostic information regarding developing cardiotoxicity. This review discusses noninvasive diagnostic options to identify and characterize cardiotoxicity and their use in prognosis and guiding therapy. We also review established protocols for cardiac safety monitoring in the treatment of malignancy.

ObjectivesThis study tried to determine the association between left atrial (LA) fibrosis, detected using delayed-enhanced magnetic resonance imaging (DE-MRI), and the CHADS2 score (point system based on individual clinical risk factors including congestive heart failure, hypertension, age, diabetes, and prior stroke) variables, specifically stroke.BackgroundIn patients with atrial fibrillation (AF), conventional markers for the risk of stroke base their higher predictive effect on clinical features, particularly previous stroke history, and not individual LA pathophysiological properties. We aimed to determine the association between LA fibrosis, detected using DE-MRI, and the CHADS2 score variables, specifically stroke.MethodsPatients with AF who presented to the AF clinic and received a DE-MRI of the LA were evaluated. Their risk factor profiles, including a CHADS2 score, were catalogued. The degree of LA fibrosis was determined as a percentage of the LA area. Any history of previous strokes, warfarin use, or cerebrovascular disease was recorded.ResultsA total of 387 patients, having a mean age of 65 ± 12 years, 36.8% female, were included in this study. A history of previous stroke was present in 36 (9.3%) patients. Those patients with previous strokes had a significantly higher percentage of LA fibrosis (24.4 ± 12.4% vs. 16.2 ± 9.9%, p < 0.01). A larger amount of LA fibrosis was also seen in those patients with a higher CHADS2 score (≥2: 18.7 ± 11.4 vs.

Atrial fibrillation is a significant public health burden, with clinically, epidemiologically and economically significant repercussions. In the last decade, catheter ablation has provided an improvement in morbidity and quality of life, significantly reducing long-term healthcare costs and avoiding recurrences compared with drug therapy. Despite recent progress in techniques, current catheter ablation success rates fall short of expectations. Late gadolinium-enhancement cardiovascular MRI is a well-established tool to image the myocardium and, most specifically, the left atrium. Unique imaging protocols allow for left atrial structural remodeling and fibrosis assessment, which has been demonstrated to correlate with clinical outcomes after catheter ablation, assessment of the individual's risks of thromboembolic events, and effective imaging of patients with left atrial appendage thrombus. Late gadolinium-enhancement MRI aids in the individualized treatment of atrial fibrillation, stratifying recurrence risk and guiding specific ablation strategies. Real-time MRI offers significant safety and effectiveness profiles that would optimize the invasive treatment of atrial fibrillation.

Atrial fibrosis is a hallmark of atrial structural remodeling (SRM) and leads to structural and functional impairment of left atrial (LA) and persistence of atrial fibrillation (AF). This study was conducted to assess LA reverse remodeling after catheter ablation of AF in mild and moderate-severe LA SRM.Catheter ablation was performed in 68 patients (age 62 ± 14 years, 68% males) with paroxysmal (n = 26) and persistent (n = 42) AF. The patients were divided into group 1 with mild LA SRM (10%, n = 31) and group 2 with moderate-severe LA SRM (10%, n = 37) by delayed enhancement magnetic resonance imaging (DEMRI). Two-dimensional echocardiography, LA strain, and strain rate during left ventricular systole by velocity vector imaging were performed pre and at 6 ± 3 months postablation. The long-term outcome was monitored for 12 months.Patients in group 1 were younger (57 ± 15 vs 66 ± 13 years, P = .009) with a male predominance (80% vs 57%, P.05) as compared to group 2. Postablation, group 1 had significant increase in average LA strain (Δ↑: 14% vs 4%, P.05) and strain rate (Δ↑: 0.5 vs 0.1 cm/s, P.05) as compared to group 2. There was a trend toward more patients with persistent AF in group 2 (68% vs 55%, P = .2), but it was not statistically significant. Group 2 had more AF recurrences (41% vs 16%, P = .02) at 12 months after ablation.Mild preablation LA SRM by DEMRI predicts favorable LA structural and functional reverse remodeling and long-term success after catheter ablation of AF, irrespective of the paroxysmal or persistent nature of AF.

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 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.

A 75-year-old man with a poorly defined intracardiac mass on transthoracic echocardiogram was referred for further evaluation by cardiac magnetic resonance (CMR) imaging. CMR cine ( Panel A ) and dark blood ( Panel B ) images demonstrated a large, hypointense mass involving a mitral valve (MV) annulus. Perfusion images revealed no enhancement of the mass compared with normal myocardium …

Cardiovascular magnetic resonance (CMR) myocardial perfusion detection of significant obstructive coronary disease (CAD) is well established. With concerns of ECG-gating in arrhythmia and true-rest after regadenoson, we investigated the diagnostic accuracy and discrimination of a rapid rest-first

Atrial fibrillation (AF) is associated with cardiac thrombus especially in LA appendage(LAA). We studied the relationship between atrial fibrosis quantified using late gadolinium enhancement MRI (LGE-MRI) and spontaneous echocardiographic contrast (SEC) and LAA thrombus on TEE. We included 213 AF

Background While late gadolinium enhanced (LGE) MRI is the gold standard for detection of focal myocardial scarring [1], it is less effective than cardiac T1 mapping (ECV) for detection of diffuse fibrosis. LGE, in principle, can be synthesized from cardiac T1 maps. We sought to derive synthetic LGE images from saturation-recovery based cardiac T1 maps for simultaneous assessment of focal and diffuse cardiac fibrosis.

Background Left ventricular late gadolinium enhancement (LV-LGE) is a known incidental cardiac magnetic resonance (CMR) finding in atrial fibrillation (AF) patients and has recently been associated with increased mortality [1]. While LV-LGE is an indicator of poor prognosis in patients with cardiomyopathy, data on the clinical significance of incidental findings of LV-LGE in AF patients is still unavailable. We aimed to evaluate the association of this incidental finding to ischemic stroke in atrial fibrillation.

Background MRI is the only non-invasive modality capable of quantifying diffuse cardiac fibrosis using late gadolinium enhanced (LGE) cardiac T1 mapping. This pulse sequence measures LGE cardiac T1, which directly correlates with the amount of extracellular contrast agent occupying the expanded extracellular matrix containing the interstitial fibrosis, and obviates the need for a reference normal tissue. A practical limitation of the LGE cardiac T1 mapping pulse sequence is that it is sensitive to contrast agent dosage and specific delayed imaging time (i.e., two factors that affect the amount of contrast agent present in tissue). Recently, a method was proposed to address this limitation by combining blood and myocardial T1 measurements preand post-contrast agent administration to calculate an index called partition coefficient (l). However, post-contrast blood T1 can vary across subjects, due to variations in hydration and renal function. We sought to evaluate intersubject variation in blood T1, myocardial T1, and l.

Background Atrial fibrillation (AF) is a common sustained cardiac arrhythmia associated with increased risks of heart failure and stroke. Late gadolinium enhanced MRI (LGE-MRI) is being routinely used to assess and manage the treatment of AF. To acquire LGE images of thin left atrial (LA) wall high-resolution 3D inversion recovery prepared GRE pulse sequence with cardiac gating and respiratory navigation should be used. This makes the image quality dependent on the patient’s heart rate and respiration pattern. In this work, we study the effect of the patient respiration on image quality of LGE-MRI of LA.

Atrial fibrillation (AF) is known to result in structural remodeling and fibrosis of the atrial myocardium. Late gadolinium enhancement (LGE) MRI has been applied to determine the extent and severity of atrial fibrosis but tissue validation is lacking. In this study, we correlated LGE MRI

We are able to detect subclinical post-irradiation changes to the heart with left atrial late gadolinium enhanced magnetic resonance imaging (LGE-MRI).

The aim of this study was to evaluate left atrial (LA) volume measurements using cardiac magnetic resonance (CMR) based angiography before and after LA radio frequency (RF) ablation therapy as a treatment strategy for atrial fibrillation (AFIB).

Methods: 5 animal models were utilized. A single RF lesion was placed at the interatrial septum. A T2w DIR-FSE sequence was performed immediately after lesion placement and repeated 10 minutes later. Sequence parameters were: TE = 83 ms, TR = 2RR, ETL = 21, fat suppression using SPAIR, in-plane resolution of 1.25 x 1.25 mm, slice thickness of 4 mm, 20 slices, GRAPPA with R = 2 and 42 reference lines. Typical scan time was 6 minutes.

Results: Patients in group 1 were younger (57±15 vs. 66±13 years, p=0.009) with a male predominance (80% vs. 57%, p

Catheter ablation is effective in symptomatic, drug refractory atrial fibrillation and can result in cure but success rates vary significantly with recurrences ranging from 40-86%. In the months following ablation, LA wall scarring on late gadolinium enhancement (LGE) is useful for determining the location and extent of injury and has been used to guide follow up ablation to 'close the gaps' after unsuccessful PVAI. More recently, imaging acute ablation injury using double inversion recovery (DIR) sequences has been shown feasible and has generated interest for its potential clinical value in guiding ablations.