Eva M. Benito

Use of delayed-enhancement magnetic resonance imaging for fibrosis detection in the atria: a review

This paper presents a review of the different approaches existing in the literature to detect and quantify fibrosis in contrast-enhanced magnetic resonance images of the left atrial wall. The paper provides a critical analysis of the different methods, stating their advantages and limitations, and providing detailed analysis on the possible sources of variability in the final amount of detected fibrosis coming from the use of different techniques.

Left atrial fibrosis quantification by late gadolinium-enhanced magnetic resonance: a new method to standardize the thresholds for reproducibility

Aims Identification of left atrial (LA) fibrosis through late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) remains controversial due to the heterogeneity and lack of reproducibility of proposed methods. Our aim is to describe a normalized, reproducible, standardized method to evaluate LA fibrosis through LGE-CMR. Methods and results Electrocardiogram- and respiratory-gated 3-Tesla LGE-CMR was performed in 10 healthy young volunteers and 30 patients with atrial fibrillation (AF): 10 with paroxysmal AF, 10 with persistent AF, and 10 with a previous AF ablation procedure. Local image intensity ratio (IIR) of the LA was calculated as the absolute pixel intensity to mean blood pool intensity ratio. The healthy atrial tissue threshold was defined in young healthy volunteers (upper limit of normality set at IIR tissue mean plus 2 SDs). Dense atrial scarring was characterized in patients with previous radiofrequency-induced scarring (post-AF ablation patients). Validation groups consisted of patients with paroxysmal and persistent AFs. The upper limit of normal IIR was 1.20; IIR values higher than 1.32 (60% of mean maximum pixel intensity in post-ablation patients) were considered dense scar. Image intensity ratio values between 1.2 and 1.32 identified interstitial fibrosis. Patients with paroxysmal and persistent AFs had less atrial fibrotic tissue compared with post-ablation patients. Endocardial bipolar voltage was correlated to IIR values. Conclusions An IIR of 1.2 identifies the upper limit of normality in healthy young individuals. An IIR of >1.32 defines dense atrial fibrosis in post-ablation patients. Our results provide a consistent, comparable, and normalized tool to assess atrial arrhythmogenic substrate.

Contact force threshold for permanent lesion formation in atrial fibrillation ablation: A cardiac magnetic resonance-based study to detect ablation gaps.

BACKGROUND Catheter contact force (CF) has a strong correlation with lesion formation during radiofrequency ablation. Delayed-enhancement cardiac magnetic resonance (DE-CMR) provides lesion information in patients with prior atrial fibrillation (AF) ablation. OBJECTIVE The aim of this study was to determine the CF threshold to create permanent lesions detected by DE-CMR. METHODS A total of 36 patients referred for AF ablation were included. A CF catheter was used during the ablation procedure, and DE-CMR was performed 3 months after the ablation procedure. Eighteen pulmonary vein (PV) segments were defined, and 3-dimensional (3D) reconstructions of the left atrium (LA) derived from the DE-CMR images were obtained. One observer evaluated the presence of any discontinuity of previous ablation lesions (gap) in the 3D reconstructions of the LA, and another observer (blinded to the gap findings) determined the minimum CF value in each PV segment. RESULTS The PV segments where a gap was observed had a lower maximal CF value than did the segments without gap in the 3D LA reconstructions (6.7 ± 4.4 g vs 12.2 ± 4.7 g; P < .001). In receiver operating characteristic analysis, a CF threshold of >8 g provided 73% sensitivity and 81% specificity in the prediction of a complete PV lesion (positive predictive value [PPV] 84%). A CF threshold of >12 g had a specificity of 94% and increased the PPV to 91% in creating a complete lesion in the LA wall (area under the curve 0.834). CONCLUSION A CF threshold of >12 g H5H20 predicts a complete lesion with high specificity and PPV when a dragging ablation strategy is used in AF ablation.

Impact of left atrial volume, sphericity, and fibrosis on the outcome of catheter ablation for atrial fibrillation

To investigate the relation between left atrial (LA) volume, sphericity, and fibrotic content derived from contrast‐enhanced cardiac magnetic resonance imaging (CE‐CMR) and their impact on the outcome of catheter ablation for atrial fibrillation (AF).

Postprocedural LGE‐CMR comparison of laser and radiofrequency ablation lesions after pulmonary vein isolation

The purpose of this study was to compare the anatomical characteristics of scar formation achieved by visual‐guided laser balloon (Laser) and radiofrequency (RF) pulmonary vein isolation (PVI), using late‐gadolinium‐enhanced cardiac magnetic resonance imaging (LGE‐CMR).

Preferential regional distribution of atrial fibrosis in posterior wall around left inferior pulmonary vein as identified by late gadolinium enhancement cardiac magnetic resonance in patients with atrial fibrillation

Aims Left atrial (LA) fibrosis can be identified by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) in patients with atrial fibrillation (AF). However, there is limited information about anatomical fibrosis distribution in the left atrium. The aim is to determine whether there is a preferential spatial distribution of fibrosis in the left atrium in patients with AF. Methods and results A 3-Tesla LGE-CMR was performed in 113 consecutive patients referred for AF ablation. Images were post-processed and analysed using ADAS-AF software (Galgo Medical), which allows fibrosis identification in 3D colour-coded shells. A regional semiautomatic LA parcellation software was used to divide the atrial wall into 12 segments: 1-4, posterior wall; 5-6, floor; 7, septal wall; 8-11, anterior wall; 12, lateral wall. The presence and amount of fibrosis in each segment was obtained for analysis. After exclusions for artefacts and insufficient image quality, 76 LGE-MRI images (68%) were suitable for fibrosis analysis. Segments 3 and 5, closest to the left inferior pulmonary vein, had significantly higher fibrosis (40.42% ± 23.96 and 25.82% ± 21.24, respectively; P < 0.001), compared with other segments. Segments 8 and 10 in the anterior wall contained the lowest fibrosis (2.54% ± 5.78 and 3.82% ± 11.59, respectively; P < 0.001). Age >60 years was significantly associated with increased LA fibrosis [95% confidence interval (CI) 0.19-8.39, P = 0.04] and persistent AF approached significance (95% CI -0.19% to 7.83%, P = 0.08). Conclusion In patients with AF, the fibrotic area is preferentially located at the posterior wall and floor around the antrum of the left inferior pulmonary vein. Age >60 years was associated with increased fibrosis.

Left atrial geometry and outcome of atrial fibrillation ablation: results from the multicentre LAGO-AF study

Aims Left atrial (LA) remodelling is a key determinant of atrial fibrillation (AF) ablation outcome. Optimal methods to assess this process are scarce. LA sphericity is a shape-based parameter shown to be independently associated to procedural success. In a multicentre study, we aimed to test the feasibility of assessing LA sphericity and evaluate its capability to predict procedural outcomes. Methods and results This study included consecutive patients undergoing first AF ablation during 2013. A 3D model of the LA chamber, excluding pulmonary veins and LA appendage, was used to quantify LA volume (LAV) and LA sphericity (≥82.1% was considered spherical LA). In total, 243 patients were included across 9 centres (71% men, aged 56 ± 10 years, 44% with hypertension and 76% CHA2DS2-VASc ≤ 1). Most patients had paroxysmal AF (66%) and underwent radiofrequency ablation (60%). Mean LA diameter (LAD), LAV, and LA sphericity were 42 ± 6 mm, 100 ± 33 mL, and 82.6 ± 3.5%, respectively. Adjusted Cox models identified paroxysmal AF [hazard ratio (HR 0.54, P = 0.032)] and LA sphericity (HR 1.87, P = 0.035) as independent predictors for AF recurrence. A combined clinical-imaging score [Left Atrial Geometry and Outcome (LAGO)] including five items (AF phenotype, structural heart disease, CHA2DS2-VASc ≤ 1, LAD, and LA sphericity) classified patients at low (≤2 points) and high risk (≥3 points) of procedural failure (35% vs. 82% recurrence at 3-year follow-up, respectively; HR 3.10, P < 0.001). Conclusion In this multicentre, real-life cohort, LA sphericity and AF phenotype were the strongest predictors of AF ablation outcome after adjustment for covariates. The LAGO score was easy to implement, identified high risk of procedural failure, and could help select optimal candidates. Clinical Trial Registration Information NCT02373982 (http://clinicaltrials.gov/ct2/show/NCT02373982).

Correlation between functional electrical gaps identified by ultrahigh-density mapping and by late gadolinium enhancement cardiac magnetic resonance in repeat atrial fibrillation procedure

Introduction Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) images can reveal previous atrial scarring due to radiofrequency (RF) lesions from atrial fibrillation (AF) ablation. Discrepancies between the electrical gap identification in the LGE-CMR and in the electroanatomic voltage map obtained using a circular catheter inside pulmonary veins (PVs) have been observed. New mapping methods able to acquire thousands of electrograms in a few minutes can identify lesion gaps very precisely. We present a case report that establishes the correlation between the gaps observed on the LGE-CMR reconstruction and those identified by ultrahigh-density activation mapping.

Presyncopal episodes after implantation of dual-chamber pacemaker programmed in SafeR pacing mode

On arrival to the emergency department, the patient had no symptoms. Laboratory studies and chest X-ray showed no significant findings, and the electrocardiogram revealed sinus rhythm at 58 bpm and a normal PR interval (160 ms) with left anterior fascicular block and complete right bundle branch block, both previously known. Device interrogation showed how all nine presyncopal episodes coincided with nine checks to detect intrinsic conduction that caused pauses>2.5 s (Figure 1). The pacemaker was adjusted to permanent DDD mode, resolving the symptomatology. Figure 1 Automatic switch to AAI mode after 100 paced ventricular cycles related to presyncopal symptoms. As the atrioventricular block is still present, the third-degree AVB criterion applies and the algorithm makes the switch to DDD mode.