Magnetic Resonance Elastography (MRE) is promising for non-invasive assessment of fibrosis, a major determinant of outcome in nonalcoholic fatty liver disease (NAFLD). However, data in children are limited. Study aims were to determine accuracy of MRE for detection of fibrosis and advanced fibrosis in children with NAFLD, and to assess agreement between manual and novel automated reading methods. We performed a prospective, multi-center study of 2D-MRE in children with NAFLD. MR-elastograms were analyzed manually at 2 reading centers and using a new automated technique. Analysis using each approach was done independently. Correlations were determined between MRE analysis methods and fibrosis stage. Thresholds for classifying the presence of fibrosis and of advanced fibrosis were computed and cross-validated. In 90 children with mean age of 13.1 ± 2.4 years, median hepatic stiffness was 2.35 kPa. Stiffness values derived by each reading center were strongly correlated with each other (r=0.83). All three analyses were significantly correlated with fibrosis stage (center 1, ρ=0.53; center 2, ρ=0.55; and automated analysis, ρ=0.52; p<0.001). Overall cross-validated accuracy for detecting any fibrosis was the same for all methods: 72.2% (61.8 – 81.1). Overall cross-validated accuracy for assessing advanced fibrosis varied by method: 88.9% (80.5% – 94.5%) for center 1, 90.0% (81.9% – 95.3%) for center 2, and 86.7% (77.9 – 92.9) for automated analysis. Conclusions 2D-MRE can estimate hepatic stiffness in children with NAFLD. Further refinement and validation of automated analysis techniques will be an important step in standardizing MRE. How to best integrate MRE into clinical protocols for the assessment of NAFLD in children will need prospective evaluation.

Background— The optimal ablation strategy for persistent atrial fibrillation (AF) remains unclear. Methods and Results— This multicentre randomized study compared circumferential pulmonary vein ablation+linear ablation (control arm) versus circumferential pulmonary vein ablation+linear ablation+complex fractionated atrial electrogram (CFAE) ablation (CFAE arm) in patients with persistent AF. Circumferential pulmonary vein ablation was performed followed by roof and mitral isthmus ablation, before CFAE ablation in the CFAE arm. Ablation strategy was maintained at the first redo procedure. Sixty-five patients were recruited in each arm. The mean age was 61±10 years, 75% were men, median AF duration was 2 years, 42% had long-lasting persistent AF, 68% had associated cardiovascular disease, mean left atrial dimension was 46±6 mm, and median CHA 2 DS 2 -VASc score was 2. Ablation and procedure times were significantly longer in the CFAE arm (70±20 versus 55±17; 201±35 versus 152±45 minutes; P <0.005). After a mean follow-up of 35±5 months, single-procedural success off antiarrhythmic drugs at 12 months (CFAE: 30/65 [46%] versus control: 37/65 [57%]; P =0.29) and multiprocedural success (CFAE: 51/65 [78%] versus control: 52/65 [80%]; P =1.0) were not significantly different. At the first redo procedure, patients in the CFAE arm had a higher incidence of organized atrial tachycardia/flutter (24/33 [73%] versus 11/31 [35%]; P =0.005) and gap-related macro–re-entrant flutter (8/33[24%] versus 1/31[3%]; P =0.03). Early recurrence of atrial arrhythmia was an independent predictor of late recurrence. Conclusions— CFAE ablation did not confer incremental benefit when performed in addition to circumferential pulmonary vein ablation and linear ablation. It was associated with a higher incidence of gap-related flutter. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01711047.

Acute sub-clinical circumflex 'injury' following MI ablation is not uncommon. Ablation within the CS, proximity of the circumflex and the CS, and a small distal circumflex were risk factors for 'injury'.

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