MAGNETIC RESONANCE IMAGING FOR THE DETECTION OF LEFT ATRIAL SCAR: CORRELATION WITH HIGH-DENSITY VOLTAGE MAPPING

Abstract

There is limited data on the accuracy and reproducibility of cardiac magnetic resonance imaging (CMR) for the detection of left atrial (LA) scar/fibrosis in patients with AF. In this study, we sought to (1) evaluate the presence and extent of left atrial scar detected using delayed enhancement-CMR and to (2) determine the correlation between CMR findings and endocardial voltage mapping-detected LA scar. Patients accepted for catheter ablation for AF were eligible for the study. Delayed enhancement CMR and endocardial voltage mapping for the assessment of LA scar data were both performed during sinus rhythm (requiring cardioversion in most patients). CMR-detected scar was identified as LA regions with tissue-to-blood signal intensity ratio > 1.25 and bipolar voltage < 0.5mV was used to define atrial scar. Scar burden was calculated by dividing the scar area by the total LA area. High-density voltage mapping was acquired using multipolar catheters and a semi-automated software to ensure homogeneous data collection (Confidense module, Biosense Webster, Inc). CMR and endocardial voltage maps were interpreted by blinded to the other investigation result. Forty-five patients were enrolled; LA scar burden assessment with CMR was completed in 43 patients. Two patients were excluded due to poor CMR image quality. Thirty-one patients had persistent and 12 paroxysmal AF. Mean age 64±9 years, LVEF 61±9%. The mean normalized LA volume was 52±17ml/m2. The average number of endocardial points acquired for atrial voltage mapping was 1387±1060. Overall, the correlation for the percentage of atrial scar detected with CMR and endocardial voltage mapping was poor (rho=0.13; 95%CI -0.17 to 0.42; P=0.3). Table1 shows the scar burden by CMR and endocardial voltage map. In this study, the correlation between high-density voltage mapping and CMR-detected atrial scar burden was poor. The overall extent of scar was generally more extensive on CMR when compared to intracardiac mapping. Further research is needed to improve the accuracy of CMR for the detection and quantification of atrial scar in patients with AF.