446 Magnetic resonance imaging in the diagnosis of childhood arrhythmogenic right ventricular cardiomyopathy

Abstract

Arrythmogenic right ventricular cardiomyopathy (ARVC) is characterized by right ventricular (RV) dysfunction and fibrofatty replacement of the myocardium. In adults, magnetic resonance imaging (MRI) has been shown to be a useful non-invasive tool in the diagnosis of ARVC. We sought to evaluate the ability of qualitative and quantitative MRI parameters to predict a diagnosis of ARVC. All cardiac MRI studies performed between 2005 and 2009 in 142 pediatric patients (mean age 11.7 ± 4.0 years) referred for imaging evaluation of suspected ARVC were reviewed. Comparisons were made between MRI findings in patients with and those without ARVC. Of all patients referred for MRI 47% had a positive family history, 38% had cardiac symptoms, 3% had had a sudden cardiac arrest, and 35% had ventricular arrhythmias. 47 subjects met the Task Force Criteria for ARVC, without using MRI criteria. Wall motion abnormalities (WMA) were found in 28/47 (60%) ARVC subjects compared to 25/96 (26%) subjects without ARVC (P = 0.0002). Of subjects with ARVC, 26 (55%) had severe WMA and 13 (28%) had moderate WMA. The Severity of WMA correlated with the probability of ARVC (P = 0.002). The specificity and sensitivity of WMA were 67% and 74%, respectively. RV end-diastolic volume was a strong predictor of ARVC with an dds ratio of 1.03/ml (P = 0.002). Abnormal trabeculations, thinning and outflow tract dilation of the RV were all very specific (>90%) but not very sensitive for ARVC (<30%). Fatty infiltration and fibrosis were identified in only 1 and 3 ARVC patients, respectively. RV regional WMA and RV size contribute to a diagnosis of ARVC, but must be integrated into the context of other MRI findings. These include RV aneurysm, trabeculation, accordion sign and wall thinning. They have high specificity and can improve the post-test probability of a diagnosis, although not part of the Task Force Criteria.