RIGHT-VENTRICULAR ARRHYTHMIA IN THE ABSENCE OF ARRHYTHMOGENIC DYSPLASIA - MR-IMAGING OF MYOCARDIAL ABNORMALITIES

PURPOSE: To evaluate right ventricular abnormalities with magnetic res onance (MR) imaging in patients with arrhythmia but without arrhythmog enic dysplasia. MATERIALS AND METHODS: In 53 patients being evaluated for right ventricular arrhythmia and 15 control subjects, MR imaging w as performed to evaluate fixed thinning, fatty replacement, or reduced systolic wall thickening or motion. A diagnosis of idiopathic right v entricular outflow tract tachycardia or indeterminate was assigned for each patient, and the severity of arrhythmia was categorized. RESULTS : Right ventricular abnormalities were revealed in 32 (60%) of the 53 patients: fixed thinning in 27 (84%), fatty replacement in eight (25%) , and reduced wall thickening or motion in 31 (97%). Right ventricular abnormalities were found in 35 (76%) of 46 patients with idiopathic r ight ventricular outflow tract tachycardia and in seven (39%) of 18 pa tients with indeterminate diagnosis (P = .022). CONCLUSION: Mild right ventricular abnormalities are likely sources for arrhythmias, even in the absence of arrhythmogenic right ventricular dysplasia.