AIMS: This study evaluates the agreement between echocardiographic and cardiac magnetic resonance (CMR) imaging data, and the impact a discrepancy between the two may have on the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS AND RESULTS: From the Nordic ARVC Registry, 102 patients with definite ARVC who had undergone both echocardiography and CMR were included (median age 42 ± 16 years, 36% female, 78% probands). Patients were divided into two groups according to CMR-positive or -negative criteria, and the echocardiographic data were compared between the two. There were 72 CMR-positive patients. They had significantly larger RV dimensions and lower fractional area change on echocardiography compared with CMR-negative patients; parasternal long-axis right ventricular outflow tract (RVOT) 37 ± 7 vs. 32 ± 5 mm, parasternal short-axis RVOT 38 ± 7 vs. 32 ± 6 mm, fractional area shortening 31 ± 9 vs. 39 ± 9% (P < 0.003 for all). Only 36 (50%) of the CMR-positive patients fulfilled ARVC criteria by echocardiography, hence the diagnostic performance was low; sensitivity 50% and specificity 70%, positive predictive value 80% and negative predictive value 37%. Individuals with regional wall abnormalities on CMR were more likely to have ventricular arrhythmias (77 vs. 57%, P = 0.047).

CONCLUSION: A significant proportion of patients with imaging-positive ARVC by CMR did not fulfil echocardiographic ARVC 2010 criteria. These findings confirm that echocardiographic evaluation of subtle structural changes in the right ventricle may be unreliable, and the diagnostic performance of CMR compared with echocardiography should be reflected in the guidelines.