P993Diagnostic accuracy of cardiac magnetic resonance and endomyocardial biopsy for arrhythmogenic right ventricular dysplasia/cardiomyopathy and myocarditis

Introduction Patients with myocarditis may fulfill the cardiac magnetic resonance (CMR) criteria set forth by the 2010 Task Force for arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), thereby increasing the risk of misdiagnosis. Purpose We sought to evaluate the role of CMR and endomyocardial biopsy (EMB) in the differential diagnosis between myocarditis and ARVD/C. Methods Consecutive patients presenting with ventricular arrhythmias, underwent a complete diagnostic work-out, which included CMR and EMB. The final diagnosis served as the gold standard to assess the diagnostic accuracy of CMR and EMB. Results Overall, 74 consecutive patients presenting with VAs underwent a complete diagnostic workout at our institution. The cohort was 70.3% male, with a mean age of 38.9±12.1 years. A final diagnosis of ARVD/C was made in 30 (40.5%) patients, whereas 19 (25.7%) had a diagnosis of myocarditis. The McNemar's test showed significant differences in the diagnostic performance of EMB and cardiac MRI (p=0.003 for ARVD/C, p=0.04 for myocarditis). At receiver operating characteristic (ROC) analyses, the area under the curve (AUC) to discriminate between controls and ARVD/C patients was 0.711 (95% CI: 0.59–0.83) for MRI and 0.944 (95% CI: 0.88–1.00) for biopsy (p<0.001). The AUC to discriminate between controls and patients with myocarditis was 0.656 (95% CI: 0.51–0.80) for MRI and 0.893 (95% CI: 0.80–0.99) for biopsy (p=0.006). Diagnostic performance of CMR and EMB Conclusion Even though CMR has good diagnostic performances as single technique, a complete diagnostic work-out including EMB may frequently reduce the risk of misdiagnoses.