P388Beyond the diagnostic value of CMR in ARVC

Abstract

A 57 year-old man from Cambodia, paraplegic since medullary trauma 20 years ago, had called the ambulance for vague symptoms of headache and abdominal pain. The ECG showed a 170 bpm wide-complex tachycardia with left-bundle-branch morphology, left superior axis and auriculo-ventricular dissociation, suggestive of ventricular tachycardia (VT) originating from the apical septal region of the right ventricle (RV). It was converted to sinus rhythm after iv procainamide. Post-pharmacological cardioversion ECG showed low voltages and diffuse T-wave abnormalities. Initial blood electrolytes counts were normal. Troponins were mildly increased. Quick-look ultrasound revealed RV enlargement. Angiothoracic scan ruled out pulmonary embolism but confirmed RV dilatation. Formal trans-thoracic echocardiogram (TTE) showed severe RV enlargement with free-wall akinesia and apical dyskinesia. Left ventricular systolic function was mildly impaired. The patient remained in sinus rhythm and hemodynamically stable. Despite high suspicion of arrhythmogenic right ventricular cardiomyopathy (ARVC) following TTE, CMR was ordered. RV volume was increased (EDV 342; 215mL/m2) and function severely impaired (RVEF 25%). On cine imaging, there was akinesia of the basal portion of the RV free wall and dyskinesia of the RV apex associated with spontaneous echo contrast and thrombi were suspected. Heterogenous and extensive late gadolinium enhancement was found in the RV free wall and multiple thrombi were identified (fig. 1). CMR major Task Force criteria for ARVC were thus met. Furthermore, in this specific case, CMR offered prognostic value of great significance. Indeed, ARVC patients are at greater risk of SCD, mainly of arrhythmic etiology. Moreover, emboliza-tion of RV thrombus can potentially increase morbidity and even mortality, especially in the setting of paradoxical embolism. Current guidelines recommend primary prevention with ICD therapy for our patient. However the presence of RV thrombi raises several questions regarding ICD implantation. Should ICD implantation be postponed despite the significant SCD risk in this patient? Should subcutaneous ICD be preferred? This case illustrates not only the important diagnostic value of CMR in ARVC but also its pronostic ability. Also, by highlighting the presence of thrombi, a rare finding associated with ARVC, CMR helped guiding subsequent management. In our patient, as the thrombi appeared chronic, ICD implantation was not postponed and risk vs. benefit evaluation was in favor of not initiating long term oral anticoagulation.