Abstract 13981: Predictive Value of Local Prolonged Electro-Mechanical Interval in the Concealed Stage of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Introduction: The concealed stage of ARVD/C is associated with increased risk of life-threatening arrhythmias. However, presymptomatic arrhythmic risk stratification of ARVD/C mutation carriers is challenging. Activation delay is a hallmark of arrhythmogenesis. Deformation imaging may unmask activation delay in the absence of ECG and structural abnormalities. Methods: From the merged transatlantic ARVD/C database three groups were compared 1) mutation-positive definite ARVD/C patients (n=108), 2) asymptomatic mutation carriers (AMC) not fulfilling Task-Force criteria (TFC) and without history of ventricular arrhythmias (n=35) and 3) healthy controls (n=50). All underwent echocardiographic deformation imaging and ECG according to TFC. As a surrogate for local activation delay the electro-mechanical interval (EMI) was measured, defined as time between first ECG-detected deflection and local onset of shortening. Arrhythmic outcome (PVC count, VT) of AMC was correlated to EMI and ECG TFC. Results: EMI was prolonged in all RV segments in ARVD/C patients. In AMC prolonged EMI was detected in the subtricuspid area in 17/35 subjects, Terminal Activation Duration ≥ 55ms was the only TFC-defined ECG abnormality found in this group (9/35). After a mean follow-up of 3.1±2.7 years 11/35 subjects experienced an increase in ventricular arrhythmia burden. Prolonged subtricuspid EMI was the only parameter significantly correlated to ventricular arrhythmias during follow-up (Figure 1). Conclusions: Deformation imaging reveals activation delay in all ARVD/C patients. In AMC prolonged EMI in the subtricuspid area is often detected without any additional abnormalities. Prolonged EMI is a new parameter unmasking activation delay in early ARVD/C stages and may contribute to risk stratification.