Background:
The concealed stage of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is associated with increased risk of sudden cardiac death. However, particular at this stage disease detection is hampered by absence of criteria. Activation delay (AD) is a hallmark of arrhythmogenesis in ARVD/C. Echocardiographic tissue Doppler imaging (TDI) may unmask AD in the absence of electrocardiographic (ECG) abnormalities.
Methods:
Three groups were compared 1) symptomatic definite ARVD/C patients with a mutation in the Plakophilin-2 (
PKP2)
gene (n=37), 2) asymptomatic
PKP2
mutation carriers (n=20) and 3) healthy controls (n=30). All groups underwent full echocardiographic examination with additional TDI of the right ventricular (RV) free wall and a routine 12-lead ECG recording. As surrogate for AD the electro-mechanical interval (EMI) was measured, defined as time between local first electrical deflection and local onset of mechanical shortening. EMI was measured in the subtricuspid, mid and apical region of the RV free wall. Detailed ECG analysis of depolarization (AD analysis) and repolarization abnormalities was performed in all subjects.
Results:
EMI was prolonged in all RV segments in ARVD/C patients compared to controls. Abnormal depolarization and repolarization was recorded in respectively 23 and 27 ARVD/C patients. In asymptomatic mutation carriers EMI was significantly prolonged in the subtricuspid area (Table 1). However, the ECG showed in 5/20 subjects only prolonged terminal activation duration and no repolarization abnormalities.
Conclusion:
TDI unmasks AD in both ARVD/C patients and asymptomatic mutation carriers. In asymptomatic mutation carriers EMI is prolonged in the subtricuspid area, whereas ECG appeared normal in the large majority. AD in the subtricuspid area is an early sign of disease in the concealed ARVD/C stage and may contribute to advanced risk stratification.
Table 1: Results
Risk Stratification in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy–Associated Desmosomal Mutation Carriers