[Signal-averaged electrocardiography in right ventricular dysplasia]

The authors report their experience of signal-averaged electrocardiography (SAE) in arrhythmogenic right ventricular dysplasia (ARVD) in a study comparing the results in 40 control subjects, 21 patients with ARVD with episodes of sustained monomorphic ventricular tachycardia (VT) (Group I), 7 patients with ARVD without sustained VT (Group II) and 10 asymptomatic members of the families of patients in Group I (Group III). There were significant differences in the results of SAE in the time domain between the control group and Group I, patients with "classical" ARVD. The RMS 40 (root mean square of the last 40 ms of the QRS complex) was the most sensitive parameter but the specificity was less than the averaged QRS width and the low amplitude signal duration. The results in Group II were more varied, some patients having clearly abnormal SAE and others strictly normal recordings. In Group III, the investigation was normal. Spectral analysis after Fourier transformation did not show significant differences between the 3 groups. A difference was observed between the diffuse and localised forms of ARVD in Groups I and II: the localised forms had a shorter QRS width and low amplitude signal duration than the diffuse forms. Also, there was a relationship in Group I between age and duration of QRS and delayed potential which increased and with the RMS 40 or 50 which decreased. This is an argument in favour of the progressive nature of ARVD with respect to time.