RESULTS OF SIGNAL - AVERAGED ELECTROCARDI OGRAPHY IN IDIOPATHIC DILATED CARDIOMYOPATHY

Idiopathic dilated cardiomyopathy carries a high risk of sudden death. It is also associated with sustained ventricular tachycardia. A compl ex ventricular arrhythmia is recorded in 3/4 of cases on Holter monito ring which has a low specificity. The aim of the study was to determin e whether signal-averaged electrocardiography could provide a better e valuation of the prognosis of this condition. The results of signal-av eraged electrocardiography were compared with those of 24 hour Holter monitoring and of systematic programmed ventricular stimulation in 58 patients with idiopathic dilated cardiomyopathy. Late ventricular pote ntials were recorded in 13 of the 14 subjects with inducible and usual ly spontaneous sustained ventricular tachycardia. The sensitivity of t he technique for evaluating the risk of sustained VT was therefore goo d (93 %). Late potentials were also recorded in 9 patients with induce d ventricular flutter or fibrillation, these patients being symptomati c (dizzy spells). Late potentials were also demonstrated in 14 of the 35 asymptomatic patients without inducible VT, indicating that this no n-invasive investigation had a limited specificity (60 %). In addition , during follow-up of the patients, the risk of sudden death was diffi cult to demonstrate. Late potentials were only found in subjects with inducible sustained VT but no in the other cases. In conclusion, signa l-averaged electrocardiography seems to be valuable for evaluating the risk of sustained VT in subjects with idiopathic dilated cardiomyopat hy and complex ventricular arrhythmias. The detection of the risk of s udden death is probably impossible by this technique.