INFLUENCE OF THE INFARCT SITE ON THE IDENTIFICATION OF PATIENTS WITH VENTRICULAR-TACHYCARDIA AFTER MYOCARDIAL-INFARCTION BASED ON THE TIME-DOMAIN AND SPECTRAL TURBULENCE ANALYSIS OF THE SIGNAL-AVERAGED ELECTROCARDIOGRAM

In a significant proportion of patients with sustained ventricular tac hycardia (VT) following anterior myocardial infarction, the areas of s low conduction are activated early during cardiac depolarization. Ther efore, they may not be detected by the standard time-domain analysis o f the signal-averaged electrocardiogram (SAECG) which is limited to th e terminal part of the QRS complex. Spectral turbulence analysis of th e SAECG is a new frequency domain technique which examines the whole Q RS complex and may improve identification of patients with sustained V T following anterior infarction. We compared the results of time-domai n and spectral turbulence analyses of the SAECG in 53 postinfarction p atients with sustained VT and in 53 age-, gender- and infarct site-mat ched patients without VT. The receiver operator characteristic curves have shown that the time-domain analysis resulted in better identifica tion of patients with VT following inferior than following anterior in farction (e.g., at the sensitivity level of 90%, the corresponding val ues of specificity were 96 and 90%, respectively), whereas the spectra l turbulence analysis performed better in the anterior site of infarct ion. When both time-domain and spectral turbulence analyses were combi ned, the accuracy of the SAECG for identification of patients with VT following anterior infarction improved, reaching a specificity of 97% at the sensitivity level of 90%. In conclusion (1) spectral turbulence analysis of the SAECG results in better identification of patients wi th VT following anterior than following inferior infarction, and (2) t he combination of time-domain and spectral turbulence analyses of the SAECG may improve identification of patients with VT following anterio r infarction.