Combined assessment of beat-to-beat micro-variability and signal-averaged ECG parameters

Increased QRS and ST-T micro-variability and ventricular late potentials are associated with an increased risk for malignant arrhythmias. However, the diagnostic power of the singular parameters is limited. In this study, we investigated the diagnostic ability of a linear combination of five (both variant and static) high-resolution ECG parameters. Continuous and signal-averaged ECGs were recorded from 51 healthy volunteers without any structural heart disease and with no cardiac risk factors and from 44 patients with coronary heart disease and ventricular arrhythmias. Beat-to-beat micro-variability measurement of the QRS complex and the ST-T segment was based on 250 consecutive sinus beats per individual. Signal-averaged ECGs were analyzed with the Simson method. The diagnostic utility of the five singular parameters and all combinations of variables were evaluated by linear discriminant analysis, maximizing the area under the receiver operator characteristic (ROC) curve. We conclude that the combination of de- and re-polarization variability with the static QRS duration markedly improves the detection of patients with inducible ventricular tachycardia (VT).