Increased QRS complex dispersion in postinfarction patients: is it clinically important?

The study was designed to analyse what is the dispersion of QRS complex in 10 normal subjects and whether 65 postinfarction patients have abnormal dispersion of QRS complex and what is its clinical meaning. QRS complex and QT interval duration were measured by means of spectrotemporal mapping of high resolution orthogonal ECG (16 bit, 2 kHz). Abnormal values of QRS complex dispersion and of derived parameters and of QT dispersion were defined as greater than mean+2.5 SD values seen in healthy subjects. Increased QRS dispersion and QT dispersion were found in more than half of post-myocardial infarction (MI) patients (52% and 55%, respectively). QRS dispersion was unrelated to the site of MI, Q-wave and left ventricular ejection fraction, but the dispersion of QRS-complex onset and QT dispersion were found useful for distinguishing MI-patients with or without non-sustained ventricular tachycardia. It is concluded that analysis of QRS complex dispersion may become a new index of increased risk of malignant ventricular arrhythmia in postinfarction patients.