QT dispersion in myocardial infarction: influence of lead combination

This study aimed at comparing QT dispersion (QTD) in various combinations of surface ECG leads among 1,000 normal subjects (NL), and in 200 patients with anterior (AMI) or inferior (IMI) myocardial infarction without previous ventricular tachyarrhythmias. On an averaged beat of 15 simultaneous leads (12-leads+XYZ-Leads) and through interactive editing, QTD is automatically computed. In each lead combination, mean values were significantly higher in AMI and IMI than in NL(p<0.01). In each clinical group, QTD was quite similar in the 12 leads and the 15 leads, whereas XYZ leads showed lower values. However, the discriminant power of XYZ leads was significantly higher since it allowed one to identify 22% of the IMI patients and 46% of the AMI patients with QTD, exceeding the 97.5 percentile of the normal group.