Clinical significance of increased QT dispersion in the 12-lead standard ECG for arrhythmia risk prediction in dilated cardiomyopathy

Cardiomyopathy. QT dispersion was determined from the 12-lead standard ECGs from 107 patients with idiopathic dilated cardiomyopathy (IDC) and compared to QT dispersion measurements in 100 healthy age and sex matched controls. QT dispersion, rate corrected QT dispersion and adjusted QT, dispersion were significantly greater in patients with IDC compared to controls. During a prospective follow-up of 13 +/- 7 months, arrhythmic events, defined as sustained VT, VF, or sudden death, occurred in 12 (11%) of 107 study patients with IDC. QT dispersion was increased in patients with arrhythmic events compared to patients without arrhythmic events during follow-up (76 +/- 17 vs 60 +/- 26 ms; P = 0.03). Differences in QT, dispersion and adjusted QT, dispersion between patients with and without arrhythmic events, however, failed to reach statistical significance. Thus, although QT dispersion was increased in patients with IDC and arrhythmic events during follow-up, its clinical usefulness for risk stratification appears to be very limited due to the large overlap of QT dispersion among patients with and without arrhythmic events.