QT dispersion as a noninvasive predictor of inducible ventricular tachycardia.

The QT dispersion (QTD) on the surface electrocardiogram is a noninvasive marker of heterogeneity of ventricular repolarization. An increased QTD has been associated with spontaneous ventricular arrhythmias. We investigated the relationship of QTD to inducible reentrant sustained ventricular tachycardia (VT) in 66 patients who underwent programmed electrical stimulation. Thirty-three patients had inducible VT and 33 had noninducible VT with up to three extra stimuli. The QTD was significantly longer in patients with inducible VT (79+/-30 ms) compared with those in whom VT was noninducible (50+/-20 ms, P < .0001). QTD of > or =70 ms had a sensitivity of 67%, a specificity of 94%, a positive predictive value of 92%, and a negative predictive value of 74% for inducible VT. We conclude that QTD is an easily measurable electrocardiographic index that is increased in patients with inducible VT, and a QTD of > or =70 ms is highly predictive of VT inducibility.