The purpose of this study was to determine whether a simple ECG algori
thm could be developed for predicting susceptibility to ventricular ta
chyarrhythmias (VT) as defined by sustained spontaneous or inducible V
T. Two different QT dispersion algorithms were determined by the diffe
rence between the longest and shortest QT interval measured in three o
rthogonal leads (1, aVF, V1; QTD3), and at least 11 of 12 leads (QTD12
) from the 12-lead ECG. These QT dispersion algorithms were investigat
ed (with and without the QRS duration from the 12-lead ECG) and compar
ed to the signal-averaged ECG (SAECG) in order to determine their sens
itivity and specificity for detecting VT. Only patients who underwent
SAECG and were referred for programmed electrical stimulation were inc
luded in this study. A positive SAECG was defined by filtered QRS dura
tion > 114 ms, and/or low amplitude signal duration > 38 ms, and/or ro
ot mean square voltage in the last 40 ms of < 20 mu V. Sixty patients
were enrolled in this study with a mean age of 63 +/- 2 years. Fifty-f
ive percent of the patients had coronary artery disease. A simple ECG
algorithm consisting of the sum of QTD3 plus the QRS duration had a se
nsitivity and specificity of 90% and 63%, respectively, whereas the SA
ECG had a sensitivity and specificity of 60% and 63%, respectively (P
= 0.022). We conclude that a simple ECG algorithm is more sensitive th
an the SAECG for predicting VT. This algorithm combines two easily mea
sured variables obtained from the 22-lead ECG, and can easily be perfo
rmed without expensive computer equipment.