A SIMPLE ELECTROCARDIOGRAPHIC ALGORITHM FOR DETECTING VENTRICULAR-TACHYCARDIA

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.