DETERMINANTS OF INDUCTION OF VENTRICULAR-TACHYCARDIA IN NONSUSTAINED VENTRICULAR-TACHYCARDIA AFTER MYOCARDIAL-INFARCTION AND THE USEFULNESSOF THE SIGNAL-AVERAGED ELECTROCARDIOGRAM

Assessment of the implications of clinical and noninvasive variables, including the results of signal-averaged electrocardiography, was perf ormed >3 weeks after myocardial infarction in 57 patients with nonsust ained ventricular tachycardia (VT) who underwent programmed ventricula r stimulation to guide antiarrhythmic therapy. The clinical and noninv asive parameters assessed included ages, left ventricular ejection fra ctions, sites of infarction, presence of akinetic or dyskinetic left v entricular segments, history of syncope, history of coronary artery by pass surgery, and presence or absence of late potentials from signal-a veraged electrocardiography. Other than the presence of late potential s, no clinical or non-invasive parameters identified such persons with a significantly higher likelihood of inducible VT. When assessed as p ositive if 1 or more variables were abnormal, 16 of 16 (100%) patients with versus 17 of 41 without inducible VT had late potentials (p < 0. 002). With more stringent criteria required (defined as prolongation o f the QRS vector complex duration and low root-mean-square voltage of the terminal 40 ms of the vector complex) 8 of 16 patients (50%) with and 4 of 41 (10%) without inducible VT had late potentials recorded (p < 0.002). Thus, the signal-averaged electrocardiogram may enable iden tification of persons with nonsustained VT after myocardial infarction who are most likely to have VT induced at programmed ventricular stim ulation.