Differences between patients with ventricular tachycardia and ventricular fibrillation as assessed by signal-averaged electrocardiogram, radionuclide ventriculography and cardiac mapping

Abstract

This study examined 65 patients with ventricular tachycardia or fibrillation late after myocardial infarction to determine whether they differed with respect to duration of ventricular activation in sinus rhythm and left ventricular ejection fraction. Patients with spontaneous ventricular tachycardia had a longer ventricular activation time in sinus rhythm than did patients with spontaneous ventricular fibrillation. This difference was detected with the signal-averaged electrocardiogram (ECG) (tachycardia 181 ± 33 ms, fibrillation 152 ± 23 ms, p < 0.001) and at epicardial mapping (tachycardia 210 ± 17 ms, fibrillation 192 ± 17 ms, p < 0.02). Left ventricular ejection fraction was lower in patients with spontaneous ventricular tachycardia (0.22 ± 0.09) than in patients with spontaneous ventricular fibrillation (0.27 ± 0.09) (p < 0.05).The patients with both spontaneous and inducible ventricular fibrillation had a shorter ventricular activation time on the signal-averaged ECG (129 ± 17 ms) and a higher ejection fraction (0.36 ± 0.05) than did either patients with spontaneous ventricular fibrillation and inducible ventricular tachycardia (158 ± 21 ms and 0.25 ± 0.08, respectively, each p < 0.01) or patients with both spontaneous and inducible ventricular tachycardia (181 ± 33 ms and 0.22 ± 0.09, respectively, each p < 0.001). Of the patients with inducible ventricular tachycardia, presentation with tachycardia rather than fibrillation was associated with a longer ventricular activation time on the signal-averaged ECG (181 ± 33 versus 158 ± 21 ms, p < 0.02) and a longer cycle length of inducible ventricular tachycardia (290 ± 61 versus 259 ± 44 ms, p = 0.05).In conclusion, conduction delay during sinus rhythm and left ventricular dysfunction appear to be greatest in patients with spontaneous and inducible ventricular tachycardia, and least in patients with spontaneous and inducible ventricular fibrillation.