DAY TO DAY REPRODUCIBILITY OF ELECTRICALLY INDUCIBLE VENTRICULAR ARRHYTHMIAS IN SURVIVORS OF ACUTE MYOCARDIAL-INFARCTION

Day to day reproducibility of the response to programmed ventricular stimulation has not been evaluated in survivors of acute myocardial infarction. Programmed ventricular stimulation was performed prospectively on 2 consecutive days in 56 patients on an average of 12 ± 5 days (range 7 to 29) after an acute myocardial infarction. No patient had a history of documented or suspected sustained ventricular tachycardia or fibrillation occurring >48 h after infarction. During initial programmed ventricular stimulation, 21 patients had induction of sustained ventricular tachycardia or fibrillation (Group I), and 35 patients had induction of either nonsustained ventricular tachycardia or no ventricular tachycardia (Group II). Repeat programmed ventricular stimulation in Group I patients induced sustained ventricular tachycardia or fibrillation in 16 of 21 patients (reproducibility 76%); the maximal induced response in the other 5 patients was nonsustained ventricular tachycardia in 2 patients and fewer than six repetitive ventricular responses in 3 patients. The day to day reproducibility was significantly higher for inducible sustained ventricular tachycardia of cycle length ≥240 ms compared with rapid sustained ventricular tachycardia of cycle length <240 ms (100% versus 44%, p < 0.009) or ventricular fibrillation (100% versus 43%, p < 0.009). Repeat programmed ventricular stimulation in Group II patients did not induce sustained ventricular arrhythmias in 31 of 35 patients (reproducibility 89%). Thus, in survivors of acute myocardial infarction, inducible slow sustained ventricular tachycardia was a highly reproducible finding, whereas inducibility of rapid sustain ventricular tachycardia and ventricular fibrillation showed a significant day to day variability. These findings should be taken into account when evaluating the prognostic significance of programmed ventricular stimulation in postmyocardial infarction patients. © 1990.