Abstract 4668: Mode of Induction of Ventricular Tachycardia and Prognosis in patients with Coronary Disease: The Multicenter UnSustained Tachycardia Trial (MUSTT)
Programmed stimulation is an important prognostic tool in the evaluation of patients with an ejection fraction ≤40% after myocardial infarction. Many believe that ventricular tachycardia (VT) requiring 3 ventricular extrastimuli (VES) for induction is less likely to occur spontaneously, and has less predictive value. However, it is unknown whether the mode of VT induction is associated with long-term prognosis. We analyzed a cohort of 371 patients enrolled in MUSTT who had inducible monomorphic VT and who were not treated with antiarrhythmic drugs and did not receive an ICD during the course of the study. Patients in whom sustained VT was induced with 1 or 2 VES or burst pacing (single VES n=15, double VES n=127, burst n=7, total n=149) were compared with those with VT induced with 3 VES (n=222). Compared with patients induced with 1,2, or burst pacing, patients induced with 3 VES were closer to their most recent myocardial infarction (17 vs 51 months, p=0.035), had a trend toward a lower median ejection fraction (26% vs. 30%, p=0.057), and a trend towards a higher prevalence of heart failure (74% vs 64%, p=0.12). VT induced with 3 VES had a shorter cycle length (240 vs 260 msec, p<0.001), and a higher incidence of syncope (70% vs 44%, p<0.001) and requirement for cardioversion during EP Study (68% vs. 44%, p<0.001). Despite these findings, there was no difference in arrhythmic death or cardiac arrest (HR 1.02; 95%CI 0.76 –1.39) or all-cause mortality (HR 1.03; 95%CI 0.69 –1.51) according to the mode of induction (singles, doubles, or burst vs. triples) in adjusted analyses. There is no difference in long term outcomes between VT induced by 3 VES compared with 1 and 2 VES, or burst pacing in patients with coronary disease and abnormal LV function.