Association of ventricular tachycardia morphology induced on electrophysiology study after myocardial infarction: long-term survival and ventricular tachyarrhythmia recurrence

Abstract

Abstract Background Electrophysiology study (EPS) presents a valuable risk stratification tool to facilitate the implantation of implantable cardioverter-defibrillators (ICDs) to prevent sudden cardiac death from ventricular tachyarrhythmia early after myocardial infarction. Purpose To investigate long-term survival of patients with inducible ventricular tachycardia (VT) at electrophysiology study (EPS) early after ST elevation myocardial infarction (MI) and possible association with site of origin of the induced VT. Methods Consecutive patients with LVEF ≤40% on day 3–5 after MI who underwent EPS were prospectively recruited. Positive EPS was defined as sustained monomorphic VT cycle length ≥200ms for >10 seconds, or shorter duration if hemodynamic compromise occurred. The primary outcome was time to death from any cause. The secondary outcome was time to the composite endpoint of first activation of ICD for ventricular tachyarrhythmia or death. Results A total of 126 patients with inducible VT on EPS early after MI were included with median follow up 6.7 years. 54% had LBBB and 46% had RBBB morphologies during induced VT. The distributions of age, sex, left ventricle ejection fraction, cardiovascular risk factors, infarct artery and EPS characteristics did not differ significantly by induced VT morphology. The estimated risk of death was independently associated with RBBB morphology of VT induced at EPS (adjusted HR 3.2, 95%CI 1.0-10.0, p=0.044). The estimated risk of the composite end-point of spontaneous ventricular tachyarrhythmia recurrence or death was also independently associated with RBBB morphology of VT induced at EPS (HR 1.8, 95%CI 1.0-3.2, p=0.043). Conclusion There is an increased risk of death and spontaneous ventricular tachyarrhythmia recurrence at median follow up of 6.7 years, associated with RBBB morphology of VT (likely origin from left ventricle) induced at EPS early after MI, in those with LVEF <40%. This study is the first to characterise the association between site of origin of VT induced at EPS after myocardial infarction, indicated by RBBB or LBBB morphology, and overall survival as well as activation free survival. The results could help to identify a group of patients that could benefit from closer monitoring post MI and more intense preventative management to improve long-term outcomes.