Optimizing Electrophysiology Studies to Prevent Sudden Cardiac Death After Myocardial Infarction.

BACKGROUND: This study assessed associations of minimum final extrastimulus coupling interval utilised within electrophysiology study (EPS) after MI and possible site of origin of induced ventricular tachycardia (VT) with long-term occurrence of spontaneous ventricular tachyarrhythmia and longterm survival.

METHODS: This prospective study recruited consecutive patients with LVEF ≤ 40% who underwent EPS day 3-5 after MI between 2004-2017. Positive EPS was defined as sustained monomorphic VT cycle length ≥200 ms for ≥10 seconds, or shorter duration if hemodynamic compromise occurred. Each of the four extrastimuli was shortened by 10 ms at a time, until it failed to capture the ventricle (ventricular refractoriness) or induced ventricular tachyarrhythmia. Outcomes included spontaneous ventricular tachyarrhythmia occurrence and all-cause mortality.

RESULTS: Shorter coupling interval length of final extra-stimulus that induced VT was associated with higher risk of spontaneous ventricular tachyarrhythmia (p < 0.001). Significantly higher rates of spontaneous ventricular tachyarrhythmia (65.2% versus 23.2%; p < 0.001) were observed for final coupling interval at EPS <200 ms versus >200 ms. RBBB morphology of induced VT, with possible site of origin from left ventricle, was associated with all-cause mortality (HR 3.2, p = 0.044) and a composite of spontaneous ventricular tachyarrhythmia recurrence or mortality (HR 1.8, p = 0.043).

CONCLUSIONS: VT induced with shorter coupling intervals were associated with higher risk of spontaneous ventricular tachyarrhythymia on follow-up, indicating that the final extrastimulus coupling interval at EPS early after MI should be determined by ventricular refractoriness. Induced VT with possible origin from left ventricle was associated with increased risk of spontaneous ventricular tachyarrhythmia recurrence or death.