Fast nonclinical ventricular tachycardia inducible after ablation in patients with structural heart disease: Definition and clinical implications.

BACKGROUND: Noninducibility of ventricular tachycardia (VT) with an equal or longer cycle length (CL) than that of the clinical VT is considered the minimum ablation endpoint in patients with structural heart disease. Because their clinical relevance remains unclear, fast nonclinical VTs are often not targeted. However, an accepted definition for fast VT is lacking. The shortest possible CL of a monomorphic reentrant VT is determined by the ventricular refractory period (VRP).

OBJECTIVE: The purpose of this study was to propose a patient-specific definition for fast VT based on the individual VRP (fVTVRP ) and assess the prognostic significance of persistent inducibility after ablation of fVTVRP for VT recurrence.

METHODS: Of 191 patients with previous myocardial infarction or with nonischemic cardiomyopathy undergoing VT ablation, 70 (age 63 ± 13 years; 64% ischemic) remained inducible for a nonclinical VT and composed the study population. FVTVRP was defined as any VT with CL ≤VRP400 + 30 ms. Patients were followed for VT recurrence.

RESULTS: After ablation, 30 patients (43%) remained inducible exclusively for fVTVRP and 40 (57%) for any slower VT. Patients with only fVTVRP had 3-year VT-free survival of 64% (95% confidence interval [CI] 46%-82%) compared to 27% (95% CI 14%-48%) for patients with any slower remaining VT (P = .013). Inducibility of only fVTVRP was independently associated with lower VT recurrence (hazard ratio 0.38; 95% CI 0.19-0.86; P = .019). Among 36 patients inducible for any fVTVRP , only 1 had recurrence with fVTVRP .

CONCLUSION: In patients with structural heart disease, inducibility of exclusively fVTVRP after ablation is associated with low VT recurrence.