Feasibility of Targeting Catheter Ablation to the Markedly Low-Voltage Area Surrounding Infarct Scars in Patients With Post-Infarction Ventricular Tachycardia

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Background In routine substrate mapping of the left ventricle, an abnormal area is defined as having an amplitude <1.5 mV. However, that is usually too large for catheter ablation in post-infarction ventricular tachycardia (VT) and the use of strict voltage criteria may produce better outcomes. Methods and Results Twenty patients with post-infarction VT underwent substrate mapping using an electroanatomic mapping system. Strict voltage criteria were defined as: non-arrhythmogenic area, >0.6 mV; low-voltage area (LVA), >0.1 to ≤0.6 mV; scar, ≤0.1 mV. Radiofrequency applications targeted the LVA only, which was 48±26 cm², 55% smaller than that of the generally targeted area with an amplitude ≤1.5 mV. The prevalence of delayed electrograms (duration ≥150 ms) was significantly higher in the LVAs than in the border areas with an amplitude of >0.6 to ≤1.5 mV (33.2% vs 3.7%, p<0.001). With the exception of 2 instances of peri-mitral VT, all VT isthmuses resided within the LVA. During follow-up of 24±13 months, 16 patients (80%) have been free of any VT episodes. Conclusions Catheter ablation targeting LVAs with an amplitude ≤0.6 mV appears to be useful for efficient and effective treatment of post-infarction VT. (Circ J 2008; 72: 1112 - 1119)