LV dysfunction and VT recurrence
In this study, the recurrence rate was lower in the patients with an LVEF≥35%, even with residual VT inducibility. In a sub-analysis of the AVID (Antiarrhythmics Versus Implantable Defibrillator) trial, the efficacy of ICD therapy was reported to depend on the degree of LV dysfunction in patients with secondary prevention of sudden cardiac death, and in patients with an LVEF<35%, ICD therapy had an advantage. On the other hand, in patients with an LVEF≥35%, the efficacy of the ICD therapy was equivalent to that of antiarrhythmic drugs.12 Also in a recent trial, Groeneveld et al. reported that in 42 patients with an LVEF>35% and a hemodynamically not tolerated VT, only 6 patients (14.3%) had VT recurrences, and all were hemodynamically tolerated.13That suggests that the classification by the degree of LV dysfunction may make sense, and may help determine how aggressively induced VT should be treated.
Patients with an EF<35% are considered to have more myocardial dysfunction and are more likely to have multiple arrhythmia substrates. Although a more aggressive induction and ablation may be necessary to reduce the VT recurrence rate in them, the dilemma is that patients with such a reduced cardiac function may be more susceptible to hemodynamic compromise and invasive procedures with a prolonged operative time. In the present study, the VT burden was significantly reduced even in the group with an EF<35%, suggesting that a balanced protocol that ensures safety is desirable.