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.