VT burden reduction
The term ”recurrence” has been used to evaluate the outcome of the
ablation therapy, however, recently the concept of a VT burden reduction
has been proposed.19, 20 The VT burden can be more
valuable in terms of clinical benefit than recurrence as a dichotomous
event. In the present study, the VT burden was reduced by 91.1% even in
patients in whom VT non-inducibility could not be achieved at the end of
RF ablation, and VT ablation significantly reduced the number of VT
episodes and shock therapies. Although the design of the current study
did not allow us to examine the prevention of mortality, a reduction in
the ICD shock therapies may improve the patient
survival.21
Clinical Implications
It is known that the achievement of VT non-inducibility at the end of
the VT ablation in patients with SHD leads to a lower recurrence. So VT
non-inducibility has been used as an endpoint in many cases. However, in
some cases, the ablation may be excessive or the risk of an induction
test may be high. In this study, we included patients in whom VT
non-inducibility could not achieved at the end of the VT ablation. We
found that the recurrence rate was lower in patients with an EF≥35% or
in patients who could successfully identify and undergo ablation of all
clinical VT isthmuses. In these patients, even if non-clinical VT
inducibility remains, it may not affect the subsequent prognosis. In
addition, the VT burden was reduced after the VT ablation, and the shock
therapy was also significantly reduced before and after the ablation.
That suggested that it may be necessary to examine the validity of the
VT non-inducibility in each patient.
Study Limitations
This study was a single-center retrospective observational analysis.
Therefore, the number of study patients was relatively small. And this
study included the patients with ICM and NICM, and the NICM consisted of
a non-uniform etiology. The response to the RF ablation and clinical
course may differ for each cardiomyopathy. Further, the methods used for
antiarrhythmic drugs were dependent on each physician. However, because
of the limited number of operators, our strategy to treat patients with
VTs has been consistent and our results can be applied to clinical
practice.
Conclusion
Even if VT non-inducibility could not be achieved at the end of the RF
ablation, 66% of the patients had no VT recurrences. Among them, in the
patients whose LVEF was more than or equal to 35% or in whom all
clinical VT isthmuses could be identified and ablated, that successful
identification and ablation of those might prevent VT recurrences. In
addition, even if the VT recurred, the VT burden decreased after the VT
ablation. The validity of VT non-inducibility for any VT should be
evaluated by each patient’s background and the results of the procedure.
Acknowledgments
The authors would like to thank Mr. John Martin for his linguistic
assistance.
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