The clinical impact of RR-NSVT in DCM patients
RR-NSVT, which meets detection criteria but terminates itself before the
delivery of defibrillator therapy, is not rare in routine ICD/CRT-D
interrogation of DCM patients. Of note, the definition of RR-NSVT is not
the same as NSVT episodes identified on a 24-hour holter. RR-NSVT is
based on the continuous recording of a patient’s heart rhythm and can
provide more accurate detection of NSVT above the lowest detection rate.
In a study enrolling patients with hypertrophic cardiomyopathy, Wang et
al. reported that 38% of patients without NSVT detected by preimplant
Holter had an NSVT detected by ICD during follow-up14. To the best of our knowledge, 2 studies examined
the clinical influence of RR-NSVT and reported that RR-NSVT was a
predictor for future ICD therapy and mortality 8, 9.
Chen et al. examined the occurrence of RR-NSVT and its association with
ICD shocks and mortality in a SCD-HeFT population, in which ICD therapy
was set only for a VF zone ≥188 beats/min 8. Recently,
Zhou et al. explored the predictive value of RR-NSVT on appropriate ICD
therapy in a real-world setting, in which they set the monitor zone of
140–170 bpm and VT therapy zone above 170–210 bpm as well as the VF
zone 9. In the present study, we focused on DCM
patients and evaluated the clinical impact of RR-NSVT in DCM patients
with a practical setting of ICD/CRT-D. We demonstrated that any RR-NSVT
was associated with a higher incidence of VTAs in both primary and
secondary prevention. On the other hand, RR-NSVT did not show a
significant association with cardiac mortality. One possible explanation
for the difference in influence of RR-NSVT on mortality between prior
studies and the current study is the background heart diseases included;
prior studies included approximately 50% of patients with other
structural heart disease than non-ischemic cardiomyopathy8,9. Further studies are needed to evaluate the
clinical influence of RR-NSVT in specific patient populations.