Definition
VTA was defined as a sustained ventricular tachycardia and fibrillation
which was treated by ICD and/or lasted >30 seconds. RR-NSVT
was defined as an episode of VT that met the ICD therapy detection
criteria which terminated before defibrillator intervention. A frequent
RR-NSVT was defined as ≥3 runs for one day observed before or without
following VTAs. A cluster RR-NSVT was defined as ≥3 episodes for 6
months observed before or without following VTAs (Supplemental Figure
1). An electrical storm was defined as ≥3 episodes of VTAs within 24
hours. A CRT responder was defined as a decrease in LV end-systolic
volume of ≥15% and/or an absolute increase of >5% in LVEF
at the 6-month or 1-year visit compared to the baseline echocardiography12.
Cardiovascular mortality was defined as death due to HF, sudden cardiac
death, or VTAs. All-cause mortality was defined as death due to
cardiovascular mortality, sepsis, or malignancy.
Study endpoints
The primary endpoint was defined as the occurrence of VTAs. The
secondary endpoints were defined as the occurrence of an electrical
storm, admission for HF, cardiovascular mortality, and all-cause
mortality.