Follow-up and outcomes
Patients were followed through regular outpatient visits at the institution after hospital discharge. Echocardiogram was performed after 6 months of the procedure. Hospitalization for heart failure was assessed at follow-up. Super responders were considered patients with LVEF > 50% at 6-month. Those patients who did not return within 1 year after CRT implantation were contacted by telephone. The primary outcome was to assess short-term mortality between upgrade and De novo-CRT implantation. Survival was assessed as the time from CRT implantation to all-cause mortality.