Population
Prospective cohort study between May 2017 and September 2019. We
included consecutive outpatients over 18 years, followed at the heart
failure unit of the Ana Nery Hospital of the Federal University of Bahia
in Brazil. The indication for CRT was based on the following criteria:
patients age over 18 years, under appropriate medical treatment,
presenting NYHA II to IV with left ventricular ejection fraction (LVEF)
less than 35% and a QRS duration > 150ms or 120–150ms
with proven dyssynchrony. Patients with previously implanted pacemakers
or implantable cardioverter-defibrillators (ICD) who developed this
criteria, with or without need for continuous ventricular pacing, were
also considered for CRT (upgrade group).
Demographic, laboratory and echocardiographic data were collected at the
time of the hospitalization for the procedure. Left ventricular ejection
fraction was measured on transthoracic echocardiograms using the
Simpson’s method at the time of the CRT implantation, and after 6
months. Chronic renal disease was defined as renal clearance, estimated
using Cockroft and Gault’s formula, <60mL/min/1.73m2. Atrial
fibrillation was defined at the time of the procedure by baseline
electrocardiogram. Chagas disease was confirmed by specific serological
tests.
Patients were excluded if they had a chronic systemic inflammatory
disease, malignant neoplasia under treatment, patients with no clear
etiology of heart failure, or who refused the procedure or declined to
give informed consent.