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.