Results
One hundred patients were evaluated for CRT implantation, seven of them
were excluded due to a LVEF higher than 35% prior the procedure. Of the
remaining 93 patients, Chagas Disease was the most prevalent cause of HF
29 (31.2%), followed by idiopathic dilated cardiomyopathy with 28
(30.1%) patients. There was no lost of follow-up for the main outcome,
with a mean duration of 1,0 (±0.6) year. Patients upgraded from a right
ventricular pacing (upgrade group) were 22 (23.7%), of those, 4
(18.2%) had previously an implantable cardioverter-defibrillator.
Baseline demographic characteristics of groups upgrade and de
novo are provided in Table 1.
Chagas disease cardiomyopathy was most prevalent in the upgraded
patients: 16 (72.7%) vs 13 (18.3%), p<0.001. The following
variables were well balanced between upgrade and de novo groups:
Atrial fibrillation 5 (22.7%) vs 15 (21.1%), p = 1.000; chronic kidney
disease 8 (36.4%) vs 17 (23.9%), p = 0.278; LVEF: 22.3% (±7.1) vs
24.4% (±7.6), p=0.249; NYHA class III-IV: 19 (86.4%) vs 57 (80.3%),
p=0.754, respectively. Cardiac resynchronization therapy with
defibrillator implantation (CRT-D) rates were: 14 (63.6%) in upgraded
group and 29 (40.8%) in de novo group, p = 0.086.
Medical treatment for heart failure with evidence-based medical
therapies were optimized in both groups: beta-blocker: 21 (95.5%) vs 65
(91.5%), p = 1.000; angiotensin-converting enzyme inhibitors or
angiotensin receptor blockers or angiotensin receptor neprilysin
inhibitor: 20 (90.9%) vs 61 (85.9%), p=0.725; and aldosterone receptor
antagonists: 18 (81.8%) vs 63 (88.7%), p=0.847; for upgrade andde novo group respectively.
Pairwise echocardiographic measurements (baseline and 6 months of
follow-up) were available in 78 (83.9%) patients. Both groups improved
the LVEF on the 6-month echocardiogram: 22.3% (± 7.1) to 27.1% (±
9.5), p < 0.001 and 24.4% (± 7.6) to 31.1% (±11.9), p
< 0.001, for upgrade and de novo , respectively, but
there was no difference of ΔLVEF improvement between groups, p = 0.246.
No patient underwent heart transplantation during the study period.
In the follow-up, overall mortality occurred in 28 (30.1%) patients,
with more frequent death in upgraded patients when compared to de
novo CRT implantation, 14 (63.6%) vs 14 (19.7%), p < 0.001
(log rank), figure 1. There were four in-hospital deaths, all of them
directly associated with the procedure and all belonging to the upgraded
group. In the univariate analysis, Chagas disease and upgraded therapy
were associated with overall mortality at follow-up, HR: 3.9, CI:
1.8-8,4, p = 0.001 and RR: 4.7, CI: 2.2-9.9, p < 0.001,
respectively. In the multivariate model including both variables, and
combined therapy with CRT-D, only upgraded therapy remained
independently associated with the outcome, adjusted HR: 2.9, CI:
1.2-7,1, p=0.019), Table 2.