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.