Secondary end-point results
Table 2 shows the echocardiographic parameters at baseline, 6 months and the changes during the 6 months of follow-up. Mean reduction in LVESV (reverse remodeling) was 25.3% and mean increase in LVEF was 9.4 absolute points. The subjects with device programmed using anatomical approach had a non-significant higher reverse remodeling than those using the electrical approach (32.2%±25.2% vs. 19.4%±36.2%, p= 0.12) and a significant higher increase in LVEF (14.2%±11.9% vs 8%±12.6%, p=0.04). Finally, non-ischemic patients had a significant higher reverse remodeling in comparison to ischemic patients (32.6±34.1% vs 10.5±28.4%, p=0.04) and a significant higher increase in LVEF (12.5%±12.1% vs 6.4%±12.8%, p=0.04).
The percentage of super-responder (mean absolute LVEF increase of >14% at 6 months post-implant compared to no pacing at baseline) was 35.1%. It was observed a non-significant increase in percentage of super-responders in patients with device programmed using anatomical vs electric approach (48.0% vs 27.8%, p=0.08) and in non-ischemic vs ischemic patients (39.1% vs 27.3%, p=0.26)
The New York Heart Association (NYHA) class changes at 6 months are shown in Table 3. Before implant 35% of patients were on class III, whereas at 6 months only 12% of patients were on class III and most remained in class I or II. At 6 months, 8% and 14% of patients programmed using the anatomical and electrical approach, respectively, remained in class III.
We also evaluated the percentage of responders using the clinical composite score. A subject was defined as non-responder if suffered any of the following: death, heart failure hospitalization or worsening of the NYHA class. At 6 months of follow-up only 5% of patients were considered as clinical non-responders.
All 105 patients that consented to participate in the study were included for the evaluation of clinical outcomes. Mortality was 1.9% and 11.4% of patients were admitted to the hospital for any reason.
Finally, we compared the QUARTO III with QUARTO II clinical outcomes to evaluate potential benefits of MPP over conventional biventricular pacing. There were significant differences in baseline characteristics between both cohorts (Table 4). Statistically significant differences were evident for baseline age, NYHA class, LVEF and prevalence of hypertension and diabetes mellitus. The response rate in Quarto II was 61.8%, that was similar to the response rate found in Quarto III (p=0.684). Incidence of the combined endpoint of mortality and or all-cause hospitalizations was lower in Quarto III in comparison to QUARTO II (12.4% vs 25.4%, p=0.004, figure 2). A multivariate analysis was performed using a Cox’s proportional hazard regression model to evaluate the benefits in clinical outcomes observed in the MPP cohort adjusting the demographic and baseline covariates. Patients included in QUARTO II had a significant higher risk of mortality and or all cause hospitalizations (HR: 1.99 (95% CI, 1.69-2.29), p=0.03).