Page 137 - Biomarkers for risk stratification and guidance in heart failure

Chapter 6
In contrast, change in NT-proBNP was an important predictor for outcome (HR for increase in NT-proBNP concentration versus decrease 5.17, 95% CI 3.06-8.75, P <0.001).
Although change in renal function had no prognostic impact, baseline eGFR was clearly related to outcome (HR for the combined endpoint per mL/min/1.73m2 0.97, 95% CI 0.96-0.98, P <0.001). Likewise, urea and NT-proBNP concentration at hospital discharge were related to the combined endpoint.
Impact of severe worsening and outspoken improvement in renal function
In total 53 patients (19.6%) experienced severe worsening in renal function (WRF), defined as a decrease in eGFR > 20%. Forty-three patients (15.9%) experienced an outspoken improvement in renal function (increase in eGFR >20%) and in 175 patients (64.6%) change in eGFR was less than 20%. After 1 year follow-up 21 patients (39.6%) with severe WRF reached the combined endpoint, versus 18 patients (41.9% ) with an increase >20%, versus 56 patients (32%) with change in eGFR less than 20% (figure 2a). This difference was not statistically significant (log-rank p=0.276).
Mortality was the same among the 3 eGFR-groups (figure 2b). Interestingly, change in NT-proBNP concentration between hospital discharge and 1 month follow-up visit was significantly different between patients with a decrease >20%, patients with a change less than 20%, and patients with an increase in eGFR >20% (median change + 9.8% (IQR -40.0% – 69.1%) versus 0.0% (IQR -30.4%-35.0%), versus 32.7 % (-20.0%-94.4%) respectively, p=0.028.
When dividing patients in groups based on 20% change in eGFR and increase versus decrease in NT-proBNP, prognosis was mainly dependent on change in NT- proBNP (supplemental figure 1a and b.).
Multivariate analysis
Multivariate analysis of baseline characteristics identified a previous episode of heart failure and myocardial infarction as independent risk factors for the combined endpoint (table 3.). After addition of eGFR, Urea, NT-proBNP and change in both eGFR and NT-proBNP the definite cardiorenal model was formed. In this model, change in eGFR had no prognostic power, whether change in NT- proBNP remained an important independent prognostic factor as depicted in table 3.
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