NT-proBNP and its correlation to left ventricular ejection fraction and heart failure – the DEMONSTRATE database

Background: Measurement of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and left ventricular ejection fraction (LVEF) are used in diagnosing heart failure (HF). The main aim was to explore the correlation between NT-proBNP and LVEF. Methods: Patient data for 14,962 patients were extracted from medical records and national registries and compiled in the Swedish DEMONSTRATE database. HF phenotype was categorised according to LVEF level: HF with reduced EF (≤40%, HFrEF); HF with mildly reduced EF (41–49%, HFmrEF); HF with preserved EF (≥50%, HFpEF). Spearman’s rank was employed for correlation analysis and ROC curves for discrimination and classification. Results: NT-proBNP correlated negatively with LVEF level (r=-0.40) and positively with age (r=0.49), creatinine (r=0.35), and cystatin C (r=0.53). Individuals with an HF diagnosis were more likely to have higher NT-proBNP levels compared to those without. The association between NT-proBNP and LVEF remained statistically significant (P<0.0001) also after adjusting for age and kidney function estimates (r=-0.20). NT-proBNP discriminated well between HFrEF (AUC=0.80) and HFpEF (AUC=0.78). In discriminating the presence of an HF diagnosis, NT-proBNP (AUC=0.81) outperformed LVEF (AUC=0.75). However, on an individual level the correlation between LVEF and NT-proBNP was modest. Conclusions: NT-proBNP levels increase when LVEF deteriorates but with large inter-individual differences. Further research is needed, but these findings show potential in optimising the use of LVEF with the aid of sequential analysis of NT-proBNP as a complementary diagnostic and prognostic tool to enhance assessment of cardiac function.