Aptamer Proteomics for Biomarker Discovery in Heart Failure With Preserved Ejection Fraction: The PARAGON-HF Proteomic Substudy

Abstract

Background: Prognostic markers and biological pathways linked to detrimental clinical outcomes in heart failure with preserved ejection fraction (HFpEF) remain incompletely defined.

Methods and results: We measured serum levels of 4123 unique proteins in 1117 patients with HFpEF enrolled in the PARAGON-HF (Efficacy and Safety of LCZ696 Compared to Valsartan, on Morbidity and Mortality in Heart Failure Patients With Preserved Ejection Fraction) trial using a modified aptamer proteomic assay. Baseline circulating protein concentrations significantly associated with the primary end point and the timing and occurrence of total heart failure hospitalization and cardiovascular death were identified by recurrent events regression, accounting for multiple testing, adjusted for age, sex, treatment, and anticoagulant use, and compared with published analyses in 2515 patients with heart failure with reduced ejection fraction from the PARADIGM-HF (Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure) and ATMOSPHERE (Efficacy and Safety of Aliskiren and Aliskiren/Enalapril Combination on Morbidity-Mortality in Patients With Chronic Heart Failure) clinical trials. We identified 288 proteins that were robustly associated with the risk of heart failure hospitalization and cardiovascular death in patients with HFpEF. The baseline proteins most strongly related to outcomes included B2M (β-2 microglobulin), TIMP1 (tissue inhibitor of matrix metalloproteinase 1), SERPINA4 (serpin family A member 4), and SVEP1 (sushi, von Willebrand factor type A, EGF, and pentraxin domain containing 1). Overall, the protein-outcome associations in patients with HFpEF did not markedly differ as compared with patients with heart failure with reduced ejection fraction. A proteomic risk score derived in patients with HFpEF was not superior to a previous proteomic score derived in heart failure with reduced ejection fraction nor to clinical risk factors, NT-proBNP (N-terminal pro-B-type natriuretic peptide), or high-sensitivity cardiac troponin.

Conclusions: Numerous serum proteins linked to metabolic, coagulation, and extracellular matrix regulatory pathways were associated with worse HFpEF prognosis in the PARAGON-HF proteomic substudy. Our results demonstrate substantial similarities among serum proteomic risk markers for heart failure hospitalization and cardiovascular death when comparing clinical trial participants with heart failure across the ejection fraction spectrum.

Registration: URL: https://www.clinicaltrials.gov; Unique Identifiers: NCT01920711, NCT01035255, NCT00853658.

Keywords: HFpEF; HFrEF; cardiovascular; ejection fraction; heart failure; proteomics.

Figure 1. Study design.

ATMOSPHERE indicates Efficacy and Safety of Aliskiren and Aliskiren/Enalapril Combination on Morbidity–Mortality in Patients With Chronic Heart Failure; CV, cardiovascular; HFH, heart failure hospitalization; HFpEF, heart failure with preserved ejection fraction; HFrEF, heart failure with reduced ejection fraction; LASSO, least absolute shrinkage and selection operator; PARADIGM‐HF, Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure; pEF, preserved ejection fraction; rEF, reduced ejection fraction; and SOMAmer, slow off‐rate modified aptamer.

Figure 2. Serum proteins associated with risk of total heart failure hospitalization and cardiovascular death.

Circulating proteins significantly associated with the primary end point, total heart failure hospitalization and cardiovascular death. Associations were considered significant (red label) if the P value was lower than the false discovery rate threshold of 0.05 both with and without inclusion of outlier values >5 SDs from the mean. (A) Minimally adjusted model includes age, sex, treatment, and anticoagulant use. (B) Risk factor adjusted model is further adjusted for ten clinical risk factors: diabetes, smoking, history of angiotensin‐converting enzyme intolerance, New York Heart Association functional class, systolic blood pressure, body mass index, left ventricular ejection fraction, total cholesterol, estimated glomerular filtration rate, and log‐transformed N‐terminal pro‐B‐type natriuretic peptide.

Figure 3. Associations between protein levels and total heart failure hospitalization and cardiovascular death in HFpEF vs HFrEF.

Only 3 proteins (red dots) demonstrated different associations with outcomes with HFrEF vs HFpEF at a significance level of Benjamini–Hochberg FDR <0.05. Light gray dots indicate proteins with no evidence of differential association between ejection fraction subtypes. Dark gray dots indicate proteins for which the difference in association was statistically significant by nominal P value <0.05 but not FDR <0.05. APOE indicates apolipoprotein E; FDR, false discovery rate; HFpEF, heart failure with preserved ejection fraction; HFrEF, heart failure with reduced ejection fraction; rEF, reduced ejection fraction; and VWF, von Willebrand factor.

Figure 4. Risk discrimination of clinical, biomarker, and proteomic risk scores for time to first heart failure hospitalization or cardiovascular death in PARAGON‐HF.

Risk discrimination was evaluated in PARAGON‐HF. The PARAGON‐HF HFpEF proteomic risk score was derived and evaluated in PARAGON‐HF using a leave‐one‐out cross‐validation method to avoid overfitting. P‐values evaluate the null hypothesis that each C‐statistic is significantly different from the C‐statistic for the PARAGON‐HF HFpEF proteomic score. ATMOSPHERE indicates Efficacy and Safety of Aliskiren and Aliskiren/Enalapril Combination on Morbidity–Mortality in Patients With Chronic Heart Failure; HFpEF, heart failure with preserved ejection fraction; HFrEF, heart failure with reduced ejection fraction; MAGGIC, Meta‐Analysis Global Group in Chronic Heart Failure; NT‐proBNP, N‐terminal pro‐B‐type natriuretic peptide; and PARAGON‐HF, Efficacy and Safety of LCZ696 Compared to Valsartan, on Morbidity and Mortality in Heart Failure Patients With Preserved Ejection Fraction.