Abstract 14023: Insulin-like Growth Factor-binding Protein 7 as a Biomarker of Diastolic Dysfunction and Functional Capacity: Results From the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Heart Failure With Preserved Ejection Fraction (RELAX) Trial

Abstract

Introduction: Insulin-like growth factor-binding protein 7 (IGFBP7) was previously found to be associated with diastolic function in heart failure (HF) with reduced ejection fraction (EF), but it is unclear whether such associations exist in HF with preserved EF (HFpEF), where diastolic function is of pivotal importance. Hypotheses: Baseline (BL) and change (Δ) in IGFBP7 will be significantly associated and correlated with BL and Δ in diastolic indices as well as peak oxygen consumption (VO2 max ) in patients with HFpEF. IGFBP7 will decrease with sildenafil therapy. Methods: At BL and 6 months (6M), IGFBP7, imaging studies, and VO2 max were obtained and compared in 160 HFpEF patients randomized to sildenafil or placebo. Results: Patients with supramedian BL IGFBP7 concentrations (>219 ng/mL) were more likely to be older, to have more congestion and worse renal function, and to have elevated concentrations of several emerging or established HF biomarkers including amino-terminal pro-B-type natriuretic peptide, cystatin C, and highly sensitive troponin (all P<0.05). Higher BL IGFBP7 was correlated with indices of worse diastolic function, including higher E velocity (ρ=0.395, P<0.001), E/e’ (ρ=0.398, P<0.001), left atrial volume index (ρ=0.386, P<0.001), right ventricular systolic pressure (RVSP; ρ=0.413, P<0.001), and transmitral E/A (ρ=0.258, P=0.006). IGFBP7 was also inversely correlated with aortic distensability (ρ= -0.301, P=0.02). There was no association or correlation with measures of systolic function. Notably, in analyses adjusted for respective baseline variables, ΔIGFBP7 was significantly correlated with Δ in E (ρ=0.114), E/A (ρ=0.225), E/e’ (ρ=0.174), and RVSP (ρ=0.282; all P<0.03). Elevated BL IGFBP7 was associated with lower BL VO2 max (13.2 versus 11.1 mL/min/kg; P<0.001) and ΔIGFBP7 was inversely correlated with ΔVO2 max (ρ=-0.19, P=0.01). Subjects receiving sildenafil had a decrease in IGFBP7 over 6M in contrast to placebo-treated patients (median ΔIGFBP7 -1.5 versus +13.6 ng/mL; P<0.001). Conclusions: In patients with HFpEF, concentrations of IGFBP7 have unique relationships with measures of diastolic dysfunction and VO2 max . Rise in IGFBP7 may reflect worsening diastology and deteriorating VO2 max .