Association of cystatin C with heart failure with preserved ejection fraction in elderly hypertensive patients: potential role of altered collagen metabolism

Objectives: Cystatin C has been shown to be associated with heart failure with preserved ejection fraction (HFPEF). In addition, myocardial fibrosis has been involved in diastolic dysfunction in HFPEF. Therefore, we hypothesized that increased cystatin C levels may be associated with altered collagen metabolism, contributing to diastolic dysfunction in patients with HFPEF. Methods: One hundred and forty-one elderly hypertensive patients with HFPEF were included. Cardiac morphology and function was assessed by echocardiography. Circulating levels of cystatin C, biomarkers of collagen type I synthesis (carboxy-terminal propeptide of procollagen type I) and degradation [matrix metalloproteinase-1 (MMP-1) and its inhibitor TIMP-1] and osteopontin were analyzed by ELISA. Twenty elderly sex-matched patients with no identifiable cardiac disease were used as controls. In-vitro studies were performed in human cardiac fibroblasts. Results: Compared with controls, cystatin C was increased (P < 0.001) in patients with HFPEF, even in those with a normal estimated glomerular filtration rate (eGFR; P < 0.05). Cystatin C was directly correlated with the estimated pulmonary capillary wedge pressure (P < 0.01), TIMP-1 and osteopontin (P < 0.001) and inversely correlated with MMP-1: TIMP-1 (P < 0.01), but not with carboxy-terminal propeptide of procollagen type I or MMP-1 in all patients with HFPEF. These associations were independent of eGFR. In vitro, osteopontin (P < 0.01) and TIMP-1 (P < 0.001) increased in the supernatant of cardiac fibroblasts exposed to cystatin C. Conclusion: In patients with HFPEF of hypertensive origin, cystatin C is increased and associated with diastolic dysfunction and alterations in collagen metabolism independently of eGFR. An excess of cystatin C might contribute to diastolic dysfunction in HFPEF by facilitating myocardial fibrosis via accumulation of osteopontin and TIMP-1.