# Serum cystatin-C and all-cause mortality in patients with hypertrophic cardiomyopathy: a retrospective cohort study

## TL;DR

Higher levels of serum cystatin-C are linked to increased risk of death in patients with hypertrophic cardiomyopathy, even after accounting for other factors.

## Contribution

This study identifies serum cystatin-C as an independent predictor of all-cause mortality in HCM patients, outperforming traditional renal markers.

## Key findings

- Higher cystatin-C levels were associated with a 2.11-fold increased risk of all-cause mortality in HCM patients.
- Cystatin-C showed a stable predictive ability (AUC between 0.70 and 0.80) over time, outperforming eGFR and creatinine.
- Subgroup analyses confirmed the robustness of cystatin-C as a mortality predictor across different demographics and kidney function levels.

## Abstract

Numerous studies across various populations have revealed that elevated cystatin-C levels are associated with an excessive risk of mortality. However, the prognostic value of cystatin-C remains unidentified in hypertrophic cardiomyopathy (HCM) patients. The objective of this study was to investigate whether serum cystatin-C could predict all-cause mortality independently in HCM patients.

Data from 456 HCM patients treated at West China Hospital were collected and stratified into two groups based on the median baseline serum cystatin-C level. All-cause mortality was the primary outcome. Cox regression models were used to analyze the association between cystatin-C levels and mortality risk.

A total of 90 deaths were recorded over a median follow-up period of 4.67 years. Patients with higher cystatin-C levels had an increased risk of all-cause mortality (adjusted hazard ratio (HR): 2.11, 95% CI [1.30–3.42], p = 0.003) compared to those with lower levels. Time-dependent area under the curves (AUC) of cystatin-C in different time points, ranging from initial measurement to follow-up, showed a relatively stable fluctuation between 0.70 and 0.80. In comparison, the commonly used renal function markers, estimated glomerular filtration rate (eGFR) and serum creatinine, yielded lower AUC values. Restricted cubic spline curves showed that with median value of cystatin-C (1.01 mg/L) as reference, there was a gradual rise in risk of all-cause mortality with cystatin-C increasing. Subgroup analyses in female, in the patients ≥ 58 years old, and in the patients with eGFR ≥ 60 mL/min/1.73 m2 consistently confirmed robustness of the main findings.

Elevated serum cystatin-C levels are associated with a higher risk of all-cause mortality in HCM patients, providing valuable prognostic information beyond traditional renal function markers such as eGFR and serum creatinine.