Serum creatinine- and cystatin C-derived sarcopenia-related indices and the risk of all-cause mortality in patients undergoing transcatheter aortic valve implantation

Background Sarcopenia is increasingly recognized as an important predictor of adverse outcomes after transcatheter aortic valve implantation (TAVI). However, the prognostic relevance of sarcopenia-related indices derived from serum creatinine and cystatin C in patients undergoing TAVI has not been fully established. Methods This prospective study included 465 patients who underwent TAVI for symptomatic aortic stenosis. Associations between sarcopenia-related indices and all-cause mortality were assessed using Kaplan–Meier survival analysis, Cox proportional hazards models, and restricted cubic spline analysis (RCS). Predictive performance and incremental prognostic value were compared across indices using time-dependent receiver operating characteristic curves (ROC), the Harrell’s C-index, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Subgroup and sensitivity analyses were performed to examine the robustness of the findings. Results During a median follow-up of 2.8 years, 59 (12.7%) deaths occurred. In the fully adjusted Cox model, each 1-standard deviation increase in eGFRcys/eGFRcr (HR 0.29, 95% CI 0.11–0.75; p = 0.011) and Cr * eGFRcys (HR 0.30, 95% CI 0.14–0.64; p = 0.002) was associated with a lower risk of all-cause mortality. Time-dependent ROC indicated that Cr * eGFRcys had the most favorable predictive performance among the evaluated indices. Adding Cr * eGFRcys to the fully adjusted model increased the concordance index from 0.696 to 0.736 and significantly improved risk reclassification and discrimination (NRI: 0.437, 95% CI 0.171–0.704, p = 0.001; IDI: 0.026, 95% CI 0.004–0.048, p = 0.022). Findings from subgroup and sensitivity analyses were broadly consistent. Conclusion Among patients with symptomatic aortic stenosis undergoing TAVI, lower eGFRcys/eGFRcr and Cr * eGFRcys were associated with a higher risk of all-cause mortality after the procedure. Notably, Cr * eGFRcys showed stronger prognostic value and may provide additional prognostic information for risk stratification in patients undergoing TAVI.