Temporal Dynamics of the Association Between Acute Kidney Injury and Mortality After Transcatheter Aortic Valve Implantation: Insights from Time-Varying and Landmark Survival Analyses

Background: Acute kidney injury (AKI) is a frequent complication following transcatheter aortic valve implantation (TAVI) and has been linked to increased mortality. However, the temporal pattern of this association remains uncertain. This study aimed to evaluate the time-dependent impact of AKI on mortality after TAVI using advanced survival analyses. Methods: We retrospectively analyzed 381 consecutive patients who underwent transfemoral TAVI between December 2016 and October 2024 at two tertiary cardiovascular centers. AKI was defined according to the Acute Kidney Injury Network (AKIN) criteria. The primary outcome was all-cause mortality. Patients were categorized into AKI and non-AKI groups. Clinical outcomes, including 30-day, 1-year, and overall mortality, were evaluated. Results: Among 381 patients who underwent TAVI, 59 (15.5%) developed AKI according to the AKIN criteria. During a 33.9 months (18.0–59.2) median follow-up of overall mortality was significantly higher in the AKI group compared with those without AKI. In the multivariate Cox regression analysis, AKI was significantly associated with long-term mortality (HR: 2.07, 95% CI 1.32–3.25; p = 0.002). The time-varying hazard ratio curve demonstrated that the excess mortality risk associated with AKI was most pronounced in the early period and gradually declined thereafter. In time-interval–specific analyses, AKI was strongly associated with mortality within the first month (HR 6.30, 95% CI 3.03–13.08, p < 0.001) and remained significant up to 12 months (HR 2.18, 95% CI 1.32–3.59, p = 0.002). Beyond the first year, this association attenuated and lost statistical significance at 12–36 months (HR 0.90, p = 0.79), 36–60 months (HR 0.57, p = 0.24), and >60 months (HR 0.43, p = 0.13). Conclusions: AKI is an important predictor of early and mid-term mortality following TAVI, but its long-term prognostic impact is less pronounced. Preventive strategies and early management of AKI may improve outcomes in this high-risk population.