Incidence and Predictors of Acute Kidney Injury Following Tricuspid Valve Surgery: The Prognostic Value of Right Ventricular Length–Force Relationship

Background/Objectives: Tricuspid valve surgery carries a high risk of postoperative acute kidney injury (AKI) due to pre-existing right ventricular dysfunction and congestive end-organ remodeling. We aimed to evaluate the incidence and predictors of postoperative AKI, with particular focus on the prognostic value of the TAPSE/sPAP index. Methods: This retrospective, single-center study evaluated adult patients who underwent tricuspid valve surgery (isolated/concomitant) between 2010 and 2025. The primary outcome was postoperative AKI of any stage, defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Predictors were identified using a pre-specified multivariable logistic regression model including baseline estimated glomerular filtration rate (eGFR), cardiopulmonary bypass time, and EuroSCORE II; TAPSE/sPAP associations with severe renal outcomes were assessed univariably and presented as exploratory. Results: Of 80 patients, postoperative AKI occurred in 32 (40.0%), with 16 (20.0%) requiring renal replacement therapy. The pre-specified multivariable model discriminated any-stage AKI (AUC 0.86, 95% CI 0.77–0.94). Lower baseline eGFR (adjusted OR 1.82 per 10 mL/min/1.73 m2 decrease, p < 0.001) and higher EuroSCORE II (adjusted OR 1.53 per point, p = 0.03) were independent predictors. The TAPSE/sPAP index was not associated with any-stage AKI (p = 0.42), but lower values predicted advanced renal outcomes, including KDIGO stage ≥ 2 AKI (OR 2.11, p = 0.03) and the requirement for renal replacement therapy (OR 2.71, p = 0.01). Outcomes did not differ between isolated (n =14) and combined procedures (n = 66; AKI 35.7% vs. 40.9%, p = 0.77). Conclusions: Lower preoperative eGFR and higher EuroSCORE II independently predict any-stage postoperative AKI. In univariable analysis, the TAPSE/sPAP index identified the subgroup with severe renal outcomes; this exploratory finding requires prospective validation. Whether perioperative renal protection depends on addressing right-sided filling pressures rather than augmenting forward flow alone requires prospective testing.