Introduction: Transcatheter aortic valve implantation (TAVI) theoretically increases renal blood flow through increasing cardiac output by relieving aortic valvular obstruction of blood flow from left ventricle, resulting in a renal functional recovery in patients with severe aortic valve stenosis (AS). However, procedural steps of TAVI including contrast use potentially damages renal medulla and may deteriorate renal function.
Purpose: The aim of this study was to investigate renal functional change and clarify preoperative predictors for renal functional improvement after TAVI in chronic kidney disease (CKD) patients with severe AS.
Methods: A total of 88 consecutive severe AS patients with CKD (grade >3) who underwent TAVI from 2015 to 2018 was enrolled in this observational study. They were divided into two groups depending on their renal functional improvement after TAVI that was defined as more than 10% increase in estimated glomerular filtration rate (eGFR) at discharge from their preoperative level.
Results: Among the whole candidates, 49 patients (55.7%) were improved their renal function. Patients with the lowest preoperative eGFR achieved the highest increase in eGFR after TAVI (CKD grade >4: +22.7 ± 23.7%, Figure). Patients in the Improved group had lower hemoglobin level, higher mean transaortic pressure gradient (TAPG), and higher aortic valve gradient before TAVI, compared to those in the Non-improved group. However, contrast volume during the procedure was not significantly different between the groups. Multivariate logistic regression analysis revealed that high mean TAPG and low left ventricular ejection fraction (LVEF) before TAVI were independent predictors for the improvement of renal function (odds ratio (OR): 1.04, 95% confidence interval (CI): 1.00-1.08; OR: 0.94, 95%CI: 0.89-0.99, respectively), even after the adjustment of baseline eGFR level and hemoglobin level that were statistically significant on univariate logistic regression analysis. Receiver Operating Characteristic (ROC) curve showed the cut-off level of preoperative mean TAPG in renal functional improvement after TAVI as 47.0 mmHg (Sensitivity: 47.9 %, Specificity: 79.5 %, area under the curve: 0.62).
Conclusions: Preoperative high mean TAPG may predict renal functional improvement after TAVI in patients with deteriorated renal function. This non-invasive predictor may help clinicians to consider to perform TAVI in a challenging case with severe CKD.