Outcomes of patients with acute kidney injury and renal artery stenosis post TAVR: Insights from the RASAKI study.

Background
Acute kidney injury post transcatheter aortic valve replacement (TAVR) predicts poor outcomes. Atherosclerotic Renal artery stenosis (RAS) is potentially an overlooked predictor of worse outcomes. We aim to evaluate the outcomes following TAVR in patients developing AKI and shed light on RAS as a potential independent predictor of poor outcomes.

Methods
302 patients underwent TAVR between 2011 and 2017 were reviewed. 6 patients with end stage renal disease were excluded. We used propensity matching analysis including age, sex, BMI, contrast volume, GFR, and comorbidities to select match pairs for analysis. AKI was defined as 0.3 mg/dl increase in serum creatinine over baseline within 48 hours or ≥1.5 times within 7 days post procedure. CT angiograms of the abdomen were used to measure the minimal luminal diameter (MLD) and luminal area at the ostium and at the site of maximum stenosis in the renal arteries, proximal to any major branch. An area stenosis of 70% or more was considered significant.

Results
We obtained 43 matched pairs for analysis of AKI and non-AKI counterparts. Patients who developed AKI post procedure had significantly higher 30 days mortality rates vs controls (20.93% vs 4.65%, p=0.0246). Both cohorts had similar length of hospital stay (Average 5.0 days in AKI vs 4.2 days in control, p=0.3056) and similar 30 days readmission rates (25.5% in AKI vs 27.9% in controls, p=0.8025). Prevalence of significant RAS was much higher in patients who developed AKI vs non-AKI group (46.51% vs 18.60%, p= 0.006). RAS presence in Non-AKI patients was associated with significantly higher readmission rates (58.33% vs 16.12%, p=0.0062). Compared to non-RAS patients, RAS patients had significant higher 30-days readmission rates (44.11% vs 15.38%, p=0.0034) and significantly higher mortality rates (64.70% vs 42.30%, p=0.0434).

Conclusions
Acute kidney injury post TAVR is associated with higher 30-day mortality rates and higher readmission rates. The presence of angiographically significant renal artery stenosis is an independent predictor of higher rates of hospital readmission and mortality in patients undergoing TAVR procedure.