Renin-angiotensin-aldosterone system Inhibitors are associated with Reno-protective Effects in Aging Patients Undergoing Transcatheter Aortic Valve Replacement

Background:
Renin-angiotensin-aldosterone system inhibitors (RAASi) use is common in aortic stenosis (AS) patients. We aimed to investigate the effects of RAASi on post-operative acute kidney injury (AKI) in ageing patients undergoing transcatheter aortic valve replacement (TAVR).

Methods:
Patients who had TAVR at a single center were retrospectively reviewed from a prospectively maintained database. AKI was defined using the AKI network classification. Patients were divided into two groups based on their history of use of RAASi. Baseline clinical characteristics were compared. Outcomes investigated were the development of post-operative AKI and improvement in baseline glomerular filtration rate (GFR) (≥ 10% increase). Multivariable logistic regression models were used to identify independent predictors of post-operative AKI.

Results:
Six-hundred and two patients with mean ± SD age of 84 ± 8 years, were reviewed. Incidence of post-op AKI was 16% (n=98). RAASi were used by 146 patients. RAASi pateints were younger (83 vs. 84 yrs.; p = 0.032), had a higher GFR at baseline (60 vs. 54 ml/min; p= 0.017), incidence of hypertension (93% vs. 84%; p=0.003), diuretic use (44% vs. 29%; p=0.0009), diabetes mellitus (44% vs. 35%; p=0.035), past history of coronary artery bypass graft surgery (27% vs. 18%; p=0.016) than non RAASi patients. All other baseline characteristics including amount of contrast volume used were similar. Post-TAVR, a ≥ 10% increase in baseline GFR was noted in 40% of RAASi users vs. 29% in the non-RAASi user group (p=0.001). Use of a RAASi was independently protective against the post-TAVR AKI (OR: 1.95, 95% C.I:1.04,3.64, p = 0.0035). Other predictors of AKI were African American (AA) race (AA vs Caucasian : OR: 3.69, 95% C.I:1.97,6.92, p <0.001), high STS risk score (OR: 1.03, 95% C.I:1.00, 1.07, p =0.025 ), history of chronic kidney disease (OR: 1.77, 95% C.I:1.02,3.07,p = 0.042) and non-trans femoral approach (OR: 2.72, 95% C.I:1.64,4.51, p = 0.0001).

Conclusions:
Our study showed that, ageing patients undergoing TAVR for the treatment of AS, the use of RAASi may have significant reno-protective effects. Larger scale clinical trials are required to ascertain the determinants of renal outcome in such patients.