Effect of Varying Definitions of Contrast-Induced Acute Kidney Injury and Left Ventricular Ejection Fraction on One-Year Mortality in Patients Having Transcatheter Aortic Valve Implantation

Abstract

The prognostic relevance of direct contrast toxicity in patients treated with transcatheter aortic valve implantation (TAVI) remains unclear because of the confounding hemodynamic effect of acute left ventricular ejection fraction (LVEF) impairment on kidney function estimation. In addition, different definitions of contrast-induced acute kidney injury (CI-AKI) may have different prognostic stratification potential. In the present study, 240 consecutive patients who underwent TAVI were prospectively enrolled. CI-AKI was defined (1) according to the postprocedural creatinine increase of ≥0.3mg/dl or (2) according to the postprocedural decrease of the creatinine clearance of at least 25%. Primary end point of the study was 1-year all-cause mortality. At a mean follow-up of 1.7 ± 1.4years, all-cause mortality was significantly higher in the CI-AKI patient group, using both CI-AKI definitions (for (1) and (2) p= 0.025 and p <0.001, respectively). In the Cox regression multivariate analysis, CI-AKI was an independent predictor of mortality (hazard ratio 2.244, 95% CI 1.064 to 4.732, p= 0.034), along with LVEF (hazard ratio 0.974, 95% CI 0.946 to 0.993, p=0.012). Although LVEF and creatinine values at admission were not significantly associated with CI-AKI, their interaction term significantly defined CI-AKI (p= 0.033). The prognostic accuracy of definition (2) was higher (area under the curve 0.704; p <0.001) as with respect to definition (1) (area under the curve 0.602; p= 0.037) for the primary end point of 1-year mortality. In conclusion, in a nonselected patient population who underwent TAVI, CI-AKI was confirmed as an independent predictor of clinical outcome. Only the interaction between LVEF and baseline creatinine values was found to determine CI-AKI. Definition of CI-AKI based to creatinine clearance values had higher prognostic accuracyin comparison with the CI-AKI definition based on creatinine absolute value changes.