Renal impairment and transapical aortic valve implantation: impact of contrast medium dose on kidney function and survival.

OBJECTIVE Patients undergoing transapical aortic valve implantation (TA-AVI) are usually over 80 years old and have a high prevalence of chronic kidney disease. However, transcatheter valve therapies require the use of contrast injections with the risk of nephrotoxicity. The aim of this study was to evaluate post-operative kidney function and survival in patients with pre-existing renal impairment with regard to the amount of contrast media used during TA-AVI. METHODS From January 2008 to March 2011, 50 patients (52% females, mean age 80.7 ± 5.3 years) with a serum creatinine level of >1.3 mg/dl were investigated. Patients receiving a dose of <100 ml of a contrast agent (low-dose group, n = 24) were separated from those who received >100 ml of a contrast agent (high-dose group, n = 26). An acute contrast-induced nephropathy (CIN) was defined as a serum creatinine increase of 0.5 mg/dl or by >25% of a baseline value within 48 h from contrast medium administration. Patients in both groups had similar characteristics in terms of age, sex, body mass index and comorbidities. RESULTS The median pre-contrast creatinine was 1.67 (1.37-1.83) mg/dl in the low-dose group and 1.51 (1.26-1.98) mg/dl in the high-dose group (P = 0.76). The post-contrast creatinine at 48 h was 1.53 (1.33-2.05) and 2.29 (1.67-2.86) mg/dl in the groups receiving low- and high-dose contrast agents, respectively (P = 0.007). CIN occurred in 41.7% (n = 10) of patients in the low-dose contrast group and in 69.2% (n = 18) in the high-dose contrast group (P = 0.046). Haemodialysis is necessary for 16.7% of the low-dose group and 38.5% of the high-dose group (P = 0.12). Trends towards longer intensive care unit and hospital stay were seen in patients with an extensive use of contrast media [4.3 (2.5-6.5) vs. 5 (3-7.8) days and 12 (9-14.3) vs. 13 (9-18) days, P = 0.091 vs. P = 0.546, respectively]. Regarding death, 3-month and 3-year mortality were significantly higher in the high-dose group (8.3 vs. 30.8%, P = 0.036 and 25 vs. 61.5%, P = 0.004, respectively). CONCLUSIONS Our results indicate a possible association between higher CIN and mortality rate and the extensive use of contrast media during TA-AVI among high-risk patients with pre-existing renal impairment.