Prediction of Acute Kidney Injury after TAVI by New Biomarkers

Objectives: Acute kidney injury (AKI) is a common complication after transcatheter aortic valve implantation (TAVI) and is associated with increased morbidity and mortality. Routinely used biomarkers such as creatinine show a diagnostic gap in the first hours after kidney injury. The aim of the present study was to examine the diagnostic value of cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) after TAVI.

Methods: This was a prospective study of 483 patients undergoing elective TAVI (via either transfemoral or transapical approach) between June 2011 and May 2015. Assessment of blood biomarkers (creatinine, cystatin C, NGAL) was performed before and 4, 24, 48, and 72 hour after TAVI. Patients were followed up for 12 months after TAVI. The primary outcome was the occurrence of post-procedural AKI as defined by the Valve Academic Research Consortium-2 (VARC-2) criteria. The secondary outcome was death within 30 days or 1 year.

Results: A total of 110/483 (22.8%) patients developed AKI. Of the 110 patients with AKI, 52 (47.3%) developed AKI stage 1, 27 (24.5%) stage 2, and 31(28.2%) stage 3. Patients with AKI had a 7.1-fold higher risk of 30-day mortality and a 3.3-fold increased risk of 1-year mortality, adjusted for STS predicted risk of mortality, than patients without AKI. NGAL levels were significantly higher starting 4 hours after TAVI and remained increased at 72h ([Table 1]). Cystatin C levels were significantly higher in patients with AKI after TAVI at baseline and follow-up ([Table 1]). Cystatin C was additionally better in distinguishing between AKI stages compared with NGAL.

Conclusions: AKI increases short- and long-term mortality in TAVI patients. Cystatin C and NGAL are valuable biomarkers for preoperative risk assessment and early detection of AKI. Earlier diagnosis and hence treatment might improve the overall patient outcome after TAVI.

Table 1

Marker	pre-op	4 hours	24 hours	48 hours	72 hours
NGAL (mg/dl)
no AKI, mean ± SD	151 ± 74	150 ± 85	170 ± 95	176 ± 95	176 ± 85
AKI, mean ± SD	172 ± 81	188 ± 110	216 ± 125	250 ± 130	230 ± 99
p-value	0.15	.0001	<.0001	<.0001	<.0001
Cystatin C (mg/L)
no AKI, mean ± SD	1.7 ± 0.6	1.6 ± 0.6	1.6 ± 0.6	1.7 ± 0.6	1.7 ± 0.6
AKI, mean ± SD	1.8 ± 0.6	1.7 ± 0.6	1.8 ± 0.6	2.0 ± 0.7	2.2 ± 0.7
p-value	<.0001	0.03	<.0001	<.0001	<.0001