Increased risk of acute kidney injury in patients undergoing tricuspid valve surgery

We aimed to determine which patients undergoing tricuspid valve (TV) surgery are at increased risk for acute kidney injury (AKI). We reviewed 951 patients [mean age 67 +/- 13 years, 573 (60%) female] having TV surgery between 2000 and 2007. Analysis focused on clinical outcome; AKI was defined by the consensus RIFLE criteria (risk, injury, failure). Surgical procedures included isolated TV surgery in 224 (24%) and TV surgery in conjunction with another cardiac operation in 727 (76%) patients. TV surgery involved redo surgery in 395 (42%). The incidence of postoperative AKI was 30% (n = 285), and 75 (7.9%) of these patients required renal replacement therapy. AKI stratified by increased RIFLE class was associated with worse postoperative outcomes (prolonged intubation, length of hospital stay and mortality; P < 0.001 for each variable). For patients with AKI, odds ratio for mortality was 4.2 [95% confidence interval (CI) 3.2-5.4, P < 0.001; area under receiver operating curves 0.85 (95% CI 0.80-0.91)], and 2.3 (95% CI 1.9-2.9, P < 0.001) for prolonged intubation for each increase in RIFLE class. Independent risk factors for AKI were older age, male gender, previous surgery, preoperative anaemia, length of cardiopulmonary bypass and TV replacement. Importantly, preoperative creatinine and pulmonary artery pressure were not independently associated with AKI. TV surgery carries a high incidence of postoperative AKI that is associated with adverse outcome. The use of the RIFLE criteria allows comparison with prior studies and is an important predictor of early mortality. The estimation of patient risk for AKI should be based on multivariable prediction.