Renal Failure After Cardiac Operations: Not All Acute Kidney Injury Is the Same

Background The Society of Thoracic Surgeons (STS) database does not distinguish between a decline in creatinine clearance vs new hemodialysis (HD) when qualifying acute renal failure (ARF) after a cardiac operation. We hypothesized that patients requiring HD experience significantly greater postoperative morbidity and death. Methods We included all patients who underwent STS index cardiac operations at our institution from 2008 to March 2015 and did not have preexisting renal failure (creatinine >4.0 mg/dL or preoperative HD). We identified patients meeting STS criteria for ARF: threefold rise in serum creatinine, creatinine exceeding 4.0 mg/dL (non-HD ARF) with minimum rise of 0.5 mg/dL, or HD (ARF-HD). After propensity matching non-HD ARF and ARF-HD groups across 14 variables (including baseline glomerular filtration rate), we compared incidences of our primary outcome, death, and secondary outcomes, intensive care unit (ICU) and hospital length of stay (LOS), and discharge to a location other than home. Results Among 4,154 study patients, we identified 113 (2.7%) that experienced new-onset non-HD ARF (n = 57) or ARF-HD (n = 56) postoperatively. Propensity matching resulted in 51 well-matched pairs who experienced non-HD ARF or ARF-HD (all p > 0.10). Patients requiring HD suffered significantly greater operative mortality (67% vs 22%, p < 0.01), longer ICU LOS (326 vs 176 hours, p < 0.01), and greater postoperative hospital LOS (34 vs 17 days, p < 0.01). ARF-HD patients also demonstrated a trend toward higher rates of discharge to a location other than home (71% vs 45%, p = 0.08). Conclusions After cardiac operations, patients who experienced ARF-HD experienced triple the mortality and double the ICU and postoperative hospital LOS compared with patients who experienced non-HD ARF.