Renal recovery and long-term survival following acute kidney injury after coronary artery surgery: a nationwide study

Background: Acute kidney injury (AKI) is a relatively common complication following CABG and is associated with adverse outcomes. Nonetheless, we hypothesized that the majority of patients make a good long-term recovery of their renal function. We studied the incidence and risk factors of AKI together with renal recovery and long-term survival in patients who developed AKI following CABG.

Methods: This nationwide study examined AKI among 1754 consecutive patients undergoing CABG in 2001-2013. AKI was defined according to the KDIGO criteria.

Results: Postoperatively 184 (11%) patients developed AKI; 121 (7%), 27 (2%), and 36 (2%) at stages 1, 2, and 3, respectively. AKI was an independent risk factor for chronic kidney disease (CKD) and AKI patients had worse post-operative outcomes. Lower pre-operative glomerular filtration rate, higher EuroSCORE and BMI, diabetes, reoperation, and units of red blood cells transfused were independent risk factors of AKI. At post-operative day 10, renal recovery rates, defined as serum creatinine ratio <1.25 of baseline, were 96 (95% CI 91-99%), 78 (95% CI 53-90%), and 94% (95% CI 77-98%) for AKI stages 1, 2, and 3, respectively. Long-term survival was predicted by AKI with 10-year survival of patients without AKI being 76% and those with AKI stages 1, 2, and 3 being 63%, 56%, and 49%, respectively (P < 0.001).

Conclusion: Depending on the severity of the initial AKI, 78-97% of patients made good recovery of their kidney function. However, AKI was significantly linked to progression to CKD and long-term survival remained markedly affected by the severity of the initial kidney injury.