P10
Risk factors associated with the development of Acute Kidney Injury following elective
coronary artery bypass grafting (CABG): A single centre retrospective observational study
Joe Wang1, Nida Ahmed2, Natalie Alexander3, Ranjit Deshpande3, Satish Jayawardene1, Alex
Isted2 & Chris Jones1
Department of Renal Medicine, King’s College Hospital
King’s College London School of Medicine
3
Department of Cardiothoracic Surgery, King’s College Hospital
1
2
Introduction: Acute Kidney Injury (AKI) has been shown to affect up to 20% of all hospitalised
patients (1). In the UK, over 28,000 Coronary Artery Bypass Graft (CABG) operations are carried out
each year under the NHS (2) and the incidence of AKI in those undergoing isolated CABG is of the
order of 2-5% (3). We undertook a study to determine the incidence of AKI in a cohort of patients
undergoing elective CABG surgery and to evaluate both ‘traditional’ (such as diabetes and
hypertension) and ‘alternative’ (such as New York Heart Association (NYHA) staging, Angina score
and duration of operative time) demographics and parameters as risk factors associated with
development of AKI post-operatively.
Methods: This was a retrospective observational study. All patients that underwent isolated, elective
CABG surgery from 1st January to 31st December 2012 were included. Patients requiring emergency
CABG surgery, who underwent concomitant valvular surgery, with CKD stage 5 or on renal
replacement therapy were excluded from the study. Patient data and operative information was
obtained from patients’ paper and electronic records and the Cardiothoracic Patient Analysis and
Tracking System (PATS) respectively. Baseline creatinine was defined as the serum measurement
taken at pre-assessment clinic. AKI incidence and staging was defined using the KDIGO AKI
classification. Univariate analysis of baseline characteristics was performed using Student’s t-test and
Chi-squared test for continuous and categorical variables respectively.
Results: 219 patients were included in this study. Incidence of AKI in this population was 20.1% [33
patients with AKI Stage 1, 3 with Stage 2 and 8 with Stage 3). Mode time for development of AKI
was 1-day post-op. Patients that developed AKI were significantly older (64.8 vs. 69.3 years old;
p<0.01), male (p<0.05) and diabetic (p=0.05). These patients also had worse NYHA staging (p<0.01),
worse left ventricular ejection fraction (53.8% vs. 49.5%; p<0.01) and higher baseline creatinine (87.3
vs. 105.7 umol/l; p<0.01). The use of post-operative IV Frusemide infusions was also seen to be
higher within the AKI cohort (p<0.01). No statistical significance was observed with regards to
medication history, operative time or procedure variations such as the number vessel grafted or on/off
pump surgery.
Conclusion: The incidence of AKI in our cohort is significantly higher than that observed in other
studies. Risk factors associated with development of AKI are related to patient demographics and
characteristics as opposed to variations in operative procedures. Identification of these patients that
are at risk of developing AKI post operatively will allow peri-operative prophylactic measures and
closer monitoring post-operatively to prevent AKI and its progression.
References
1. National Confidential Enquiry into Patient Outcomes and Death (NCEPOD) Report: Adding
Insult to Injury (2009)
2. NHS Choices. Coronary artery bypass graft. http://www nhs uk/conditions/coronary-arterybypass/Pages/Introduction aspx 2012 April 22;
3. Mariscalco G, Lorusso R, Dominici C, Renzulli A, Sala A. Acute kidney injury: a relevant
complication after cardiac surgery. Ann Thorac Surg 2011 October;92(4):1539-47.