Outcomes of off-pump coronary artery bypass grafting in non-dialysis-dependent patients with stage 2 and stage 3 chronic kidney disease.

Purpose: To assess the short-term outcomes in non-dialysis-dependent patients with stage 2 and stage 3 chronic kidney disease (CKD), undergoing off-pump coronary artery bypass (OPCAB). To examine whether there was a difference in mortality between stage 2 and stage 3 CKD patients and whether mortality in diabetics was different compared to non-diabetics. Outcomes would be judged on the basis of possible cardiovascular, pulmonary, infective, neurological and renal complications, duration of stay at the intensive therapy unit (ITU), and overall duration of stay at the hospital. A comparative study of outcomes between stage 2 and stage 3 CKD would be undertaken. Also, given the impact of diabetes mellitus in this patient population, a comparative study of outcomes would be made between diabetics and non-diabetics.

Methods: Three hundred fifteen consecutive patients undergoing OPCAB were included in this observational prospective study. Of them, 201 (64%) had stage 3 CKD and 114 (36%) had stage 2 CKD. Nearly half of the study group (49.52%) were diabetics. Data was collected from patients' files, patient observation charts at the ITU, and patient interviews. Continuous variables were expressed as mean ± standard deviation or median (Q1, Q3) as appropriate and qualitative variables presented with the frequency and corresponding percentage. Comparison between diabetic and non-diabetic patients was performed by the Student's test or chi-square test as appropriate. And when assumptions of parametric test failed, then an appropriate non-parametric test was performed. Repeated measures ANOVA (analysis of variance) was used to see the trend of estimated glomerular filtration rate (eGFR) values. Statistical analysis was done by using SPSS version 19.0 (SPSS Inc., Chicago, IL, USA). All values <0.05 were considered statistically significant.

Results: The eGFR was measured pre-operatively, on the day following OPCAB and at the time of discharge and the mean eGFR, remained more or less the same throughout (mean of 55.86 ml/min/1.73 m pre-operatively, 58.39 ml/min/1.73 m on the day following OPCAB and 58.39 ml/min/1.73 m at discharge). One patient with stage 2 CKD (0.9%) required hemodialysis post-operatively while 3 patients (1.5%) required the same in the stage 3 CKD group, which was not statistically significant. Nineteen patients (6.03%) required re-intubation for hypoxia in the post-operative period. Post-operative myocardial infarction developed in 12 patients (3.81%). Twenty patients (6.35%) patients needed an intra-aortic balloon pump (IABP) insertion in the peri-operative period owing to hemodynamic compromise. Fifteen patients (4.76%) were re-explored for bleeding following surgery and fifteen patients (4.76%) had a deep sternal wound infection in the post-operative period. New-onset atrial fibrillation was found to be present in 42 stage 3 CKD patients (11%) while it occurred in 21 stage 2 CKD patients (9.6%) ( value = 0.014), which was statistically significant. The mean duration of ITU stay was 84 ± 6.22 h in the stage 2 CKD group and 92.9 ± 8.18 h in the stage 3 CKD group ( value = 0.01), which was statistically significant. Mean duration of ITU stay was 94 ± 10.12 h in the diabetic group while it was 86.7 ± 11.08 h in the non-diabetic group ( value = 0.008) which was statistically significant. Duration of post-operative hospital stay was a mean of 8 ±0.08 days in the diabetic group whereas it was 7 ± 0.04 days in the non-diabetic group ( value = 0.012), which was statistically significant. Surgical mortality was 6 out of 315 patients (1.9%).

Conclusion: OPCAB is a safe and effective revascularization strategy in patients with stage 2 and stage 3 CKD. Short-term outcomes of OPCAB have been good in the patient population in this study, in terms of both surgical morbidity and mortality. Surgical mortality was 1.9%. New-onset atrial fibrillation was found in eleven patients (9.6%) in the stage 2 CKD group and 42 patients (21%) in the stage 3 CKD group ( value =0.014) which was statistically significant. The results of this study reflect the reno-protective nature of OPCAB. The duration of ITU stay and the post-operative duration of stay at the hospital were found to be significantly more in diabetics than in non-diabetics.