Impact of preoperative renal dysfunction on outcomes of off-pump coronary artery bypass grafting

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 t 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 p 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 m² pre-operatively, 58.39 ml/min/1.73 m² on the day following OPCAB and 58.39 ml/min/1.73 m² 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%) (p 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 (p 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 (p 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 (p 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 (p 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.

Impact of occult renal disease on the outcomes of off-pump and on-pump coronary artery bypass grafting

Purpose

Occult renal disease (ORD) is a clinical condition in which glomerular filtration rate (GFR) is less than 60 ml/min/1.73 m², while serum creatinine is ≤ 1.3 mg/dl. The aim of the study was to compare the incidence of postoperative stage I acute kidney injury (AKI) according to Acute Kidney Injury Network (AKIN) classification in patients with ORD undergoing either off-pump or on-pump coronary artery bypass grafting.

Methods

A single center prospective randomized study was conducted from March 2011 through January 2014. A total of 120 coronary artery disease (CAD) patients with ORD undergoing coronary artery bypass grafting (CABG) were randomized to either off-pump (group1, n = 62) or on-pump (group2, n = 58) CABG in 1:1 ratio by computer-generated random number table. The GFR and serum creatinine levels were measured preoperatively and postoperatively on day 1 and day 5. The primary outcome (postoperative AKI (stage I)) and secondary outcomes (AKI (stage III) requiring renal replacement therapy (RRT) death, myocardial infarction (MI), cerebrovascular accident, atrial fibrillation (AF), and re-exploration for bleeding) at 30 days were analyzed between the groups.

Results

There is no significant difference in baseline characteristics of patients between off-pump and on-pump group. The incidence of postoperative AKI (stage I) was similar between on-pump (20.69%) and off-pump (16.13%) groups (p = 0.51). There was no significant difference in mortality (p = 0.33), postoperative MI (p = 0.34), cerebrovascular accident (p = 1.00), re-exploration (p = 0.96), and AF (p = 0.50). The number of patients of stage III AKI requiring RRT was higher in the off-pump group (3 patients, 4.8%) and none in the on-pump group (p = 0.08).

Conclusions

This study demonstrated that on-pump CABG is associated with significantly lower GFR and significantly higher serum creatinine on postoperative day 1 which return to baseline by postoperative day 5. In patients with ORD undergoing CABG, the incidence of postoperative AKI and major adverse cardiac and cerebrovascular events were similar between off-pump or on-pump CABG patients.

Results of Protocol-based Perioperative Management in Off-Pump Coronary Artery Bypass Grafting for Patients with Non-dialysis-dependent Chronic Kidney Disease

BACKGROUND

Recent studies have demonstrated the benefits of off-pump coronary bypass grafting over the on-pump technique in patients with chronic kidney disease (CKD). To further reduce the risk of acute kidney injury and the need for renal replacement therapy, even in patients undergoing off-pump coronary artery bypass grafting, we adopted protocol-based perioperative management for patients with CKD.

METHODS

From December 2012 to March 2015, 265 patients underwent isolated off-pump coronary artery bypass grafting. To analyze renal function in a stable condition, we excluded 12 dialysis-dependent end stage renal failure and 10 emergency or urgent cases. Among the remaining 243 patients, 208 patients had normal kidney function (normal group), and 35 patients had CKD (CKD group). Minimizing contrast exposure, ensuring adequate hydration, using strict drug dosage adjustment, and optimizing hemodynamic status were key elements of the protocol for the CKD group.

RESULTS

The risk of acute kidney injury was about ×3 higher in the CKD group than in the normal group (p=0.01). Estimated glomerular filtration rates and serum creatinine levels deteriorated until the third postoperative day in the CKD group. However, by adopting protocol-based perioperative management, this transient renal dysfunction recovered to preoperative levels by the fifth postoperative day without requiring renal replacement therapy in all cases.

CONCLUSION

Off-pump coronary bypass surgery combined with this protocol-based perioperative management strategy in patients with non-dialysis-dependent CKD could mostly be performed without renal replacement therapy.

Impact of increasing degrees of renal impairment on outcomes of coronary artery bypass grafting: the off-pump advantage

OBJECTIVES

Increasing degrees of renal impairment are associated with higher rates of morbimortality after coronary artery bypass grafting (CABG). This incremental risk has not been well studied in off-pump procedures (OPCAB). We assessed its impact on OPCAB and on-pump CABG (ONCAB).

METHODS

A total of 1769 patients undergoing primary CABG (January 1995 through June 2011) had complete data on glomerular filtration rate (eGFR). 930 patients had Stage 2 renal insufficiency, 330 Stage 3, 27 Stage 4 and 465 normal renal function (Stage 1). Seventeen patients with end-stage disease (Stage 5) were excluded. The OPCAB technique was selectively used in 350 high-risk patients. Preoperative variables and postoperative outcomes were compared among eGFR subgroups and between matched and unmatched OPCAB vs ONCAB groups.

RESULTS

Stages 3-4 patients were older (P < 0.0001), with higher prevalence of diabetes (36.8, 35.0, 39.7 and 74.1%, P < 0.01, 1-4 eGFR groups) peripheral arteriopathy (6.0, 9.0, 15.8 and 29.6%, P < 0.0001) and lower left ventricular ejection fraction (LVEF) (GFR-LVEF correlation: Pearson: 0.12, P < 0.0001). On-pump GFR groups had increasingly higher in-hospital mortality (1.0, 1.2, 3.5 and 15.4%, P < 0.0001), but no differences were observed in OPCAB (5.5, 4.8, 5.4 and 7.1%, P = 0.97). Similar trends on in-hospital morbidity were observed in ONCAB vs OPCAB groups: low cardiac output (P < 0.01), pneumonia (P < 0.01) and stroke (P < 0.05). GFR only predicted mortality in ONCAB patients (odds ratio (OR): 0.96, 95% CI: 0.94-0.98; P < 0.01). Patients with higher eGFR stages had statistically more reduced long-term survival, and this pattern was similar in the three treatment groups, also including the OPCAB group, who had the lowest survival in patients with eGFR stage 4.

CONCLUSIONS

Patients with low GFR (Stages 3-4) undergoing ONCAB were at increased risk of early morbimortality. In contrast, there were no significant differences in operative morbimortality among eGFR groups in OPCAB patients. This 'off-pump advantage' on early outcomes was not observed at the long-term follow-up.