Comparison of Postoperative Renal Function Test between Off-pump

Coronary Artery Bypass Grafting and On-pump Coronary Artery

Bypass Grafting in 10 Years in Haji Adam Malik Hospital Medan

Yosef Aloys Hamonangan Siregar

, Marshal

, Doddy Prabisma Pohan

Department of General Surgery, University of Sumatera Utara/ Haji Adam Malik Hospital, Medan, Indonesia

Department of General Surgery, Division of Thoracic and Cardiovascular Surgery, University of Sumatera Utara/ Haji

Adam Malik Hospital, Medan, Indonesia

Keywords: Off-pump CABG, On-pump CABG, Renal Function

Abstract: To analyze the difference between the results of the examination of renal function before and after the on-

pump CABG (CABG) action compared to the off-pump CABG (OPCAB) action for 10 years. A cross-

sectional study using medical record evaluated the ureum, creatinine, and creatinine clearance between

OPCAB and CABG. This was also followed by urea differences after the procedure of either CABG or

OPCAB with a p-value of 0.049. There was no statistically significant difference at the time after the

procedure, where the result of the p-value obtained was 0.187. When viewed from the median value, the

creatinine value in the CABG group is 0.82 compared to the OPCAB group of 0.89. While the last variable

assessed was CrCl, after the procedure, the value of p = 0.926 is obtained. However, when viewed at the

median OPCAB value is 89 compared to CABG which is 86.81. Coronary artery bypass grafting procedures

with either the on-pump or off-pump method only minimally affect kidney function. The different

procedures also do not differ from each other against creatinine clearance and also serum creatinine.

However, there are differences in urea levels.

1 INTRODUCTION

CABG is one of the main surgical procedures most

often performed, approximately 400,000 operations

performed annually in the United States. However,

over the past decade, there has been almost a 30%

reduction in CABG procedures in the United States,

despite an aging population and increasing evidence

to support the effectiveness and safety of operations.

This decrease was accompanied by an increase in

percutaneous coronary revascularization procedures

(Alexander & Smith, 2016).

Off-pump coronary artery bypass grafting

(OPCAB) is a surgical technique for coronary

revascularization that eliminates the use of a cardiac

pulmonary bypass (CPB) machine in managing

ischemic heart disease. On-pump Cardiac arrest

CABG has been the gold standard in CABG for a

long time, however, off-pump CABG (OPCAB) has

been developed along with advancements in the

device to avoid the damaging effects of the

extracorporeal circulation.

Renal dysfunction is a major complication that is

well known after CABG. Reported incidents vary

with the criteria used, ranging from 1% to almost

40%. Plasma creatinine levels are very specific

markers of kidney function. Plasma creatinine levels

are easily obtained but depend on the patient's

muscle mass. The relationship between preoperative

renal dysfunction and postoperative morbidity and

mortality is stronger when creatinine clearance

(CrCl) is used than the creatinine level used. Several

authors have reported the beneficial effects of

OPCAB in high-risk patients in terms of prevention

of potential ARF. Based on these findings, this study

aimed to analyze the difference between the results

of the examination of renal function before and after

the CABG action compared to the OPCAB action

for 10 years.

160

Marshal, ., Siregar, Y. and Pohan, D.

Comparison of Postoperative Renal Function Test between Off-pump Coronary Artery Bypass Grafting and On-pump Coronary Artery Bypass Grafting in 10 Years in Haji Adam Malik Hospital

Medan.

DOI: 10.5220/0009862401600163

In Proceedings of the 2nd International Conference on Tropical Medicine and Infectious Disease (ICTROMI 2019), pages 160-163

ISBN: 978-989-758-469-5

2 METHODS

A cross-sectional study was performed based on

secondary data from the medical record in Haji

Adam Malik General Hospital, Medan from January

2019 to March 2019. Age between 20 to 60 years

old who underwent coronary artery bypass grafting

in Cardiothoracic Surgery Department in Haji Adam

Malik General Hospital from January 2009 to

December 2018, having ureum less than or equal to

40 mg/dL and creatinine less than or equal to 1,1

mg/dL were the inclusion criteria in this study, while

previous history of chronic renal failure and

incomplete medical record were the exclusion

criteria. The ureum, creatinine, and creatinine

clearance were measured twice, preoperative and

postoperative. Normally distributed data were

presented in mean (± SD) and non-normal data

distribution were presented in median (min-max)

and nominal data in frequency (%). Analysis using

the Wilcoxon test was used to analyze the pre- and

postoperative renal function and Mann-Whitney test

to compare the CABG to OPCAB procedure.

Statistical analyses were made using SPSS version

23.0.

3 RESULTS

Patients characteristics were presented in table 1.

Table 1. Patients characteristics

Characteristics CABG OPCAB

Age (mean ± SD) 52.10 ± 5.22 52.30 ± 6.28

Gender

Male (n, %) 72 (87.8) 34 (85.0)

Female (n, %) 10 (12.2) 6 (15.0)

Body Weight 63.5 ± 13.9 66.28 ± 12.5

Table 2. Renal function before and after CABG

Characteristics

Before

CABG

After

CABG

p-value

Ureum

23.95

(11.0-39.8)

39.00

(17.0-71.0)

0.0001*

Creatinine

0.83 (0.49-

1.08)

0.82 (0.40-

1.15)

0.052

Creatinine

Clearance

93.06

(38.28-

184.53)

86.81

(39.06-

175.00)

0.106

Statistical analyses were performed using the

Wilcoxon test

*Statistical significant was found in p-value <0.05

In table 2, based on the characteristics of patients

who underwent the CABG procedure, for ureum

before CABG, the median was 23.95 with a

minimum value of 11.0 and the highest value was

39.8. Whereas after CABG, the median value is 39.0

with a minimum of 17.0 and a maximum of 71.0.

The statistical test results show significance with a

value of p = 0.0001. While other variables did not

show any differences.

Table 3. Renal function before and after OPCAB

Characteristics

Before

OPCAB

After

OPCAB

value

Ureum

26.0 (12.9-

90.0)

32.5 (15.0-

86.0)

0.016

Creatinine

0.93 (0.57-

1.10)

0.88 (0.38-

1.11)

0.061

Creatinine

Clearance

85.96 (34.81-

162.44)

89.00

(40.49-

215.50)

0.060

Statistical analyses were performed using the

Wilcoxon test

*Statistical significant was found in p-value <0.05

Based on table 3, the characteristics of patients

who underwent the OPCAB procedure, for ureum

before OPCAB, the median was 26.0 with the

minimum value being 12.9 and the highest value

was 90.0. Whereas after OPCAB, the median value

is 32.5 with a minimum of 15.0 and a maximum of

86.0. The statistical test results show significance

with a value of p = 0.016.

Table 4. Comparison of kidney function of patients

undergoing CABG and OPCAB procedures

Characteristics CABG OPCAB

value

Preoperative ureum

23.95

(11.0-39.8)

26.0 (12.9-

90.0)

0.018*

Postoperative

ureum

39.00

(17.0-71.0)

32.5 (15.0-

86.0)

0.049*

Preoperative

creatinine

0.83 (0.49-

1.08)

0.93 (0.57-

1.10)

0.0001

Postoperative

creatinine

0.82 (0.40-

1.15)

0.88 (0.38-

1.11)

0.187

Preoperative

Creatinine

Clearance

93.06

(38.28-

184.53)

85.96

(34.81-

162.44)

0.086

Postoperative

Creatinine

Clearance

86.81

(39.06-

175.00)

89.00

(40.49-

215.50)

0.926

Statistical analyses were performed using Mann-

whitney test

*Statistical significant was found in p-value <0.05

Comparison of Postoperative Renal Function Test between Off-pump Coronary Artery Bypass Grafting and On-pump Coronary Artery

Bypass Grafting in 10 Years in Haji Adam Malik Hospital Medan

161

Table 4 showed results of the urea examination

before the procedure, there were differences between

the two groups with a p-value of 0.018. This was

also followed by urea differences after the procedure

of either CABG or OPCAB with a p-value of 0.049.

Furthermore, for creatinine before the procedure,

there was a statistically significant difference with a

p-value of 0.0001. Based on the median value, it was

seen that the serum creatinine of patients in the

OPCAB group was higher than CABG (0.93 versus

0.83). However, there was no statistically significant

difference at the time after the procedure, where the

result of the p-value obtained was 0.187. When

viewed from the median value, the creatinine value

in the CABG group is 0.82 compared to the OPCAB

group of 0.89. While the last variable assessed was

CrCl, where no significant difference was found at

the time before the action (p = 0.086). Likewise,

after the procedure, the value of p = 0.926 is

obtained. However, when viewed at the median

OPCAB value is 89 compared to CABG which is

86.81.

4 DISCUSSION

Coronary artery bypass grafting (CABG) is a

procedure that uses autologous arteries or veins as

an alternative graft of coronary arteries that have

been blocked due to atherosclerotic plaques either

partially or completely (Alexander & Smith, 2016).

Based on research from Asimakopoulos in 2005,

the age of patients undergoing the CABG procedure

was in the range of 55 years to 75 years. slightly

different results were obtained in Reents's 2014

study, where the average age of patients was 78

years, slightly older than the upper limit of the

Asimakopoulos study. Whereas in this study, the

average age of patients in the CABG on-pump group

was 52.1 years with a standard deviation of 5.22

years. similar results were found in the OPCABG

group of 5.23 ± 6.28 years. In our study, there were

no significant differences based on age in the two

groups (Asimakopoulos, 2005; Reents, 2014).

For sex, the majority of our study was male, and

the figure was almost 90% in the CABG group, with

87.8% compared to OPCABG at 85%. Whereas in

previous studies, male groups ranged from 70% to

80% (Asimakopoulos, 2005; Reents, 2014).

The use of a cardiopulmonary bypass (CPB)

machine or what is often called an on-pump

(CABG) is considered to play a role in the risk of

acute postoperative kidney injury when compared to

an off-pump (OPCAB). This decrease can reach

17%. Even this relative and absolute risk reduction

can be found in patients with chronic kidney disease

before surgery (Garg, 2014).

The Aimakopoulos study carried out an analysis

of 704 patients divided into two groups, 404 patients

who underwent the OPCAB procedure and 300

patients who underwent the CABG procedure. In

this study measurement of kidney function in the

form of creatinine clearance (CrCl) (mL/min) and

plasma creatinine (µmol/L). The study compared

plasma CrCl and creatinine in the condition before

surgery and followed up on the first and fourth days

postoperatively. In both groups, there were no

differences in initial values before the procedure,

both in the group with OPCAB or with CABG.

Whereas at follow-up, there was only a difference in

plasma creatinine on the first day, and the difference

was not significant at the fourth day of follow-up

(Asimakopoulos, 2005).

Another study from Wang in 2003 stated that

CrCl use in post-cardiac surgery evaluation was

better estimated than plasma creatinine (Wang,

2003). The results of these studies form the basis of

research from Asimakopoulos in 2005.

In our study, we used serum creatinine values,

urea levels, and creatinine clearance. This study

divides patients who run the CABG procedure with

the on-pump method and also off-pump. We

compared each preoperative value of urea,

creatinine, and CrCl. However, there were

significant differences in the baseline data before the

procedure on urea (CABG= 23.95; OPCAB= 26.0)

with p= 0.018 and creatinine (CABG= 0.83;

OPCAB= 0.93) with p= 0.0001.

Then a postoperative kidney function

examination was performed and compared the

results of each. In this study, there were significant

results between urea after the OPCAB and CABG

procedures with a p-value of 0.049 with urea values

in the CABG group having a higher median (39.00)

compared with the OPCAB group (32.50).

Furthermore, creatinine after the CABG procedure

was higher than creatinine after the OPCAB

procedure and this difference had a statistically

significant value (p= 0,0001). However, when seen

the median decline that occurred, in the CABG

group, the median decrease was only 0.01 while in

the OPCAB group, the median decline occurred at

0.05. The last component we assessed was CrCl

where there was a statistically significant reduction

in the group with the on-pump CABG procedure

when compared to the group of patients who

underwent the OPCAB procedure ie between 89.00

in the OPCAB group and 86.81 in the CABG group

(p= 0.926).

The same results were obtained in the Garg

study, 2014 which compared the variable serum

creatinine between on-pump and off-pump. The

ICTROMI 2019 - The 2nd International Conference on Tropical Medicine and Infectious Disease

162

result was that the off-pump group had an average of

114 versus the on-pump group with an average of

120 (Garg, 2014).

When viewed one by one the comparison

between the values before and after the CABG

procedure, the area is obtained before the median is

23.95 (11.0-39.8) and after 39.00 (17.0-71.0) with a

p-value of 0,0001. This indicates an increase in urea

in postoperative conditions. Furthermore, for

creatinine variables, in the condition before the

procedure, the median value of 0.83 and after was

0.82 and there were no significant differences in the

two variables (p= 0.052). The last variable was

creatinine clearance, where before the CABG

procedure, the median was 93.06 and after the

median CABG, it was 86.81. However, there was no

difference that was statistically significant (p=

0.106).

Whereas in the OPCAB procedure, the median

urea before surgery is 26.0 while after, the median

increases to 32.5. There was a statistically

significant difference (p= 0.016). Furthermore, in

creatinine, obtained before the OPCAB procedure,

the median value was 0.93 while after the procedure

it was 0.88 with a p-value of 0.061. However, when

viewed in comparison, the creatinine value appears

to have improved after the OPCAB procedure. The

latest data assessed were creatinine clearance, where

the median value before OPCAB was 85.96 and this

median value increased to 89.00 after OPCAB, but

the increase was not statistically significant (p=

0.060).

Based on Asimakopoulos's research in 2015, for

plasma creatinine values obtained a median of 95 in

the OPCAB condition before surgery, this result was

decreased after the first day's operation to 96, and on

the fourth day, the value decreased to 98. Whereas in

the CABG procedure, the median value was

preoperative of the plasma creatinine is 93, the first

and fourth postoperative days are 99. However, there

is no difference between these three variables

between the pre and post values both those

undergoing the CABG or OPCAB procedures

(Asimakopoulos, 2015).

For creatinine clearance values, the value also

decreased in OPCAB, the median value at

preoperative was 72, the postoperative first day was

71, and postoperative fourth day was 68. As for

CABG, the preoperative median was 74, the

postoperative first day is 71, and the fourth day is 70

(Asimakopoulos, 2015).

Coronary artery bypass grafting procedures with

either the on-pump or off-pump method only

minimally affect kidney function. The different

procedures also do not differ from each other against

creatinine clearance and also serum creatinine.

However, there are differences in urea levels.

REFERENCES

Alexander, J. H., and Smith, P. K. (2016) ‘Coronary-

Artery Bypass Grafting', New England Journal of

Medicine, 374(20), pp. 1954–1964. doi:

10.1056/NEJMra1406944.

Asimakopoulos, G., Karagounis, A.P., Valencia, O.,

Alexander, N., Howlader, M., Sarsam, M.A., et al.

(2005) ‘Renal function after cardiac surgery off-

versus on-pump coronary artery bypass: analysis using

the Cockroft-Gault formula for estimating creatinine

clearance’, Annals of Thoracic Surgery, 79(6), pp.

2024-2031.

Garg, A. X. et al. (2014) ‘Kidney Function after off-pump

or on-pump Coronary Artery Bypass Graft Surgery: A

randomized clinical trial’, JAMA - Journal of the

American Medical Association, 311(21), pp. 2191–

2198. doi: 10.1001/jama.2014.4952.

Reents, W. et al. (2014) ‘Acute kidney injury after on-

pump or off-pump coronary artery bypass grafting in

elderly patients’, Annals of Thoracic Surgery, 98(1),

pp. 9–15. doi: 10.1016/j.athoracsur.2014.01.088.

Wang, F., Dupuis, J.-Y., Nathan, H., Williams, K. (2003)

‘An analysis of the association between preoperative

renal dysfunction and outcome in cardiac surgery’,

Chest, 124, pp. 1852– 1862.

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Bypass Grafting in 10 Years in Haji Adam Malik Hospital Medan

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