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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 5, September/October 2019
276
AFRICA
and McNemar’s tests were performed during the evaluation of
qualitative data. Multiple regression analyses were performed
to explain the relationship between group 1 and group 2.
The results were evaluated within a 95% confidence interval.
Statistical significance level was established at
p
<
0.05.
Results
The study population consisted of 110 patients with dialysis-
dependent ESRD among a total of 1 886 patients who underwent
CABG surgery between 2010 and 2017. There were 74 patients
(26 female, 48 male) in group 1 with a mean age of 60
±
7 years;
36 patients (12 female, 24 male) were in group 2 and the mean
age was 61.5
±
7.5 years.
There were no statistically significant differences between the
two groups with regard to age, gender, old myocardial infarction
and other demographic variables (Table 1). Drainage (800
±
350
vs 600
±
325 ml,
p
=
0.044), blood transfusion (3
±
1 vs 2
±
0.5
units,
p
=
0.020) and length of stay in intensive care unit (ICU)
(6
±
5.3 vs 4
±
4.5 days,
p
=
0.033) were statistically significantly
higher in group 1 (Table 2).
Although pre-operative levels of creatine kinase (CK)
and creatine kinase-muscle/brain (CK-MB) were similar,
postoperative CK (1076.45
±
2411.97 vs 208.45
±
171.94 mg/dl,
p
=
0.003) and CK-MB levels (102.32
±
115.5 vs 53.15
±
66.53 mg/
dl,
p
=
0.044) were statistically significantly higher in group 1. In
the comparison of pre-operative and postoperative CK levels, it
was observed that postoperative CK (111.94
±
139.63 vs 1076.45
±
2411.97 mg/dl,
p
=
0.0001) and CK-MB levels (102.32
±
115.5
vs 44.47
±
124.9 mg/dl,
p
=
0.0001) of group 1 were statistically
significantly increased.
Similarly, postoperative troponin values of group 1 were
statistically significantly higher than those in the pre-operative
period (0.07
±
0.09 vs 9.15
±
22.54 mg/dl,
p
=
0.043). Postoperative
requirement for inotropic agents (22.2 vs 29.70%,
p
=
0.557) and
intra-aortic balloon pump (IABP) (16.7 vs 21.6%,
p
=
0.666)
were similar in both groups (Table 3).
Univariate tests were significantly higher in group 1 in terms
of blood transfusion, drainage, length of stay in ICU, and
postoperative CK and CK-MB values. In the logistic regression
analysis, only post-operative CK levels remained statistically
significantly higher (
p
=
0.038) (Table 4).
Discussion
This study demonstrates that OPCAB had the advantage of
decreased incidence of bleeding, lower rates of requirement
for transfusion, shorter length of stay in ICU, decreased CK
and CK-MB elevation and lower rates of need for IABP when
compared to ONCAB in dialysis-dependent patients.
Patients with ESRD have significantly higher risk for
cardiovascular morbidity and mortality.
7,8
Most patients with
ESRD have left ventricular hypertrophy secondary to systemic
arterial hypertension, hyperparathyroidism secondary to chronic
renal disease, and several systemic co-morbidities such as
cerebrovascular disease or diabetes mellitus. All these factors
can lead to accelerated atherosclerosis of the coronary arteries.
9
Table 1. Baseline demographic characteristics of patients
Variable
Group 1 (
n
=
74) Group 2 (
n
=
36)
p
-value
Age (years)
60
±
7
61.5
±
7.5
0.781
Gender (male/female)
65/35
67/33
0.895
BMI (kg/m
2
)
26.9
±
3
27
±
2.56
0.979
Ejection fraction
55
±
15
52.5
±
14.5
0.422
LVH (
n
)
16 (21.6%)
6 (16.7%)
0.266
Ejection fraction
61.5
±
7.5
60
±
7
0.701
Hypertension (
n
)
68
78
0.434
Hyperlipidaemia (
n
)
27
44
0.196
Diabetes mellitus (
n
)
51
72
0.141
Smoking (
n
)
35
44
0.505
COPD (
n
)
31
39
0.540
PAH (
n
)
19
22
0.774
Creatinine (mg/dl)
4.8
±
1.32
5
±
1.35
0.802
Previous MI (
n
)
70
56
0.282
EuroSCORE
8
±
2
7
±
2.25
0.421
BMI
=
body mass index, LVH
=
left ventricular hypertrophy, COPD
=
chronic
obstructive pulmonary disease, PAH
=
pulmonary arterial pressure, MI
=
myocardial infarction.
Table 2. Operative and postoperative outcomes
Variable
Group 1 (
n
=
74) Group 2 (
n
=
36)
p
-value
Number of the grafts (
n
)
3
±
1.5
2
±
0.5
0.114
Use of IMA (
n
)
74
36
1.00
Urgent operation (
n
)
3 (4%)
11 (30%)
0.198
Blood transfusions (units)
3
±
1
2
±
0.5
0.02
Drainage (ml)
800
±
350
600
±
325
0.044
Entubation time (hours)
16
14
0.723
ICU stay (days)
6
±
5.3
4
±
4.5
0.033
Sternal wound infection (
n
)
2 (2.7%)
4 (11.1%)
0.051
Pneumonia (
n
)
3 (4.1%)
11 (30.1%)
0.198
Hospital mortality (
n
)
16 (21.6%)
11 (30.1)
0.716
IMA
=
internal mammary artery, ICU
=
intensive care unit.
Table 4. Results of logistic regression analysis
Variable
B SE
p-
value Exp(B)
95% CI for Exp(B)
Lower
Upper
Blood transfusions 1.33 0.8 0.94
3.8
0.8
18.11
Drainage
0.00 0.00 0.345 1.00
1.00
1.01
ICU stay
0.09 0.11 0.441 1.09
0.88
1.35
CK
0.01 0.00 0.038 1.01
1.00
1.01
CK-MB
0.00 0.01 0.773 1.00
0.98
1.01
ICU
=
intensive care unit, CK
=
creatinine kinase, CK-MD
=
creatine kinase-
muscle/brain, SE
=
standard error, CI
=
confidence interval, Exp(B)
=
odds
ratio.
Table 3. Comparison of laboratory results and need for inotropic support
Variable
Group 1
(
n
=
74) p
1
Group 2
(
n
=
36) p
2
p
3
Pre-operative CK (mg/dl)
11.9
±
139.6
0.001
115.9
±
11.6
0.07
0.382
Postoperative CK (mg/dl)
1076.5
±
2412
208.5
±
171.9
0.003
Pre-operative CK-MB (mg/dl)
44.5
±
124.9
0.001
23.6
±
16.84
0.055
0.677
Postoperative CK-MB (mg/dl)
102.3
±
115.5
53.2
±
66.5
0.044
Pre-operative troponin (mg/dl)
0.45
±
0.69
0.011
0.07
±
0.09
0.043
0.108
Postoperative troponin (mg/dl)
27.8
±
73.9
15.1
±
22.5
0.409
Pre-operative inotropic support (
n
)
1
0.002
1
0.25
0.596
Postoperative inotropic support (
n
)
11
4
0.557
Pre-operative IABP (
n
)
1
0.016
1
0.5
0.596
Postoperative IABP (
n
)
8
3
0.666
CK
=
creatine kinase, CK-MD
=
creatine kinase-muscle/brain, IABP
=
intra-aortic
balloon pump,
p
1
=
comparison of pre-operative and postoperative data in group 1.
p
2
=
comparison of pre-operative and postoperative data in group 2.
p
3
=
comparison
of group 1 and group 2.