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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 2, March/April 2017
110
AFRICA
There was no statistically significant difference with regard
to the rate of use of intra-aortic balloon pump (IABP) in the
pre-operative period (
p
>
0.05) between the two groups. The rate
of use of IABP in the postoperative period was significantly
higher in the deceased cases (
p
<
0.01; OR: 61.000; 95% CI:
11.422–325.788) than in the survivors.
There was no statistically significant difference with regard
to mortality rate in terms of use of inotropic medicines
pre-operatively between the two groups (
p
>
0.05). The rate
of use of inotropic medicines in the postoperative period was
statistically significantly higher in the patients who died than in
surviving patients (
p
<
0.01; OR: 6.400; 95% CI: 2.181–18.784;
Table 5). Patients who had undergone emergency operations
and were administered inotropic medications had statistically
significantly higher mortality rates.
Although complete revascularisation was not significantly
related to mortality rate in both groups, the results were different
when analysed with regard to the on- and off-pump group
distribution (Table 6). Complete revascularisation was more
frequently performed on patients in the on-pump group. The
complete revascularisation rate was 23.3% in the off-pump and
85.2% in the on-pump group, and this difference was statistically
significant (
p
<
0.01). A comparison of the mortality rates of
the two groups, however, revealed no statistically significant
difference (
p
>
0.05).
Discussion
The mortality rate associated with cardiovascular surgical
procedures is higher for patients experiencing chronic renal
failure than for patients with normal renal function.
8,9
A restricted
tolerance to decreased blood pressure, bleeding complications
due to coagulatory problems, insufficient excretion of toxic
metabolites, and sensitivity to infection may play a significant
role in cases of uraemic patients.
A maturity series of 296 cases reported by Ko
et al
.
revealed
a mortality rate of 9%; the study showed that mortality
occurred in patients with high NYHA functional class, left main
coronary artery disease, accompanying cerebrovascular disease,
or emergent surgical procedures.
8
Krishnaswami
et al
. reported
survival rates as follows: first 30 days: 91–92%; first year:
77–78%.
10
Nwiloh
et al
. found a 20.8% mortality rate as a result
of subgroup analyses in isolated CABG with ESRD patients.
11
In Kaul and co-workers’
series of 35 cases published in
1994, the surgical mortality rate was 11.4%. They observed
that congestive heart failure and a high NYHA class were
determinants of mortality and that left main coronary artery
disease did not affect mortality rates.
12
Most surgeons prefer the
off-pump technique because it obviates the complications of
cardiopulmonary bypass (CPB) and reduces in-hospital length
of stay and associated costs; however, the patient’s clinical status
and risk factors limit this procedure’s applicability.
In research conducted by Chu
et al
., the authors examined
all data and follow-up results relating to patients on whom
off- and on-pump techniques were performed. The findings
revealed that in-hospital mortality rates of patients in whom the
on- and off-pump techniques were used were similar (3 and 3.2%,
respectively). Moreover, no difference was found between the two
groups with regard to postoperative stroke development in patients
who were discharged.
13
Despite this, extended hospitalisation and
increased costs were observed for the off-pump group.
The physiological and anatomical features of the coronary
arteries also limit the benefits of the off-pump technique. Factors
that limit the success of a distal anastomosis are as follows: difficulty
in reaching the coronary artery, intra-myocardial coronary artery,
poor quality of the artery and arterial plaque formation, and
extent of the surgeon’s experience. The results obtained from
Table 4. Enzyme levels
Mortality
+
p
-value
Yes, Mean
±
SD No, Mean
±
SD
CK-MB (U/I)
Pre-op
51.90
±
153.75
20.55
±
16.36
0.478
Postop
135.95
±
140.39
44.62
±
50.56
0.006**
++
p-
value
0.003**
0.001**
Troponin (ng/ml)
Pre-op
27.15
±
123.57
0.15
±
0.38
0.379
Postop
33.14
±
72.52
9.29
±
10.61
0.019*
++
p
-value
0.001**
0.001**
+
Mann–Whitney
U
-test;
++
Wilcoxon sign test; *
p
<
0.05; **
p
<
0.01.
Table 5. Pre-operative vs postoperative assessments in exitus patients
Mortality
+
p
-value
Yes, n (%)
No, n (%)
MI,
n
(%)
Pre-op
17 (81.0)
35 (55.6)
0.038*
Postop
11 (52.4)
7 (11.1)
0.001**
++
p
-value
0.070
0.001**
CVA,
n
(%)
Pre-op
2 (9.5)
7 (11.1)
0.839
Postop
2 (9.5)
1 (1.6)
0.153
++
p
-value
1.000
0.031*
IABP,
n
(%)
Pre-op
2 (9.5)
0 (0)
0.060
Postop
14 (66.7)
2 (3.2)
0.001**
++
p
-value
0.001**
0.500
Inotrope,
n
(%)
Pre-op
2 (9.5)
0 (0)
0.060
Postop
14 (66.7)
15 (23.8)
0.001**
++
p
-value
0.001**
0.001**
+
Chi-squared and/or Fisher’s exact test;
++
McNemar test; *
p
<
0.05; **
p
<
0.01.
MI: myocardial infarction, CVA: cerebrovascular accident, IABP: intra-aortic
balloon pump.
Table 6. Surgical technical results
On-pump
Mean
±
SD
Off-pump
Mean
±
SD
p
-value
Blood transfusion (units)
1.81
±
1.31
2.10
±
1.42
+
0.225
Extubation time (min)
29.77
±
67.07
24.80
±
43.44
+
0.110
ACC (min)
64.74
±
26.18
–
–
TPT (min)
104.18
±
32.08
–
–
Hypothermia (°C)
30.95
±
1.81
–
–
Chest tube drainage (ml)
694.44
±
447.91 758.33
±
467.76
+
0.539
ICU stay (days)
5.98
±
5.99
5.66
±
6.47
+
0.712
Postoperative creatinine (mg/dl)
5.10
±
2.23
5.52
±
2.12
+
0.404
(μmol/l)
(450.84
±
197.13) (487.97
±
187.41)
Redo surgery,
n
(%)
1 (1.9)
1 (3.3)
++
1.000
Postoperative dialysis,
n
(%)
49 (90.7)
27 (90.0)
++
0.912
Complete revascularisation,
n
(%)
46 (85.2)
7 (23.3)
++
0.001**
Pneumonia,
n
(%)
9 (16.7)
3 (10.0)
++
0.403
Exitus,
n
(%)
12 (22.2)
9 (30.0)
++
0.430
+
Student’s
t
-test for drainage and postoperative creatinine levels; Mann–Whitney
U
-test for other variables;
++
Chi-squared test and/or Fisher’s exact test; **
p
<
0.01.
ACC: aortic cross clamp time, TPT: total perfusion time.