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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 3, May/June 2017
AFRICA
193
microalbuminiria levels in each group (
p
<
0.001) (Table 3).
Pre-operative, first hour postoperative and POD 5 values were
statistically significantly different between the groups (
p
=
0.018,
p
=
0.008 and
p
=
0.001, respectively) (Table 3). However,
the difference in POD 1 values between the groups was at the
threshold of significance (
p
=
0.071).
Pre-operative plasma levels of hsCRP (0.35
±
0.17 vs 0.50
±
0.32 mg/l) showed a trend towards significance (
p
=
0.069).
Although POD 1 hsCRP levels (10.0
±
2.0 vs 17.8
±
3.9 mg/l)
did not differ (
p
=
0.405) between the groups, a decrease in POD
5 hsCRP levels in group T (8.6
±
2.9 vs 10.9
±
3.2 mg/l) was
statistically significant between the groups (
p
=
0.024) (Table 4).
All CABG surgeries were performed successfully. There was
no repeat surgery for bleeding or peri-operative myocardial
infarction in either group. The only complication was one
cerebrovascular accident in the N-T group. There was no clinical
or laboratory evidence of postoperative renal dysfunction in
either group. Urine output during surgery and in the postoperative
period did not differ between the groups. No wound infection
was observed for any patient.
Discussion
Coronary artery bypass grafting is often followed by a systemic
inflammatory response. The clinical relevance of CABG-
related systemic inflammation varies with patients and such
inflammation may be accompanied by intermittent organ
dysfunction and finally, multi-organ failure, including renal and
pulmonary dysfunction.
9,10
In some patient groups, the effect of extracorporeal
circulation is serious after open-heart surgery and it is well
known that diabetic patients are frequently associated with
renal and cardiovascular disease, requiring surgical and medical
intensive care. Some pathophysiological mechanisms such
as microalbumiuria and urinary protein over-excretion are
responsible for these damaging effects in this particular group
of patients.
In patients with diabetes, angiotensin II is believed to play
a main role in the progression of renal damage, not only
through haemodynamic effects but also non-haemodynamic
effects, including stimulation of growth factors and cytokines
and changes in extracellular matrix metabolism.
11
Angiotensin
II gives rise to glomerular hypertension and can alter the
filtration properties of the glomerular basement membrane,
leading to proteinuria.
12-13
Angiotensin receptor antagonists have
been shown to consistently produce favourable mortality and
morbidity outcomes in endpoint trials in patients with type 2
diabetes and diabetic nephropathy.
14-16
Microalbuminuria refers to the increased excretion of
albumin into the urine, which is so slight that it can be detected
only by sensitive immunological analysis. Microalbuminuria is
measured in diabetic patients to predict incipient nephropathy.
The predictive value of microalbuminuria for the expression of
cardiovascular diseases has also been investigated and, in fact,
is as powerful for predicting hyperlipidaemia or hypertension.
17
Microalbuminuria also occurs in acute conditions where capillary
permeability increases.
Microalbuminuria increases during major surgery such as
CABG, and extracorporeal circulation activates an inflammatory
cascade, which may increase capillary permeability and cause
microalbuminuria. The increase in capillary permeability may
induce exudation of proteins from the lung capillaries into the
capillary–alveolar interspace and alveoli, causing the so-called
post-perfusion lung, which resembles pulmonary oedema.
We found that telmisartan, as an angiotensin II receptor
antagonist, had a significant lessening effect onmicroalbuminuria
in type 2 diabetes patients undergoing coronary bypass surgery
in our study. A significant decrease in hsCRP levels on day 5 was
also noticed between the groups.
Several previous studies have shown that angiotensin receptor
antagonists are effective anti-inflammatory agents, and our
patients receiving telmisartan revealed decreased levels of
systemic inflammation after CABG. This anti-inflammatory
effect of telmisartan may help preserve postoperative renal
function and also vascular endothelial function, which may also
be seen after bypass surgery.
Table 1. Clinical and demographic characteristics of the study group
Characteristics
Group T Group N-T
p
-value
Age (years)
65.6
±
7.8
64.4
±
9.5
0.680
Gender (M/F)
15/5
14/6
0.723
Body mass index
28.0
±
4.7
26.5
±
2.8
0.234
Smoking,
n
(%)
11 (55)
10 (50)
0.752
Hypertension,
n
(%)
18 (90)
16 (80)
0.661
Hyperlipidaemia,
n
(%)
19 (95)
18 (90)
1.000
History of myocardial infract,
n
(%)
12 (60)
13 (65)
0.744
Group T
=
telmisartan group; group N-T
=
non-telmisartan group.
Table 2. Operative and postoperative features of the patients
Surgical parameters
Group T Group N-T
p
-value
Number of bypasses
2.9
±
1.0
2.9
±
0.9
0.876
Cardiopulmonary bypass time (min) 87.4
±
31.3 86.6
±
20.4 0.920
Cross-clamp time (min)
52.6
±
21.6 53.2
±
18.5 0.925
Flow (cm
3
)
4469.0
±
362.4 4491.0
±
295.0 0.834
Atrial fibrillation,
n
(%)
4 (20)
6 (30)
0.716
Inotrope usage,
n
(%)
3 (15)
6 (30)
0.451
Mortality,
n
(%)
0
2 (10)
0.487
Group T
=
telmisartan group; group N-T
=
non-telmisartan group.
Table 3. Pre- and postoperative microalbuminuria levels
Group T
Mean
±
SD
Group N-T
Mean
±
SD
p
-value
Pre-operative
16.5
±
17.2 30.0
±
17.7 0.018
Postoperative 1st hour
28.5
±
17.2 51.0
±
28.4 0.008
Postoperative 1st day
59.0
±
29.8 75.0
±
25.6 0.071
Postoperative 5th day
23.0
±
20.0 52.5
±
27.5 0.001
Group T
=
telmisartan group; group N-T
=
non-telmisartan group; SD
=
stan-
dard deviation.
Group T: Pre-op vs 1st day:
p
<
0.001; pre-op vs 5th day:
p
=
0.036; 1st hour vs
5th day:
p
=
0.021; 1st day vs 5th day:
p
=
0.036.
Group N-T: Pre-op vs 1st day:
p
<
0.001; 1st hour vs 1st day:
p
<
0.001; 1st hour
vs 5th day:
p
<
0.001; 1st day vs 5th day:
p
<
0.001.
Table 4. High-sensitivity C-reactive protein levels (mg/l).
Group T
Mean
±
SD
Group N-T
Mean
±
SD
p
-value
Pre-operative
0.35
±
0.17 0.50
±
0.32 0.069
Postoperative 1st day
10.0
±
2.0
17.8
±
3.9
0.405
Postoperative 5th day
8.6
±
2.9
10.9
±
3.2
0.024
Group T
=
telmisartan group; group N-T
=
non-telmisartan group; SD
=
stan-
dard deviation.