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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 6, November/December 2016
340
AFRICA
20% in patients who underwent CABG, 37.5% in patients
who underwent AVR + CABG, and 18.2% in patients who
underwent the Bentall procedure. The most frequently observed
co-morbidities were DM (48%) in patients who underwent
CABG, COPD (12.5%) in patients who underwent AVR +
CABG, and PAD (25%) in patients who underwent AVR +
CABG. All patients (100%) who underwent the Bentall procedure
required inotrope, while 25% of patients who underwent AVR +
CABG required IABP support.
Univariate logistic regression analysis showed that the
mortality risk was increased 2.321-fold in patients ≥ 70 years
of age and 1.36-fold in men. The mortality risk was increased
2.25-fold in patients requiring RAA + AVR, 4.5-fold in patients
requiring RAA + CABG, 10.8-fold in patients requiring RAA
+ AVR + CABG, and four-fold in patients requiring the Bentall
procedure.
Patients with COPD were at 1.462 times higher risk of
mortality, those with PAD were at 1.429 times higher risk and
those with DMwere at 2.281 times higher risk. Patients requiring
inotropic drugs were at 13.329 times higher risk and those
requiring IABP were at 13.333 times higher risk of mortality
(Table 5).
Multivariate logistic regression analysis final model results
showed that the mortality risk was 9.779-fold higher in patients
who required inotropic drugs and 9.029-fold higher in patients
who required IABP compared to those who did not (Table 6).
Five variables were included in the initial multivariate logistic
regression model and three variables (gender, COPD, PAD) were
excluded, based on the likelihood ratio test (
p
<
0.20). In the final
model, the following were identified as being associated with
mortality: inotrope (OR, 9.779) and IABP (OR, 9.029) (Table
6). The final model fit was tested using the Hosmer–Lemeshow
test. The H–L statistic had a significance of 0.889, which means
that it was not statistically significant and therefore our model
was a good fit.
Discussion
Ascending aortic aneurysms start from the aortic valve and
extend to the innominate artery, and they generally require open-
heart surgery. Increasing age, hypertension, smoking, genetics,
atherosclerosis and connective tissue disorders are aetiological
factors that are associated with ascending aortic aneurysms.
5
Medical therapy or various surgical interventions may reduce
the risk factors.
Diameter, connective tissue disease (e.g. Marfan or Loeys–
Dietz syndrome), pregnancy, bicuspid aortic valve (BAV),
familial history of thoracic aortic aneurysm and dissection,
hypertension, gender, and aortic growth are factors that may
influence the need for surgery.
5
Size of the aneurysm is considered
the most important independent factor in the decision for a
patient to undergo surgery.
The required indications for RAA are acute dissection, rupture
and intramural haematoma.
6
Elective indications are generally
prophylactic in nature, and they aim to prevent progression of
aortic insufficiency and aortic rupture or dissection.
Aortic aneurysms are usually asymptomatic, with slow
growth and they may develop distal thromboembolism, rapid
expansion and rupture, with catastrophic complications. The
law of Laplace predicts that, as the aneurysm size increases, wall
tension also rises.
7
Dissections have a high early mortality rate of up to 1–2% per
hour. In patients with atherosclerotic aneurysms of the ascending
aorta, rupture is the most common cause of death.
8
Joyce
et al
.
(1964) found that approximately 50% of patients with thoracic
Table 3. Descriptive statistics (mean
±
standard deviation) of the examined variables for additional operations
Additional operations
Variables
No
AVR
CABG
AVR+CABG
Bentall
Age (year)
64.5
±
8.68
64.3
±
8.17
67.7
±
5.65
71.3
±
12.74
58.7
±
11.36
Aortic diameter (mm)
56.2
±
4.03
51.5
±
5.59
49.6
±
3.57
52.3
±
7.85
54.3
±
5.48
Cross-clamping time (min)
80.9
±
48.46
97.2
±
34
104.0
±
29.43
167.8
±
63.04
130.7
±
53.87
TCA time (min)
26.6
±
4.88
24.6
±
8.10
29.4
±
8.70
22.6
±
3.50
25.5
±
5.07
EF (%)
58.6
±
8.42
55.4
±
11.78
54.0
±
9.81
50.4
±
11.96
52.1
±
4.88
CPB time (min)
144.0
±
54.52
164.5
±
44.28
159.6
±
59.21
202.3
±
61.6
229.5
±
82.79
Extubation time (hour)
17.4
±
4.41
15.2
±
5.12
16.9
±
9.21
11.4
±
10.47
15.6
±
11.36
ICU stay (day)
2.11
±
0.46
4.06
±
7.10
5.08
±
8.04
2.5
±
2.07
3.36
±
2.80
Bleeding (ml)
373.7
±
175.1
533.8
±
355.7
541.3
±
259.7
700.0
±
539.3
716.7
±
557.9
Discharge from hospital
6.89
±
1.79
6.08
±
2.98
6.04
±
3.48
4.57
±
4.5
8
±
4.82
CBP: cardiopulmonary bypass, EF: ejection fraction, ICU: intensive care unit, TCA: total circulatory arrest.
Table 4. Frequencies and percentages [
n
(%)] of the examined variables
for additional operations
Additional operations
Variables
No
AVR CABG
AVR +
CABG Bentall
Mortality
No
18 (94.7)
32 (88.9)
20 (80.0)
5 (62.5)
9 (81.8)
Yes
1 (5.3)
4 (11.1)
5 (20.0)
3 (37.5)
2 (18.2)
COPD
No
17 (89.5)
35 (94.6)
22 (88.0)
7 (87.5)
9 (90.0)
Yes
2 (10.5)
2 (5.4)
3 (12.0)
1 (12.5)
2 (10.0)
PAD
No
16 (84.2)
37 (100.0)
25 (100.0)
6 (75.0)
11 (100.0)
Yes
3 (15.8)
0 (0.0)
0 (0.0)
2 (25.0)
0 (0.00)
DM
No
17 (89.5)
33 (89.2)
13 (52.0)
6 (75.0)
6 (54.5)
Yes
2 (10.5)
4 (10.8)
12 (48.0)
2 (25.0)
5 (45.5)
Inotrope use
No
10 (52.6)
22 (61.1)
9 (36.0)
1 (12.5)
0 (0.0)
Yes
9 (47.4)
14 (38.9)
16 (64.0)
7 (87.5)
11 (100.0)
IABP
No
19 (100.0)
34 (94.4)
21 (84.0)
6 (75.0)
9 (81.8)
Yes
0 (0.00)
2 (5.6)
4 (16.0)
2 (25.0)
2 (18.2)
COPD: chronic obstructive pulmonary disease, DM: diabetes mellitus, PAD:
peripheral arterial disease, IABP: intra-aortic balloon pump.