16 / 64
CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 1, January/February 2016
14
AFRICA
was a significant correlation with mortality rate (OR
=
6.6) (95%
CI: 1.03–42.23).
Discussion
Pre-operative diagnostic studies of EVAR patients are important.
Implantation of the graft in the correct manner is directly related
to the anatomy of the patient. It is known that patients with
aneurysms whose neck length is longer than 1.5 cm, without a
surrounding thrombus, and with limited angulation, are ideal
cases for implementation of EVAR. However, with recent
increased surgical experience and the improvement in graft
technology, difficult cases can now also be treated with EVAR.
1,5-7
It is therefore possible that, in our study, the pre-operatively
measured aneurysm diameter, neck length and neck angle were
not found to have an effect on mortality rate. However, the
mortality rate was observed to be higher in patients with detected
endoleaks, even though they were treated (
p
=
0.001).
We know that as the aneurysm diameter increases, the risk of
rupture also increases. In their study, Brown
et al
.
2
showed that
the annual rate of rupture in aneurysms was 2.2%. The female
gender, COPD, smoking and hypertension were indicated as
risk factors for rupture.
2
In the current study, urgent EVAR was
performed due to aneurysm rupture in four of 56 patients and
the success rate of treatment in these patients was 100%. All of
the ruptured aneurysms were in group II and the correlation
between the increase in aneurysm diameter and rupture was
significant (
p
=
0.001).
In recent studies, it has been found that in all patients, not
only in those with a high surgical risk, EVAR should be the first-
line treatment method in the presence of suitable anatomical
conditions.
1-7
Brewster
et al
. found that the most important fatal
complication in endovascular treatment was aneurysm rupture,
which was seen at a rate of 1% following repair. The mortality
rate was found to be the same in the surgical group one year after
the procedure.
5,6
In a large, randomised study in the United Kingdom, it
was found that the early mortality rate was lower with EVAR;
however, with long-term follow up, the mortality rate was found
to be similar to that with surgical repair. Additionally, in the
EVAR group, further additional interventions were required and
more graft complications were observed.
9
In their five-year EVAR follow up, Zarins
et al
. stated that
small aneurysms (5 cm) responded best to treatment, and they
reported the survival rate at 99%. With large aneurysms, rupture,
deaths and additional surgical requirements were reported to be
higher.
10
In their study, Peppelenbosch
et al
. found that aneurysms with
large diameters caused increased early and long-term mortality
rates and risk of rupture when compared to aneurysms with
intermediate and small diameters. The mortality rate increased,
particularly after the fourth year.
11
In our study, no correlation
was found between diameter of aneurysm and mortality rate in
the early to intermediate period.
In the study by Schanzer
et al
., endoleak, advanced age,
increased aneurysm neck angle (
>
60°), and diameter of the main
iliac artery larger than 20 mm were found to be independent
risk factors for increase in aneurysm diameter following the
procedure.
12
However, there are no data related to the treated
endoleaks at the conclusion of these studies.
Tsilimparis
et al
. showed that long-term survival of the AAA
patients whose aortic diameter was less than 60 mm was superior
to the ones whose aortic diameter was more than 60 mm.
13
In our
study, the diameter of the aneurysm had no effect on long-term
survival. The factors affecting long-term survival were identified
as high EuroSCORE values and endoleak formation during the
procedure, even if it had been repaired.
In a single-centre retrospective review, Wisniowski
et al
.
described age, American Society of Anesthesiologists (ASA)
score, and chronic obstructive pulmonary disease as predictive
factors for mortality at three years; and age, ASA score, renal
failure and serum creatinine level as predictive factors for
mortality after five years of follow up.
14
They did not include
aneurysm size as a predictive factor in their study. Similarly,
Wang
et al
. found no significant difference in outcome of EVAR
with small versus large AAA.
15
There are some limitations to this research study. The first is
related to the selection of stent types. We carried out this study
with heterogeneous stent types in order to get initial preliminary
results, avoiding bias. These results could be improved with
homogenous stent types in further studies. The second limitation
is related to follow-up period. Long-term data have not yet been
obtained.
Conclusion
As a result of our studywe observed that pre-operative anatomical
characteristics of the aneurysms did not increase mortality rate
at a mean period of 50 months of follow up after treatment
with EVAR. However, the complications that developed during
and after the procedure increased the mortality rate. Moreover,
we believe that early intervention would be more helpful, as
confirmed rupture is more frequently seen in large aneurysms.
References
1.
Johnston KW, Rutherford RB, Tilson MD, Shah DM, Hollier L,
Stanley JC. Suggested standards for reporting on arterial aneurysms.
Subcommittee on reporting standards for arterial aneurysms,
ad hoc
committee on reporting standards, Society for Vascular Surgery and
North American Chapter, International Society for Cardiovascular
Surgery.
J Vasc Surg
1991;
13
: 452–458.
2.
Brown LC, Powell JT. UK Small Aneurysm Trial participants. Risk
factors for aneurysm -rupture in patients kept under ultrasound surveil-
lance.
Ann Surg
1999;
230
: 289–297.
3.
Craig SR, Wilson RG, Walker AJ, Murie JA. Abdominal aortic aneu-
rysm: still missing the message.
Br J Surg
1993;
80
: 450–452.
Table 4. Effects of anatomical data on mortality rate
Deaths
(
n
=
6)
Survivals
(
n
=
50)
p
-value
Mean age (years)
72.1
69.5
>
0.05
Aneurysm diameter (cm)
6.9
6.7
>
0.05
Neck angle (°)
66
65
>
0.05
Neck length (cm)
1.5
1.69
>
0.05
Right iliac angle (°)
90
92
>
0.05
Left iliac angle (°)
92
90
>
0.05
Endoleak,
n
(%)
6 (100)
5 (10)
0.001*
EuroSCORE
7
4
0.02*
* Statistically significant.