Surgical Science, 2011, 2, 166-172
doi:10.4236/ss.2011.24036 Published Online June 2011 (http://www.SciRP.org/journal/ss)
Copyright © 2011 SciRes. SS
Predictors of Time to Graft Failure Following
Infrainguinal Arterial Reconstruction
Patrick D. Hallihan, Niamh Ni Choileain, Eddie Myers, H. P. Redmond, Greg F. Fulton
Department of Surgery, Cork University Hospital, Wilton, Ireland
Received February 22, 2011; revised April 25, 2011; accepted April 28, 2011
Infrainguinal arterial reconstruction increases limb salvage rates, however, the factors that predict time to
graft failure remain ill-defined. The aim of this study was to define such predictors. A retrospective analysis
of infrainguinal arterial reconstructions performed for symptomatic peripheral arterial disease refractory to
medical/interventional therapies over a 6 year period was performed. Demographics and adverse outcomes
were analysed and statistical significance was determined using Chi-squared analysis, the Student t test and
the Wilcoxon signed-rank test. 170 procedures were analysed. The male to female ratio was 4:3. The median
age was 70.1 years. The post-operative complication rate was 12%. On univariate analysis, female gender,
the use of a synthetic graft, and the presence of critical ischaemia at the time of surgery were predictive of
time to graft failure (p ≤ 0.05, p ≤ 0.03, p ≤ 0.02 respectively). On multivariate analysis, the 3 most signifi-
cant predictors of graft failure were the occurrence of a post-operative complication, female gender and a
high ASA grade. The presence of diabetes mellitus and smoking did not adversely affect graft outcome, (p ≤
0.23, p ≤ 0.20 respectively). This study suggests that female gender adversely affects graft patency while a
history of smoking and the presence of diabetes mellitus do not. Our findings also suggest that the occur-
rence of a post-operative complication, and a high ASA grade at time of surgery are additional important
predictors of early and late graft failure.
Keywords: Infrainguinal, Vascular Surgery, Bypass, Graft, Patency
Infrainguinal arterial reconstruction is an effective treat-
ment for symptomatic peripheral arterial disease, (PAD),
in patients who remain symptomatic despite medical and
intervention therapies [1-4]. Treatment of symptomatic
PAD involves risk factor reduction as well as pharma-
cological and radiological intervention. However, in pa-
tients whose symptoms remain refractory to conservative
management, arterial reconstruction may be necessary.
Time to graft failure in lower limb bypass surgery has
been shown to be adversely affected by the construction
of a distal anastomosis and the use of prosthetic graft
material . Prosthetic grafts are a suitable alternative to
autologous vein when the distal anastomosis is above the
knee joint . Continued smoking post-operatively, (but
not a prior history of smoking), also predicts graft failure
. Conflicting evidence regarding the effect of gender
on graft patency exists. Several studies have identified
female gender as an adverse prognostic indicator in
lower limb bypass surgery but evidence to the contrary
also exists . In this study we constructed multivariate
models in order to determine all possible predictors of
2. Methods and Materials
Data relating to patients who underwent infrainguinal
arterial reconstruction for symptomatic peripheral arterial
disease refractory to medical/interventional therapies
over a six year period from January 1998 to December
2004 was retrieved from the theatre register and hospital
in-patient enquiry databases. Databases were accessed by
one of the authors, (PH). Patients who required revision
surgery for graft failure were excluded from the study.
Critical limb ischaemia was defined as chronic rest pain
or the presence of ischaemic skin lesions, either ulcers or
gangrene. All operations were performed by a consultant
P. D. HALLIHAN ET AL.
vascular surgeon or a senior vascular trainee. The pri-
mary endpoint was the time to graft failure while secon-
dary endpoints included the post-operative complication
rate, need for revision surgery, length of hospital stay
and overall patient survival. Primary graft patency was
determined by ankle-brachial pressure indices (ABPIs)
and duplex ultrasonography. Data analysis included pa-
tient demographics, vascular risk factors, operative indi-
cation, ASA grade, graft material used at time of surgery
and type of surgical bypass performed. Reconstructive
surgery was only offered to patients who discontinued
smoking. Compliance with smoking cessation was
monitored using CO breath testing. Target artery selec-
tion varied with indication for surgery and degree of
patency as per pre-operative angiography. Autologous
vein was the preferred conduit for all procedures. Ipsilat-
eral long saphenous vein was the conduit of choice fol-
lowed by the contralateral long saphenous and upper
limb basilic veins respectively. In patients with inade-
quate autologous vein, a prosthetic graft was used with a
Miller vein cuff. Veins were deemed unsuitable if they
were varicose or thrombosed or found to be non-com-
pliant as determined by absence of response to injection
of papaverine. Suitable veins included those that were
not dilated or varicose and veins which were not affected
by thrombophlebitis. At the end of the bypass procedure,
graft patency was determined by duplex ultrasound.
Post-operatively, grafts were followed-up with duplex
ultrasonography and ABPIs performed before discharge,
every three months for 1 year and every 6 months there-
after. The median follow up was 32 months (range 6 - 64
months). Suspected graft occlusion was confirmed an-
giographically. All patients were commenced on pro-
phylactic aspirin and a statin post-operatively. Patients
with concomitant chronic atrial fibrillation were com-
menced on warfarin therapy.
Statistical analysis was performed using SPSS 12.0 for
Windows (SPSS Inc., Chertsey, UK). Univariate analy-
ses were conducted with either the Pearson chi-
square/Fisher’s exact test or the Student t test for com-
paring continuous variables. Cumulative graft patency
rates were calculated using the Kaplan-Meier method
and comparisons between graft survivals were made us-
ing the Wilcoxon sign-rank test (p ≤ 0.05 significant). A
Cox proportional hazards model was employed to exam-
ine the relationship between graft patency and potential
influential variables. Based on this, multivariate models
were constructed in order to define which combination of
variables best predicted outcome in terms of graft
patency. The following variables were entered with graft
patency as the outcome variable: age, gender, smoking,
diabetes mellitus, ASA grade, graft type, inflow, outflow,
and the overall complication rate. A stepwise procedure
was used to select the variables that were significant in
187 patient records were analysed. Complete records
were available in 170 patients who were then entered in
the study. Table 1 shows demographic data, risk factors,
and associated medical conditions. Procedures were
classified as femoral-above-knee-popliteal, femoral-distal
and popliteal-distal bypasses, (Table 2). The 30-day
mortality rate was 3.5% while the 5-year mortality rate
was 17.1%. There were no peri-operative deaths and 1
post-operative death. The mean length of hospital stay
was 14.1 ± 1.2 days (range 2 - 91 days). The complica-
tion rate was 12% (Table 3). The post-operative inter-
vention rate was 20.6% (n = 35). 21 patients (14.5%)
required further arterial reconstruction, 2 (1.2%) required
graft angioplasty, and 12 (7.1%) needed a thrombectomy.
No patient required amputation.
Overall, primary cumulative graft patency rates at 1
month and 5 yrs were 91.8% and 75.3% respectively. All
graft occlusions were associated with recurrence of lower
extremity symptoms. Univariate analysis revealed that
the use of a synthetic graft was significantly associated
Table 1. Demographic data, risk factors and medical co-
morbidities of patient population.
CHARACTERISTICS n, (%)
Sex—male 97, (57)
female 73, (43)
Age median +/– SEM, (range) 70.2 +/– 0.7, (51-88)
ASA median, (range) 3, (2-5)
Vascular risk factors
Prior history of smoking 92, (54)
Diabetes mellitus 43, (25)
type 1 8, (19)
type 2 35, (81)
Hypercholesterolaemia 18, (11)
Hypertension 44, (26)
Ischaemic heart disease 79, (41)
Cerebrovascular disease 20, (13)
Chronic lung disease 29, (17)
Chronic renal failure 23, (14)
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168 P. D. HALLIHAN ET AL.
Table 2. Indication for surgery, graft type and type of pro-
CHARACTERISTICS OF SURGERY n, (%)
Intermittent claudication 27, (16)
Critical ischaemia 143, (84)
—with rest pain 37, (26)
—with tissue loss 106, (74)
Reversed vein 93, (55)
In-situ vein 18, (11)
Synthetic graft 59, (35)
Femoral-above-knee-popliteal 145, (85)
Femoral-distal 14, (8)
Popliteal-distal 11, (7)
Table 3. Morbidity and mortality rates.
Lower respiratory tract infection 2
Pulmonary embolus 1
Myocardial infarction 2
Cardiac dysrhythmia 1
Thromboembolic events 3
Compartment Syndrome 1
Wound infection 3
30 day 2
5 year 42
30 day 170
5 year 47
with an increased 30 day graft failure rate, (p ≤ 0.03).
Female gender was associated with both 30 day and 5
year graft failure, (p ≤ 0.01, p ≤ 0.01 respectively). Fe-
male gender also influenced the 5-year mortality rate (p ≤
0.03). In addition, the presence of critical ischaemia at
the time of surgery was significantly associated with
graft failure at 5 years, (p ≤ 0.02). In our study, even
though use of a synthetic graft and the construction of an
infragenicular anastomosis were associated with lower
graft patency rates, statistical significance was not
reached, (p ≤ 0.09, p ≤ 0.15). There was no statistically
significance difference between femoral-popliteal and
femoral-distal bypass graft patency rates (77% vs. 67%
respectively). However, femoral-distal bypasses using
synthetic graft material were associated with signifi-
cantly reduced patency rates compared with autologous
vein grafts, (p ≤ 0.001). 35% of subjects received pros-
thetic grafts and females were significantly more likely
to receive a synthetic graft than males, (p ≤ 0.02).
On multivariate analysis, the 3 most significant pre-
dictors of graft patency were the occurrence of a post-
operative complication, gender and ASA grade. Kaplan-
Meier survival curves were constructed in order to cal-
culate patient graft patency rates and curves were com-
pared using the Wilcoxon signed-rank test. Females had
significantly reduced graft patency rates compared with
their male counterparts (p ≤ 0.01), (Figure 1). Interest-
ingly however, neither the presence of diabetes (p ≤
0.20), (Figure 2), nor a prior history of smoking, (p ≤
0.23), (Figure 3), was significantly associated with graft
Despite advances in both the medical and endovascular
management of peripheral arterial disease, infrainguinal
Figure 1. Disease-free survival in males vs. females.
Copyright © 2011 SciRes. SS
P. D. HALLIHAN ET AL.
Figure 2. Disease-free survival in diabetics vs. non diabetics.
Figure 3. Disease-free survival in smokers vs. non smokers.
arterial reconstruction remains a necessary and effective
treatment in select patients. Identification of predictors of
graft failure facilitates appropriate patient selection and
follow-up. Here, using a Cox-proportional hazards model
to perform multivariate analyses, we identified the oc-
currence of a post-operative complication, female gender,
and a high ASA grade as predictors of graft failure.
Previously, studies have attempted to identify factors
associated with reduced graft patency in lower limb by-
pass procedures. In a review of 373 femoral-popliteal
bypass grafts, Budd et al. found that the factors that con-
sistently correlated with reduced late graft patency were
graft material and the site of distal anastomosis. They
also suggested that prosthetic grafts are a suitable alter-
native to autogenous vein when the distal anastomosis is
above the knee, . Other studies have postulated that
the risk factors for graft occlusion in femoral-popliteal
bypass include the construction of an infragenicular dis-
tal anastomosis, an early revision procedure, or contin-
ued smoking post-operatively [9,10]. In our study, how-
ever, even though use of a prosthetic graft and the con-
struction of an infragenicular anastomosis were associ-
ated with lower graft patency rates, statistical signifi-
cance was not reached. Our rates of morbidity and mor-
tality, re-intervention, length of hospital stay and ampu-
tation-free survival are comparable to other published
data [11,12]. The autologous and synthetic graft rates are
also comparable [11,12].
We found that the occurrence of a post-operative
complication, female gender, and a high ASA grade sig-
nificantly reduced the long-term patency of infrainguinal
grafts. Several studies in lower limb bypass surgery have
reported that female sex has an adverse effect on graft
patency [11-13]. The cardiology and cardiac surgery
literature report higher morbidity and mortality rates in
women compared with men as well as lower graft
patency rates [15-17]. Several factors have been impli-
cated for this, including older age at presentation in fe-
males and a greater number of comorbidities, diffuse
rather than focal atheromatous disease in females,
smaller vessel size and the influence of oestrogenic hor-
mones [18,19]. In contrast, Roddy et al have shown that
female gender does not influence outcome following
bypass surgery, but is associated with significantly in-
creased wound complication rates compared with males
. In this study, females had significantly lower graft
patency rates on both univariate and multivariate analysis.
However, significantly more females underwent bypass
with synthetic graft material than did males. This may be
explained by the fact that females generally have a
higher incidence of venous disease than males [19,20] as
well as a smaller calibre long saphenous vein . In
many cases therefore, it may not have been possible to
use autologous vein as the conduit of choice for females
included in the study. Interestingly, when all of the above
variables were entered into a Cox proportional hazards
model, female gender was found to be the most powerful
predictor of early graft failure.
There are a number of methods for classifying patients
as low or high risk for a given operation. One of these is
the classification system set forth by the American Col-
lege of Anaesthetists (ASA) [21,22]. In our study, the
median ASA grade was 3—reflecting the multiple co-
morbities of this patient population. We found that a high
ASA grade was also significantly associated with lower
graft patency rates on multivariate analysis. This finding
emphasises the importance of pre-operative patient risk
stratification and optimisation for surgery.
Diabetes mellitus was not associated with time to graft
failure on either univariate or multivariate analysis. In
recent years, comparable graft patency and limb salvage
rates between diabetic and non-diabetic patients have
Copyright © 2011 SciRes. SS
170 P. D. HALLIHAN ET AL.
been reported . Some groups have even reported im-
proved graft patency rates and operative mortality in
diabetics [24,25], as we did in this study. Gahtan et al.
retrospectively reviewed 170 patients undergoing in-
frainguinal arterial bypass over a 5-year period. They
concluded that DM did not affect graft patency, operative
morbidity or overall survival but it did affect the length
of post-operative stay . Ahchong et al. found that
diabetes mellitus adversely affects hospital mortality and
long-term survival, but not graft patency . In our
study, there was no significant difference between dia-
betic and non-diabetic complication rates or overall mor-
Smoking is one of the major risk factors associated
with the development and progression of peripheral arte-
rial disease [28,29]. A host of studies have attempted to
define the role of smoking in the pathogenesis of venous
and prosthetic graft occlusion [30-33]. In our study,
pre-operative smoking was not associated with lower
graft patency rates. This is in accord with a recent large
meta-analysis which reported that continued smoking
after lower limb bypass surgery results in an at least a
threefold increased risk of graft failure. Smoking cessa-
tion, even if instigated after the operation, restored graft
patency towards the patency of patients who had never
smoked . These findings highlight the importance of
implementing smoking cessation strategies for patients
eligible for lower limb bypass surgery.
In infrainguinal bypass surgery, the decision as to
which conduit to use is mostly based on the site of the
planned distal anastomosis and the availability of ade-
quate autologous long saphenous vein. It is universally
accepted that autologous saphenous vein is the superior
conduit for infrainguinal revascularization, particularly
when the vein is of normal size and free of sclerotic seg-
ments. However, many studies have reported acceptable
results with synthetic grafts for femoro-popliteal bypass
grafting, particularly in ‘claudicants’ and when the distal
anastomosis is supragenicular [35-37]. The preferred
conduit in our study was reversed long saphenous vein.
Overall, the graft material was not associated with vari-
able graft patency rates. However, when the different
surgical subgroups are examined separately, femoral-
distal bypass with synthetic graft material is associated
with significantly reduced patency rates than femoral-
distal bypass using vein grafts. This finding concurs with
many of those described in the published vascular litera-
ture to date [38,39].
We conclude that among the demographic and operative
factors which can predict graft failure, the most impor-
tant are female gender, the presence of critical ischaemia
at time of primary surgery, the occurrence of a post-op-
erative complication and high ASA grade. A pre-operative
history of smoking was not shown to adversely affect
long-term graft patency. Similarly, the presence of dia-
betes mellitus was not associated with graft failure,
though the number of diabetics in this patient population
is relatively low and larger series may be required in
order to prove this conclusively. We submit that these
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