P200
ARTERIOVENOUS FISTULA (AVF) THROMBOSIS. RISK FACTORS AND ROLE OF
ANTIPLATELET THERAPY, WARFARINISATION AND THOMBOPHILIA SCREEN?
K Abdulnabi1, M Morcos1, N Denham1, A Ullah1, A Khalil1, M Howse1, H Anijeet1, J Alexander1,
P pai1, I Rylands4, S Powell2, Mr D Ridgway3
Nephrology department1, Radiology department2, Renal transplant department3, The Royal Liverpool
University Hospital, Edge Hill University4
INTRODUCTION:
AVF thrombosis is the most common cause of fistulae failure and related complications. It is almost
always associated with the presence of stenosis. The evidence for using anticoagulation and
antiplatelet therapy and testing for thrombophilia is conflicting. This study was designed to assess the
effect of comorbidities, pharmacological therapy on AVF/ graft thrombosis.
Andrassy et al (cumulative survival), Dember et al, Gorbani et al (primary patency) illustrated that
antiplatelet therapy decreases AVF failure while Yevzlin and Kooistra et al show worse outcome or
no benefit for the later. Crowther et al and DOOPS demonstrated that warfarin increases failure risk
for fistulae and grafts respectively.
METHODS:
Retrospective data analysis on 426 AVF and 54 arteriovenous graft (AVG) on prevalent
haemodialysis patients at a tertiary renal centre. Thrombosis was defined as thrombosis which renders
AVF/AVG non-functioning and requiring intervention. Data on AVG was not processed due to small
sample
RESULTS:
Thrombosis was reported in 63% of AVG compared only to 28% of AVF, p≤0.0001.
With regards of AVF; univariate analysis shows that age, gender, AF, PVD, IHD, CVA, LVD, HTN,
type 2 DM, hypercoagulable state, and intra-dialytic hypotension were not associated with the risk of
thrombosis. However, type 1 DM, Aspirin (75mg) proximal AVF site and vascular calcification,
metallic fistula stent, vintage on dialysis, previous AVF failure and history of sever venous stenosis
were associated with thrombosis.
On multivariate analysis, only sever venous stenosis, metallic stent and Aspirin were predictors of
fistula thrombosis.
Variable
Sever venous stenosis
Aspirin
Clopidogrel
Dipyridamole
Warfarin
Previous AVF Failure
Calcification
Hypercoagulable state
Previous VTE
Positive HIT test
Proximal AVF site
OR, CI 95%
3.57(2.22 – 5.75)
1.66 (1.05 – 2.63)
0.80 (0.35 – 1.83)
0.36 (0.04 – 3.44)
1.19 (0.47 – 2.99)
1.63 (0.99 – 2.69)
1.49 (0.88 – 2.50)
1.36 (0.77 – 2.38)
1.56 (0.64 – 3.80)
2.08 (0.38 – 11.38)
1.39 (0.88 – 2.27)
P
0.0001
0.03
0.59
0.38
0.72
0.057
0.13
0.29
0.32
0.34
0.20
Thrombophilia screen was performed in 18 patients. Only one of them had positive test but his fistula
has been functioning for 4 years with no thrombotic event reported.
CONCLUSION:
Aspirin with a dose of 75 mg was associated with risk of thrombosis. Other Anti-platelet including
dual therapy did not decrease the risk of AVF thrombosis. Warfarin didn’t decrease the risk of
thrombosis in AVF. Thrombophilia screen in patients with recurrent fistula thrombosis might not be
justified based on its complexity, cost and this study results. Finally, not surprisingly, significant
correlation was noted between sever stenosis requiring angioplasty and thrombosis