In their recent systematic review and meta-analysis, Venkata Sai Jasty (University of Arizona, Tuscon, USA) and colleagues found that the risk of ischaemic steal syndrome, “one of the most feared complications in vascular access,” and patency rate are comparable for both tapered and non-tapered prosthetic arteriovenous grafts (AVGs) in dialysis access.
Writing in The Journal of Vascular Access (JVA), Jasty et al detail that end-stage renal disease (ESRD) “remains one of the leading causes of mortality and morbidity”. They note that there are currently three treatment options for ESRD—haemodialysis, peritoneal dialysis, and organ transplantation—but mention that a shortage of organ supply for a rising need has led to “a continued and increased call” for haemodialysis.
Upper extremity arteriovenous access “remains the preferred vascular access for haemodialysis in ESRD patients,” the authors relay, detailing that an arteriovenous fistula (AVF) or AVG are generally favoured over a central venous catheter, “due to lower rates of infection, hospitalisation, cardiovascular events, and all-cause mortality rate”.
They write that prior guidelines recommended AVFs as the initial choice for haemodialysis access due to more durability, higher patency rates, and lower morbidity and mortality compared to AVGs. However, “due to high failure rates of AVF from inadequate maturation and interventions required to achieve and maintain a functional AVF,” they stress that the latest guidelines from the National Kidney Foundation Kidney Disease Quality Outcomes Initiative (NKF KDQOI) “challenge the use of AVFs on certain populations” and recommend AVGs as the “preferable option” for haemodialysis.
Jasty and colleagues note that one of the biggest complications of vascular access placement is ischaemic steal syndrome, where blood is diverted from the hand to the graft, leading to hand ischaemia. To mitigate this problem, they detail that tapered grafts were created. These grafts have a smaller diameter at the arterial anastomosis, they write “which leads to decreased blood flow from the artery to the graft, thus lowering the risk of ischaemic steal”.
“It is unclear whether tapered AVGs are superior to non-tapered AVGs when it comes to preventing upper extremity ischaemic steal syndrome,” Jasty and colleagues state, noting that this gap in the literature led them to evaluate the outcomes of both graft types using a systematic review and meta-analysis.
The investigators performed a literature search in order to identify all English language publications from 1999 to 2019 that directly compared the outcomes of upper extremity tapered and non-tapered AVGs. They evaluated primary patency at one year (number of studies [n]=4), secondary patency at one year (n=3), and risk of ischaemic steal (n=5) and infection (n=4).
Of 5,808 studies screened, Jasty et al identified a total of five studies involving 4,397 patients that met the inclusion criteria and were therefore included in the analysis. They write in JVA that the meta-analyses revealed no significant difference for the risk of ischaemic steal syndrome (pooled odds ratio [OR] 0.92, 95% confidence interval [CI] 0.29–2.91, p=0.12, I2=48%) between the tapered and non-tapered upper extremity AVG.
In addition, they report that the primary patency (OR 1.33, 95% CI 0.93–1.9, p=0.12, I2=10%) and secondary patency at one year (OR 1.49, 95% CI 0.84–2.63, p=0.17, I2=13%), and rate of infection (OR 0.62, 95% CI 0.3–1.27, p=0.19, I2=29%) were also similar between the tapered and non-tapered AVGs.
The authors acknowledge certain limitations of this meta-analysis, including a low number of studies, unknown reasons for surgeons’ preference for one graft over the other, and a low number of patient samples and short follow-up (usually up to one year only) in the included studies.
Jasty and colleagues conclude: “This meta-analysis does not support the routine use of tapered graft over non-tapered graft to prevent ischaemic steal syndrome in upper extremity access”. However, due to the small number of studies and sample sizes, as well as limited stratification of outcomes based on risk factors, they stress, “Future studies should take such limitations into account while designing more robust protocols to elucidate this issue”.