Twelve-month results from the WRAPSODY Arteriovenous Access Efficacy (WAVE) pivotal trial show a statistically significant improvement in target lesion primary patency (TLPP) with the Wrapsody (Merit Medical) cell-impermeable endoprosthesis (CIE) when compared to percutaneous transluminal angioplasty (PTA).
The prospective, multicentre, international WAVE trial, conducted across 43 centres in the USA, South America and the UK, includes patients with arteriovenous fistula (AVF) with venous outflow stenosis or occlusion in their peripheral venous outflow circuit.
These results were presented by Dheeraj Rajan (University of Toronto, Toronto, Canada) at the Society of Interventional Radiology (SIR) annual scientific meeting (29 March–2 April, Nashville, USA). Rajan detailed that treatment efficacy was determined by the proportion of patients with TLPP, defined as freedom from clinically driven target lesion revascularisation or target lesion thrombosis. A key secondary endpoint at 12 months was access circuit primary patency (ACPP).
A total of 245 patients were randomised, 122 to treatment with Wrapsody and 123 to PTA. Rajan reported that no statistically significant difference in the proportion of patients free from a safety event was observed through to 30 days post procedure (Wrapsody CIE: 96.6%; PTA: 95%; non-inferiority p<0.001). At six months, the TLPP was higher for patients treated with Wrapsody versus PTA (89.8% vs. 63%; p<0.0001) and remained higher than the PTA cohort at 12 months (70.1% vs. 41.6%, p<0.0001). The six-month ACPP was higher for patients treated with Wrapsody versus PTA (72.8% vs. 58%, p=0.014) and remained higher at 12 months (58.1% vs. 34.4%, p=0.0003).
“Looking at our 12-month primary patency, you can see the survival benefit is maintained and actually separates over time,” said Rajan, reflecting on their results. “As the curves continue to separate, I argue that there’s a continued therapeutic benefit [with Wrapsody] over time, and for access circuit primary patency as well.”
Rajan added: “Within dialysis access, those of us that do it, we know that the outcomes of vascular access directly contribute to the mortality and morbidity of patients. There’s a really high cost to maintaining these accesses, and to date, all comparative studies still consider PTA as the gold standard for treatment.
“Although PTA has done reasonably well [in trial settings], there has always been room for improvement, and we’ve chased that [via the WAVE trial],” Rajan told the SIR audience. “We’ve seen improved TLPP with covered stents in the past, but the access circuit primary patency doesn’t change much. The argument has always been why would you use these devices if you aren’t changing the overall lifespan of the access,” said the speaker.
The WAVE trial is currently ongoing and 24-month results are forthcoming, announced Rajan. In light of the sustained improvement in TLPP and ACPP with Wrapsody, and the “limited options available to restore and maintain access circuit primary patency”, the authors state that these findings are of “high value” to clinicians who treat stenosis/occlusion in the venous outflow circuit of haemodialysis patients, and for the patients themselves.
