Arteriovenous anastomosis creation brings blood pressure down

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The ROX CONTROL HTN, an international randomised controlled trial, published online ahead of print in The Lancet in late January, has demonstrated that creation of a central arteriovenous anastomosis in patients was associated with significantly reduced blood pressure and hypertensive complications at six months. The study was funded by Rox Medical.

Investigators led by Melvin D Lobo, Queen Mary University of London, UK, randomised 83 patients with uncontrolled hypertension to either receive arteriovenous coupler therapy in addition to their antihypertensive regimen (n=44) or continue on their current pharmaceutical treatment alone (n=39). They found that the group treated with the intervention had a significant drop in blood pressure whereas patients who were on medication alone did not experience a significant change in their blood pressure.

Creation of the arteriovenous anastomosis involves Rox Medical’s flow procedure, a minimally invasive, catheter-based procedure in which a small nitinol coupler is inserted between the artery and vein in the upper leg. The procedure reduces peripheral vascular resistance and is fully reversible. The ROX coupler device holds CE Mark approval in Europe but remains investigational in the USA.

In order to be considered for enrolment in the ROX CONTROL HTN trial, patients had to have an office systolic BP of at least 140mmHg and an average daytime ambulatory pressure of at least 135/85mmHg while taking at least three antihypertensive medications of different classes, including a diuretic. The primary endpoint was mean change from baseline in office and 24h ambulatory systolic blood pressure at six months.

The investigators found that mean office systolic blood pressure reduced by 26.9mmHg in the arteriovenous coupler group (p<0·0001) and by 3.7mmHg in the control group (p=0·31). Mean systolic 24h ambulatory blood pressure reduced by 13.5 mmHg (p<0·0001) in the group that received arteriovenous coupler and by 0.5mmHg (p=0·86) in controls.

This early stage research was described as promising by an accompanying Lancet commentary and is a shot in the arm for interventional treatments of resistant hypertension in the aftermath of decreasing referrals and cessation of reimbursement for renal denervation.

As reported, the investigators further observed that implantation of the arteriovenous coupler was associated with late ipsilateral venous stenosis in 12 (29%) of 42 patients and was treatable with venoplasty or stenting. “This approach might be a useful adjunctive therapy for patients with uncontrolled hypertension,” the authors wrote.