Older Australians with a build-up of plaque in the arteries leading to their legs and feet have been given good cause to celebrate, with researchers trialling a new type of stent that could help reduce the need for limb amputation.
Developed by University of NSW (UNSW) researchers, the stent is a mechanical scaffold inserted into blocked lower leg arteries that dissolves in the body over 18 to 24 months.
Principal investigator, UNSW Medicine & Health Conjoint Associate Professor Ramon Varcoe, said the stent is designed to only require the artery to be held open for a limited time to restore blood flow and resolve the blockage.
Referred to as Esprit BTK, the stent is coated with a drug that prevents the blood vessel from narrowing, he said.
“The Esprit scaffold gives mechanical support to the recently opened artery, it delivers a drug to the blood vessel wall that prevents re-narrowing, and then it dissolves, leaving nothing behind to irritate the blood vessel and induce scar tissue formation,” he said. “It also avoids burning bridges should the patient require bypass surgery in the future.”
Peripheral Artery Disease (PAD), which most commonly affects the lower limbs, is estimated to affect over 200 million people globally. While no official records are kept in Australia, it was the primary cause of almost 60,000 hospitalisations here in 2020/21. It causes the narrowing of the peripheral arteries, which in severe cases leads to patients experiencing pain, gangrene, and non-healing ulcers. It may require limb amputation, with poor survival rates.
“The prognosis after amputation is worse than most cancers,” says A/Prof. Varcoe, who as well as being a clinical academic is also a vascular surgeon.
When PAD occurs in the blood vessels below the knee, the current treatment is balloon angioplasty where a tiny balloon is inserted into the blocked artery, then inflated to widen the opening and increase blood flow.
During this procedure, which has been around since the 1950s, the treated blood vessel often becomes narrower and the balloon doesn’t stay inflated for long enough. This results in the blood vessel becoming blocked again over time.
Esprit BTK clinical trials done by A/Prof. Varcoe and his team involved 261 patients globally with blocked lower leg arteries, who were at risk of requiring limb amputation. These patients were treated with either balloon angioplasty or Esprit BTK.
The researchers found Esprit BTK was much more effective at keeping the artery open, which is critical for preventing the need for limb amputation. About 75 percent of the Esprit BTK group experienced this outcome, compared to 44 percent of the balloon angioplasty group.
Following the success of the Phase 3 trials, researchers intend to submit Esprit BTK to the Food and Drug Administration (FDA) for approval in the US initially, followed by further submissions in Australia, Europe, and Japan.
The researchers are also working through the Therapeutic Goods Administration’s Authorised Prescriber Scheme to gain early access for patients at the Prince of Wales Hospital.
