A finger-prick blood test could help suspected stroke patients by fast-tracking them straight to hospitals that offer a groundbreaking procedure and boost the chance of recovery.
Over the next six months the London Ambulance Service will pilot the ten-minute test, with paramedics checking patients in ambulances.
It has 95 per cent accuracy and can show whether a person is likely to benefit from a life-saving mechanical thrombectomy. If a blood test has a positive result, it means a patient can be taken straight to a hospital that provides the procedure.
For patients with the most severe strokes, a thrombectomy can cut mortality by a fifth and doubles the chance of recovery without lasting disability.
Dr Robert Simister, a consultant neurologist at the University College London Hospitals NHS Trust, who is leading the pilot programme, said: “It’s an exciting time in pre-hospital stroke care. We are really hopeful that this pilot gives us the clearest possible signal that blood biomarkers can help us make pre-hospital decisions. If you can do that, then you can save lots of time by avoiding going to the wrong hospital.”
There are two types of strokes, ischaemic and haemorrhagic. The first involves a clot in the blood vessels to the brain, and when this occurs in the largest vessels it can be treated with a thrombectomy, and the second is a brain bleed that requires a different approach.
In theory thrombectomies could benefit 15 per cent of the 100,000 UK stroke victims a year. The snag is that only 24 hospitals in England offer the procedure, which ideally needs to happen within six hours of a stroke.
In the £100 test, a drop of blood from the fingertip is applied to two cartridges, similar to those used for Covid-19 nose-swab tests. These measure the D-dimer and GFAP biomarkers, linked to clot formation and a brain bleed respectively. If the first is positive and the second negative, an ambulance will go directly to a hospital that can give a thrombectomy.
The pilot scheme will involve 280 ambulances in London. Ken Crossley, of London Ambulance Service, said: “Our paramedics are often the first clinicians to assess stroke patients. Tools that help identify the most severe strokes earlier could improve how quickly patients receive specialist treatment.”
In a thrombectomy, a catheter and guidewire is inserted into a blood vessel in the groin. A surgeon uses an x-ray scanner and a contrast dye to direct the catheter towards the brain and the blocked artery. A special device is then sent through the catheter to remove the clot and restart blood flow.
The procedure has transformed stroke recovery. Trials have shown that when patients with serious strokes receive the procedure along with clot-busting drugs, 21 per cent show good recovery within 24 hours and 46 per cent within three months.
Of those given drugs alone, only 8 per cent can be expected to recover within 24 hours and 26 per cent within three months. Other trials have shown that, at 90 days, a thrombectomy cuts mortality by 19 per cent.
The NHS wants to increase thrombectomy rates from the current 5 per cent to 10 per cent then 15 per cent.
Simister believes the finger-prick test, called LVOne, could significantly increase the use of thrombectomies by sending patients to the right hospitals. At present they are sent to a nearby hospital for a scan and only then go to a thrombectomy-enabled hospital if needed. Often that delay is too long.
Maeva May, director of research for the Stroke Association, which helped to fund the development of the test, said: “Timely treatment for stroke patients is vital: some 1.9 million brain cells die every minute following the onset of stroke. Thrombectomy is a game-changer, which can make the difference between a stroke survivor living independently, or relying on the support of the state and loved ones just to carry out everyday tasks.”
She added: “Improving how we identify and triage stroke patients before they reach hospital is one of the biggest opportunities to strengthen stroke care.”
LVOne is made by UpFront Diagnostics of Cambridge. Gonzalo Ladreda, its chief executive and co-founder, said the pilot was a “milestone” for stroke care, adding: “After eight years’ research and development, we are bringing this technology into real-world emergency care.”
Simister said he hoped to see stroke care undergo a transformation similar to that with cardiac care when ECGs were first used. “By enabling paramedics to identify likely large vessel occlusion stroke in the ambulance, we can prepare specialist teams before the patient arrives and potentially reduce delays significantly,” he said.
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