Transcatheter Aortic Valve Implantation (TAVI)

Transcatheter Aortic Valve Implantation (TAVI) is a minimally invasive treatment for Aortic Stenosis (AS), a condition where blood flow out of the heart is restricted by the narrowing of the aortic valve. Researchers from the London School of Hygiene and Tropical Medicine. are currently carrying out the biggest-ever UK TAVI trial to try to improve outcomes for patients.

During a TAVI, a fine wire is inserted, usually into the leg artery, through the aortic valve and into the heart. A folded artificial valve is passed over the wire and positioned inside the old valve.

One risk associated with TAVI is stroke, which affects 2 to 3 in every 100 people undergoing a TAVI. During the procedure, debris (made up of parts of the diseased aortic valve and the surrounding tissue) can be released into the bloodstream. Most strokes occurring at the time of TAVI are due to this debris blocking the arteries that supply the brain.

There are devices available which use tiny filters to capture this debris and stop it from reaching the brain, these are called Cerebral Embolic Protection (CEP) devices. These filters are inserted through a small artery in the arm and are guided into position over a fine wire. The device containing any debris is then removed at the end of the TAVI procedure.

Click here to watch the animated patient information video. 

Studies have shown that the CEP device is safe, but we do not know whether the devices definitely reduce stroke.

BHF PROTECT-TAVI is a randomised controlled trial to assess whether using a CEP device during TAVI can reduce the chance of a patient having a stroke. The trial is based in the UK and will recruit 7,730 patients.

TAVI patients who consent to participate in the trial will be allocated to either the control group, where TAVI is performed in the standard way, or to the intervention group where TAVI is performed with the CEP device.  The groups are decided randomly by a computer. This is called randomisation which means patients have a 50:50 chance of being in either group.

Randomisation ensures that there are two groups which can be compared scientifically and answer the question of whether these devices reduce stroke. This allows clinicians to better understand how to guide the treatment of patients in the future. Both groups are equally important in this study.


The trial has recruited 4200 participants from 31 out of the 33 TAVI centres in the UK. Recruitment for the trial will continue until April 2025.

Clinical trials are essential to improving care for future patients. If you are waiting for TAVI and would like to be a part of the trial, email and a member of the team will discuss it with you.

Patient Story: Lewis

At the very height of the COVID-19 outbreak, retired postman and hospital worker, Lewis Benn, was awaiting treatment for severe aortic stenosis. Having been told he would have to wait till September, Lewis feared for his life, but thanks to the excellent work of Dr Dan Blackman and the team at Leeds General Infirmary, Lewis was admitted, treated and discharged over the course of just 3 days.

Read Lewis’s story in full…