Imperial College London

Academic Institute

Ali Alsafi

Unknown

No

NIBDAPC_2026_0055

Strokes are an important cause of disability or death, and people who have multiple little strokes may develop dementia. For these reasons, preventing stokes is an important part of healthcare. Strokes can be caused by abnormal blood vessels in the lungs called pulmonary arteriovenous malformations (PAVMs). This is because PAVMs allow small blood clots and blood-bourne infections to reach the brain, instead of being removed or made safe in lung capillaries. Of 10 people with PAVMs, at least 2 or 3 will have an ischaemic stroke (‘infarct’) or brain abscess. Doctors at Hammersmith Hospital pioneered PAVM stroke preventation treatments, and continue to deliver preventative care, including online advice on general approaches. With improved hospital scanners, much smaller PAVMs are now detected than in the past. They might be as tiny as a pinhead, and difficult to diagnose for certain. Doctors do not know if tiny PAVMs increase risks of stroke. Patients have identified many problems that shaped the research. Some said their lives were ‘put on hold’ while they had their diagnostic tests, or waited to see an expert. Some said when their PAVM was found, this delayed other important treatments including for cancer. Others worry that the smallest PAVMs cannot be cured. The research team will look at the data from people with PAVMs treated at Imperial to see if smaller PAVMs cause strokes as often as larger PAVMs. Patients with lived experience of PAVMs will be the first to see the results and consider how best to reduce risks in the future. They will help the research team communicate the research findings to other patients, to doctors, to NHS Commissioners who recently asked Imperial to lead a national PAVM network to improve care, and to scientists to discover new treatment approaches.

Pulmonary arteriovenous malformations (PAVMs) are important because they can lead to early strokes, brain abscesses, and other complications, even if someone is very healthy. Preventing these strokes has been a priority for the PAVM clinical teams at Hammersmith for more than 40 years. Stroke prevention is also a general priority for the public, with stroke prevention a clinical priority in the NHS Long Term Plan. Our research will enhance awareness of the general care that is recommended if PAVMs are present. Most people diagnosed with a PAVM have not had a stroke, and will never have one. We realised extra awareness was needed because there are more than 20,000 people with PAVMs in the UK, and almost all who come to our clinical service find the stroke-preventative treatments valuable, while getting on with their daily lives. Antibiotics are prescribed for immediately before a visit to the dentist or any surgery - because blood flowing through the PAVMs bypasses the lung capillaries that normally make safe any bacteria (bugs) that enter the bloodstream. Blood thinners are recommended to use as in the general population, even if someone has nosebleeds. Patients telling us when this ideal advice was not received helped NHS England to recognise that greater awareness of PAVMs is needed from doctors around the country resulting in the NHS Rare Disease Collaborative Network for PAVMs that Imperial leads. Our research will enhance awareness of strokes due to PAVMs. Strokes can be minor, but many are devastating for the person and their family, especially it someone is in the prime of their life, or has caring responsibilities for young children. One patient provided a vivid description of how a brain abscess due to an undiagnosed PAVM affected her and her family for a paper we published in 2025. She and many others report long-term physical burdens such as difficulties speaking, reading, walking, or functioning normally. Other patients have reported the hidden burdens where they may seem to have made a good recovery but have had to adapt their lifestyle, or live with the worry they may have another stroke. A discussion on this topic at our 4th Imperial HHT Family Meeting in 2017 was led by one of the authors of HiddenInMe. Our research will test whether very small PAVMs now found on CT scans increase stroke risks. We have had the priviledge to hear directly from patients over many decades. In the current proposal, one focus is on these much smaller PAVMs that patients tell us were also the most difficult for their doctors to diagnose. Our research questions are also designed so that better stroke preventative treatments can be given to people whose PAVMs cannot be treated completely. Patient observations prompted us to incorporate new types of data compared to our previous studies, and we will be working with them as we use the new evidence from the database, their lived experience and our professional insights to improve stroke prevention for people with PAVMs.

Public Health Research

04/02/2026

Not applicable

Not applicable

One-off

TRE