A groundbreaking clinical trial led by London Health Sciences Centre Research Institute (LHSCRI) and Western University's Schulich School of Medicine & Dentistry may enhance how medical professionals detect hidden blood clots responsible for strokes. The study, published in The Lancet Neurology, is the first to show that extending imaging to include the heart within minutes of a patient's arrival to hospital with an acute stroke significantly improves the ability to determine the stroke's underlying cause. This innovative diagnostic approach can be used to determine an effective and tailored treatment plan for preventing future strokes.
Strokes caused by blood clots or other mechanisms that obstruct blood flow in the brain account for about 85 per cent of all strokes. In this study, scientists from LHSCRI and Schulich Medicine & Dentistry set out to determine whether strokes with undetermined causes could be identified using computed tomography (CT) scans that include images of the heart and aorta, a main blood vessel.
Identifying where the clot came from is essential because it determines the safest and most effective treatment. If the clot originated in the heart, we typically use blood thinners to prevent future strokes."
Dr. Luciano Sposato, Scientist at LHSCRI, Head of the Southwestern Ontario Regional Stroke Centre at London Health Sciences Centre (LHSC), and Professor of Neurology at Schulich Medicine & Dentistry
The clinical trial included 465 patients admitted to LHSC's University Hospital who were treated for an acute stroke or transient ischemic attack. The study found that using the extended CT scan increased the detection of blood clots in the heart by 600 per cent compared to standard imaging practice. They also found the extended CT scan did not delay completion of CT imaging in these emergency situations. The study found one clot for every 14 patients scanned with the new approach.
"If we did not extend the CT scan, some of these blood clots may not have been found and these strokes would have been classified as having an undetermined cause," says Dr. Rodrigo Bagur, researcher at LHSCRI, Cardiologist at LHSC, and Professor at Schulich Medicine & Dentistry.
The study was funded by the Department of Medicine, the Kathleen and Dr. Henry Barnett Chair in Stroke Research, and the Saraydar Neurosciences Fund.
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Journal reference:
Sposato, L. A., et al. (2025). Extended CT angiography versus standard CT angiography for the detection of cardioaortic thrombus in patients with ischaemic stroke and transient ischaemic attack (DAYLIGHT): a prospective, randomised, open-label, blinded end-point trial. The Lancet Neurology. doi.org/10.1016/S1474-4422(25)00111-5.
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