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October 24, 2024 – Montreal, Canada — A simple extension of CT angiography (CTA) scans to include the upper part of the heart in patients presenting with acute stroke has dramatically enhanced the detection of cardioaortic clots, according to findings from the DAYLIGHT trial, presented at the 16th World Stroke Congress.
This approach, which detects heart-originated clots nearly six times more frequently than the standard stroke workup, was led by Dr. Luciano Sposato, a neurology professor and head of the Stroke Program at London Health Sciences Centre, Ontario. “This simple and easy extension of the scan adds minimal extra work but helps us identify high-risk patients with heart clots, who can then be prioritized for anticoagulation and atrial fibrillation monitoring,” Sposato told Medscape.
Typically, 25% of ischemic stroke patients are classified as having an embolic stroke of undetermined origin due to inconclusive diagnostic results, leading to limited options for secondary prevention. In conventional practice, patients may undergo a transthoracic echocardiogram, which has low diagnostic yield, or, in rare cases, a transesophageal echo, which is more effective but expensive and invasive.
The DAYLIGHT trial explored a straightforward solution. Instead of stopping at the neck, the researchers extended the routine CTA by 6 cm to capture the top of the heart, particularly the left atrial appendage, which is a common clot location. Among 465 ischemic stroke or transient ischemic attack (TIA) patients in the trial, those receiving the extended CTA scan showed a clot detection rate of 8.8%, compared to 1.7% in the standard group.
“This approach allows us to identify clots within seconds, without requiring AI or extensive post-processing,” said Sposato. The minor adjustment added only one minute to the scan time and had a negligible impact on radiation exposure.
Potential Changes in Stroke Management
The DAYLIGHT trial could alter stroke management, although its implications for clinical practice are still evolving. Dr. Craig Anderson, chair of the World Stroke Congress session, described the study as “novel and well conducted.” He pointed out that while this method is safe and minimally disruptive to workflow, questions remain regarding the clinical relevance of detected clots.
Sposato, however, believes that patients with identified clots should be considered for early anticoagulation to prevent secondary strokes. “When no other stroke cause is identified and clots are visible in the left atrial appendage, it’s likely these are contributing to the stroke,” he explained. Typically, clot-detection imaging is delayed until after acute treatment, at which point thrombolytic therapy may have dissolved any existing clots, preventing detection.
The extended CTA scan also revealed additional conditions. “We found slow blood flow in the left atrial appendage in 24.3% of the extended CTA patients compared to 7.1% in the standard group, which could suggest an underlying atrial fibrillation risk,” Sposato noted. The extended scans also identified previously unknown pulmonary nodules and asymptomatic pulmonary embolisms in some patients, offering an opportunity for early intervention.
The Future of CTA in Stroke Care: DAYLIGHT 2
Following the DAYLIGHT trial’s success, a follow-up study, DAYLIGHT 2, is underway to refine this imaging protocol. The researchers plan to introduce an immediate delayed-phase CT scan for more accurate visualization of clots. This phase would allow the intravenous contrast to reach the left atrium, providing a clearer picture and taking only a few additional minutes.
As evidence grows, Dr. Sposato has already begun using the extended CTA approach in his hospital. “While we await definitive outcome data, knowing a clot is there helps guide my clinical decisions,” he concluded.
