The Extended CTA for the Successful Screening of Cardioaortic Thrombus in Acute Ischemic Stroke and TIA (DAYLIGHT) Trial

Embolic strokes of undetermined source (ESUS) represent a subset of cryptogenic strokes that are suspected to have an occult embolic source. The risk of stroke recurrence in patients with ESUS varies between 1.9%/year and 19.0%/year depending on the prevalence of vascular risk factors. Part of the elevated recurrence rate is due to the inability to identify high-risk treatable causes such as cardiac thrombi as those found in the left atrial appendage (LAA), left atrium (LA), left ventricle (LV), valves, or aortic arch. The most frequently used diagnostic method in clinical practice to detect cardioaortic thrombi is transesophageal echocardiography (TEE). However, the relatively low availability, higher cost, and invasive nature of TEE limit its large-scale usability. In most stroke centers, patients presenting with an acute ischemic stroke or TIA undergo a tomography (CT) angiography (CTA) of the neck and intracranial vessels. This standard of care CTA (sCTA) classically includes the aortic arch, the higher portion of the ascending/descending aorta, and the rostral portion of the cardiac chambers, but does not involve the LAA, LV, or cardiac valves. A recent study performed among 300 patients with an acute ischemic stroke showed an overall LAA thrombus detection of 6.6% and 15% in patients with AF by extending the CTA 6 cm below the carina. This is an extraordinarily high prevalence of LAA compared to 0.5% to 4.8% of intracardiac thrombi identified on TEE in most previous studies. The major limitation of previous CTA and TEE studies is their observational design, so the differing prevalence of LAA thrombi could be explained by dissimilar population characteristics or selection bias. Based on the methodological limitation of prior studies and the promising role of extended CTAs (eCTA), a randomized controlled trial comparing eCTA + standard of care stroke workup vs. sCTA + standard of care stroke workup is needed.