Cardiac imaging is one of the main components of the etiological investigation of ischemic strokes. However, basic and advanced cardiac imaging remain underused in most stroke centers globally. Computed tomography angiography (CTA) of the supra-aortic and intracranial arteries is the most frequent imaging modality applied during the evaluation of patients with acute ischemic stroke to identify the presence of a large vessel occlusion. Recent evidence from retrospective observational studies has shown a high detection of cardiac thrombi, ranging from 6.6 to 17.4%, by extending the CTA a few cm below the carina to capture cardiac images. However, this approach has never been prospectively compared against usual care in a randomized controlled trial. The DAYLIGHT (ExtendeD computed tomogrAphy angiographY for the successfuL DIaGnosis of cardioaortic tHrombus in Acute Ischemic stroke and TIA) prospective, randomized, controlled trial will evaluate whether an extended CTA (eCTA) + standard of care stroke workup results in higher detection rates of cardiac and aortic source of embolism compared to standard CTA (sCTA) + standard of care stroke workup. DAYLIGHT is a single-center, prospective, randomized, open blinded end-point trial, aiming to recruit 830 patients with suspected acute ischemic stroke or transient ischemic attack (TIA) being assessed under acute code stroke at the Emergency Department or at a dedicated urgent stroke prevention clinic. Patients will be randomized 1:1 to eCTA vs sCTA. The eCTA will expand image acquisition caudally, 6 cm below the carina. All patients will receive standard of care cardiac imaging and diagnostic stroke workup. The primary efficacy endpoint will be the diagnosis of a cardioaortic thrombus after at least 30 days of follow-up. The primary safety endpoint will be door-to-CTA completion. The diagnosis of a qualifying ischemic stroke or TIA will be independently adjudicated by a stroke neurologist, blinded to the study arm allocation. Patients without an adjudicated ischemic stroke or TIA will be excluded from the analysis. The primary outcome events will be adjudicated by a board-certified radiologist with subspecialty training in cardio-thoracic radiology and a cardiologist with formal training in cardiac imaging. The primary analysis will be performed according to the intention-to-diagnose principle and without adjustment by logistic regression models. Results will be presented with odds ratios and 95% confidence intervals Conclusion. The DAYLIGHT trial will provide evidence on whether extending a CTA 6 cm below the carina results in an increased detection of cardio-aortic thrombi compared to standard of care stroke workup. gov registration: NCT05522244.