Ischemic stroke is one of the leading causes of death and disability. Atrial fibrillation (AF) is a well-recognized risk factor for ischemic stroke.We aimed to investigate the impact of AF on in-hospital mortality of ischemic stroke patients and to identify parameters associated with intra-cardiac thrombogenic material.Patients were selected by screening the nationwide sample for ischemic stroke by ICD-Code (I63), stratified for AF. In this cohort, the association between in-hospital deaths and AF was investigated.In a second study, we performed a retrospective analysis of patients who underwent transesophageal echocardiography (TEE) for various reasons, assigned these to 2 groups based on the heart-rhythm (sinus-rhythm [SR] vs AF) and examined associations between clinical and echocardiographic parameters and intra-cardiac thrombogenic material.The Nationwide sample comprised 292,401 inpatients (48.5% females) with ischemic stroke. Incidence was 360 per 100,000 citizens, with an age-dependent increase. In-hospital mortality rate was 8.2%; AF patients had 1.85-fold higher mortality rate (12.1% vs 6.5%).In the retrospective study, 219 patients (median age 67 [59.1-77.3] years, 39.3% females) were included: 115 patients with AF (median age 71 [59.0-78.0] years, 41.7% females) and 104 patients (median age 68 [56.3-76.8] years, 36.5% females) with SR. Solid thrombus or spontaneous-echo-contrast) was detected in 16 TEEs. Atrial dimensions were significantly enlarged in AF patients. Age, blood-flow velocity in LAA, LAA diameters, atrial areas, AF, and CHA2DS2-VASc-score were associated with thrombogenic material.Incidence of ischemic stroke increased with age. AF was connected with higher stroke mortality. Presence of intra-cardiac thrombogenic material was associated with AF and most CHA2DS2-VASc-score factors. AF was associated with larger atrial dimensions and larger cavities favored thrombogenic material.