Supplementary Material for: Clinical Relevance of Patent Foramen Ovale and Atrial Septum Aneurysm in Stroke: Findings of a Single-Center Cross-Sectional Study M.Schnieder T.Siddiqui A.Karch M.Bähr G.Hasenfuss J.Liman M.R.Schroeter 2017 <i>Background:</i> A significant proportion of ischemic strokes are cryptogenic. In this context, the clinical pertinence of patent foramen ovale (PFO) with and without atrial septum aneurysm (ASA) remains controversial. The aim of this study was to identify how PFO +/–ASA and cryptogenic stroke are associated in a representative sample of stroke patients. <i>Methods:</i> We enrolled all patients (<i>n</i> = 909) with ischemic stroke or transient ischemic attack admitted to the certified stroke unit or neurological intensive care unit of our university medical center who underwent transesophageal echocardiography (TEE) between 2012 and 2014. The baseline characteristics, cardio-/neurovascular risk factors, clinical parameters and TEE findings were analyzed. <i>Results:</i> PFO was present in 26.2%, and PFO was combined with an ASA in 9.9%. In cryptogenic stroke, the prevalence of PFO was higher compared to other etiologies (30.9 vs. 21.9%; <i>p</i> < 0.002). Patients with PFO had lower National Institute of Health Stroke Score (NIHSS) values at admission than those without (2 [0–5] vs. 3 [1–7]; <i>p</i> = 0.001; 95% CI [0.62–0.88]). No difference was found in NIHSS values of PFO patients with or without ASA (2 [0–5] vs. 2 [0–5]; <i>p</i> = 0.683; 95% CI 0.94 [0.68–1.28]). <i>Conclusions:</i> Our study indicates that a detected PFO +/–ASA could exhibit a stroke-relevant finding, if classical risk factors for the stroke were lacking.