Acute ischaemic stroke in the absence of established vascular risk factors: Patient characteristics, stroke mechanism and long‐term outcome

Background and purpose Some acute ischaemic stroke (AIS) patients do not display established vascular risk factors (EVRFs). The aim was to assess their clinical characteristics, stroke subtype etiological classification and long‐term outcome. Methods All consecutive AIS patients from the Acute Stroke Registry of Lausanne (2003–2018) were retrospectively analyzed with complete assessment of the following EVRFs: hypertension, diabetes, major cardioembolic sources, dyslipidemia, smoking, obesity, alcohol abuse, previous stroke/transient ischaemic attack and depression/psychosis. Patients without EVRFs were compared to patients with one or more EVRFs using appropriate statistical models. Results Of 4889 included patients, 103 (2.1%) had no EVRFs. In multiple regression analysis, patients without EVRFs were significantly younger (odds ratio [OR] 0.13; 95% confidence interval [CI] 0.08–0.20) and had more multiterritorial strokes (OR 3.38; 95% CI 1.26–9.05). Strokes were more often related to patent foramen ovale (PFO) (OR 3.02; 95% CI 1.44–6.32) and less to atherosclerosis, cardioembolism or small vessel disease. In patients