A 37-year-old male patient presented to the stroke unit of our neurology department with weakness and paresthesia of the right arm and slight anomia. Physical examination revealed distal palsy of both arms, predominantly on the right side. No other pathologic findings were observed. Cranial MRI revealed bilateral territorial infarction in the supply territories of the middle and posterior cerebral arteries. A 12-lead electrocardiography showed incomplete right bundle branch block, negative T waves and ST depression in II, III, aVF and V4–V6 (Fig. 1a). Transesophageal and transthoracic echocardiography revealed normal dimensions of both ventricles with regular systolic and diastolic function. No intracardiac thrombi and no patent foramen ovale could be detected at that time. Holter-ECG did not show paroxysmal atrial fibrillation. Carotid artery stenosis was ruled out by duplex ultrasound.