osis ▁may ▁result ▁in ▁par ado x ical ▁em bol ism ▁in ▁patients ▁with ▁P FO . ▁About ▁ 4 0 % ▁of ▁patients ▁with ▁crypt ogen ic ▁stroke ▁have ▁P FO ▁compared ▁with ▁ 2 5 % ▁of ▁the ▁general ▁population . ▁However , ▁the ▁actual ▁em bol ic ▁source ▁can ▁often ▁not ▁be ▁identified . ▁▁▁ ▁Non - sten otic ▁ar ter ial ▁pla ques : ▁Comp licated ▁pla ques ▁with ▁signs ▁indic ative ▁of ▁int ra - pla que ▁ha emor rh age ▁in ▁an ▁i ps il ater al ▁car ot id ▁ar tery ▁are ▁detected ▁in ▁ 1 ▁in ▁ 4 ▁of ▁patients ▁with ▁crypt ogen ic ▁stroke . ▁A ort ic ▁arch ▁a ther os cl eros is ▁is ▁believed ▁to ▁be ▁a ▁specific ▁cause ▁of ▁ES US , ▁particularly ▁with ▁pla ques ▁> 4   mm ▁diameter . ▁ ▁Further ▁card iop ath ies : ▁the ▁risk ▁of ▁is cha em ic ▁stroke ▁is ▁increased ▁by ▁sup ra vent ric ular ▁t ach y card ias . ▁This ▁also ▁applies ▁to ▁patients ▁with ▁elev ated ▁N T - pro B NP ▁levels ▁and ▁patients ▁with ▁at rial ▁en larg ement ▁in ▁card iac ▁ul tras ound . ▁ ▁Other ▁causes : ▁Ar ter ial ▁dis sections , ▁in fection - related ▁vas cul op ath ies ▁( esp . ▁Var ic ella ▁z oster ▁virus ), ▁th rom b oph ilia , ▁cancer - related ▁th rom b osis , ▁mig raine , ▁Fab ry ▁disease