A 64-year-old man was brought to the emergency department because of lefthemiplegia with impaired consciousness. On physical examination, consciousnesslevel was GCS E4V4M6, blood pressure 164/82 mmHg, pulse rate 96/min andirregular. Neurological examination was unremarkable except for left hemiplegia.Nocarotidbruitwasheardoneitherside.BrainMRIisshowninthefigure(別冊No.22).Which of the following is the most likely ECG diagnosis?