A 55-year-old gentleman with a left-sided glioblastoma multiforme (GBM) presented with palpitations which were shown to be atrial flutter (AFL) on ECG. Approximately 6 h later, he developed ataxia and expressive dysphasia. A brain CT scan showed no acute haemorrhage and no progression of the brain tumour. Ischaemic stroke was the top differential diagnosis. However, the authors could not perform thrombolysis due to the risk of intratumour haemorrhage. The AFL reverted to sinus rhythm with metoprolol and digoxin after 3 days. His neurological signs resolved within 24 h, and a diagnosis of transient ischaemic attack secondary to AFL was made. This case highlights the challenge of managing thrombo-embolic complications of arrhythmias in cancer patients.