Lessons of the month 2: FAST is not always FAST.

Thrombolytic treatment with tissue plasminogen activator is an established therapy for selected patients with ischaemic stroke within a narrow time window of 3 hours from the onset of symptoms. However, severe complications and poor outcomes are likely to ensue if a patient with acute aortic dissection is inadvertently treated with thrombolytic agents.We describe a patient presenting as facial droop, arm weakness, speech disturbance and time to call emergency services (FAST) positive (clinical picture of ischaemic stroke) who received thrombolysis and in whom the underlying diagnosis of acute thoracic aortic dissection was made by a combination of chance and a high clinical suspicion. © Royal College of Physicians 2020. All rights reserved.