An ischaemic stroke occurs when a blood vessel supplying part of the brain is blocked by a clot or other obstruction, cutting off the blood and oxygen supply to an area of brain tissue. Within minutes, the affected brain cells begin to die, causing neurological deficits that reflect the function of the area damaged. Ischaemic strokes account for approximately 85 percent of all strokes; the remainder are haemorrhagic (caused by a burst blood vessel).
Ischaemic stroke and cardiac arrest are closely linked in several ways. Atrial fibrillation (AF) is the most common cardiac cause of ischaemic stroke: irregular atrial contraction allows blood to pool in the left atrial appendage, where it can clot and embolise to the brain. This cardioembolic stroke is typically larger and more severe than strokes from other causes. Additionally, a patent foramen ovale (PFO, a hole in the atrial septum) can allow clots from the venous circulation to pass into the arterial circulation and reach the brain. After cardiac arrest, cerebral hypoperfusion during the period of circulatory arrest can itself cause ischaemic brain injury across multiple territories.
The early management of acute ischaemic stroke centres on restoring blood flow as quickly as possible. Thrombolysis (clot-dissolving medication, most commonly alteplase) is given intravenously within 4.5 hours of symptom onset in eligible patients. Mechanical thrombectomy (physically removing the clot using a catheter-based device) is increasingly used for large vessel occlusions within a longer time window and has transformed outcomes for major strokes. Anticoagulation is used to prevent further cardioembolic strokes in patients with AF.
For survivors of cardiac arrest, particularly those with a complex hospital course, stroke is a recognised complication. Cardioembolic events can occur if atrial fibrillation develops post-arrest or if left ventricular thrombus forms on a stunned or infarcted heart. Any new neurological symptoms in a cardiac arrest survivor, including facial weakness, arm weakness, speech difficulty or sudden visual change, require urgent medical assessment following the FAST (Face, Arms, Speech, Time) guidance.
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