Mechanical Thrombectomy Has Revolutionised Treatment of Acute Ischemic Stroke

Understanding Acute Ischemic Stroke

An ischemic stroke occurs when a blood vessel supplying the brain is suddenly blocked most commonly by a blood clot (thrombus or embolus). Brain tissue deprived of blood begins to die within minutes. The famous maxim in stroke care is 'time is brain': every minute of untreated large vessel occlusion, approximately 1.9 million neurons are lost. Large vessel occlusion (LVO) blockage of the internal carotid artery, middle cerebral artery (M1 or M2 segment), basilar artery, or other major intracranial vessels accounts for approximately 25–40% of ischemic strokes but is responsible for the most severe neurological deficits and deaths.

• Stroke is the second leading cause of death worldwide
• LVO strokes are the most devastating type
• Brain loses 1.9 million neurons per minute without treatment
• 'Time is brain' every second counts
• Mechanical thrombectomy now offers hope for LVO stroke patients

What is Mechanical Thrombectomy?

Mechanical thrombectomy is a minimally invasive Interventional Radiology/Neurointerventional procedure in which a clot is physically retrieved from a blocked brain artery using a stent retriever device or aspiration catheter. The procedure is performed under X-ray fluoroscopy guidance. A microcatheter is advanced from the groin artery (femoral artery) through the aorta, up the carotid artery, and into the blocked intracranial vessel. A stent retriever is deployed across the clot, which entraps the thrombus, allowing it to be retrieved. Alternatively, a large-bore aspiration catheter is advanced to the face of the clot and suction is applied the ADAPT (A Direct Aspiration First Pass Technique) approach. Modern practice often combines both techniques.

The Evidence Why Thrombectomy Changed Everything

Prior to 2015, intravenous thrombolysis (IV-tPA) was the only proven treatment for acute ischemic stroke effective only for smaller vessel occlusions and with a narrow time window. Then, in 2015, five landmark randomised controlled trials (MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, and THRACE) simultaneously published results showing that mechanical thrombectomy was dramatically superior to IV-tPA alone for LVO strokes. The number needed to treat (NNT) was approximately 2.5 meaning for every 2–3 patients treated with thrombectomy, one additional patient had a good functional outcome who would not have done so with medical treatment alone. This is among the highest treatment effect sizes ever seen in a neurological intervention.

• Landmark 2015 trials proved thrombectomy's dramatic efficacy
• NNT of 2.5 — extraordinary treatment effect
• Results led to worldwide adoption as standard of care
• Time window extended to 24 hours with advanced imaging selection
• Successful recanalisation achieved in 70–90% of cases

Who Can Benefit from Mechanical Thrombectomy?

The ideal candidate for mechanical thrombectomy is a patient with acute ischemic stroke caused by large vessel occlusion, who has a significant volume of potentially salvageable brain tissue (the ischemic penumbra), and presents within the treatment window. CT angiography confirms vessel occlusion. Advanced imaging (CT perfusion or MRI diffusion-perfusion) identifies the penumbra. Time windows have been extended significantly up to 6 hours based on stroke onset alone (DAWN and DEFUSE-3 trials), and up to 24 hours in selected patients with favourable imaging profiles. Dr. Shetty works closely with the neurology team at Sparsh Hospitals to rapidly identify eligible patients and bring them to the angio suite as quickly as possible — minimising door-to-reperfusion time.