The ISAT trial (International Subarachnoid Aneurysm Trial) compared neurosurgical clipping versus endovascular coiling for ruptured intracranial aneurysms. What was its primary finding regarding dependency and death at 1 year?
- A Clipping was superior to coiling for all aneurysm locations including middle cerebral artery
- B Coiling and clipping had equivalent outcomes with no significant difference in dependency at 1 year
- C Clipping was superior for posterior circulation aneurysms; coiling for anterior circulation
- D Coiling resulted in significantly lower dependency/death at 1 year (23.7% vs 30.6%) but higher late rebleed rate ✓
Explanation
The ISAT trial showed that endovascular coiling significantly reduced death or dependency at 1 year compared to neurosurgical clipping (23.7% vs 30.6%, absolute risk reduction 6.9%). However, coiling was associated with a higher risk of late rebleeding and a greater likelihood of needing retreatment. MCA aneurysms were underrepresented in the trial and are generally more amenable to surgical clipping. ISAT fundamentally shifted practice toward coiling for eligible ruptured aneurysms. The BRAT trial and subsequent analyses confirmed coiling advantage but emphasized case-specific decision-making.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.