The ISAT trial (International Subarachnoid Aneurysm Trial) compared endovascular coiling with neurosurgical clipping for ruptured intracranial aneurysms. Its main conclusion was:

• A Surgical clipping was superior in all anatomical locations and should be the first-line treatment
• B Endovascular coiling resulted in better 1-year clinical outcomes (reduced death and dependency) in suitable patients, but coiled aneurysms had higher long-term rebleeding rates requiring surveillance ✓
• C Coiling and clipping had identical long-term outcomes; the choice should be based only on neurosurgeon preference
• D Surgical clipping should be preferred for aneurysms <7 mm; coiling for aneurysms >7 mm

Explanation

ISAT (Molyneux et al., Lancet 2002) demonstrated that endovascular coiling of ruptured intracranial aneurysms resulted in significantly better 1-year clinical outcome (independent survival) compared to neurosurgical clipping (23.7% vs 30.6% death or dependency). However, coiled aneurysms had a higher risk of rebleeding (2.9% vs 0.9% over 5 years) and more frequently required retreatment due to aneurysm recurrence/recoiling. ISAT fundamentally changed practice, making coiling the preferred treatment for suitable ruptured aneurysms at centres with adequate endovascular expertise. Surgical clipping remains preferred for wide-neck MCA bifurcation aneurysms and cases with significant hematoma requiring evacuation.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.