International Subarachnoid Aneurysm Trial - ISAT part II: study protocol for a randomized controlled trial

Area of Science:

• Neurosurgery
• Interventional Neurology
• Clinical Trials

Background:

• The International Subarachnoid Aneurysm Trial (ISAT) favored endovascular coiling over surgical clipping for good-grade subarachnoid hemorrhage (SAH) patients with small anterior circulation aneurysms.
• Clinical practice often deviates from ISAT findings, with surgical clipping used for presumed better outcomes or durability, despite a lack of formal validation.
• Uncertainty persists regarding the optimal treatment for many ruptured intracranial aneurysm patients.

Purpose of the Study:

• To compare clinical outcomes between endovascular coiling and surgical clipping in a broad population of non-ISAT patients with subarachnoid hemorrhage.
• To validate or refute the extrapolated superiority of coiling in a wider patient group.
• To provide evidence-based guidance for ruptured intracranial aneurysm treatment decisions.

Main Methods:

• ISAT II is a pragmatic, multicenter, randomized trial comparing coiling versus clipping.
• Inclusion criteria are broad, encompassing patients not eligible for the original ISAT.
• The primary endpoint is poor clinical outcome (modified Rankin Scale >2) at one year, with secondary endpoints including safety and recurrence rates.

Main Results:

• The study is designed to enroll 1,896 patients across at least 50 international centers.
• A projected 23% poor outcome rate for coiling versus 30% for clipping is hypothesized.
• The trial is estimated to take approximately 12 years to complete, with intention-to-treat analysis.

Conclusions:

• The ISAT II trial will provide crucial data on the comparative effectiveness of coiling and clipping for a wider spectrum of ruptured intracranial aneurysm patients.
• Findings will inform clinical decision-making and potentially refine treatment guidelines for subarachnoid hemorrhage.
• The study addresses the ongoing debate regarding the optimal management strategy for ruptured aneurysms beyond the ISAT cohort.