International Subarachnoid Aneurysm Trial

International Subarachnoid Aneurysm Trial (ISAT) was a large multicenter, randomized clinical trial conducted to compare the outcomes of two different treatments for patients with ruptured intracranial aneurysms. The trial aimed to determine whether endovascular coiling or neurosurgical clipping was the more effective treatment in terms of patient survival and level of independence. The ISAT was pivotal in shaping the management and treatment strategies for subarachnoid hemorrhage (SAH) resulting from ruptured intracranial aneurysms.

Background

A subarachnoid hemorrhage is a form of stroke caused by bleeding into the space surrounding the brain, often due to a ruptured aneurysm. Before the ISAT, neurosurgical clipping was the standard treatment. This procedure involves a craniotomy to access the aneurysm and placing a metal clip across its neck to stop the bleeding. In the 1990s, endovascular coiling, a less invasive procedure where coils are placed inside the aneurysm via the blood vessels to induce clotting and seal off the aneurysm from the circulation, emerged as an alternative treatment.

Study Design

The ISAT was initiated to compare the long-term outcomes of patients treated with endovascular coiling versus neurosurgical clipping. Patients with ruptured intracranial aneurysms suitable for both treatments were randomly assigned to undergo either procedure. The primary outcomes measured were death or dependency at one year post-treatment, with secondary outcomes including rebleeding rates and the need for additional surgical interventions.

Results

The results of the ISAT, published in 2002, showed that at one year, patients who underwent endovascular coiling had a significantly higher rate of survival free of disability compared to those who underwent neurosurgical clipping. Specifically, 23.7% of patients in the neurosurgical group were dead or dependent at one year, compared to 30.6% in the coiling group. These findings led to a shift in clinical practice towards favoring endovascular coiling for certain patients with ruptured intracranial aneurysms.

Controversies and Criticisms

Despite its impact, the ISAT faced criticism regarding its methodology and the generalizability of its findings. Critics argued that the trial's inclusion criteria led to the selection of patients more likely to benefit from coiling, potentially biasing the results. Additionally, concerns were raised about the long-term durability of endovascular coiling, with some studies suggesting higher rates of aneurysm recurrence and rebleeding compared to clipping.

Conclusion

The International Subarachnoid Aneurysm Trial significantly influenced the management of ruptured intracranial aneurysms, establishing endovascular coiling as a viable and often preferred treatment option for certain patients. However, the debate over the best treatment approach continues, with ongoing research focusing on long-term outcomes, technological advancements, and patient selection criteria.