AHA/ASA Guidelines Published for Management of Unruptured Intracranial Aneurysm

June 24, 2015—The American Heart Association/American Stroke Association has published online guidelines for the management of patients with unruptured intracranial aneurysms (UIAs). The document by writing group chair B. Gregory Thompson, MD, et al is available online ahead of print in Stroke. The aim of this updated statement is to provide comprehensive and evidence-based recommendations for management of patients with UIAs.

The document provides evidence-based guidelines for the care of patients presenting with UIAs and addresses presentation, natural history, epidemiology, risk factors, screening, diagnosis, imaging, and outcomes from surgical and endovascular treatment.

The following are the guidelines’ key conclusions:

• Several factors should be considered in selection of the optimal management of a UIA, including the size, location, and other morphological characteristics of the aneurysm; documented growth on serial imaging; the age of the patient; a history of previous aneurysmal subarachnoid hemorrhage; family history of cerebral aneurysm; the presence of multiple aneurysms; or the presence of concurrent pathology such as an arteriovenous malformation or other cerebrovascular or inherited pathology that may predispose to a higher risk of hemorrhage.
• Patients with unruptured cerebral aneurysms who are considered for treatment should be fully informed about the risks and benefits of both endovascular and microsurgical treatment as alternatives to secure the UIAs and prevent bleeding.
• The results of UIA treatment are inferior at low-volume centers, and hence treatment is recommended to be performed at higher-volume centers.
• Data from prospective and retrospective studies from multiple national and international investigations indicate that microsurgical clip ligation may confer more durable protection against aneurysm regrowth, but coil embolization may be superior to surgical clipping with respect to procedural morbidity and mortality, length of stay, and hospital costs, so it may be reasonable to choose endovascular therapy over surgical clipping in the treatment of select UIAs, particularly in cases for which surgical morbidity is high, such as at the basilar apex and in the elderly.
• The treatment risk of patients with UIAs is related to advancing age, medical comorbidities, and aneurysm location and size, so in older patients (aged > 65 years) and those with associated medical comorbidities with small asymptomatic UIAs and low hemorrhage risk by location, size, morphology, family history, and other relevant factors, observation is a reasonable alternative.

The document notes that since the last recommendation document in 2000, major changes have emerged in the treatment of UIAs, largely in the widespread use of endovascular techniques. The use of coil embolization increased substantially after publication of the results of the International Subarachnoid Aneurysm Trial (ISAT) in 2002 and 2005. ISAT was a randomized trial comparing clip ligation to coil occlusion in ruptured aneurysms that showed improved clinical outcomes in the coiling arm at 1 year. 

Although trials of UIAs and ruptured aneurysms cannot be compared on the basis of outcomes or future risk, the relative safety and medium-term efficacy of both coiling and surgical clipping in preventing future hemorrhage from the treated aneurysm has been better established after ISAT. Furthermore, experience in treating aneurysms continues to increase, with an improved measure of safety and with better devices, stated the guidelines.

The recommendations for endovascular therapy include one new recommendation that addresses emerging technologies:

• Endoluminal flow diversion represents a new treatment strategy that may be considered in carefully selected cases. Other emerging technologies to treat unruptured cerebral aneurysms, such as liquid embolic agents, represent new treatment strategies that may be considered in carefully selected cases. The long-term effects of these newer approaches remain largely unknown. Strict adherence to the US Food and Drug Administration’s indications for use is probably indicated until additional trial data demonstrate an incremental improvement in safety and efficacy over existing technologies.

Additional endovascular recommendations are:

• Use of coated coils is not beneficial compared with bare-metal coils. 
• Endovascular treatment of UIAs is recommended to be performed at high-volume centers.
• The procedural risk of radiation exposure should be explicitly reviewed in the consent process for endovascular procedures. 

Regarding the comparative efficacy of clipping versus coiling, the recommendations are:

• Surgical clipping is an effective treatment for UIAs that are considered for treatment.
• Endovascular coiling is an effective treatment for select UIAs that are considered for treatment.
• Patients with UIAs who are considered for treatment should be fully informed about the risks and benefits of both endovascular and microsurgical aneurysm clipping.
• Endovascular coiling is associated with a reduction in procedural morbidity and mortality over surgical clipping in selected cases but has an overall higher risk of recurrence.