Flow Diverter Devices Effective in Intracranial Aneurysms, But Complications a Concern

The use of flow diverter stents in patients with intracranial aneurysms results in a high rate of complete occlusion regardless of aneurysm size, according to a meta-analysis published online January 15, 2013, ahead of print in Stroke. However, the procedure carries a significant risk of complications including mortality.

Researchers led by Waleed Brinjikji, MD, of the Mayo Clinic (Rochester, MN), conducted the meta-analysis of 29 studies including 1,451 patients with 1,654 treated intracranial aneurysms. The studies involved either the Pipeline embolization device (Covidien/ev3, Irvine, CA) or the Silk flow diverter (Balt Extrusion, Montmorency, France) and were conducted between 2009 and 2012. The US Food and Drug Administration approved Pipeline in 2011 based on results from the Pipeline for Uncoilable or Failed Aneurysms trial. Silk was approved in Europe in 2008 but is not approved for use in the United States.

High Efficacy, Even in Largest Aneurysms

At 6 months, the complete occlusion rate was 76% in the entire cohort, with only minor fall-off for large (74%) and giant (76%) aneurysms.

Rates of mortality and morbidity, including subarachnoid and intraparenchymal hemorrhage, total stroke, and perforator infarction, were not negligible (table 1).

Table 1. Outcomes at 6 Months

Patients with small aneurysms had a lower rate of postoperative subarachnoid hemorrhage (OR 0.10; 95% 0.02-0.42; P < 0.0001) and ischemic stroke (OR 0.26; 95% CI 0.07-0.91; P = 0.03). Additionally, patients with anterior circulation aneurysms had lower rates of ischemic stroke (OR 0.15; 95% CI -0.08 to 0.27; P < 0.0001) and perforator infarction (OR 0.01; 95% CI 0.00-0.08; P < 0.0001) than those with anterior circulation aneurysms. Aneurysm size was not associated with perforator infarction risk.

Analysis of aneurysm occlusion, total ischemic stroke, and perforator infarction showed substantial heterogeneity, suggesting unexplained differences in study populations and procedures as a causative factor. The remaining analyses had minimal heterogeneity.

Concern About Complications

The authors acknowledge that the complications associated with flow diverter treatment are not infrequent and suggest that higher morbidity in larger aneurysms “may relate to the technical challenges as well as the inherent instability of these lesions.” They add that given the “alarmingly high association between perforator infarction and posterior location of intracranial aneurysms,” practitioners need to be careful when selecting patients for flow-diverter therapy, especially among those with large or posterior circulation aneurysms.

Furthermore, the investigators say the findings emphasize that postoperative subarachnoid hemorrhage from delayed rupture “is a real and significant complication of flow-diverter patients, especially for those with large or giant aneurysms.” In 2010, Balt Extrusion issued an alert instructing practitioners not to use the Silk flow diverter without endovascular coils owing to the potential for delayed rupture and patient death. Dr. Brinjikji and colleagues say it is unknown whether the practice of using coils in association with flow diverters in the treatment of larger aneurysms has resulted in a decreased incidence of this complication.

Advantage of Flow Diverters

In an email communication with TCTMD, coauthor Giuseppe Lanzino, MD, also of the Mayo Clinic, said the complications reported in the meta-analysis are in line with what is known about these devices.

He added that the similar high rates of occlusion regardless of aneurysm size “is a major advantage of this technique because traditional endovascular techniques short of parent artery occlusion have limitations for very large and giant aneurysms given the high risks of recurrence and/or further aneurysm growth.”

A multicenter study of the Pipeline device by Kan et al (Neurology. 2012;71:1080-1088) reported findings similar to those of the meta-analysis. In that study of 56 patients treated at 7 US centers, clinicians used an average of 2 Pipeline devices to treat each aneurysm. Coils were used in 25%. Of 19 patients with 3-month follow-up angiography, 68% achieved complete occlusion. The major complication rate was 8.5%, higher than in the current meta-analysis. Fatal hemorrhages were reported in 4 patients, all of whom had giant aneurysms.

 

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Source:
Brinjikji W, Murad MH, Lanzino G, et al. Endovascular treatment of intracranial aneurysms with flow diverters: A meta-analysis. Stroke. 2013;Epub ahead of print.

 

 

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