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May 28, 2024

Complications were more common when treating large/giant aneurysms, but it was still lower than seen with first-generation devices.



Periprocedural mortality and major complications are rare with use of the Pipeline Flex device for treatment of unruptured intracranial aneurysms, according to a new meta-analysis. The findings, which were published online May 30, 2019, ahead of print in the Journal of NeuroInterventional Surgery, also demonstrate that treating aneurysms ≥ 10 mm is a significant predictor of major complications.


“I was struggling to tell patients who were about to have a flow-diverter procedure what the risks were going to be,” lead author Kartik Dev Bhatia, MD (Toronto Western Hospital, Canada), told Neurovascular Exchange. “All of the information we had was based on the older devices, and it suggested pretty high complications rates. This made it sometimes hard to justify to patients during the consent process why we were using a flow diverter. A 5% risk of major complications would make patients quite scared, even though the risk of rupture of the aneurysm was fairly low over the long term.”


Bhatia et al conducted a systematic search of three databases to identify studies involving at least 10 treatments using the Pipeline Flex (Medtronic) for unruptured intracranial aneurysms that were conducted between 2014 and 2019. They found eight studies covering 901 treatments in 879 patients.


The periprocedural (< 30 days) rate of mortality was 0.8% (95% CI 0.4%-1.5%). Major complications, including death, major ischemic stroke, or symptomatic intracranial hemorrhage, occurred at a rate of 1.8% (95% CI 1.0%-2.7%). No significant heterogeneity was found.


Aneurysm size ≥ 10 mm emerged as a significant predictor of a major complication (OR 6.4; 95% CI 2.0-20.7). The risk of a major complication was 0.9% for aneurysms < 10 mm and 4.4% for large/giant aneurysms.


The meta-analysis was limited by the predominance of anterior-circulation aneurysms. Bhatia speculated that the lower complication rate seen when treating aneurysms of the anterior circulation is likely to apply to posterior-circulation aneurysms as well, but there are currently no data to back this up. Prospective studies are needed, he said. Similarly, more data are needed on how coated flow diverters measure up with respect to complication rates.


Bhatia acknowledged to NVX that the data were more positive than he had anticipated. Nevertheless, he believes they represent a realistic picture. “It seems fairly consistent across all the studies included,” he pointed out. Also, “more and more practitioners are treating these small- and medium-sized aneurysms with flow diverters. If they were seeing high complication rates, I think they would stop doing it fairly quickly. I think that happened with the first-generation devices. Everyone was very excited, and then the complications started coming out, and people started being a bit more cautious about their use.”


With regard to the higher complication rate with the large aneurysms, Bhatia said his findings are in line with previous published data showing higher complication rates with large/giant aneurysms. Still, his reported complication rate with these aneurysms using the Pipeline Flex is lower than previously published complication rates in large/giant aneurysms being treated with first-generation devices.


He expects that improved complication rates will eventually be reported in all second-generation flow diverters that allow for recapture of the device for better positioning. “People have been using flow diverters for around a decade, so the operators are quite used to putting them in,” he said. “We have a lot more operator experience, and we are better with antiplatelet regimens. All of that together is improving the complication rates.


“We used to think maybe we shouldn’t be treating these more medium aneurysms because the risks might be too large. I think the risks that we showed in this analysis might suggest that this is a fairly safe treatment,” he concluded.




Bhatia KD, Kortman H, Orru E, et al. Periprocedural complications of second-generation flow diverter treatment using Pipeline Flex for unruptured intracranial aneurysms: a systematic review and meta-analysis. J NeuroInterv Surg. 2019;Epub ahead of print.




Bhatia reports no relevant conflicts of interest.