Introduction/Purpose Early and safe revascularization of the primary occlusion correlates with favorable clinical outcome in acute ischemic stroke treatment. One factor in assessing safety of mechanical thrombectomy devices is embolization to a previously uninvolved or new territory (ENT). The Penumbra System is an embolectomy device specifically designed to remove thrombus in acute ischemic stroke through two mechanisms: aspiration and extraction. The purpose of this study is to examine the rate of ENT in the three published Penumbra System trials.

Materials and Methods Three papers reporting results of the Penumbra System trials were analyzed for ENT procedure-related adverse events and total number of cases.

Results Our analysis of the Penumbra System ENT adverse event rate in the three Penumbra trials is summarized below. In the three studies, which included a total of 303 patients, only one incident of ENT was observed.

Conclusion The unintentional embolization of new territory during mechanical thrombectomy can close collateral flow that is vital to preserving the penumbra. An assessment of the results from three Penumbra trials demonstrates a low rate of ENT of <0.5% using the Penumbra System in treatment for acute ischemic stroke. Aspirating immediately proximal to the thrombus ensures capture of clot at the site of occlusion into a catheter, which may reduce the potential for ENT. Combined with a revascularization rate of 86%, the experience in the three papers shows the ability of the Penumbra System to safely and effectively revascularize the site of primary occlusion.

Competing interests B Baxter: Stryker Neurovascular, EV3, Penumbra, Rapid Medical, Reverse Medical, Codman, Silk Road.