The Penumbra System: a mechanical device for the treatment of acute stroke due to thromboembolism

Abstract

Background and purpose: Data from recent reports have indicated that mechanical thrombectomy may have potential as a treatment for acute ischemic stroke. The purpose of this study was to assess the safety and performance of the Penumbra System (PS): a novel mechanical device designed to reduce clot burden in acute stroke due to large-vessel occlusive disease.

Materials and methods: A prospective, single arm, independently monitored and core laboratory adjudicated trial enrolled subjects with an acute neurologic deficit consistent with acute stroke, presenting within 8 hours of symptom onset and an angiographically verified occlusion (Thrombolysis in Myocardial Infarction [TIMI] grade 0 or 1) of a treatable intracranial vessel. The primary end point was revascularization of the target vessel to TIMI grade 2 or 3. Secondary end points were the proportion of subjects who achieved a modified Rankin Scale (mRS) score of 2 or less or a 4-point improvement on the National Institutes of Health Stroke Scale (NIHSS) score at 30-day follow-up, as well as all-cause mortality.

Results: Twenty-three subjects were enrolled, and 21 target vessels were treated in 20 subjects by the PS. At baseline, mean age was 60 years, mean mRS score was 4.6, and mean NIHSS score was 21. Postprocedure, all 21 of the treated vessels (100%) were successfully revascularized by the PS to TIMI 2 or 3. At 30-day follow-up, 9 subjects (45%) had a 4-point or more NIHSS improvement or an mRS of 2 or less. The all-cause mortality rate was 45% (9 of 20), which is lower than expected in this severe stroke cohort, where 70% of the subjects at baseline had either an NIHSS score of more than 20 or a basilar occlusion.

Conclusion: Thus, early clinical experience suggests that the PS allows revascularization in certain subjects experiencing acute ischemic stroke.

Fig 1.

Schematic diagram of the Penumbra device.

Fig 2.

Angiographic illustration of a target vessel before (A) and after (B) treatment by the PS. This patient was a 66-year-old man who presented 3 hours from symptom onset with an NIHSS score of 24, which improved to 8 at 24 hours after revascularization by the PS. He continued to recover with a 30-day NIHSS score of 2 and an mRS of 1.

Fig 3.

Subjects outcome based on baseline NIHSS scores.

Fig 4.

A comparison of the observed and expected mortality rates for the entire study cohort and after stratification by location of the target vessel. The expected rates were derived from historical rates from the natural history of the disease reported in the literature, prorated to the proportion of target vessel locations treated in this study (see References –3).