A novel self-expanding shape memory polymer coil for intracranial aneurysm embolization: 1 year follow-up in Chile

BACKGROUND: Aneurysm recurrence remains a challenge when coiling cerebral aneurysms. Development of next generation coils has focused on accelerating thrombus maturation and increasing coil packing density. Ultra low density shape memory polymer is a novel embolic material designed for this purpose. The polymer is crimped over a platinum–tungsten coil for catheter delivery and self-expands to a predefined volume on contact with blood. METHODS: This prospective study in humans evaluated aneurysms 5–16 mm (inclusive) in diameter that were indicated for endovascular coil embolization. At least 70% coil volume was required to be shape memory polymer coils. Patients were followed-up according to standard of care for 12 months. RESULTS: Nine patients (89% women, mean age 55.8±11.7 years) were treated with shape memory polymer coils and completed 12 months of follow-up. Aneurysms were all unruptured and were in the ophthalmic segment of the internal carotid artery (n=7), posterior communicating artery, and anterior cerebral artery A1–A2 segment. Aneurysms were a mean of 7.8±2.9 mm in diameter (range 5.2–14.9 mm). The mean packing density based on unexpanded polymer was 17±6%. Packing density based on expanded polymer was 43±13%. At 12 months, no recurrence had occurred, and a Raymond–Roy occlusion classification of 1 (n=5) or 2 (n=4) was observed. No serious adverse events related to the study device occurred over the 12 months after the procedure. CONCLUSIONS: Shape memory polymer coils were safe and effective in treating intracranial aneurysms over 12 months in this first study in human subjects.