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.