Over a 16-year period, 570 patients presenting with acute aneurysmal subarachnoid hemorrhage were successfully treated using endosaccular coil embolization within 30 days of hemorrhage by a single surgeon. Patients were followed to assess the stability of aneurysm occlusion and its longer-term efficacy in protecting against rebleeding.
Patients were followed for 6 to 191 months (mean 73.7 months, median 67 months) by clinical review, angiography performed at 6 and 24 months posttreatment, and questionnaires sent via the postal service every 5 years. Late rebleeding was defined as > 30 days after treatment.
Stable angiographic occlusion was evident in 74.5% of small, 72.2% of large, and 60% of giant aneurysms. Recurrent filling was found in 119 (26.3%) of 452 aneurysms. Rebleeding was diagnosed in 9 patients (6 treated aneurysms) and occurred between 2 and 114 months posttreatment. It was due to aneurysm recurrence in 6 patients, rupture of a coincidental untreated aneurysm in 2 patients, and rupture of a de novo aneurysm in 1 patient. Rebleeding occurred in 3 (2.5%) of 119 unstable aneurysms and in 3 (0.9%) of 333 stable aneurysms, as seen on initial follow-up angiography studies. Annual rebleeding rates ranged from 0.2% to 0.6% for all causes and from 0.2% to 0.4% for rebleeding of treated aneurysms. No rebleeding was recorded after the first decade, with 138 patients having more than 10 years of follow-up.
Periodic follow-up with angiographic studies after coil embolization is recommended to identify aneurysm recurrence and patients at a high risk of late rebleeding in the medium term. More frequent follow-up is recommended for patients harboring coincidental unruptured aneurysms.