Introduction: Radiographic aneurysm growth is a significant risk factor for unruptured intracranial aneurysm (UIA) rupture. Growth per aneurysm year (GPAY) ranges from 1.6% to 18.4%. Work in both patients and animal models has identified the inflammatory cascade as a mediator of UIA growth. Previous authors demonstrated attenuation of inflammatory markers in the aneurysm wall with daily aspirin. We hypothesize that a daily aspirin regimen will decrease the incidence of radiographic UIA growth during surveillance.
Methods: Single institution retrospective review (2001-2012) of patients undergoing radiographic surveillance of UIAs. Our UIA surveillance protocol recommends imaging every 6-months for 24-months then annually through five years. Imaging modalities included magnetic resonance (87%); computed tomographic (9%); and digital subtraction (4%) angiography. Aspirin use was recorded by dose and frequency. Statistical analysis included a two-tailed Student’s t-test.
Results: There were 223 UIAs in 186 patients undergoing radiographic surveillance and with documentation of aspirin status. Mean follow-up time was 3.27 years. Daily aspirin use was documented in 59 patients. Of 127 patients not taking daily aspirin, 16.5% demonstrated growth for a GPAY of 4.1%. Among 59 patients on a daily aspirin regimen, 11.9% demonstrated growth for a GPAY of 3.0% (p=0.410). There was no significant difference between those on aspirin 325mg daily—23.1% growth, 4.93% GPAY (N=13)—and those on aspirin 81mg daily—8.7% growth, 2.36% GPAY (N=46)( p=0.162).
Conclusions: The rate of radiographic UIA growth was less in patients on daily aspirin but the difference was not statistical significance. Our study is likely underpowered to demonstrate the effect of aspirin on UIA growth. Further investigation using larger sample sizes, prospective design, and data from multiple centers is needed to adequately evaluate the protective effect of daily aspirin on aneurysm growth.
Patient Care: We demonstrate daily aspirin is associated with reduced incidence of unruptured intracranial aneurysm growth that does not reach statistical significance; this highlights the need for multicenter prospective trial of daily aspirin for patients with unruptured intracranial aneurysms.
Learning Objectives: (1) Recognize radiographic growth as a risk factor for rupture of previously unruptured intracranial aneurysms.
(2) Raise role of aspirin in influencing inflammation-mediated growth of unruptured intracranial aneurysm growth on aspirin regimen
(3) Recognize future directions for evaluating role of aspirin in attenuating growth of previously unruptured intracranial aneurysms.