Small unruptured intracranial aneurysm verification study: SUAVe study, Japan

Abstract

Background and Purpose-: The natural history and optimal management of incidentally found small unruptured aneurysms <5 mm in size remain unclear. A prospective study was conducted to determine the optimal management for incidentally found small unruptured aneurysms. Methods-: From September 2000 to January, 2004, 540 aneurysms (446 patients) were registered. Four hundred forty-eight unruptured aneurysms <5 mm in size (374 patients) have been followed up for a mean of 41.0 months (1306.5 person-years) to date. We calculated the average annual rupture rate of small unruptured aneurysms and also investigated risk factors that contribute to rupture and enlargement of these aneurysms. Results-: The average annual risks of rupture associated with small unruptured aneurysms were 0.54% overall, 0.34% for single aneurysms, and 0.95% for multiple aneurysms. Patient <50 years of age (P=0.046; hazard ratio, 5.23; 95% CI, 1.03 to 26.52), aneurysm diameter of ≥4.0 mm (P=0.023; hazard ratio, 5.86; 95% CI, 1.27 to 26.95), hypertension (P=0.023; hazard ratio, 7.93; 95% CI, 1.33 to 47.42), and aneurysm multiplicity (P=0.0048; hazard ratio, 4.87; 95% CI, 1.62 to 14.65) were found to be significant predictive factors for rupture of small aneurysms. Conclusions-: The annual rupture rate associated with small unruptured aneurysms is quite low. Careful attention should be paid to the treatment indications for single-type unruptured aneurysms <5 mm. If the patient is <50 years of age, has hypertension, and multiple aneurysms with diameters of ≥4 mm, treatment should be considered to prevent future aneurysmal rupture. © 2010 American Heart Association, Inc.