Visit-To-Visit Variability in Systolic Blood Pressure Is a Novel Risk Factor for the Growth of Intracranial Aneurysms

Abstract

Background: Although rupture of unruptured intracranial aneurysms (UIAs) is closely associated with UIA growth during follow-up, few studies have investigated how UIAs grow during observation. Hypertension appears to affect the formation of intracranial aneurysms. However, few studies have investigated the association of blood pressure variability with UIA growth. Visit-to-visit variability (VVV) in systolic blood pressure (SBP) is a newly defined concept which appears to be a good predictor of stroke. With this factor in mind, here we conducted a prospective analysis of the results of 2 years of observation of UIAs by magnetic resonance angiography (MRA) and sought to identify risk factors for UIA growth and rupture. Methods: From December 2006 through June 2010, two hundred patients with 212 UIAs were followed for 2 years. Patient ages ranged from 31 to 91 years. Putative risk factors for the growth of UIAs were evaluated. Subjects were divided into two groups: a UIA growth group consisting of patients whose UIAs increased by 1 mm or more in size or who developed subarachnoid hemorrhage (SAH), and an unchanged group. Brachial blood pressure values were recorded at the time of diagnosis and during follow-up in the outpatient clinic. All blood pressure values were then averaged, and the VVV of SBP was defined as the standard deviation (SD) of a minimum of 5 blood pressure measurements at outpatient visits. Results: UIA growth occurred in 20 patients and SAH occurred in 1 patient. Current smoking tended to be more prevalent in the UIA growth group (p < 0.01). Five of the 12 patients with multiple UIAs showed UIA growth within 2 years and multiplicity was a significant risk factor for UIA growth (p < 0.01). The mean baseline size in the UIA growth group was larger than that in the unchanged group (p = 0.01) and 7 of the 18 patients with large UIAs, categorized as having an initial diameter of 7 mm or more, had an increase in UIA size over the 2 years (p < 0.01). On multivariable logistic regression analysis, current smoking, multiplicity, and UIA size ≥7 mm were significant risk factors for UIA growth. Although no significant difference was seen between the UIA growth and unchanged groups in office SBP during the observation period, VVV in SBP was significantly higher in the UIA growth group than in the unchanged group, and it was significantly and independently associated with UIA growth. Conclusions: VVV in SBP is a novel risk factor for the growth of UIAs and may be a key factor for the prevention of UIA rupture. Future research is needed to confirm that SBP stability prevents UIA rupture.