Smoking, aneurysm size on CTA predict rupture risk

Growing aneurysms, monitored using CT angiography, have a 12-fold higher risk of rupture compared with aneurysms without growth, according to a study published online July 2 in Radiology.

The study also found that aneurysm size and patient smoking status were both significant independent growth predictors.

“We found that growth of asymptomatic unruptured intracranial aneurysms of all sizes was not uncommon and was associated with a higher rupture risk, thus supporting follow-up imaging of all aneurysms, including those smaller than the current 7-mm treatment threshold,” wrote J. Pablo Villablanca, MD, of Ronald Reagan University of California Los Angeles (UCLA) Medical Center, and colleagues.

Digital subtraction angiography is traditionally used to follow patients with cerebral aneurysms, but Villablanca and colleagues sought to evaluate the use of CT angiography to characterize risk factors associated with growth and rupture. “Identification of risk factors for rupture is critical to therapeutic decision making regarding unruptured aneurysms,” they wrote.

A total of 165 patients with known asymptomatic unruptured intracerebral aneurysms were included in the study and followed for an average of 2.24 years from time of diagnosis using CT angiography. Collectively, the patients had 258 aneurysms, 18 percent of which grew larger. Spontaneous rupture occurred in four of the aneurysms with an average size of 6.2 mm.

In breaking down the risk factors, Villablanca and colleagues explained that risk of rupture per patient-year was 2.4 percent in aneurysms exhibiting growth and 0.2 percent in those without growth. All of the ruptured saccular aneurysms in the study demonstrated growth before rupture, including the formation of blebs, or blisters signaling rupture is imminent.

Initial size, along with tobacco smoking, were independent covariates that predicted 78.4 percent of growing aneurysms, according to the authors.

“The positive association of cigarette smoking and the size and growth of aneurysms suggests that the combination of these factors is associated with an increased risk of rupture, which may influence consideration for therapeutic intervention,” they wrote.