VANCOUVER, B.C.—Data from a large registry of patients with unruptured arteriovenous malformations of the brain suggest that a watchful waiting approach is safer than an attempt at surgical treatment.
The results were presented at the Fifth World Stroke Congress sponsored by the International Stroke Society.
Unruptured arteriovenous malformations (AVMs) are “relatively benign when left untreated,” based on analysis of data collected from a 15-year registry at Columbia University, New York. The AVM registry has enrolled 622 patients, including 328 with unruptured lesions, said Christian Stapf, M.D., of the university, also an attending neurologist in the department of neurology at Hôpital Lariboisière, Paris.
He presented two studies based on the registry data; one reported on outcomes of unruptured AVM, and another identified risk factors for subsequent AVM rupture in both unruptured and ruptured lesions.
In the study of unruptured AVM, interventional treatment was associated with a significant 3.61 hazard ratio for spontaneous hemorrhage and a significant 8.17 hazard ratio for acute worsening.
“These patients came in with no symptoms, but after something was done to their brains, their lives were changed—significantly,” Dr. Stapf commented.
The mean age of the patients was 33 years; 56% were women. All were referred to Columbia for evaluation and treatment. Columbia established its AVM registry in 1989; the average follow-up for patients with unruptured AVM was 4.9 years. Overall, 78% had some type of treatment, he said.
The data suggest that “AVM may not be as dangerous as previously believed. The hazard of treatment, however, appears to be greater than previously believed,” Dr. Stapf said in an interview.
Traditionally, untreated AVMs were believed to carry a 3% annual risk of hemorrhage, while treated lesions where thought to have a 1% risk of spontaneous hemorrhage.
“Our results suggest the exact opposite: The risk for spontaneous hemorrhage is 3% with treatment and 1% without treatment,” he said.
The results are so unexpected that Dr. Stapf and his colleagues are planning a multicenter, international randomized trial to compare treatment, including surgery and embolization, with no treatment in 500 patients with unruptured AVM.
In the second study, analysis of data from all 622 registry patients indicates that three risk factors—hemorrhage at presentation, deep brain location, and exclusive deep venous drainage—are independent predictors of subsequent hemorrhage. “Age is also a risk factor, with the relative risk increasing by each year of age at presentation,” Dr. Stapf said.
Patients who have all three of those risk factors have a 34.4% annual hemorrhage rate, compared with 0.9% in patients who have none of the factors. Overall, “46% of the patients presented with no risk factors for subsequent hemorrhage,” he said.
Hemorrhage at presentation poses the greatest risk. “Patients who present with hemorrhage have a 47% increased risk for hemorrhage,” Dr. Stapf said.