Peggy Peck

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.

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.

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.

VANCOUVER, B.C.–Results of a small prospective study suggest that almost half of patients hospitalized for treatment of ischemic stroke or transient ischemic attack (TIA) are “aspirin resistant.”

But some stroke experts are not convinced, citing a lack of evidence that the results of the platelet function analyzer (PFA-100) assay used in the study are a true measure of antiplatelet function.

Of 59 patients tested, 47% had aspirin resistance, which was defined as a clotting time of 171 seconds or less, Dr. Mark J. Alberts reported at the Fifth World Stroke Congress, sponsored by the International Stroke Society.

In an earlier study of outpatients, Dr. Alberts, professor of neurology at Northwestern University, Chicago, reported that 37% of such patients were aspirin resistant. That study, first reported at the American Stroke Association meeting in 2003, was recently published (Stroke 35[1]:175–78, 2004).

In the later study, the 59 patients had a mean age of 64 years and had been taking aspirin for at least 3 days prior to an acute event (stroke or TIA). PFA-100 testing was done at the time of hospital diagnosis, before any loading dose of antiplatelet therapy was administered. The PFA-100 device measures the clotting time of a blood sample that is pumped through a collagen-coated membrane, a test design that mimics the behavior of circulating blood. The device, about the size of a drip coffee maker, costs about $15,000 and produces results in about 5 minutes at a cost of $15–$20 per assay, he said.

Overall, 63% of patients were taking 325 mg/day of aspirin and 37% were using baby aspirin (81 mg). Aspirin resistance was seen in 73% of patients taking low-dose aspirin and in 32% of those taking high-dose aspirin, a significant difference. Patients using enteric-coated aspirin also were more likely than others to show resistance.

The results suggest that “dose-adjusted therapy is where the field is headed. … 'One size fits all' therapy doesn't work for aspirin,” Dr. Alberts said.

Dr. Ralph L. Sacco, director of the stroke and critical care division at Columbia University, New York, said in an interview that Dr. Alberts' findings were “thought-provoking, but I don't know how an abnormal finding on PFA correlates with clinical outcomes.”

VANCOUVER, B.C.–Results of a small prospective study suggest that almost half of patients hospitalized for treatment of ischemic stroke or transient ischemic attack (TIA) are “aspirin resistant.”

But some stroke experts are not convinced, citing a lack of evidence that the results of the platelet function analyzer (PFA-100) assay used in the study are a true measure of antiplatelet function.

Of 59 patients tested, 47% had aspirin resistance, which was defined as a clotting time of 171 seconds or less, Dr. Mark J. Alberts reported at the Fifth World Stroke Congress, sponsored by the International Stroke Society.

In an earlier study of outpatients, Dr. Alberts, professor of neurology at Northwestern University, Chicago, reported that 37% of such patients were aspirin resistant. That study, first reported at the American Stroke Association meeting in 2003, was recently published (Stroke 35[1]:175–78, 2004).

In the later study, the 59 patients had a mean age of 64 years and had been taking aspirin for at least 3 days prior to an acute event (stroke or TIA). PFA-100 testing was done at the time of hospital diagnosis, before any loading dose of antiplatelet therapy was administered. The PFA-100 device measures the clotting time of a blood sample that is pumped through a collagen-coated membrane, a test design that mimics the behavior of circulating blood. The device, about the size of a drip coffee maker, costs about $15,000 and produces results in about 5 minutes at a cost of $15–$20 per assay, he said.

Overall, 63% of patients were taking 325 mg/day of aspirin and 37% were using baby aspirin (81 mg). Aspirin resistance was seen in 73% of patients taking low-dose aspirin and in 32% of those taking high-dose aspirin, a significant difference. Patients using enteric-coated aspirin also were more likely than others to show resistance.

The results suggest that “dose-adjusted therapy is where the field is headed. … 'One size fits all' therapy doesn't work for aspirin,” Dr. Alberts said.

Dr. Ralph L. Sacco, director of the stroke and critical care division at Columbia University, New York, said in an interview that Dr. Alberts' findings were “thought-provoking, but I don't know how an abnormal finding on PFA correlates with clinical outcomes.”

VANCOUVER, B.C.–Results of a small prospective study suggest that almost half of patients hospitalized for treatment of ischemic stroke or transient ischemic attack (TIA) are “aspirin resistant.”

But some stroke experts are not convinced, citing a lack of evidence that the results of the platelet function analyzer (PFA-100) assay used in the study are a true measure of antiplatelet function.

Of 59 patients tested, 47% had aspirin resistance, which was defined as a clotting time of 171 seconds or less, Dr. Mark J. Alberts reported at the Fifth World Stroke Congress, sponsored by the International Stroke Society.

In an earlier study of outpatients, Dr. Alberts, professor of neurology at Northwestern University, Chicago, reported that 37% of such patients were aspirin resistant. That study, first reported at the American Stroke Association meeting in 2003, was recently published (Stroke 35[1]:175–78, 2004).

In the later study, the 59 patients had a mean age of 64 years and had been taking aspirin for at least 3 days prior to an acute event (stroke or TIA). PFA-100 testing was done at the time of hospital diagnosis, before any loading dose of antiplatelet therapy was administered. The PFA-100 device measures the clotting time of a blood sample that is pumped through a collagen-coated membrane, a test design that mimics the behavior of circulating blood. The device, about the size of a drip coffee maker, costs about $15,000 and produces results in about 5 minutes at a cost of $15–$20 per assay, he said.

Overall, 63% of patients were taking 325 mg/day of aspirin and 37% were using baby aspirin (81 mg). Aspirin resistance was seen in 73% of patients taking low-dose aspirin and in 32% of those taking high-dose aspirin, a significant difference. Patients using enteric-coated aspirin also were more likely than others to show resistance.

The results suggest that “dose-adjusted therapy is where the field is headed. … 'One size fits all' therapy doesn't work for aspirin,” Dr. Alberts said.

Dr. Ralph L. Sacco, director of the stroke and critical care division at Columbia University, New York, said in an interview that Dr. Alberts' findings were “thought-provoking, but I don't know how an abnormal finding on PFA correlates with clinical outcomes.”