More frequent migraines with aura are linked to stroke, while less frequent attacks are associated with any cardiovascular event among women.
Women who experience migraines with aura at least weekly have a fourfold increased risk of ischemic stroke, according to research published in the August 25 issue of Neurology. The study also found “strong and significant associations” between low migraine frequency (fewer than 12 times a year) and major cardiovascular disease in women with migraines with aura.
“The association between migraine and cardiovascular disease varies by migraine frequency,” reported Tobias Kurth, MD, ScD, Senior Scientist at Institut National de la Santé et de la Recherché Médicale in France and Associate Epidemiologist at Brigham and Women’s Hospital in Boston, and colleagues. “Significant associations were only found among women with migraine with aura. Ischemic stroke was the only outcome associated with a high-attack frequency, while a low-attack frequency was associated with any vascular event.”
The findings confirm previous research linking migraines with aura with heart disease and stroke. However, Kurth et al were the first group to find that low-frequency migraineurs have an increased risk for cardiovascular disease. Dr. Kurth also noted that his study categorized subjects into three groups based on migraine frequency, while earlier studies dichotomized participants.
“The association between migraine with aura and cardiovascular disease seems to be limited to subgroups of patients,” Dr. Kurth told Neurology Reviews. “Migraine frequency may help to identify those at further increased risk.”
Identifying At-Risk Patients
Using data collected from 27,798 participants in the Women’s Health Study, Dr. Kurth and colleagues identified 3,568 subjects ages 45 and older who had experienced a migraine in the year prior to the start of the study and had no history of cardiovascular disease. The investigators further categorized the women based on migraine frequency—fewer than one a month, monthly, and at least once a week—and whether they had experienced migraine with aura.
During an average of 11.9 years of follow-up, 706 major cardiovascular disease events occurred, including 305 first myocardial infarctions, 310 ischemic strokes, and 151 deaths due to cardiovascular disease. In addition, 655 women had coronary revascularization procedures, and 418 women reported angina.
The association between migraine frequency and major cardiovascular disease events “appeared J-shaped with increased risks for fewer than once a month and once a week or more, a pattern also seen for stroke,” the researchers noted. When the data were stratified by migraine with aura status, there were “no significant associations between migraine frequency and any ischemic vascular event among women with migraine without aura.
“In contrast we found strong and significant associations between low migraine frequency (less than monthly) and major cardiovascular disease among women with active migraine with aura,” the authors continued. “In addition, women with active migraine with aura with a migraine frequency of at least weekly had over fourfold increased risk for ischemic stroke, but not for any other ischemic vascular event.”
However, noted Dr. Kurth, “Vascular events may be a consequence for very few patients with migraine with aura. [Each patient’s] cardiovascular risk profile should be evaluated.”
Relative Versus Absolute Risk
“This important study increases our knowledge about the association of migraine and cardiovascular events,” Hans-Christoph Diener, MD, Chairman of the Department of Neurology at University Duisburg-Essen, Germany, and Christopher A. Beck, PhD, Assistant Professor in the Department of Biostatistics and Computational Biology at the University of Rochester Medical Center in New York, pointed out in a related editorial.
“The results of this study might be communicated to the lay population as a 93% increased risk of major cardiovascular events in women with migraine attacks greater than or equal to weekly,” the editorialists stated. However, this percentage represents the relative risk, whereas the absolute risk is considerably low, Drs. Diener and Beck commented.
“Women with migraine with aura and very infrequent or frequent migraine attacks should be advised to treat vascular risk factors when present and particularly to avoid smoking,” Drs. Diener and Beck recommended.
—Rebecca K. Abma