SAN DIEGO—Patients with transient ischemic attack (TIA) should be considered for noninvasive testing for cardiovascular disease, according to Robert D. Brown Jr., MD, MPH, who led the study along with Joseph D. Burns, MD, and colleagues at the Mayo Clinic in Rochester, Minnesota.
Persons with TIA have approximately double the risk of subsequent myocardial infarction, compared with the general population, and this risk remains constant over time, Dr. Brown reported at the 2009 International Stroke Conference. Younger patients with TIA have an even higher risk of myocardial infarction than age-matched controls.
“The key point from this study is not to remain so focused on the neurologic implications that you ignore the systemic implications of the TIA,” said Dr. Brown, Professor and Chair of Neurology at the Mayo Clinic.
Predictors of Myocardial Infarction After Transient Ischemic Attack
Findings were based on data from the Rochester Epidemiology Project, a medical records-linkage system that documents the care delivered to residents of Rochester and Olmsted Counties in Minnesota. Community residents with myocardial infarction after incident TIA were identified using this database, and this incidence rate was compared with the age-, gender-, and period-specific incidence of myocardial infarction in the general population of Olmsted County.
Between 1985 and 1994, 388 residents without a history of myocardial infarction had a TIA. During a median follow-up of 10.2 years, 44 patients had a myocardial infarction after TIA, yielding an average yearly incidence of myocardial infarction of 0.95%. The risk of myocardial infarction after TIA was essentially constant over time.
The age-, gender-, and period-specific relative risk for incident myocardial infarction in residents with a TIA compared with that of the general population was 2.09. In those younger than 60, the relative risk was 15.1.
In a multivariate analysis, independent predictors of myocardial infarction after TIA were increasing age, male gender, and the use of lipid-lowering therapy. The hazard ratio for myocardial infarction was 1.51 per each 10 years of age, 2.19 for men, and 3.10 for treatment with lipid-lowering drugs.
The use of lipid-lowering therapy as a predictor of myocardial infarction is likely a surrogate for systemic atherosclerosis, according to Dr. Brown. “These patients may have had multivessel arterial disease, and that is why they were started on lipid-lowering therapy,” he said.
After adjustment for factors associated with mortality in patients with TIA, Dr. Brown’s group found that myocardial infarction was a significant independent predictor of death after TIA, tripling the risk.
Screening for Coronary Artery Disease
The etiology of the TIA was not a predictor of future myocardial infarction, which suggests that all patients with TIA, regardless of the specific etiology, should be considered for risk factor assessment for coronary artery disease, noted Dr. Brown.
“Once you’ve evaluated for the mechanism of the TIA and you’ve implemented secondary prevention strategies for stroke, step back and ask if the patient has a risk profile placing him or her at high risk of myocardial infarction,” advised Dr. Brown. “If so, consider if you should be doing some kind of noninvasive study of the coronary arteries, either a stress test or an imaging study ... to screen for evidence of coronary artery disease. If you find evidence of coronary artery disease, then there may be some additional management strategies that should be implemented. This is a way in which we may be able to prevent some myocardial infarctions.”
—Wayne Kuznar