The Treatment of TIAs: The Long and Short of It
ABSTRACT & COMMENTARY
By John J. Caronna, MD
Vice Chairman, Department of Neurology, Cornell University Medical Center and Professor of Clinical Neurology, New York Hospital
Dr. Caronna reports no consultant, stockholder, speaker’s bureau, research, or other relationship related to this field of study.
Synopsis: Acute MRI is useful in making triage decisions for patients with TIA or minor stroke because it reliably divides such patients into benign, intermediate, and poor prognosis groups.
Sources: van Wijk I, et al. Long-Term Survival and Vascular Event Risk After Transient Ischaemic Attack or Minor Ischaemic Stroke: A Cohort Study. Lancet. 2005;365:2098-2104; Hankey GJ. Redefining Risks After TIA and Minor Ischaemic Stroke. Lancet. 2005;365:2065-2066; Coutts SB, et al. Triaging Transient Ischaemic Attack and Minor Stroke Patients Using Acute Magnetic Resonance Imaging. Ann Neurol. 2005;57:848-854.
The short-term prognosis and risk factors for stroke after TIA have been well studied (Johnston SC, et al. JAMA 2000; 284: 2901-2906). In most clinical studies reported so far, however, the follow-up of patients with TIA or stroke has lasted no more than 3 to 5 years. Therefore, Van Wijk and colleagues sought to study determinants of survival and the occurrence of vascular events in the long term after a TIA or minor or ischemic stroke. They prospectively followed more than 2400 patients who had had a TIA or minor stroke and had been enrolled in the Dutch TIA Trial between 1986 and 1989. (The Dutch TIA Trial Study Group. N Engl J Med. 1991;325:1261-1266).
Follow-up was complete in 2447 patients (99%). After a mean follow-up of 10 years, 1489 patients (60%) had died. Of these, three quarters were vascular deaths (ischemic stroke, cerebral hemorrhage, myocardial infarction, congestive heart failure, sudden death, or other vascular cause). The cumulative risk of death was approximately 3% at one year, 19% at 5 years, and 43% at 10 years after enrollment.
The strongest predictors of death from any cause were age over 65 years (Risk Ratio {RR} 3.33), diabetes (RR 2.10), previous peripheral vascular surgery (RR 1.94), history of claudication (RR 1.77), and pathological Q-waves or negative T-waves on baseline electrocardiogram (RR 1.59). Angina pectoris was not a predictor of death (RR 1.3).
During the period of follow-up, 1366 patients (54%) had at least one vascular event. The 10-year risk of vascular events for patients with TIA was 36%, and for those with minor stroke, it was 48%. Cumulative risk of a major vascular event was 7% at one year, 24% at 5 years, and 44% at 10 years. The mean yearly recurrence rate was 6%; it gradually declined during the first 3 years from 7% to 3.5%, but steadily increased over time thereafter. The strongest predictors of a vascular event were identical to the strongest predictors of death.
Coutts and colleagues prospectively examined the predictive value in the short term (90 days) of acute MRI scanning and MR angiography in patients presenting with an acute TIA or minor stroke. One hundred twenty TIA or minor ischemic stroke patients (NIH Stroke scale score < 3) presenting to a single academic institution in Canada were examined by a stroke neurologist within 12 hours of onset and had brain MRI scanning and MR angiography performed with 24 hours.
The 90-day risk for stroke in this cohort was 12%, and the high risk period was within the first 48 hours of the initial event. Sixty-four percent of events occurred within this period. Patients with a diffusion weighted imaging (DWI) lesion were at greater risk for stroke than patients without a lesion, and the risk was greatest in those with both a DWI lesion and an intracranial vessel occlusion. The 90-day risk rate for patients with no DWI lesion was 4%; for those with a DWI lesion but no vessel occlusion, the risk rate was 11%; and for those with a DWI lesion and a vascular occlusion, the risk rate was 33% (P = 0.02). At 3-month follow-up, a high proportion of these patients (21%) were dependent vs 2% of patients with no DWI lesion and 6% of patients with only a DWI lesion. Coutts et al conclude that acute MRI is useful in making triage decisions for patients with TIA or minor stroke because it reliably divides such patients into benign, intermediate, and poor prognosis groups.
Commentary
Van Wijk et al confirmed that the risk of stroke and other major vascular events remains high over the 10 years after TIA or minor ischemic stroke. Interestingly, the annual risk for recurrent vascular events was not linear: it was high early, declined to a low point at 3 years, and then progressively increased. This late increase probably reflects continued exposure to vascular disease-inducing risk factors, an increase in atherosclerotic plaque burden, and increasing age. In this particular cohort, however, it could reflect a decline in drug compliance after the end of the Dutch TIA Trial and reduced attention to lifestyle factors. If so, risk-factor modification and drug therapy may improve the long-term secondary prevention of vascular events.
The study of Coutts et al underlines the utility of the tools now available to aid in the emergent diagnostic evaluation of patients with cerebrovascular disease. DWI and perfusion MRI performed early can help the clinician to select patients who might benefit from reperfusion and neuroprotectant agents. Nevertheless, as pointed out by Hanley in his comments, the report of Van Wijk showed the predictive power of history taking alone. Simply by asking the patient about age, history of myocardial infarction, diabetes, hypertension, and peripheral vascular disease, the clinician can obtain almost as much information about risk of a future vascular event as from the neurological examination and diagnostic procedures.
By John J. Caronna, MD Vice Chairman, Department of Neurology, Cornell University Medical Center and Professor of Clinical Neurology, New York Hospital Dr. Caronna reports no consultant, stockholder, speakers bureau, research, or other relationship related to this field of study. Synopsis: Acute MRI is useful in making triage decisions for patients with TIA or minor stroke because it reliably divides such patients into benign, intermediate, and poor prognosis groups.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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