Hospital Admission After Transient Ischemic Attack
Unmasking Wolves in Sheep's Clothing
Patients with TIA are at high risk of short-term stroke, myocardial infarction, and vascular death. Because stroke risk is reduced by immediate medical or surgical intervention, emergent evaluation and treatment is warranted. The Effect of urgent treatment of transient ischemic attack and minor stroke on early recurrent stroke (EXPRESS) and effectiveness of round-the-clock access (SOS-TIA) studies1 showed that urgent evaluation and initiation of preventive treatments such as antiplatelets, statins, anticoagulation, and carotid revascularization markedly reduce the risk of early stroke after a TIA or minor stroke. The ABCD2 score, based on clinical features and demographic data, has been shown to predict the short-term stroke risk after TIA and is being increasingly used to triage patients with TIA. However, its low interrater reliability, poor correlation with imaging findings, and its inability to identify patients who require in-hospital intervention preclude the use of the ABCD2 scores as a sole decision-making tool. In other words, the ABCD2 score represents field glasses that help shepherds to visualize a flock at a long distance in an attempt to discriminate sheep (low-risk TIAs) from wolves (high-risk TIAs).
Our TIA shepherds do not thrust with their field glasses. They concur that all patients with TIA should be evaluated and diagnosed urgently regardless the ABCD2 score. However, they defend divergent strategies to identify wolves in a flock of sheep. Cucchiara and Kasner recommend that the entire flock should be admitted for both observation and rapid diagnosis. In contrast, Amarenco prefers to shear all sheep to depict wolves in the field, out of the farm, releasing the rest of the flock of sheep.
Although neuroimaging is helpful to establish the ischemic nature of the transient event and rule out TIA mimics, both emergent neurovascular imaging and comprehensive cardiac evaluation are critical to identify the TIA mechanism, stratify the risk of stroke, and establish the appropriate emergent intervention. Rapid neurovascular imaging, including CT angiography, MRI, or ultrasound, is becoming standard of care in most academic centers for TIA and stroke. In contrast, emergent detection of a cardiembolic source on a 24/7/365 basis is not always available and completing diagnostic work-up remains a cause of hospitalization in remarkable numbers of patients with TIA.
Regardless of its location—emergency department-based, day hospital, or outpatient clinic—24/7 availability of urgent-access dedicated TIA clinics requires optimal organization and resources. Drs Cucchiara and Kasner express a common concern about the logistics and administrative barriers to ensure a rapid and efficient access to in-hospital interventions when patients with TIA are evaluated in outpatient settings. Hospitalized patients are more likely to receive prompt endarterectomy or stenting after the diagnosis of severe carotid stenosis compared with their outpatient counterparts. Although differences in health systems around the world preclude a general recommendation, urgent-access TIA clinics should develop efficient patient flow systems to ensure emergent in-hospital interventions. On the other hand, routine hospital admission for all patients with TIA may be unnecessary and cost-ineffective. In fact, hospitalization after TIA has demonstrated to be not cost-effective compared with same-day clinic evaluation after TIA. As Dr Amarenco points out, the stroke risk is low (1.28%) in up to 75% of patients with TIA evaluated in a TIA clinic who are discharged after rapid evaluation and treatment, indicating that a very small fraction of patients with TIA would benefit from hospitalization if urgent assessment is available. The low stroke risk in these patients also argues against the need for admission of all patients with TIA for cardiac telemetry and echocardiography, especially in those with no clinical suspicion for a cardioembolic source and those in whom 12-lead electrocardiography does not show significant conduction abnormalities or ST-T wave changes. Detailed cardiac assessments (Holter monitor and echocardiography) can be safely carried out on an outpatient basis, if not available 24/7, in the vast majority of patients with TIA.2
Because up to 20% of “low-risk TIA” patients (ABCD2 score <4) are wolves in sheep's clothing, emergent neurovascular evaluation should be performed as soon as possible after TIA presentation regardless of ABCD2 score. It is human nature to slow down a process when it is at safe shores. Expedited neurovascular evaluation is mandatory in all patients with TIA because the 48-hour stroke risk in patients with carotid stenosis is up to 3-fold higher than those without carotid stenosis. Similarly, the Vision In Stroke Intervention Or Not (VISION) study showed that up to 20% of patients with TIA have intracranial occlusions and that these patients have up to 46% risk of early clinical worsening.
Effort should be made to implement rapid access of patients with TIA to the emergency department or outpatient clinic settings. High-risk patients with TIA, based on actual findings rather than on risk-stratification scores, should be admitted for medical or surgical intervention. In few cases, however, patients with TIA with intracranial or extracranial occlusive lesions, despite symptom resolution, should be admitted for observation to optimize measures to maintain cerebral blood flow or eventual thrombolytic therapy in case of clinical deterioration.
The opinions expressed in this article are not necessarily those of the editors or of the American Heart Association. This article is Part 3 of a 3-part article. Parts 1 and 2 appear on pages 1446 and 1448, respectively.
- Received December 11, 2011.
- Accepted December 19, 2011.
- © 2012 American Heart Association, Inc.