Ischemic stroke is the result of a sudden blockage of blood flow to the central nervous system due to thrombotic or embolic phenomena, and it is a major cause of morbidity and mortality worldwide. In 2019, stroke was the fifth leading cause of death in the United States.¹ Although stroke can be hemorrhagic or ischemic, approximately 87% of strokes in the United States are ischemic.² Almost 800,000 strokes occur annually in the United States, often leading to long-term disability.²

Transient ischemic attack (TIA) is defined as a transient neurologic dysfunction caused by ischemia without infarction on imaging. Because the subsequent risk of stroke after TIA is similar to that of an initial stroke, TIA is treated similarly to a minor, nondisabling stroke. In this article, TIA is included with ischemic stroke, except where noted.

It is estimated that 87% of stroke risk is attributable to modifiable risk factors.² Risk factors for ischemic stroke are listed in Table 1.^3,4

Similar to many conditions, stroke is associated with health disparities. Compared with White people, Black people in the United States have strokes at younger ages and have more poststroke disability, much of which is related to modifiable risk factors.⁵ Increasing age and female sex are associated with greater poststroke disability.⁵ Stroke risk also varies with education level, income, zip code, health insurance, and social isolation, and assessing these factors is important for the primary and secondary prevention of stroke.⁶

Diagnostic Evaluation

Although the initial management of acute stroke usually occurs in the emergency and hospital settings, the outpatient follow-up evaluation is critical to ensure that the appropriate testing has been completed, reviewed, and discussed with the patient.⁷ Certain parts of the evaluation to determine the cause of the stroke may be deferred until outpatient follow-up. Table 2 summarizes the evaluation of stroke on the basis of pathogenesis.^3,7,8

At the first primary care visit after stroke, diagnostic imaging should be reviewed to confirm the diagnosis.³ Although computed tomography (CT) and magnetic resonance imaging (MRI) are both used to diagnose stroke, MRI has 99% sensitivity for stroke, compared with 39% with CT, and can diagnose acute ischemic strokes missed by CT.8 If initial imaging was negative for stroke despite characteristic symptoms, follow-up CT or MRI may be indicated to confirm the diagnosis.^3,7

Atrial fibrillation is estimated to cause approximately 1 in 7 strokes.⁹ In addition to electrocardiography performed during the initial evaluation of stroke, continuous cardiac rhythm monitoring is often performed during hospitalization.³ Long-term cardiac rhythm monitoring (e.g., 30-day event monitor, implantable loop recorder) increases the detection of atrial fibrillation and is useful in the evaluation of cryptogenic stroke.^3,10

The initial evaluation of stroke includes laboratory testing to identify underlying risk factors and determine therapeutic targets.³ Complete blood count, prothrombin time, partial thromboplastin time, glucose, A1C, creatinine, and lipid profile are recommended to identify risk factors such as diabetes, dyslipidemia, chronic kidney disease, and blood cell dyscrasia. If stroke is determined to be cryptogenic based on the initial evaluation, expanded laboratory assessment, including testing for hypercoagulable states (e.g., prothrombin gene mutation, factor V Leiden, protein C and S deficiencies, antithrombin deficiency), infection, drug use, and connective tissue, inflammatory, and genetic disorders, may be indicated.

Polysomnography can also be considered to evaluate for obstructive sleep apnea. This condition is both a risk factor for stroke and a common comorbidity in patients with previous stroke (approximately 40% of stroke cases); however, it is unclear whether treatment with continuous positive airway pressure prevents recurrent vascular events.³