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Key Clinical Updates in Transient Ischemic Attacks

Dual antiplatelet therapy with aspirin and clopidogrel for 90 days after a TIA or stroke due to 70–99% stenosis of an intracranial artery is recommended.

The left atrial appendage is the source of embolism in most patients with atrial fibrillation. Several randomized trials showed percutaneous left atrial appendage closure was equivalent to anticoagulation in preventing stroke and systemic embolization, and several devices are approved for this indication in the United States and Europe. The procedure should be considered in patients with a contraindication to long-term anticoagulation, although short-term anticoagulation (45 days) followed by dual antiplatelet therapy (4.5 months) and then indefinite aspirin monotherapy is usually necessary after device placement.

Kleindorfer DO et al. 2021 Stroke. [PMID: 34024117]

ESSENTIALS OF DIAGNOSIS

  • Focal neurologic deficit of acute onset.

  • Clinical deficit resolves completely within 24 hours.

  • Risk factors for vascular disease often present.

GENERAL CONSIDERATIONS

Transient ischemic attacks (TIAs) are characterized by focal ischemic cerebral neurologic deficits that last for less than 24 hours (usually less than 1–2 hours). About 30% of patients with stroke have a history of TIAs and 5–10% of patients with TIAs will have a stroke within 90 days. The natural history of attacks is variable. Some patients will have a major stroke after only a few attacks, whereas others may have frequent attacks for weeks or months without having a stroke. The risk of stroke is high in the first 3 months after an attack, particularly in the first month and especially within the first 48 hours. The stroke risk is greater in patients older than 60 years, in patients with diabetes, or after TIAs that last longer than 10 minutes and with symptoms or signs of weakness, speech impairment, or gait disturbance. In general, carotid ischemic attacks are more liable than vertebrobasilar ischemic attacks to be followed by stroke.

Urgent intervention in TIA patients reduces rates of subsequent stroke, and the condition should be treated with a similar sense of urgency as unstable angina.

ETIOLOGY

An important cause of transient cerebral ischemia is embolization. In many patients with these attacks, a source is readily apparent in the heart or a major extracranial artery to the head, and emboli sometimes are visible in the retinal arteries. An embolic phenomenon explains why separate attacks may affect different parts of the territory supplied by the same major vessel. Cardiac causes of embolic ischemic attacks include atrial fibrillation, heart failure, infective and nonbacterial thrombotic endocarditis, atrial myxoma, and mural thrombi complicating MI. Atrial septal defects and patent foramen ovale may permit venous thromboemboli to reach the brain (paradoxical emboli). An ulcerated plaque on a major artery to the brain may serve as a source of emboli. In the anterior circulation, atherosclerotic changes occur most commonly in the region of the carotid bifurcation extracranially; these changes ...

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