Embolic stroke of undetermined source (ESUS) can be diagnosed if certain features are identified. There is a substantial risk of recurrent stroke during antiplatelet therapy. The authors are from McMaster University and University of Thessaly.

Criteria for an embolic stroke of undetermined source:

(1) ischemic stroke detected on imaging study (CT or MRI scan)

(2) not lacunar (see below)

(3) exclusion of possible sources

(3a) absence of significant (>= 50%) extracranial or intracranial atherosclerosis in the arteries supplying the area of ischemia

(3b) no evidence of a cardiac source (see below)

(3c) no evidence of arteritis, dissection, migraine, vasospasm, drug abuse or other specific cause


The workup of the patient should include cardiac rhythm monitoring with automated rhythm detection for >= 24 hours. Prolonged monitoring can detect cryptogenic episodes of atrial fibrillation.


Features of a lacunar infarct:

(1) subcortical infarct

(2) <= 1.5 cm in largest dimension (<= 2.0 on MRI diffusion image)

(3) in the distribution of the small, penetrating cerebral arteries of the cerebral hemispheres and pons


Cardiac sources of emboli include:

(1) permanent or paroxysmal atrial fibrillation

(2) sustained atrial flutter

(3) intracardiac thrombus

(4) prosthetic cardiac valve

(5) atrial myxoma or other cardiac tumor

(6) mitral stenosis

(7) recent myocardial infarction (within past 4 weeks)

(8) left ventricular ejection fraction less than 30%

(9) valvular vegetations

(10) infective endocarditis

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