ESUS and Atrial Fibrillation

ESUS (Embolic Stroke of Undetermined Source) is a cryptogenic embolic stroke.

The overall prevalence of ischemic stroke is 2–3% (> 7% in the population > 65 years).

According to CT or MR imaging, ischemic stroke can be classified as:

Lacunar

A small subcortical lesion < 15 mm (on CT) or < 20 mm (on MR)
Caused by disease of small intracerebral arterioles, mainly arterial hypertension and diabetes mellitus.

Non-lacunar

A large subcortical and cortical lesion > 15 mm (on CT) or > 20 mm (on MR).
Mainly caused by embolization in atrial fibrillation (AF) or rupture of an atherosclerotic plaque.

Infographic illustrating the ESUS concept within ischemic stroke, highlighting the proportion of cryptogenic events and the relationship to silent atrial fibrillation as a potential cardioembolic source.

Cryptogenic stroke is a broad term referring to any ischemic stroke (embolic or non-embolic) without a diagnosed cause. Once a cause is identified, e.g. atrial fibrillation (AF), the cryptogenic stroke is reclassified as cardioembolic stroke in AF.

Cryptogenic stroke accounts for 35% of all ischemic strokes.

Cryptogenic stroke may be embolic or non-embolic. The term ESUS is used to designate cryptogenic embolic ischemic stroke.

ESUS is a cryptogenic embolic stroke of undetermined source.

ESUS (Embolic Stroke of Undetermined Source)

30% of ESUS cases are due to silent AF (undiagnosed, asymptomatic)
It is a cryptogenic stroke that fulfils the following criteria:

Non-lacunar lesion (cortical or cortico-subcortical)
No significant stenosis (> 50%) of the artery supplying the ischemic area
No diagnosed cardioembolic source:

Atrial fibrillation
Atrial flutter
Intracardiac thrombi
Prosthetic valve (valve thrombosis)
Cardiac tumour
Mitral stenosis (moderate or severe)
Myocardial infarction (within the last 1 month)
Endocarditis

No other diagnosed cardioembolic cause:

Vasculitis, arterial dissection, migraine/vasospasm, drug abuse, etc.

ESUS (Embolic Stroke of Undetermined Source) – Causes
Atrial fibrillation (accounts for 30% of ESUS)
Atrial flutter
Intracardiac thrombi
Prosthetic valve (valve thrombosis)
Cardiac tumour
Mitral stenosis (moderate, severe)
Myocardial infarction (within the last 1 month)
Endocarditis

ESUS accounts for

17% of all ischemic strokes and
50% of all cryptogenic strokes

The annual risk of ESUS recurrence is 4.5%.

Cryptogenic stroke vs. ESUS (Embolic Stroke of Undetermined Source)
Characteristic	Cryptogenic stroke	ESUS
Type of ischemic stroke	Lacunar, non-lacunar	Non-lacunar
Aetiology	Embolic, non-embolic	Embolic
Arterial stenosis (supplying the ischemic lesion)	Unspecified	< 50 % in the affected artery
Cardioembolic source	Possible	Highly probable (most commonly silent atrial fibrillation)
Practical use	General term for ischemic stroke of unclear cause	Rapid identification of patients with suspected silent atrial fibrillation

Once AF is diagnosed in a patient with ESUS, ESUS is reclassified as cardioembolic stroke in AF.

Screening for atrial fibrillation in patients after ESUS (Embolic Stroke of Undetermined Source)	Class
Implantation of a loop recorder is recommended.	I
During symptoms (specific or non-specific), immediate ECG recording using a smart device with ECG capability (ECG watch, blood pressure monitor with ECG, ECG card) is recommended.	I
ECG Holter monitoring may be considered: 24-hour or 7-day (preferably).	IIa

Anticoagulation therapy and ESUS (Embolic Stroke of Undetermined Source)	Class
Anticoagulation therapy is not recommended in patients after ESUS without documented AF.	III