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Cryptogenic Stroke Cardiac Diagnostics and Monitoring

Atrial fibrillation detection and treatment matters

The Cryptogenic Stroke Challenge

Each Year, at Least 200,000 Cryptogenic Strokes Occur in the United States1

Infographic of two blue people and one green person illustrating one in three odds

One-third of Ischemic Strokes are Cryptogenic (Unexplained)

Cryptogenic stroke accounts for approximately one-third of ischemic strokes in the modern stroke registries and databases.2

Cryptogenic stroke is as prevalent as large vessel stroke.

The Link between Stroke and Atrial Fibrillation 

Impact of Prolonged Cardiac Monitoring (PCM) on Secondary Stroke Prevention3    

2.5x Increased incidence of AF detection

2.1x Increased incidence of anticoagulant initiation

55% Decreased risk of recurrent stroke

The use of prolonged cardiac monitoring has a potential impact on secondary stroke prevention, as patients with cryptogenic IS/TIA undergoing PCM had higher rates of AF detection and anticoagulant initiation, and lower stroke recurrence.

2019 AHA/ACC/HRS Atrial Fibrillation Guidelines

The 2019 AHA/ACC/HRS atrial fibrillation guidelines provide a Class IIa, Level B-R recommendation for device detection of AF in patients with cryptogenic stroke (i.e., stroke of unknown cause).4

Class of Recommendation (COR)

Level of Evidence (LOE)


I B-NR 1. In patients with cardiac implantable electronic devices (pacemakers or implanted cardioverter-defibrillators), the presence of recorded atrial high-rate episodes (AHREs) should prompt further evaluation to document clinically relevant to AF to guide treatment decisions (S7.12-1-S7.12-5).
IIa* B-R 2. In patients with cryptogenic stroke (i.e., stroke of unknown cause) in whom external ambulatory monitoring is inconclusive, implantation of a cardiac monitor (loop recorder) is reasonable to optimize detection of silent AF (S7.12-6).

2016 ESC Atrial Fibrillation Guidelines5

Long-term Cardiac Monitoring Recommended for Cryptogenic Stroke Patients

  • Guidelines developed by the Task Force for the management of atrial fibrillation of the European Society of Cardiology (ESC)
  • Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC
  • Endorsed by the European Stroke Organisation (ESO)






In stroke patients, additional ECG monitoring by long-term non-invasive ECG monitors or implanted loop recorders should be considered to document silent atrial fibrillation.

30 Days of Cardiac Monitoring Is Not Long Enough in Cryptogenic Stroke Patients6

Atrial Fibrillation Is Frequently Asymptomatic and/or Paroxysmal

The CRYSTAL-AF study found that short- and intermediate-term cardiac monitoring may miss many patients with paroxysmal AF.

At 12 months, 97% of patients in whom AF was detected received oral anticoagulant6

79% of first AF episodes were asymptomatic at 12 months

88% of patients who had AF would have been missed if only monitored for 30 days

Reveal LINQ™ ICM Patient Selection Considerations


  • Patients with clinical syndromes or situations at increased risk of cardiac arrhythmias


  • Stroke detected by CT or MRI that is not lacunar7
  • Absence of extracranial or intracranial atherosclerosis causing ≥ 50% luminal stenosis in arteries supplying the area of ischaemia7
  • No major-risk cardioembolic source of embolism1
  • No other specific cause of stroke identified (e.g., arteritis, dissection, migraine/vasospasm, drug misuse)7
  • Any age
  • First event — stroke or high-risk TIA§
  • CHADS2 score ≥ 2 (minimal risk factors)

Not Appropriate

  • Indication for chronic anticoagulation or already on anticoagulation
  • Patients with a relative contraindication for long-term anticoagulation and not appropriate for LAA closure device

Class IIa is Benefit >> Risk and LOE B-R is moderate quality of evidence from 1 or more RCTs or meta-analyses of moderate quality RCTs.

Based on Kaplan-Meier estimates.

See full brief statement for complete indications for use.


ABCD2 Score > 5.



Mozzafarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics – 2015 update: a report from the American Heart Association. Circulation. January 27, 2015;131(4):e29-e322.


Sacco RL, Ellenberg JH, Mohr JP, et al. Infarcts of undetermined cause: the NINCDS Stroke Data Bank. Ann Neurol. April 1989;25(4):382-390.


Tsivgoulis G, Katsanos AH, Grory BM, et al. Prolonged Cardiac Rhythm Monitoring and Secondary Stroke Prevention in Patients With Cryptogenic Cerebral Ischemia. Stroke. August 2019;50(8):2175-2180.


January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation. Circulation. July 9, 2019;140(2):e125-e151.


Kirchhof P, Benussi, S, Kotecha D, et al. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Eur Heart J. October 7, 2016;37(38):2893-2962.


Sanna T, Diener HC, Passman RS, et al. Cryptogenic stroke and underlying atrial fibrillation. N Engl J Med. June 26, 2014;370(26):2478-2486.


Hart RG, Diener HC, Coutts SB, et al. Embolic strokes of undetermined source: the case for a new clinical construct. Lancet Neurol. April 2014;13(4):429-438.