Each year in the United States, 795,000 people suffer a stroke. 610,000 of those strokes are first occurrences and 185,000 are recurrent.1
Fifteen percent of the strokes are hemorrhagic, and 85% are ischemic. Of those ischemic strokes, approximately 30% are cryptogenic (unknown cause).2
Ischemic Stroke Breakdown
The Link between Atrial Fibrillation and Cryptogenic Stroke
- Studies indicate that undiagnosed atrial fibrillation is present in patients with cryptogenic stroke that is not detected during routine diagnostic procedures.3
- Episodes are intermittent and may not be caught during monitoring.4
- Holter Monitors are often used for cardiac monitoring after a cryptogenic stroke. The yield of three to seven days of ambulatory Holter monitoring after
cryptogenic stroke is estimated to be 6%.5
Identification of AF changes therapy to OAC, which can prevent a second stroke. OAC offers a 64% relative risk reduction for stroke compared to placebo.6
Patient Selection Considerations
For cryptogenic stroke patients, Reveal LINQ ICM may be an appropriate choice due to the median time to AF detection over 12 months of 84 days (CRYSTAL-AF Study).7 However, the patient's age and the rigor of the stroke work-up they received leading up to the cryptogenic stroke classification should be considered:
CRYSTAL AF Study Work Up/Patient Inclusion Criteria:
- ≥40 years of age
- Cryptogenic stroke (or clinical TIA), with infarct seen on MRI or CT, within the previous 90 days; and no mechanism (including AF) determined after:
- 12-lead ECG
- 24-hour ECG monitoring (e.g. Holter)
- Transesophageal echocardiography (TEE)
- CTA or MRA of head and neck to rule out arterial source
- Screening for hypercoagulable states in patients <55 years old
- Hajat C, Heuschmann PU, Coshall C, Padayachee S, Chambers J, Rudd AG, et al. Incidence of aetiological subtypes of stroke in a multi-ethnic population based study: the South London Stroke Register. J Neurol Neurosurg Psychiatr. 2011;82:527–533.
- Liao J, Khalid Z, Scallan C, Morillo C, O’Donnell M. Noninvasive cardiac monitoring for detecting paroxysmal atrial fibrillation or flutter after acute ischemic stroke: a systematic review. Stroke 2007;38:2935–2940.
- Cotter, P.E., et al., Incidence of atrial fibrillation detected by implantable loop recorders in unexplained stroke. Neurology, 2013 Apr 23;80(17):1546-50;
- Ritter, M.A., et al., Occult Atrial Fibrillation in Cryptogenic Stroke: Detection by 7-Day Electrocardiogram Versus Implantable Cardiac Monitors. Stroke, 2013 May;44(5):1449-52.
- Tayal AH, Tian M, Kelly KM, Jones SC, Wright DG, Singh D, et al. Atrial fibrillation detected by mobile cardiac outpatient telemetry in cryptogenic TIA or stroke. Neurology. 2008;71:1696–1701.
- Stroke Prevention in Atrial Fibrillation Study. Final results. Circulation. 1991; 84:527-39.
- Sanna T, Diener HC, Passman RS, et al. Cryptogenic Stroke and Underlying Atrial Fibrillation (CRYSTAL AF). N Engl J Med. 2014; 370(26):2478-2486.