From the Guidelines
A cryptogenic stroke is a stroke that has no identifiable cause despite thorough medical investigation, accounting for approximately 25-40% of all ischemic strokes, as reported in a systematic review of international clinical practice guidelines 1. When a patient experiences a stroke, doctors typically perform various tests to determine the cause, such as:
- Brain imaging
- Heart monitoring
- Blood vessel studies
- Blood tests However, in cryptogenic strokes, these standard evaluations fail to reveal a clear source. Potential hidden causes may include:
- Undetected heart rhythm abnormalities like paroxysmal atrial fibrillation
- Small blood clots passing through a patent foramen ovale (a small hole between the heart chambers)
- Undiagnosed atherosclerosis Management typically involves:
- Antiplatelet medications like aspirin (81-325mg daily) or clopidogrel (75mg daily) to prevent recurrence
- Risk factor modification such as controlling blood pressure, managing diabetes, quitting smoking, and maintaining a healthy lifestyle In some cases, extended cardiac monitoring for up to 30 days may be recommended to detect intermittent arrhythmias, as suggested by the American Heart Association/American Stroke Association and the American College of Cardiology Foundation 1. The diagnosis of cryptogenic stroke is important because it guides further testing and preventive strategies, even though the exact cause remains unknown, and recent studies have highlighted the need for completion of randomized clinical trials to establish an evidence base for optimal care 1. According to the most recent study, the optimal therapy for prevention of recurrent stroke or transient ischemic attack in patients with cryptogenic stroke and patent foramen ovale has not been defined, and enrollment in clinical trials is critical to establish an evidence base for informed decisions regarding the best therapy for individual patients 1.
From the Research
Definition of Cryptogenic Stroke
- Cryptogenic stroke refers to a stroke that remains without a definite cause even after extensive work-up, accounting for about 30-40% of all strokes 2.
- The determination of stroke aetiology is a valuable procedure to avoid the risk of stroke recurrence, especially in young patients 2.
Causes of Cryptogenic Stroke
- The cause of stroke may be transitory or reversible, and the diagnostic work-out is not therefore performed at the appropriate time 2.
- All known causes of stroke may not be fully investigated 2.
- Some causes of stroke remain unknown 2.
Treatment Options for Cryptogenic Stroke
- Patent foramen ovale (PFO) closure, antiplatelet therapy, and anticoagulation are treatment options for patients with cryptogenic stroke and PFO 3, 4.
- PFO closure probably results in substantial reduction in ischemic stroke recurrence compared with antiplatelet therapy alone 3.
- Anticoagulation, compared with antiplatelet therapy, may reduce the risk of ischemic stroke recurrence, but probably increases the risk of major bleeding 3, 5, 6.
Risks and Benefits of Treatment Options
- PFO closure is associated with a lower risk of recurrent stroke compared with antithrombotic therapy, but incurs a risk of persistent atrial fibrillation and device-related adverse events 4.
- Anticoagulation conveys no net benefit in prevention of recurrent stroke over antiplatelets in patients with PFO-related stroke, but may be beneficial in patients with high RoPE score 5.
- Oral anticoagulants compared with antiplatelet therapies were associated with a lower risk of recurrent ischemic stroke and a non-significantly increased risk of major bleeding in patients with cryptogenic stroke and potential cardiac emboli 6.