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An estimated 26 million people suffer a stroke each year, making it a significant source of mortality and long-term disability. Up to two-thirds of strokes are ischemic in origin, and approximately 25 percent of all ischemic strokes are cardioembolic. Cardioembolic strokes are frequently more severe than atherothrombotic strokes. Additionally, they are more prone to both early and late recurrences. This activity reviews the etiology, evaluation, and management of cardioembolic strokes and highlights the role of interprofessional teams in caring for affected patients.
- Describe the etiology of cardioembolic stroke.
- Explain the evaluation of a cardioembolic stroke.
- Review the treatment options for cardioembolic strokes.
- Summarize the importance of improving coordination amongst the interprofessional team to enhance care for patients affected by cardioembolic strokes.
An estimated 26 million people suffer from a stroke every year, making it one of the most significant contributors to both mortality and long-term disability. Up to two-thirds of these are ischemic. Approximately 25% of all ischemic cases are believed to be cardioembolic in origin. However, despite accounting for a relatively small proportion of all ischemic strokes, cardioembolic strokes are particularly important as they are frequently more severe than atherothrombotic strokes. Additionally, they are more prone to both early and late recurrences.
Cardioembolic strokes can occur from at least a dozen specific cardiac disorders, including atrial fibrillation, left ventricular thrombi, cardiac tumors, valvular vegetations, and paradoxical emboli. For the most part, cardioembolic strokes can be prevented.
Cardioembolic strokes can occur as a consequence of any cardiac insult that could cause the fulfillment of Virchow triad of endothelial injury, stasis, and hypercoagulability.
Commonly encountered causes include:
- Atrial disease:
- Atrial fibrillation, specifically non-valvular atrial fibrillation, is believed to be the most prevalent cause of cardioembolic strokes. Considered the most frequently encountered sustained arrhythmia, it occurs in approximately 5% of people aged 65 years and above. In western populations, most cases are believed to occur secondary to ischemic or hypertensive heart disease. Other contributing factors include hyperthyroidism and heavy alcohol consumption. The contribution of valvular heart disease, particularly the involvement of the mitral valve, is on the decline in terms of the number of cases. However, concerning relative risk, patients with valvular atrial fibrillation have a 17-fold increased risk of cardioembolic stroke, as opposed to the 2-7 fold increased risk in patients with non-valvular atrial fibrillation. The CHADS2 risk stratification tool is often used to predict the stroke risk in patients with atrial fibrillation
- Sick sinus syndrome, also known as a bradycardia-tachycardia syndrome, is also associated with an increased risk of stroke.
- Structural disease:
- Patent foramen ovale: The role of a patent foramen ovale in strokes, particularly the so-called “cryptogenic strokes,” is currently an area of great interest. Current evidence is insufficient to conclude about its role as a causative factor, or merely as a conduit for paradoxical emboli.
- Valvular heart disease: Even with the absence of arrhythmias, valvular heart diseases correlate with an increased risk of stroke. These include:
- Rheumatic valvular disease; the most common is rheumatic mitral stenosis. Without anticoagulation, the risk of stroke is very high.
- Infective endocarditis: Approximately 10% of cases of infective endocarditis develop embolic strokes. The risk of stroke occurrence is highest before instituting, or within the first two weeks of antibiotic therapy. Anticoagulation is contraindicated because, usually, they are associated with superimposed microhemorrhages. However, current recommendations are to start anticoagulation seven days after a stroke.
- Non-infective endocarditis such as marantic endocarditis
- Valvular calcifications: Native valvular calcification, particularly of the mitral valve, increases the risk of developing a cardioembolic stroke. Mitral annular calcification correlates with a relative risk of 2.1 for the development of embolic stroke.
- Mechanical prosthetic heart valves have a stroke rate of 2% to 4%, even in patients maintained on oral anticoagulation. Permanent anticoagulation with an INR between 2.5-3.5 is mandatory. Bioprosthetic heart valves have a lower risk of stroke, and aspirin is recommended unless the patient has atrial fibrillation.
- Mitral valve prolapse has a low risk of stroke, and anticoagulation is not recommended. However, long-term aspirin is recommended.
- Structural and functional ventricular diseases:
- Ventricular aneurysms
- Septal aneurysms
- General ventricular hypokinesia (heart failure with reduced ejection fraction): The annual rate of stroke in patients with heart failure with reduced ejection fraction (HFrEF) is approximately 2%, with a direct correlation between the risk of a stroke, and the degree of ventricular compromise.
- Myocardial infarction: The occurrence of myocardial infarction increases the risk of the development of a stroke, with the degree of left ventricular dysfunction, the presence of a ventricular aneurysm or mural thrombus, and the presence of arrhythmias significantly influencing the degree of risk. Approximately 2.5% of cases will develop a stroke within the first four weeks of the infarction, and nearly 10% will over six years.
Cardioembolic strokes appear to occur more frequently with increasing age. Studies have estimated that they account for 14.6% of cases below the age of 65 years, but this proportion has gone up to 36% for patients aged 85 years and older.
About 20% of strokes are considered to cardioembolic. The risk of these strokes increases with age.