American Board of Internal Medicine (ABIM) Certification Practice Exam

What percentage of patients with cryptogenic ischemic stroke may have paroxysmal atrial fibrillation upon prolonged cardiac monitoring?

1. 10%

2. 25%

3. 50%

4. 75%

The correct answer is: 25%

In patients experiencing a cryptogenic ischemic stroke, prolonged cardiac monitoring can reveal underlying paroxysmal atrial fibrillation (AF) in a significant number of cases. Research indicates that approximately 25% of these patients may indeed be found to have paroxysmal AF when monitored over an extended period, typically through devices such as Holter monitors or implantable loop recorders. The identification of AF is crucial because it significantly influences the management and prevention strategies in patients who have suffered an ischemic stroke. AF is a well-known risk factor for stroke due to the potential for thromboembolic events originating from the left atrial appendage. By recognizing that around one-quarter of those with unexplained ischemic strokes may harbor AF, clinicians can implement appropriate anticoagulation therapy, which can be instrumental in preventing future cerebrovascular events. Overall, understanding the prevalence of paroxysmal atrial fibrillation in this specific population emphasizes the importance of thorough evaluation and monitoring to improve patient outcomes.