Identification of Covert Atrial Fibrillation in Cryptogenic Ischemic Stroke: Current Clinical Practice in Japan

A new insertable cardiac monitor, Reveal LINQ (Medtronic, Dublin, Ireland), was approved for clinical use in Japan in March 2016 for detecting atrial fibrillation in patients who develop ischemic stroke with no clearly definable etiology even after extensive workup, so-called cryptogenic ischemic stroke. Cooperation between a specialist of the Japan Stroke Society and a trained cardiologist or cardiac surgeon is needed both for appropriate patient selection and appropriate management of the device. In this paper, the clinical significance of and diagnostic methods for cryptogenic stroke and covert atrial fibrillation are explained, along with our proposal for the clinical indications for this new device.

The majority of cryptogenic ischemic strokes are considered to be embolic. In particular, covert atrial fibrillation is drawing attention as the causal emboligenic disease, and it was identified in 30% of patients with long-term observation using an insertable cardiac monitor. Should atrial fibrillation be present, there is a high risk of recurrent stroke, and the cardioembolic stroke that appears is generally severe. The ability to identify atrial fibrillation would be beneficial for preventing stroke recurrence, as anticoagulants can then be used as an established method of secondary prevention. Because the use of insertable cardiac monitors is somewhat invasive, and long-term care systems are also needed, patients suitable for examination using the new device would need to be identified on the basis of detailed diagnostics in accordance withcurrent medical practice in Japan.