Kevin O’Connor, MD
Embolic strokes of undetermined source (ESUS) account for about a fifth of all ischemic strokes and comprise pathologies including cardioembolic sources, undiagnosed malignancy, and arteriogenic emboli. There is no single strategy for investigating suspected cardioembolic strokes, and initiating empiric anticoagulation for these patients may result in more harm than benefit.
Cardiac monitoring — whether implanted or external — is an important part of a cardioembolic workup, but the ideal timeframe for monitoring is unclear. In the CRYSTAL AF trial, the median time for atrial fibrillation (AF) detection via implanted cardiac monitor (ICM) was 8.4 months. A meta-analysis of ICM use in patients monitored for AF reported detection rates of 5% for <6 months, 26% for 12-24 months, and 34% for >24 months of monitoring. Although prolonged monitoring appears beneficial, the utility may be limited by patient adherence, accurate interpretation of captured rhythms, and patient cost.