Cardiac Diagnostics and Monitoring


The Reveal LINQ™ insertable cardiac monitor (ICM) is superior to standard monitoring for AF detection in cryptogenic stroke patients.1

Reveal LINQ ICM shown vertically

Reveal LINQ™ ICM

Study design

  • Randomized, controlled clinical trial with 441 patients
  • Compared continuous, long-term monitoring with Reveal LINQ ICM vs. conventional follow-up
  • Assessment at scheduled and unscheduled visits
  • ECG monitoring performed at the discretion of the site investigator

Patient inclusion criteria

  • ≥ 40 years of age
  • Cryptogenic stroke (or clinical TIA) with infarct seen on MRI or CT within the previous 90 days and no mechanism identified after:
    • 12-lead ECG
    • 24-hour ECG monitoring (e.g., Holter)
    • Transesophageal echocardiography
    • CTA or MRA of head and neck to rule out arterial source
    • Screening for hypercoagulable states in patients < 55 years old

End points


The primary end point is the time to first detection of AF at six months of follow-up.


  • Time to first detection of AF at 12 months of follow-up
  • Recurrent stroke or TIA
  • Actions taken after patient diagnosed with AF

Study results

The landmark CRYSTAL-AF study found that continuous monitoring with the Reveal LINQ ICM is superior to standard monitoring for detection of atrial fibrillation (AF or AFib) in patients with a cryptogenic stroke.1

Key findings

30% AF detected at three years versus 3% for standard of care:

  • 6.4x more AF detected at 6 months: 8.9% in ICM group versus 1.4% in control
  • 7.3x more AF detected at 12 months: 12.4% in ICM group versus 2.0% in control
  • 8.8x more AF detected at 36 months: 30% in ICM versus 3.0% in control

At 12 months, 97% of patients in whom AF was detected received oral anticoagulant.

79% of first AF episodes were asymptomatic at 12 months.

Detection of atrial fibrillation by 36 months

Results of the CRYSTAL-AF study of patients with AF detected with the Reveal LINQ ICM continuous monitoring

Hazard ratio, 8.8 (95% CI, 3.5–22.2)
p < 0.001 by log-rank test

30 days of monitoring is not enough.

  • Extensive external monitoring found few patients with AF.
    • In the control group at six months, only three patients were found to have AF; yet there were 88 conventional ECGs, 20 24-hour Holters, and one event recorder used.
  • Reveal LINQ ICM detected over seven times more patients with AF at the 12-month end point.
  • 88% of patients who had AF would have been missed if only monitored for 30 days.*

*Based on Kaplan-Meier estimates.

"Atrial fibrillation after cryptogenic stroke was most often asymptomatic and paroxysmal and thus unlikely to be detected by strategies based on symptom-driven monitoring or intermittent short-term recordings."1

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Sanna T, Diener HC, Passman RS, et al. Cryptogenic Stroke and Underlying Atrial Fibrillation (CRYSTAL AF). N Engl J Med. June 26, 2014;370(26):2478–2486.