Cardiac Diagnostics and Monitoring

CRYSTAL-AF study

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

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Alert Indications, Safety, and Warnings

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

Primary

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

Secondary

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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Resources and downloads

On-demand education

Watch webinars on secondary stroke prevention and the role of insertable cardiac monitoring

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Reference

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.

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