Medtronic has announced one-year results from a real-world study of patients who had a cryptogenic stroke, or stroke of unknown cause. The study found that the Reveal LINQ insertable cardiac monitor (ICM) detected atrial fibrillation (AF) at a greater rate than previously reported in a randomised controlled clinical trial (the CRYSTAL AF Study, published in The New England Journal of Medicine in 2014). The results from the observational real-world study were presented at the 68th American Academy of Neurology Annual Meeting in Vancouver, Canada.
The study evaluated 1,247 patients across the US to understand the incidence and duration of AF episodes in a large, real-world population of cryptogenic stroke patients with an ICM after one year of follow up and to compare the AF detection rates among these patients to those of the CRYSTAL AF Study. At 12 months, 1,737 AF episodes were detected in 192 patients, resulting in an AF detection rate of 16.3%. This represents a 32% relative increase compared to the rate observed in the CRYSTAL AF Study at the same time.
The real-world study found that 72% of patients diagnosed with AF would have been undiagnosed if their cardiac monitoring had been limited to 30 days.
“In clinical practice, we continue to see increased AF detection rates using the insertable cardiac monitor compared to the rigorously-controlled CRYSTAL AF study,” says co-author John Rogers, a cardiologist at Scripps Clinic in La Jolla, USA. “What is most significant, however, is that the vast majority of patients had their first AF episode beyond the range of 30-day conventional monitoring, reinforcing the need to re-evaluate the standard AF monitoring guidelines for cryptogenic stroke patients.”
According to a press release, the Reveal LINQ ICM system is the smallest insertable cardiac monitoring device available (~1 cc, or one-third the size of an AAA battery). Placed just beneath the skin through a small incision of less than 1cm in the upper left side of the chest, the Reveal LINQ ICM is inserted using a minimally invasive procedure, and its presence is often nearly undetectable to the naked eye once the incision has healed. The device should communicate wirelessly with a patient bedside monitor that uploads device data to the Medtronic CareLink network and is MR-conditional, allowing patients to undergo magnetic resonance imaging (MRI), if needed. The Reveal LINQ ICM automatically and continuously detects and records abnormal heart rhythms for up to three years.