VANCOUVER, British Columbia — At 1-year follow-up, nearly 1 in 6 patients with cryptogenic stroke had episodes of atrial fibrillation (AF) detected with an insertable cardiac monitor (ICM), as determined by registry data presented at the 2016 annual meeting of the American Academy of Neurology (AAN).
“The incidence of AF detected in this real-world population of cryptogenic stroke patients at 1 year was higher than previously reported in the CRYSTAL AF study,” John D. Rogers, MD, study researcher from the Scripps Clinic in La Jolla, California, told Neurology Advisor. “These results confirmed our expectations of a higher incidence of AF in patients with cryptogenic stroke.”
Dr Rogers said that ICMs had been shown to be superior to other types of intermittent, short-term or intermediate-term monitoring for detecting AF in patients with cryptogenic stroke, such as those used in the CRYSTAL AF (Cryptogenic Stroke and Underlying AF) trial.
“The patients in CRYSTAL AF were deemed to have had a cryptogenic stroke only after a thorough and extensive evaluation to search for the cause of stroke. This extensive evaluation may not be performed in a real-world population of stroke patients,” he said. “The catalyst for examining this real-world population was to determine the incidence of AF at 12 months in a registry of patients who had an ICM implanted with the diagnosis of cryptogenic stroke, as determined by the treating physician regardless of prior testing performed.”
In the study, Dr Rogers and colleagues included 1247 patients (53% male; mean age at device insertion, 65.3 ± 13 years) from the de-identified Medtronic Discovery Link database who received an ICM (Reveal LINQ, Medtronic) for AF detection after cryptogenic stroke. Patients were monitored for up to 365 days, with all detected AF episodes (≥2 minutes) receiving adjudication.
The AF detection rate was measured with Kaplan-Meier survival estimates and compared with the results of the CRYSTAL AF study, which rigorously excluded patients with evidence of AF prior to enrollment and ICM insertion, according to study background. Researchers also investigated the maximum duration of AF episodes and the time to initial AF detection.
During follow-up (326 ± 85 days), 1737 episodes of AF were reported in 192 patients. This led to a 16.3% AF detection rate at 12 months, demonstrating a 32% relative increase compared with CRYSTAL AF at 12 months.
In addition, the researchers found that the median duration of the longest detected AF episode was 2.8 hours, while the median AF detection time was 86 days.
“In the cryptogenic stroke population, the ICM has been shown to be superior to short-term and intermediate-term heart rhythm monitoring for the detection of AF,” Dr Rogers said. “This was shown in the CRYSTAL AF study and has now been validated with this real-world registry evaluation of cryptogenic stroke patients.”
Dr Rogers added that not only was the median time from stroke until detection of AF greater than 50 days, but the symptoms were not reliable for AF detection.
“Long-term monitoring with an ICM is the only way to accurately diagnose AF in a population of stroke patients who are at risk for further strokes,” he said.
Rogers JD, Nichols AJ, Richards M, et al. Incidence of atrial fibrillation within one year of cryptogenic stroke among a large, real-world population with insertable cardiac monitors. Presented at: The 68th Annual Meeting of the American Academy of Neurology; April 15-21, 2016; Vancouver, Canada. Abstract I2.005.