Medtronic revealed new data Wednesday that shows a 10-fold increase in atrial fibrillation detection using the Reveal Linq insertable cardiac monitor (ICM) in stroke patients.
The new data, presented at the American Stroke Association's International Stroke Conference, builds on the STROKE AF study 12-month primary endpoint results published in June 2021 in the Journal of the American Medical Association.
The study showed large and small vessel disease stroke patients had a 10-fold increase in atrial fibrillation detection with the Reveal Linq ICM at three years compared to patients randomized to standard of care who did not receive continuous, long-term monitoring.
Over the first year, 12.5% of patients in the ICM arm had atrial fibrillation (AF) detected compared to 1.8% of patients randomized to standard of care (consisting of external cardiac monitoring such as 12-lead ECGs, Holter monitoring, telemetry, or event recorders). At three years, the rate of AF detection increased to 21.7% of patients in the ICM arm compared to 2.4% in the control arm, resulting in a statistically significant hazard ratio of 10 (95% CI 4.0-25.2, p
"What these data show us is that we can't always rely on patients to tell us they are having palpitations or irregular heartbeats because the majority of AF detected in the study was asymptomatic," said Lee H. Schwamm, MD, chief digital advisor, Mass General Brigham, C. Miller Fisher endowed chair in vascular neurology and professor of neurology at Massachusetts General Hospital and Harvard Medical School. "Importantly, these outcomes underscore the criticality of long-term monitoring with ICMs in these patients as much of the AF detected would have been missed at 30 days. AF is a risk that we can't afford to miss for patients who have already suffered a stroke — the consequences could be devastating."
Patients with AF are at a five-fold increased risk for ischemic stroke, Medtronic noted.
While the STROKE AF study was not designed to detect or explain treatment differences, only 70% of patients with atrial fibrillation detected in the ICM arm were subsequently started on anticoagulation therapy—medication that helps prevent blood clots.
New insights on predictors of atrial fibrillation
The one-year outcomes from the STROKE AF study Predictors of AF analysis recently published in JAMA Neurology add insights for predicting atrial fibrillation in patients with small or large vessel ischemic strokes. Patients with either congestive heart failure (CHF) and/or left atrial enlargement (LAE), for example, had an AF detection rate of 23.4% compared to 5% for patients with neither attribute, suggesting these patients are at greater risk of having AF.
"The STROKE AF Predictors analysis helps us better identify the patients who are most at-risk of unsuspected AF, which can inform stroke prevention strategies," Schwamm said. "Not every ischemic stroke patient may need an ICM, but these data suggest some patients are more likely to experience AF and should be monitored more closely."
The STROKE AF study is a prospective, randomized study of 496 large and small vessel stroke patients across 33 U.S. centers. FDA cleared Medtronic's Reveal Linq ICM in 2014 and the device is available worldwide.
How Medtronic made a smarter heart monitor
After Medtronic released its Reveal Linq insertable cardiac monitor in 2014, the company immediately wanted to make the device better. In 2017, a Medtronic manager told MD+DI about the aggressive timeline the R&D team followed to deliver a more accurate version of the Reveal Linq ICM.
"The timeline for development was very aggressive as we wanted to bring these enhancements to physicians as quickly as possible," Chris Landon, who was the general manager of diagnostics at Medtronic at that time, told MD+DI in the 2017 interview. Landon now works for Philips, according to his LinkedIn page. "After in-depth analysis, the R&D team mobilized to develop and test new algorithms and design clinical evidence to support their performance."
Those new algorithms resulted in 95% fewer false bradycardia (slow heartbeat) episodes and a 47% reduction in false pause episodes (brief absences of cardiac activity) compared to the original device. The new version also includes a self-learning atrial fibrillation algorithm, designed to learn and adapt to a patient's heart rhythm over time.
Atrial fibrillation episodes are more likely to trigger false positives with ICMs, Medtronic noted, and the new algorithms reduce false detections by 49% compared to the earlier version of the Reveal Linq ICM.
The device is designed to allow continuous and wireless heart monitoring for up to three years. It's about a third the size of a AAA battery and is placed just beneath the skin in the upper left side of the chest. The device communicates wirelessly with a patient bedside monitor that uploads device data to the Medtronic CareLink network. It is MR-Conditional, so patients can undergo MRI if needed.