Study: Tiny, insertable Medtronic cardiac monitor found more effective in AF detection

Medtronic's Reveal Linq wireless cardiac monitoring implant--Courtesy of Medtronic

The latest clinical trial results for Medtronic's ($MDT) insertable cardiac monitor show that it's effective at detecting atrial fibrillation at an even higher rate than found in a previous study. That could help the company make its case for reimbursement for the smallest cardiac monitor available, the Reveal Linq, which was launched early last year.

In a real-world, observational trial of 1,247 cryptogenic stroke patients using the Reveal Linq Insertable Cardiac Monitor, 147 patients, or 12.2%, were found to have atrial fibrillation after a median of 182 days of monitoring. That AF detection rate is 37% than in a prior randomized study, the CRYSTAL AF trial that used the slightly larger Reveal XT Insertable Cardiac Monitor.

"Unlike a randomized study, an observational study provides a practical way to study real-world clinical practice. What's most exciting is that the detection of AF in real clinical practice exceeded that observed in the rigorously controlled CRYSTAL AF study, allowing physicians to intervene even more with stroke preventive therapies," said study co-author Dr. Mark Richards, director of Arrhythmia Services at ProMedica Physicians Cardiology in Toledo, OH, said in a statement.

He added, "This suggests that AF may go undetected at an even greater rate and reinforces the benefits of long-term rhythm monitoring in cryptogenic stroke patients."

Cryptogenic strokes have an unknown cause by definition; each year about 692,000 Americans have ischemic strokes--of which about 20% to 40% are cryptogenic. Patients with AF are five times more likely to have a stroke.

Linq device insertion process, as shown in a video from Medtronic--Courtesy of Medtronic

The Linq device is inserted through a small incision via an injection device about 8 mm under the skin of the chest over the heart. It has sufficient battery life to allow for three years of continuous monitoring. The device communicates wirelessly with a patient bedside monitor that uploads the device data to the Medtronic CareLink network for analysis and tracking.

The cardiac monitor is the smallest available--only about one cubic centimeter or one-third the size of a AAA battery. In addition to monitoring cryptogenic stroke patients, it can be used to monitor syncope patients for potential episodes of bradycardia/asystole and patients suffering from intermittent chest palpitations for potential episodes of atrial or ventricular arrhythmias.

In the CRYSTAL AF study, the Reveal XT was found superior to conventional monitoring methods in the detection of AF. In the study, it detected AF in 30% of the cryptogenic stroke patients after three years of monitoring, while the standard follow-up arm that used a traditional approach detected only a 3% rate of AF.

Medtronic is working to make the cost-effectiveness argument. It noted that the Reveal XT  has been found to be within the cost effectiveness ratio desirable for the United Kingdom's National Institute of Clinical Excellence of at least £20,000 per Quality Adjusted Life Year.

"These results show that continuous cardiac monitoring with an ICM is a cost-effective tool," Dr. Klaus Witte, associate professor, consultant cardiologist and lead clinician for cardiology at the University of Leeds and Leeds Teaching Hospitals NHS Trust in the United Kingdom, said in a statement. "Detecting AF in cryptogenic stroke patients enables physicians to change their medical therapy so we can reduce their risk of having a second stroke."

- here is the release