Medtronic has announced the results of a new real-world study of patients who have had a cryptogenic stroke, in which the Reveal LINQ insertable cardiac monitor detected atrial fibrillation in everyday practice at an even greater rate than that found in a recent, rigorously-conducted clinical trial (CRYSTAL-AF study, published in The New England Journal of Medicine).
The observational real-world study, which is being presented at the American Stroke Association’s International Stroke Conference 2015 (10–12 February 2015, Nashville, USA) evaluated 1,247 cryptogenic stroke patients across the USA to determine whether atrial fibrillation could be detected using long-term, continuous cardiac monitoring (Reveal LINQ). At 182 days of monitoring (median), atrial fibrillation was detected in 147 patients, resulting in a detection rate of 12.2%, which was nominally 37% higher than the rate observed in CRYSTAL-AF at the same time point.
“Unlike a randomised study, an observational study provides a practical way to study real-world clinical practice. What is most exciting is that the detection of atrial fibrillation in real clinical practice exceeded that observed in the rigorously-controlled CRYSTAL-AF study, allowing physicians to intervene even more with stroke-preventive therapies,” says study co-author Mark Richards, director of arrhythmia services at ProMedica Physicians Cardiology, Toledo, USA. “This suggests that atrial fibrillation may go undetected at an even greater rate and reinforces the benefits of long-term rhythm monitoring in cryptogenic stroke patients.”
In addition, results from a new analysis (based on the atrial fibrillation detection rates found in the randomised CRYSTAL-AF study) demonstrated for the first time that the use of long-term, continuous cardiac monitoring is a cost-effective method of detecting atrial fibrillation in cryptogenic stroke patients. Presented at the International Stroke Conference, the incremental cost-effectiveness ratio associated with the Reveal XT in the study compared with the present standard-of-care, was well within the cost effectiveness range that the UK National Institute of Clinical Excellence (NICE) considers acceptable based on an established cost effectiveness threshold, recently set by NICE to be £20,000 per Quality Adjusted Life Year.
In the CRYSTAL-AF study, detection of atrial fibrillation with the long-term cardiac monitor was superior to conventional monitoring methods (30% with the insertable cardiac monitor, and 3% with standard monitoring at three years; p=<0.0001) that are the current standard of care over a three-year follow-up.
“These results show that continuous cardiac monitoring with an insertable cardiac monitor is a cost-effective tool,” says Klaus Witte, associate professor and consultant cardiologist, and lead clinician for cardiology at the University of Leeds and Leeds Teaching Hospitals NHS Trust in the United Kingdom. “Detecting atrial fibrillation in cryptogenic stroke patients enables physicians to change their medical therapy so we can reduce their risk of having a second stroke.”
Cleared by the US Food and Drug Administration last year, Medtronic says that the Reveal LINQ insertable cardiac monitor system is the smallest cardiac monitor available (~1cc, or one-third the size of a AAA battery). Common uses include monitoring syncope patients for potential episodes of bradycardia/asystole, monitoring cryptogenic stroke patients for possible episodes of atrial fibrillation, and monitoring patients suffering from intermittent chest palpitations for potential episodes of atrial or ventricular arrhythmias.
Like its predecessor, this LINQ device is placed under the skin of the chest, and its battery allows for up to three years of monitoring. Additionally, the device communicates wirelessly with a patient bedside monitor that uploads device data to the Medtronic CareLink network.