Insertable monitors shown to detect atrial fibrillation more reliably than short-term strategies

By Donna Loyle, communications specialist, LIMR

An increasing variety of short-term cardiac monitoring techniques have been introduced in recent years, including skin patches, mobile outpatient devices and smartwatch apps. But can such strategies detect atrial fibrillation (AF) as reliably as an insertable cardiac monitor? That was the question a group of researchers, including Peter Kowey, MD, set out to answer.

The researchers used data from the REVEAL AF study, a multicenter clinical trial in which Main Line Health participated. They reviewed clinical information from 385 trial participants who were not previously diagnosed with AF but who had risk factors for the disorder and had cardiac monitors inserted.

“Our analysis one year after cardiac-monitor insertion showed the incidence of AF of six minutes or longer was 27 percent in this patient population, which was significantly greater than the short-term continuous monitoring strategies we studied,” said Dr. Kowey,  a world-renowned cardiologist at Lankenau Medical Center and the William Wikoff Smith Chair in Cardiovascular Research at Lankenau Institute for Medical Research.

“We concluded that most AF episodes that were detected by insertable cardiac monitors would go undetected by conventional short-term monitoring tactics,” Dr. Kowey continued. “That is problematic, because we know that diagnosing AF in a timely fashion means a patient can start appropriate treatment that is likely to prevent long-term harm or even death.”

Because all data in the comparative analysis was from patients who had cardiac monitors already inserted, the researchers used an ingenious modeling strategy. For example, one-time monitoring (meant to simulate short-term monitoring techniques) was assessed by computing AF incidence in the patient cohort at one, two, seven, 14 and 30 days post-insertion. Similarly, repeated short-term monitoring was simulated by assessing results on randomly selected days within a 30-day cycle over a one-year period.

The results showed the incidence of AF with insertable cardiac monitoring (ICM) at 12 months was more than eight times higher than the incidence of AF with 14-day monitoring (simulating 14-day cardiac monitoring skin patches). And it was more than four times higher than the incidence of AF with 30-day monitoring (simulating 30-day loop devices or mobile outpatient monitoring services).

The authors concluded that a significant portion of high-risk patients with previously unknown AF who have AF detected by ICMs would go undetected using routine or other ambulatory short-term monitoring strategies. This, in turn, would inhibit clinicians’ opportunities for prophylactic anticoagulation to prevent strokes and other negative outcomes.

“It’s important to note that in many patients, the symptoms of AF are silent or minor,” said Dr. Kowey. “So while we welcome the introduction of numerous new technologies to track heart rates for short periods of time, the results of this study compel us to caution patients that those techniques may not be fail-safe methods to detect AF. In short, these technologies cannot replace your doctor.”

The results from this comparative analysis were included in the manuscript “Rhythm monitoring strategies in patients at high risk for atrial fibrillation and stroke: A comparative analysis from the REVEAL AF study” published in American Heart Journal.

This study was funded by the medical device maker Medtronic, Inc.

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