Screening for Atrial Fibrillation: Studies Presented at American College of Cardiology 2019 Highlight Novel Opportunities to Diagnose AF Early
By Debra Gordon and Mellanie True Hills
Insertable Cardiac Monitor Identifies Atrial Fibrillation Up to 40 Times Better than Short-Term Methods
In order to prevent strokes in people with atrial fibrillation (AF), it’s important to diagnose the condition as early as possible. But that can be challenging since many people have no symptoms and the irregular heartbeats of AF often occur infrequently. That’s why so-called “point-in-time” screening options, like a 30-second electrocardiogram (ECG) or taking a pulse in the doctor’s office, miss many AF episodes.
However, a tiny device about the size of a Tootsie Roll could change that, researchers reported at the American College of Cardiology Scientific Sessions conference in Orlando in March. The device, called an insertable cardiac monitor (ICM), can record heart rhythms for up to 3 years. It is implanted under the skin in a 10-minute procedure in the doctor’s office.
In a large study called REVEAL-AF, 335 people at high risk for AF who had not been diagnosed with the disease agreed to have the devices implanted. They were followed for up to 30 months, with the device automatically transmitting information back to the researchers.
After 18 months, a third of the patients had been diagnosed with AF; at 30 months, AF had been detected in 40 percent. About 10 percent of patients had an AF episode that lasted more than a day. Most were started on blood thinners.
Atrial fibrillation would have gone undetected in about three-fourths of the participants if they had only been monitored 30 days, said lead researcher James A. Reiffel, MD, of Columbia University College of Physicians and Surgeons in New York City.
Using other forms of intermittent monitoring such as ECG, the researchers found, would have identified just 1.1 to 13.5 percent of those with AF.
“The detection of incident AF in at-risk patients is clearly dependent on the duration of monitoring,” Dr. Reiffel said, and the vast majority of these patients would have their AF undetected with the use of routine or other external monitoring approaches. Thus, he said, they may not have received the care they needed to prevent a stroke.
Self-Applied Chest Patch: A New Option for Diagnosing Atrial Fibrillation
If your watch can track your steps, heart rate, and sleep patterns, why can’t something similar be used to track arrhythmias and, possibly, help diagnose atrial fibrillation? Turns out it can.
In fact, getting people to wear a small patch about the size of a large bandage on their chest for two weeks can detect up to 75 percent of AF events, according to a study presented during the American College of Cardiology Annual Scientific Sessions conference in Orlando, Florida in March.
The study, mHealth Screening to Prevent Strokes (mSToPS), was designed to see if a wearable electrocardiogram (ECG) patch could improve the identification of AF compared to routine screening. Such screening typically involves a few minutes monitoring of the patient’s pulse or tracking the heartbeat with an ECG for a few minutes.
Early diagnosis is important, said lead author Steven R. Steinhubl, MD, director of digital medicine at the Scripps Translational Science Institute, La Jolla, Calif., because 37 percent of adults 55 and older are at risk of developing AF, which is associated with a five-fold increased risk of stroke. Yet because there are often no or few symptoms of AF, the condition remains underdiagnosed.
He and his team conducted a digital clinical trial to see if the data available through an FDA-approved, wearable ECG patch could improve the detection of AF compared to routine care. The use of digital technology has the potential to transform clinical trials, he said, since participants don’t have to live near study centers or be seen in person. This makes it easier to recruit volunteers and collect data. “It allows us to build a system that focuses on the participant wherever that participant may live,” he said.
The researchers partnered with health insurer Aetna to identify members at moderate risk of AF. This included people 75 years or older, or younger individuals who had already had a stroke and/or been diagnosed with some form of cardiovascular disease, high blood pressure, diabetes, or obstructive sleep apnea. Nearly 360,000 members met the criteria and about 100,000 were invited to participate.
The researchers enrolled 1,732 members (average age 74) into the study and compared the results with another 3,476 Aetna members who were not enrolled. Half of those in the trial received the wearable patch immediately via mail, the other half in four months. All received detailed instructions on using it and access to a web site to ask questions.
Participants wore the patch for 14 days then returned it via mail to the researchers. The data from the FDA-approved patch was then analyzed via a computer algorithm as well as reviewed by clinicians. The results were returned to the participants, many of whom shared the information with their doctors.
In the year following the start of the study, 6.3 percent of those who wore the patch were diagnosed with AF while just 2.3 percent of the comparison group was diagnosed. In addition, in the group that started using the patch 4 months after receiving it, less than 1 percent were diagnosed with AF prior to wearing the patch, while 5.1 percent were diagnosed with AF after using the patch.
Those wearing the patch were far more likely to receive blood thinners and other interventions for AF, such as pacemakers, and to visit their primary care physician and/or a cardiologist.
“Through remote digital involvement and participant-generated data we observed a markedly improved rate of Afib diagnosis compared to routine care,” Dr. Steinhubl concluded. That, in turn, led to the initiation of guideline-recommended therapies. The investigators will continue to follow participants for another two years to see if the earlier diagnosis translates into fewer strokes and other medical issues.