By Dennis Thompson
HealthDay reporter
WEDNESDAY, June 9, 2021 (HealthDay News) – Norman Mayer, 86, is walking around with a computer chip in his chest and thinking nothing of it.
Doctors implanted a tiny heart monitor chip in Mayer’s chest after a mini-stroke in late 2015 to track his heartbeat and possibly detect an irregular heart rhythm called atrial fibrillation (a-fib).
“They don’t even know it’s there,” said Mayer, the 32-year acting mayor of the Alberta community of Camrose, Canada. “You don’t mind. It’s just there and a part of life.”
But thanks to the chip, doctors were able to better track Mayer’s heartbeat and adjust his medication to save him from another stroke, he said.
Mayer took part in one of two new clinical studies that showed that implantable cardiac monitor chips are much more effective at detecting cardiac arrhythmias than the external devices that are now more commonly prescribed after a stroke.
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One study showed that the implanted monitor recorded three times more atrial fibrillation than an external device that patients would have to carry around, and the other study recorded six times more atrial fibrillation.
The results represent “a dramatic increase in the incidence of atrial fibrillation,” said Dr. Brian Buck, lead researcher in one of the clinical trials and stroke neurologist at the University of Alberta.
Atrial fibrillation increases a person’s risk of stroke four to five times, and at least one in seven strokes is caused by the irregular heartbeat, according to the U.S. Centers for Disease Control and Prevention.
The jerky heartbeat causes blood to pool and clot in the upper chambers of the heart. When a clot gets into the brain, it causes a stroke.
“We know a-fib is a high-risk stroke disease,” said Dr. Dawn Kleindorfer, Chair of Neurology at the University of Michigan Medical School. “We know that treating a-fib with anticoagulation reduces your risk by almost 80%.”
The problem is that atrial fibrillation is very similar to the sound of your car – you can’t trust the sound to occur when the car is checked by a mechanic.
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Buck stated that “the arrhythmia can be present for a few minutes in a month and then stop showing up several months later and then only be there for a few hours and then go away.”
Stroke victims are usually given a portable monitor the size of a deck of cards that they can carry around for 30 days, he noted. They put sticky electrodes on their chest that are connected to the monitor, which constantly records their heart rhythm.
But a month of monitoring is usually not enough, and patients experience the external monitor as real neck pain, Buck said.
“They actually hate carrying the loop recorder around,” said Buck. “Carrying an external box around for thirty days is really difficult. It has a huge impact on your ability to exercise, work and things like that.”
So two different research teams decided to test whether an implanted device would work better at tracking the heart’s rhythm. The implant can track the heart rhythm for up to three years and does not cause any problems for the patient.
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Mayer said implanting the device was a breeze.
“It’s not a big deal,” said Mayer. “I went in one morning and they just take a small sharp knife and chop off a piece of you, stick that thing in your chest, put a band-aid on and tell you to go home.”
A monitoring station on a counter fed the data captured by Mayer’s chip to the hospital, where neurologists analyzed it for signs of atrial fibrillation.
“I never got a call because it fluctuated, but I had quite regular conversations with the girl who was responsible,” said Mayer. “They could monitor different peaks at different times of the day depending on my activities or whatever. As such, they used this to adjust my medications, blood thinners, and high blood pressure.”
Buck’s team found that doctors could see signs of a-fib in 15% of patients with the implant versus 5% with the external monitor in 300 patients who had recently had a stroke.
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The other team, led by Dr. Richard Bernstein from the Feinberg School of Medicine at Northwestern University in Chicago achieved even better results.
The chip detected atrial fibrillation in 12% of patients, up from approximately 2% seen by external cardiac monitoring in nearly 500 recent stroke patients.
The implantable chips are approved for use in the United States and Canada, but they still face obstacles, experts said.
Implanted device used in Alberta study Implanted device used in Alberta study
In Canada, the national health system requires that a device prove cost-effective before the government pays for it, Buck said.
The implant costs more than $ 5,000 per patient, versus about $ 1,000 for the external monitor, the researchers said in the background notes.
“Before our healthcare system is ready to pay for a device that costs several thousand dollars, we have to show that it is affordable,” said Buck. “Not only does it stop atrial fibrillation, it actually lowers stroke rates and improves patient quality of life and benefits the health system as a whole.”
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The same goes for coverage by insurance companies in the United States, which often balk at both the device’s expense and the cardiologists’ expense, who must sift through the data for signs of a-fib, Kleindorfer said.
“A cardiologist has to read that over and over again somewhere,” says Kleindorfer. “The disadvantages are more on the insurance and financial side, but it is clear to me that you will find more a-fib with the implantable monitor than with the external one.”
None of the clinical trials were large enough to show that the devices actually prevented strokes, Kleindorfer and Buck found. More research is needed to prove that implants can better protect people from stroke.
However, the current evidence is strong enough that the American Heart Association, in its recently updated guidelines on secondary stroke prevention, recommended monitoring a-fib, said Kleindorfer, who served as lead author of the guidelines.
“In my opinion as a clinician, I would of course prefer to use the implantable monitor than the external one, because I find more a-fib and they rely more on anticoagulation, which should reduce their risk of stroke,” said Kleindorfer.
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Both clinical studies were recently published in the Journal of the American Medical Association.
More information
The U.S. Centers for Disease Control and Prevention has more about atrial fibrillation.
SOURCES: Brian Buck, MD, PhD, Stroke Neurologist, University of Alberta, Canada; Dawn Kleindorfer, MD, Department of Neurology, University of Michigan Medical School, Ann Arbor; Norman Mayer, 86, Camrose, Alberta, Canada; Journal of the American Medical Association, June 1, 2021
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