A recent innovation in heart rhythm monitoring has given neurologists and cardiologists a crucial new tool in detecting a potentially dangerous irregular heartbeat known as atrial fibrillation, or AFib.
A-fib, one of the leading causes of stroke, is a condition that leaves blood stagnating in the heart instead of being pumped through the body, forming a clot that can break off, travel to the brain and cause a stroke.
For about a third of strokes that occur, the cause is unclear, which limits the effectiveness of therapy to prevent the next one.
Fortunately, a recent heart monitoring innovation called an Implantable Loop Recorder (ILR) can monitor heart rhythm around the clock for up to three years, giving patients and their physicians important insight for diagnosis and treatment.
About the size of three matchsticks, the ILR is placed under the skin of the patient’s chest. The brief procedure requires only a small incision and local anesthesia. The electrodes transmit heart rhythm data to a module outside the body, and then over the internet to the doctor.
Why is this important?
Researchers long had thought that many patients who suffered cryptogenic strokes — the strokes where the cause could not be determined — had AFib. But in a lot of people, AFib is asymptomatic and they don’t feel anything. And intermittent monitoring for short periods often could not detect the condition.
What they needed was a way to monitor a patient’s heart for a longer period of time, which is where the ILR comes in.
A landmark study published in 2014 in the New England Journal of Medicine made a significant difference for patients who had suffered cryptogenic strokes. The continuous implanted monitor detected AFib six times more often than the typical short-term testing.
Now even smaller than the device used in the 2014 study, the ILR has changed how physicians evaluate treatment options for people who don’t have an answer for the cause of their stroke.
Aspirin, which is a blood thinner, is used to prevent certain kinds of strokes, but we know that method is not effective enough to prevent a stroke related to atrial fibrillation. But until we find evidence of AFib, we’re not justified in treating people with stronger medications.
This monitor has also dramatically changed the way neurologists practice. We receive a lot of referrals from neurologists to implant this device in stroke patients who may have undiagnosed AFib. If we can make the diagnosis, we change the therapy right away and help prevent another stroke.
Additional studies currently underway might change therapies even more. Because people can have intermittent AFib and may only need blood thinning when they’re having an episode, studies are looking at using implantable monitors as a guide. Blood thinners prevent clots but also expose patients to the risk of bleeding if used on a long-term basis. If we can monitor heart rhythms 24/7, maybe we can tailor therapy more accurately.
Regardless of where the future takes us, the ILR is already a game changer.
Learn more about heart and vascular care at Baylor Scott & White Health.
About the author
Manish Assar, MD, is a cardiac electrophsyiologist on the medical staff at Baylor Scott & White Heart and Vascular Hospital – Dallas and Baylor University Medical Center. He was a principal investigator of the CRYSTAL AF trial comparing long-term implanted heart monitors to standard external monitors.