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Experts say people who survive an ischemic stroke should have their heart healthy regularly monitored. Luis Alvarez/Getty Images
  • Researchers are reporting that 1 in 5 people who survive a type of ischemic stroke develop atrial fibrillation (AFib).
  • They say AFib is many times undetected in stroke survivors and more thorough medical follow-up is necessary.
  • Experts say the onset of AFib can also increase a person’s risk of another stroke.

One in five people who have survived an ischemic stroke due to a build-up of plaque in the arteries has an irregular heart rhythm.

That finding was part of new research presented this week at the American Stroke Association’s International Stroke Conference.

In their study, which hasn’t been published yet in a peer-reviewed journal, researchers reported that 20% of ischemic stroke survivors experienced atrial fibrillation (AFib) during cardiac monitoring three years after their stroke.

“We found that the rate of atrial fibrillation continued to increase over the course of the three years. Therefore, it’s not just a short-lived event and self-resolving related to the initial stroke. Fibrillation is common in these patients. Relying on routine monitoring strategies is not sufficient and neither is placing a 30-day continuous monitor on the patient. Even if fibrillation is ruled out in the first 30 days, most of the cases are missed — because, as we found, more than 80 percent of the episodes are first detected more than 30 days after the stroke,” Dr. Lee Schwamm, the lead author of the study and a professor of neurology at Harvard Medical School in Boston, said in a press release.

An ischemic stroke happens when a vessel that gives blood to the brain is blocked or obstructed.

The main cause of this is atherosclerosis, when fatty plaque deposits build up in the arteries.

Typically, survivors of an ischemic stroke caused by atherosclerosis don’t receive continuous cardiac monitoring after they leave the hospital.

However, Schwamm says that irregular heart rhythms that go undetected may be a contributing factor for recurrent strokes.

“There is still a lot that we don’t yet understand about why people who have had a previous stroke have another one. However, this study contributes important information to one potential cause — namely, unsuspected atrial fibrillation — for some of those 25 percent of patients with recurrent strokes,” he said.

“These patients are at increased risk of recurrent strokes due to their known vascular risk factors, such as hypertension and elevated cholesterol and blood pressure. What we need to sort out is what additional risk does atrial fibrillation add, and can the use of anticoagulation reduce that risk, especially for the type of major and disabling strokes that are often associated with atrial fibrillation,” Schwamm added.

Just six minutes of atrial fibrillation can significantly increase the risk of a stroke.

“During atrial fibrillation, the blood inside the left atrium (upper chamber) can pool which can cause clots. These clots can break off which can lead to a stroke,” said Dr. Nikhil Warrier, a cardiac electrophysiologist and medical director of electrophysiology at MemorialCare Heart & Vascular Institute at Orange Coast Medical Center California.

“Anything we can do to diagnose an underlying arrhythmic issue that could be contributing to this increased risk is critical,” he told Healthline.

The findings presented this week are part of an analysis from the Stroke AF Randomized Clinical Trial.

The study was funded by Medtronic, a monitoring device manufacturer.

As part of the research, 492 people who had an ischemic stroke caused by a clot in an artery and not the heart. Study participants had no known history of AFib and were split evenly into two groups.

One group received an insertable cardiac monitor to record the rhythm of their heart 24 hours a day for three years.

The other group received standard medical treatment and follow-up care every six months for three years. This did not involve continuous heart monitoring.

The researchers reported that the continuous cardiac monitor detected AFib in more than 20% of the participants over three years.

In contrast, in the group that received standard care and follow-up, AFib was detected in less than 3% of subjects. The researchers said this suggests a 10-fold increased rate of detection with the 24-hour cardiac monitor.

The majority of the AFib episodes occurred after 30 days.

“It is apparent from the study that the 30-day cardiac monitor is insufficient for detecting paroxysmal atrial fibrillation. They found that more than 80 percent of the [AFib] cases were detected after 30 days. Typically, patients have the 30-day external cardiac monitor initially due to insurance requirements. We need to do a better job of inserting the implantable cardiac monitor after the 30-day event monitor is completed if it doesn’t detect [AFib],” Dr. Colleen Lechtenberg, a neurologist and director of The Advanced Comprehensive Stroke Center at the University of Kansas Health System, told Healthline.

Atrial fibrillation may cause symptoms such as dizziness, heart palpitations, chest pain, and shortness of breath.

However, many people will experience no symptoms at all.

While it is not always possible to prevent AFib, maintaining a heart-healthy lifestyle is important. This includes regularly exercising, maintaining a healthy weight, and having a healthy diet.

More than 80% of the people studied didn’t experience symptoms of AFib, but AFib was still captured by the continuous monitor.

“One of the big reasons people can have a stroke from the arrhythmias is that we don’t know they’re having it. So we don’t put them on the blood thinners or the therapies to reduce that risk,” Dr. Shephal Doshi, a cardiac electrophysiologist and director of cardiac electrophysiology and pacing at Providence Saint John’s Health Center in California, told Healthline.

“By putting these monitors, I think it sheds light that we need to be more aware that these patients who have these risk factors for atherosclerosis are also high risk for atrial fibrillation and for these arrhythmias. And as such, we may need to consider putting these longer-term monitors to pick it up so that we can treat them,” he added.