Home Heart Monitoring Effective for Detecting Irregular Heart Rhythm

A transatlantic study collaboration involving a U of T researcher has demonstrated that a wearable heart monitor device can significantly improve the detection of atrial fibrillation, a major risk factor for stroke.

The study, which involved researchers from Canada and Germany, was published online in JAMA Cardiology on February 24, 2020.

Atrial fibrillation (also known as “AF” or “A-Fib”) is a type of irregular heart rhythm or arrhythmia that affects over 30 million people worldwide and is a leading cause of deadly strokes, particularly in the elderly. Atrial fibrillation can cause blood clots that can lead to stroke if they reach the brain. Because atrial fibrillation can be episodic and may not produce any symptoms, people may not be aware of having it until it is too late.

“The big challenge is that atrial fibrillation is often a silent risk factor that can be difficult to detect with current methods,” says David Gladstone, the study’s principal investigator, who is an associate professor in the Temerty Faculty of Medicine’s Department of Medicine and a stroke neurologist at Sunnybrook Health Sciences Centre.

“If we are able to better detect atrial fibrillation, then more people could receive treatment for it earlier, and more strokes ought to be prevented,” adds Gladstone, who recently presented the research findings at the World Stroke Congress.

The multicentre randomized trial called SCREEN-AF tested an innovative miniature heart monitor, Zio by iRhythm, which records every heartbeat and can pick up silent atrial fibrillation. This device is not currently available in Canada for use outside of a clinical trial.

The study recruited 856 individuals from 48 primary care clinics between 2015 and 2019. It involved participants aged 75 years or older who had high blood pressure but no previous diagnosis of atrial fibrillation. The study was coordinated at the Population Health Research Institute in Hamilton, Canada.

“The SCREEN-AF trial showcases the success of inter-institutional and international collaboration and helps advance knowledge about the role of atrial fibrillation screening in stroke prevention,” says Jeff Healey, senior author of the study, who is a senior scientist at the Population Health Research Institute and a professor of medicine at McMaster University. He is also a founding member of the Canadian Stroke Prevention Intervention Network, which supported the trial.

Half of the participants were given the adhesive heart monitor to stick on their chest like a bandage and wear it at home for up to four weeks. The other half of participants received standard medical care. All participants were followed for six months.

The researchers found that the portable heart monitor was well-tolerated by participants and led to a tenfold increase in the detection of atrial fibrillation. One out of every 20 patients in the heart monitoring group was found to have a new diagnosis of atrial fibrillation. As a result, 75 per cent of those patients were subsequently prescribed a blood thinner medication for protection against strokes.

“These results are an important step towards stroke prevention by early detection of atrial fibrillation. Blood thinners for AF can lower the risk of stroke by nearly 70 per cent. However, more data is needed whether the approach used in SCREEN-AF reduces strokes,” says Rolf Wachter, co-principal investigator, cardiologist at the University Hospital in Leipzig, Germany and scientist at the German Center for Cardiovascular Research (DZHK).

Worldwide, stroke ranks as the second leading cause of death in adults and a leading cause of disability and dementia, making prevention of stroke a top public health priority.

“In clinical practice, we routinely screen for high blood pressure, diabetes, and cholesterol, but proactive screening like this for atrial fibrillation is not currently being done for asymptomatic individuals,” says Dr. Gladstone. “New digital health technologies, if used appropriately, hold great promise for improving early detection and treatment of atrial fibrillation​, especially for older individuals who are most at risk of developing this arrhythmia.”

The researchers note that not all heart monitoring devices, wearable or smartphone applications are designed to detect atrial fibrillation. The investigators also emphasize that more research is needed before the results can be implemented widely.

Gladstone adds, “These study results are encouraging and now support the need for large clinical trials to determine the overall impact of screening on the occurrence of stroke and other patient outcomes.”

This study was funded by operating grants from the Canadian Stroke Prevention Intervention Network (CSPIN) [www.cspin.ca] and the German Center for Cardiovascular Research (DZHK), supplemented by funding from Boehringer Ingelheim and in-kind support from Microlife Corporation, ManthaMed, and iRhythm Technologies Inc.