More recently, smartwatches have added capabilities that can flag potentially dangerous, fast or irregular heartbeats, known as atrial fibrillation (a type of arrhythmia). But should we trust these devices to tell us such important details about our hearts? Dr. Christopher Cheung, a cardiac electrophysiologist (cardiologist specializing in heart rhythm) in the Schulich Heart Program at Sunnybrook, shares his expert advice.

What is atrial fibrillation and why does it matter?

Dr. Cheung: Atrial fibrillation is the most common abnormal heart rhythm, affecting approximately 200,000 Canadians. If treated, most people with atrial fibrillation lead active, normal lives; but left untreated, it can lead to stroke and heart failure, not to mention interfere with your daily quality of life. According to the Heart and Stroke Foundation, one quarter of all strokes after age 40 are caused by atrial fibrillation. So, if we can detect atrial fibrillation early, we can prevent stroke and other life-threatening circumstances.

How do smartwatches capture your heart rhythm vs. traditional tests?

Dr. Cheung: Smartwatches use a technology called photoplethysmography. Light from the device flashes against your skin to detect blood flow and measures your heart rate using elaborate algorithms. The technology is used in other medical devices such as oxygen monitors (oximeters) and is generally accurate when you have a regular pulse.

Some smartwatches have an added feature of recording an electrocardiogram (ECG), which is the electrical signal of the heartbeat. This provides much more information, including not only heart rate but also heart rhythm. Unlike traditional cardiac tests, however, the ECG feature in a smartwatch is not always active: the user must manually record an ECG. When diagnosing an arrhythmia, we use longer-term ECG monitors, like Holter monitors, that record your ECG signals continuously for 24-48 hours. It gives us an accurate recording of your heart rate and heart rhythm during a longer period so we can assess any irregularities.

How accurate is the information from my smartwatch?

Dr. Cheung: For most healthy users, studies have shown that the heart rate measured on your smartwatch matches well with the heart rate measured with our cardiac tests – usually within five beats per minute. When it comes to irregular heart rate monitoring for atrial fibrillation, the accuracy is lower.

There have been a few large studies using the Apple Watch, FitBit, and Huawei watches to evaluate their ability to detect arrhythmia and the results have been promising, but these studies are done with mostly healthy individuals.

The challenge is that the algorithms are not perfect, so there is a risk that the watch may alarm you with an incorrect result (called a “false-positive”). Until we know more, pay attention to the information, but don’t rely on it to diagnose you.
 

What should I do if my smartwatch flags an irregular heartbeat?

Dr. Cheung: You don’t need to run to your doctor the second a notification of an irregular heartbeat pops up on your smartwatch but take into consideration your heart health, such as any pre-diagnosed atrial fibrillation and any symptoms you may be feeling. If you are noticing episodes of heart racing that come unexpectedly while you are at rest, a sensation of an irregular heart rate or fluttering in your chest, or even the sense of a panic attack, these can sometimes be signs of a heart arrhythmia. Take note and speak to your doctor. They may choose to order a medical-grade heart monitor to document one of these episodes and determine whether you really are having an arrhythmia.

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When a person has ventricular tachycardia, faulty electrical signals in the ventricles of the heart cause their heart to beat too fast or irregularly, impeding proper blood flow to the body. “This is a very urgent problem,” says Dr. Fumin Guo, a postdoctoral fellow working in the cardiovascular imaging lab of Dr. Graham Wright at SRI. “Most of these events occur, without previous symptoms, at home or in a public space, not in hospital. And they can be fatal within minutes. We are trying to improve diagnosis and therapy to prevent sudden cardiac death.”

One of the current treatments for ventricular tachycardia is radiofrequency ablation, which involves guiding a device into the heart and using an electrical current to heat up and destroy a small area of tissue that may lead to the abnormal electrical signals (arrhythmia). But about 35 per cent of ablation procedures result in either initial failure or later recurrence.

Preclinical work by Dr. Guo and others in Dr. Wright’s lab is focused on improving the outlook for those with VT in three ways: identifying the underlying structural and functional issues in the hearts of individuals, pinpointing damaged tissue with greater precision, and delivering treatment with more accuracy and efficiency.

The lab has demonstrated success using 3D magnetic resonance imaging (MRI) to guide radiofrequency ablations with improved precision. “Imaging, and in particular MRI, shows great promise in helping to improve management in this patient population, and we are working at the state of the art to look at all aspects from identifying those at risk, to improving the effectiveness of procedures,” says Dr. Wright, who is a senior scientist in the Physical Sciences Platform and Schulich Heart Research Program at SRI.

Dr. Guo recently won the prestigious Polanyi Prize in Physiology and Medicine for his significant contribution to this work. With his background in biomedical engineering, he is developing, using artificial intelligence and computer vision methods, automated image analysis systems that map the heart and pinpoint the damaged tissue. He is also advancing computer algorithms to plan, guide and assess VT treatment.

“Fumin’s work means the image analysis needed to guide procedures will be more repeatable, faster, and hopefully more accessible to others,” says Dr. Wright. “The Polanyi Prize is very prestigious. Winning the prize is emblematic of the clinical relevance of the work and the excellence of Sunnybrook’s program in image-guided, personalized, precision therapy.”

Dr. Wright adds that his lab is collaborating with clinical heart programs and partnering with industry to ensure the preclinical work can be translated to patient care as quickly as possible.

For his part, Dr. Guo is enthusiastic about what lies ahead. “Our ultimate objective is to cure patients with ventricular tachycardia conditions. We want patients to live longer, healthier and happier.”

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“Curiosity drew me,” says Adrianus, who has arrhythmia, an irregular heart beat that can cause the heart to beat too fast, too slowly, or with an irregular rhythm. “There’s not really a lot in the media about arrhythmia and I was keen to see it there was new information from a trusted source: cardiologists who specialize in this area.”

He joined the International Arrhythmia School virtual event on November 21 from the comfort of his home in northern Ontario. The event featured a session for medical professionals, followed by a tailored presentation for patients and families, covering alcohol use and unrelated procedures in arrhythmia patients.

“These are two hot topics for patients,” explains Dr. Eugene Crystal, the founder of the International Arrhythmia School and a cardiologist at Sunnybrook. “From a physician’s perspective, it’s challenging when you’re seeing 20 to 30 patients a day to address questions that those living with arrhythmia may have. The session we hosted is a pragmatic and efficient way to present an overview of the latest evidence, in layperson language, and also have time for questions from patients.”

Participants were provided with practical tips on drinking alcohol with an arrhythmia, such as ensuring two full days of abstinence and avoiding heavy consumption. Procedures covered included MRI tests, radiation procedures and general tips on what could impact the functioning of patients’ pacemakers and implantable cardioverter-defibrillators (ICDs).

Suzette Turner is a nurse practitioner with the Arrhythmia Clinic at Sunnybrook’s Schulich Heart Centre and assisted with the event. “The opportunity to virtually learn – although not a new phenomenon – is one of the silver linings of this pandemic. It’s beneficial to both patients and staff and allows for a wider demographic reach, especially during the winter months,” says Suzette.

For Adrianus, the opportunity to engage with experts was a big draw. “Hearing from heart doctors who are on the leading edge of this type of heart issue was really valuable. And the topics were relevant – many of us wonder about having a glass of wine from time-to-time. At the same time, arrhythmia patients will at some point have another medical procedure, like an MRI, and are concerned our condition or heart device may be impacted.”

The International Arrhythmia School was founded when Dr. Crystal spotted a gap between arrhythmia knowledge, rising technology, medical techniques and saw an opportunity to develop an organization specializing in innovation and education. Dr. Crystal hopes that the patient engagement section will continue each year, and notes that the response from patients who attended the inaugural session was overwhelmingly positive.

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