How wearable tech helps people monitor atrial fibrillation and other stroke risk factors
Fact checked by Jim Lacy
Picture this: You’re walking or jogging when your Fitbit buzzes on your wrist, your heart rhythm has gone irregular. Or maybe you’re grocery shopping after work, and your Apple Watch gives a similar warning.
When your watch does the same thing the next morning, you call your doctor. They tell you to come in, and soon you have a diagnosis: atrial fibrillation (AFib) — the most common type of irregular heartbeat, also called arrhythmia, which increases stroke risk fivefold if untreated.
Raffay Khan, MD, a cardiologist and cardiac electrophysiologist at Chicago Cardiology Institute, says people shouldn’t panic when their watch alerts them. “When these watches and wearables pick up an irregular rhythm, they don’t signify an immediate risk of stroke. It’s more of a long-term risk,” Khan says.
But this doesn’t mean timely treatment isn’t important. Whether you’re already diagnosed with afib or just monitoring your heart, wearable tech can aid early detection, tracking, and stroke prevention — as long as you discuss the findings with your physician.
How smartwatches detect atrial fibrillation
Most smartwatches use the same technology. Photoplethysmography, or PPG, uses light to detect changes in blood volume. “If you look on the back of your smart watch, there are these lights. It’s a photodetector looking at any changes,” says Moeen Saleem, MD, an electrophysiologist at Midwest Cardiovascular Institute.
PPG detects irregularities by tracking blood volume, Khan says. “When you’re in atrial fibrillation, you can get changes in blood volume from beat to beat.”
“They [can] really help inform medical care, but they don’t replace medical judgment.”
Studies show PPG is largely accurate. A 2020 study found that Fitbit’s PPG detection accurately identified AFib 98% of the time. In a similar Apple Heart Study, the detection rate was 84%.
Some devices allow users to record an electrocardiogram (EKG or ECG) if the watch detects an irregular heartbeat.
“For example, [some] Apple watches have a crown that, if you put your finger on the crown and the back of the watch is on your wrist, you can essentially create a direct EKG recording,” Khan says. “That’ll give you more direct visualization of an irregular rhythm such as atrial fibrillation.”
What to do with heart health data
Assist with diagnosis
Sharing this data with your doctor is crucial, Saleem says. “If you record an ECG, it can be stored, and then you can show it to [your] healthcare provider and [they] can make a diagnosis with that information.”
Physicians can confirm accuracy and determine if AFib is present. “If that’s the case, [you] would be prescribed medications to protect from the risk of stroke, specifically a blood thinner,” Saleem says.
Start and monitor treatment
Most people with AFib take blood thinners, which cut stroke risk by more than half. Only about 10% of people with AFib have a low enough stroke risk to skip blood thinners, but 20% aren’t taking them when they should, making early detection critical.
AFib ablation offers another option. It uses heat or cold to create tiny scars on the heart that interrupt signals, causing irregular rhythm.
“Some patients will use their Apple Watch to monitor symptoms, to give physicians feedback on the effectiveness of treatment,” Saleem says.
Identify AFib triggers
Khan says smartwatches also can help identify triggers. “For example, people [who] have been going on late-night drinking binges, they’ve oftentimes been alerted the next day that they’re in atrial fibrillation,” he says. “They don’t even feel [it], but their watch has told them that they’re in [afib].”
Overall, Khan calls wearables useful. “They [can] really help inform medical care, but they don’t replace medical judgment.” This is why consulting a healthcare provider is essential if your watch flags a potential problem.
Smartwatches today can track more than time. Paired with medical guidance, they can help save lives.
