Smartwatches can track heart rate and flag irregular rhythms, but cardiologists explain why a normal reading can’t rule out heart disease.
Your smartwatch may know how fast your heart is beating. It can also record an electrocardiogram (ECG), flag an irregular rhythm, and send an alert when something seems unusual. This can be useful. But there’s a big difference between spotting a warning sign and knowing that your heart is healthy.
As wearable devices become more sophisticated, it’s easy to assume that a normal reading means everything is fine. Cardiologists warn against this assumption. A smart watch can help monitor certain aspects of heart activity, but it cannot replace a proper cardiac evaluation.
“Smartwatches can be helpful in identifying some warning signs, especially changes in heart rate or rhythm,” says Dr Ashok Malpani, Interventional Cardiologist, BM Birla Heart Hospital. “The short answer is, not quite.”
What can a smartwatch actually detect?
Most commercial smartwatches use optical sensors to continuously monitor pulse rate. Some also have a single-lead electrocardiogram (ECG) feature that records the electrical activity of the heart.
This combination can sometimes lead to an abnormally high heart rate, irregular rhythm or patterns that may indicate atrial fibrillation (AF), a type of irregular heartbeat.
Dr Chirag D, consultant interventional cardiologist at Aster Whitfield Hospitals, says the devices could be valuable as screening tools. “A smartwatch can be valuable as a detector for some heart conditions, but it cannot on its own tell you that your heart is completely healthy.”
More of LifestyleNormal reading does not mean heart health
This may be the most important thing to remember if you regularly check your heart rate on your watch.
“A smartwatch generally cannot assess whether a person has clogged arteries, serious structural heart disease, valve problems, or other conditions that may be present without obvious symptoms,” says Dr. Malpani.
Someone could have coronary artery disease, a valve disorder, or cardiomyopathy and still have their heart rate readings look normal.
Dr. Chirag also points out that even when a smartwatch has an ECG function, it is not equivalent to a test performed in a hospital or clinic. “Furthermore, even an ECG-equipped smartwatch can only provide an incomplete view of the heart’s electrical activity compared to a regular 12-lead ECG.”
A 12-lead electrocardiogram (ECG) records electrical activity from multiple points in the body. A smartwatch typically uses a single wire, so the information it provides is much narrower.
Research is also exploring whether smartwatch ECG recordings combined with artificial intelligence could help screen for some structural heart diseases. But Dr. Chirag says the work is still at an early stage.
What about clogged arteries and high cholesterol?
This is where people can easily overestimate what wearable technology can do. A smartwatch may monitor your pulse or rhythm, but it generally can’t tell you if your arteries are narrow or blocked. It also cannot independently diagnose high blood pressure or high cholesterol.
“Someone may have high blood pressure, high cholesterol, or premature coronary artery disease without having any symptoms, and a smartwatch may not detect these issues,” says Dr. Malpani.
Smartwatch alerts can also be false
There’s another aspect to wearable monitoring: an alert doesn’t automatically mean something is seriously wrong.
Smartwatch readings can be affected by movement, poor skin contact, and limitations of the sensor and signal quality, says Dr. Chirag. This means that wearable devices can sometimes produce false positive notifications.
“Smartwatch photoplethysmography is useful for detecting arrhythmias, but it is not a reliable test on its own to make a diagnosis; ECG results must be interpreted clinically,” he says, referring to the American Heart Association’s guidelines for atrial fibrillation.
In simple terms, a notification is a reason for attention, not a diagnosis you have to make yourself. The same applies in reverse. A watch that doesn’t send an alert can’t tell you that nothing is wrong.
What should you do when your watch indicates an irregular rhythm?
Don’t panic, but don’t ignore it either. Persistent or recurring abnormal readings are worth discussing with your doctor, especially if you are experiencing symptoms at the same time.
Unusual readings accompanied by “chest discomfort, shortness of breath, dizziness, fainting, or unexplained palpitations” should warrant medical attention, Dr. Malpani says.
Likewise, Dr. Chirag advises that frequent heart palpitations, chest pain, unexplained shortness of breath, fainting, or unexpected fatigue should be evaluated by a doctor regardless of the smartwatch reports.
Your doctor may then decide whether you need a clinical EKG, blood tests, echocardiogram, ambulatory monitoring or other heart tests.
So, how should you use a smartwatch?
Think of it as a monitoring tool that can help you notice changes, not a machine that can make sure your heart is healthy. It can be particularly useful for people with intermittent symptoms that may not occur during a short consultation. Recording heart rate patterns or alerting an irregular heartbeat can give the doctor another piece of information to act on.
But it doesn’t replace the basics. “At the end of the day, your smartwatch can tell you a lot about your heart activity, but it can’t give your heart a clean bill of health,” says Dr. Malpani.
Regular medical checkups, monitoring of blood pressure and cholesterol, a healthy lifestyle, and proper heart evaluation remain important, even if your wrist keeps telling you that everything looks normal.
