Should I get a smart watch if I have heart issues?

Smart watches are offering more than fitness tracking. The latest wearables also measure health-monitoring features, including sleep, heart monitoring and fall (or crash) detection. If you have a heart condition, smart watches can measure everything from heart rate to blood pressure.

Monitoring for heart problems is an important tool for public health. Heart disease is a leading cause of death for all people in the United States, and hospitalizations from the common heart arrhythmia atrial fibrillation, or AFib, costs the U.S. health system more than $4 billion each year. Smart watches offer an accessible way to keep tabs on what’s happening in your cardiovascular system.

The U.S. Food and Drug Administration (FDA) has approved several smart watches for health monitoring. This includes popular wearables such as the Apple Watch series, the Samsung Galaxy watch, the Fitbit Sense and the Garmin watch series. The FDA says these wearables are generally as accurate as traditional cardiac monitoring and offer people convenient ways to monitor their cardiovascular health.

Smart watches are helpful, but there are limitations to consider when wearing them. Learn how smart watches work, what they measure and what they don’t.

How do smart watches monitor your heart?

Smart watches use a technology called photoplethysmography, or PPG, to measure your heart rate. Using a flashing green light on the underneath side of the smart watch, PPG reflects light to the red blood vessels under your skin and records changes in your blood volume. The sensors in these wearables can also measure how the blood pulsates and identify irregularities or palpitations that indicate AFib.

PPG is also used to monitor other areas of your health in real time, such as your activity level, sleep and other health measures.

How do smart watches compare to traditional heart monitoring devices?

When a doctor needs to check a patient’s heart due to symptoms like chest pain, fainting heart arrhythmias or routine checkups, they use 12-lead electrocardiograms, or ECGs. This diagnostic test evaluates the heartbeat rhythm for potential irregularities. Using wires placed on 10 points on the body, an ECG combines the information and presents it as a dozen views of the electrical signals coming from the heart.

A smart watch works like these medical electronic devices because it’s basically a single-lead ECG. Wearable devices do not provide as much accuracy or details as a full 12-lead ECG, but smart watches:

• Are more widely available
• Are present when needed
• Offer continuous heart monitoring
• Do not require a prescription
• Include several features in one device

A study by the prestigious American College of Cardiology (ACC) found that overall, smart watches are very sensitive and specific in detecting AFib. This is particularly useful to patients who already have symptoms of AFib and want to monitor their heart rates. The study also found that smart watches can help detect AFib, even for patients who have no symptoms. One study testing the Apple Watch found that about 34% of patients who received an irregular heartbeat notification from their Apple Watch actually had AFib based on ECG monitoring.

It's possible for smart watches to occasionally deliver “false positives,” or false alerts of AFib. These can be caused by sensor interference or the watch misreading the heart rate. However, one study on Apple Watches found that rates of false positives were low among people with known AFib. Similar studies found that Samsung and FitBit watches are also good at identifying AFib with minimal false positives.

Cardiologists say these devices are helpful, but there are some limitations to keep in mind when using smart watches as heart rate monitors.

Limitations of smart watches for heart health

While smart watches offer useful heart monitoring capabilities, they do have some limitations. Wearable devices are:

• Not as accurate as standard 12-lead ECGs
• Limited in how well they can detect certain heart conditions
• Affected by interference
• Dependent upon proper wrist positioning
• Not intended to provide a diagnosis of a medical condition
• Lack features that cater to older patients, such as larger screens and interfaces

The false positives smart watches deliver can be problematic. One study found that repeat false positive alerts for AFib negatively impacted the quality of life and chronic disease self-management for older stroke survivors.

Smart watches are also less effective for people with darker skin tones. One study found that heart rate measurements were much less accurate in people with darker skin tones when compared with people with lighter skin, or by validating results with an ECG. Researchers also found that smart watches recorded fewer data points for people with darker skin. This is likely due to how much green light is absorbed in darker skin when the smart watch sensors monitor heart rates through the wrist.

Smart watches cannot yet detect a heart attack because the sensors do not provide enough information to understand what is happening inside the organ. Ideally, these wearable devices provide you with enough information to identify heart problems early so you can prevent a minor heart condition from turning into a serious one.

Do cardiologists recommend smart watches?

By viewing regular information about your heart rate and recognizing patterns or irregularities, you can learn more about your own body. This can be helpful in identifying problems early.

It’s especially beneficial for people with heart conditions to know more about what’s happening with their heart. In fact, people with AFib who wear smart watches tend to pay more attention to their symptoms and heart monitoring and report concerns. Cardiologists with the ACC say the popularity of smart watches could help increase early detection of AFib and relieve its burden as a leading health problem in the United States.

What to look for in smart watches for heart monitoring

If you are considering getting a smart watch to monitor your heart health, there are a variety of devices on the market that offer ECG technology. As you shop, consider which features are most important to you:

• ECG monitoring. Not every smart watch uses ECG monitoring, so consider how the device delivers AFib and heart rate information.
• ECG app. Most smart watches send all the heart-monitoring data to an app on your phone, where you can view or share the information. Different apps and smart watches offer different ways to collect data from heart monitoring.
• Battery life. Smart watches must typically be plugged in and recharged. These batteries can last for days or even weeks, depending on the watch and the exercise activities you monitor. Consistency is important for heart monitoring, so it’s good to keep your watch charged.
• Exercise tracking. Wearable devices have a variety of ways and options for tracking your exercise and monitoring your health throughout. Look for a watch that matches your activity interests. For instance, if you enjoy swimming or water aerobics, be sure to get a waterproof device. If you enjoy triathlons, you may want a watch that tracks both swimming and bicycling.
• Watch face. Be sure the face of the watch is easy for you to view, and the buttons are simple to navigate.
• Breathing and sleep monitoring. Some watches will track how you breath and sleep. This information can help you get a better picture of how hard your heart is working.
• Cost. Given the wide variety of options and capabilities, smart watches can run from $50 to $500. Be sure to check if your device requires a subscription service to use its options.
• Dependence on other devices. Some watches work best, or uniquely, with smart phones by the same manufacturer. If you don’t already own or plan on buying a device that matches your phone, certain smart watch brands may not be the best choice.

Online reviews of other user experiences with different smart watches can help you decide which (if any) best suits your needs. While smart watches are not perfectly accurate tools for diagnosing AFib and other heart conditions, they are a useful guide or screening option to monitor your heart rhythm. By using a wearable device, you can better understand your heart rate and habits. Remember: detecting atrial fibrillation and diagnosing or treating heart conditions should still be done by your doctor.