You have probably heard that wearable technologies like smartwatches can help you monitor your heart health. But do they really work, and how do you decide which is right for you?
In this Q&A, Matthew I. Tomey, MD, Associate Professor, Medicine (Cardiology), Icahn School of Medicine at Mount Sinai, says they can be useful, with a few things to keep in mind. He discusses what features to look for and why it’s important to talk to your cardiologist before you decide on a device.
Matthew I. Tomey, MD
What can a smartwatch or fitness tracker tell me about my heart?
Wearables like smartwatches and fitness trackers can measure several things related to your heart and overall health:
- Heart rate. Most devices use a technology called photoplethysmography (PPG), a light sensor on the back of the watch that shines into your skin and measures blood flow to estimate your pulse. In controlled settings, wrist-worn devices have been shown to measure heart rate with roughly ±3 percent error compared to standard medical equipment, though accuracy decreases during physical activity.
- Heart rhythm. Some devices can alert you to an irregular heartbeat that may suggest atrial fibrillation (AFib), a common heart rhythm disorder that increases the risk of stroke. Devices do this either by analyzing your pulse pattern in the background or by recording a single-lead electrocardiogram (ECG) when you place your finger on the watch.
- Physical activity. Built-in motion sensors track steps, distance, and calories burned. Research shows that using a wearable activity tracker can help people with heart disease increase their daily walking by roughly 2,000 steps per day compared to not using one.
- Sleep. Many devices estimate sleep duration and quality, which is relevant because poor sleep is linked to higher cardiovascular risk.
- Blood oxygen level. Some devices estimate blood oxygen saturation, though the accuracy of this feature in consumer devices is still being studied.
These devices are not replacements for medical equipment, but they can provide useful day-to-day information about your health trends.
Are there any risks or limits to using a wearable to check my heart?
Yes. There are several important limitations and concerns to be aware of:
- Accuracy varies. Not all devices perform equally. Accuracy depends on the brand, model, type of sensor, and what is being measured. For example, in a head-to-head study of five popular smartwatches, the sensitivity of automated algorithms for detecting AFib ranged from only 58 to 85 percent, and the devices could not determine the heart rhythm in 17 to 26 percent of recordings. When a doctor reviewed those same recordings, the rhythm could be identified 99 percent of the time. This highlights that these devices are screening tools, not diagnostic instruments.
- Skin and fit matter. Accuracy can be affected by darker skin tones, tattoos, cold body temperature, obesity, poor skin contact, and how tightly the device is worn. Movement, especially during exercise, is a major source of error.
- False alarms. The device may flag something as abnormal when nothing is actually wrong (a “false positive”). This can cause unnecessary worry and lead to additional medical visits and testing that may not have been needed. On the other hand, a normal reading does not guarantee that nothing is wrong.
- They are not the same as medical devices. While some consumer wearables have received clearance from the U.S. Food and Drug Administration (FDA) for specific features, such as ECG recording or irregular rhythm notification, this clearance is for screening purposes only. An irregular rhythm alert from a wearable does not diagnose AFib. A doctor must review the data and confirm any diagnosis. Many other health features on these devices (such as blood oxygen or sleep tracking) have not been FDA-cleared at all.
- Data overload. These devices generate large volumes of data continuously. Without a clear plan for how to use the information, it can become overwhelming rather than helpful, for both patients and doctors.
- Privacy. Wearable devices collect sensitive health information. Privacy protections vary significantly across manufacturers, and health data from consumer devices are generally not protected by the same laws (such as HIPAA) that protect your medical records. It is worth reviewing a device’s privacy policy before purchasing.
How can I use a wearable to track my heart and build healthier habits?
Wearables are most useful when paired with clear goals and a plan. Before purchasing a device, consider:
- What do I want to learn? For example, do I want to track how active I am, monitor my heart rhythm, or keep an eye on my resting heart rate over time?
- What will I do with the information? Data alone does not improve health; acting on it does. For instance, setting a daily step goal and using the device to track progress has been shown in clinical studies to help people become more physically active.
- Am I prepared to discuss the data with my doctor? If the goal is to manage a health condition, the device is most valuable when its data are shared with and interpreted by a health care provider.
- Wearables can also support exercise safety. For people with heart disease, a doctor can help set a target heart rate range for exercise, and a wearable can help monitor whether activity stays within that safe zone.
What should I tell my doctor if I am using a wearable to check my health?
Start by letting your doctor know that you are using a device and what you hope to learn from it. Setting expectations early can prevent frustration on both sides. Key points to discuss:
- What role will the device play in your care? Clarify what your doctor is willing and able to review. Doctors may not be able to monitor continuous data streams on an ongoing basis, and there are currently no standardized systems for integrating consumer wearable data into most electronic health records.
- What should prompt a call or visit? Ask your doctor which alerts or readings should lead you to seek medical attention and which can be noted for your next scheduled visit.
- Share data selectively. Rather than presenting weeks of raw data, focus on trends or specific events (such as an irregular rhythm alert or a sustained change in resting heart rate) that are most relevant to your health questions.
Ideally, discuss the idea of using a wearable before purchasing one, so your doctor can recommend features that align with your health goals.
What features should I look for to track my heart and health correctly?
The best features depend on why you are getting the device:
- For heart rhythm monitoring: Choose a device with ECG capability, not just pulse-based (PPG) monitoring. Devices with ECG functionality are superior for determining heart rhythm. Several smartwatches from major manufacturers have received FDA clearance for ECG recording and irregular rhythm detection. However, even ECG-equipped devices require you to actively initiate a recording; they do not continuously record your heart’s electrical activity.
- For general fitness and activity tracking: Most major-brand devices are reasonably accurate for step counting and heart rate at rest. If you plan to monitor heart rate during vigorous exercise, a chest strap is more accurate than a wrist-worn device.
- Look for FDA clearance for the specific feature you care about. A device may be FDA-cleared for one function (such as ECG) but not for others (such as blood oxygen). Check the manufacturer’s website for details.
- Consider comfort and battery life. A device only works if you wear it consistently. Choose something comfortable enough for daily and overnight use.
How can I know if a device has been validated by research?
Look for studies published in peer-reviewed medical journals that have tested the device against standard medical equipment (such as a 12-lead ECG or hospital-grade heart monitor). A few things to keep in mind:
- Manufacturer claims are not the same as independent validation. When independent researchers have tested popular wearables head-to-head, the accuracy has sometimes been lower than what manufacturers report.
- Watch for excluded data. Some studies exclude recordings that the device labeled as “inconclusive” or “unreadable.” When those are included in the analysis, accuracy drops significantly. In real-world use, you will encounter inconclusive readings.
- Study populations matter. Most large wearable studies have been conducted in people in their 40s and 50s. Performance may differ in older adults or people with other medical conditions.
Your doctor or a medical librarian can help you find relevant research on a specific device.
What else should I know about wearables for my heart?
Wearable technology for heart health is a rapidly evolving field. A few additional points:
- Wearables may help manage chronic conditions. Beyond rhythm monitoring, there is growing research into using wearables to help manage conditions like heart failure, for example, by tracking activity levels, weight trends, and other signals that may indicate worsening symptoms before a hospitalization occurs. However, this area is still in its early stages, and most consumer devices are not yet designed for this purpose.
- Artificial intelligence is expanding what devices can do. Newer algorithms are being developed to detect a wider range of heart conditions and to reduce the number of inconclusive or unreadable recordings. These advances are promising but still require further validation.
- Equity matters. Not everyone has equal access to these technologies, and accuracy can vary across different skin tones and body types. Efforts are underway to improve device performance across diverse populations, but gaps remain.
- The doctor-patient relationship is central. Wearables generate data, but clinical judgment is needed to interpret that data and make decisions. The most effective use of these devices will come from a partnership between patients and their health care teams.
Both doctors and patients should stay informed as this technology continues to develop. The ways wearable devices are used in medical care will continue to evolve, and staying engaged with your health care provider is the best way to make the most of these tools.