When To Trust a Smartwatch for Your Heart (And When Not To!).

The holiday season is prime time for thoughtful gifts, and plenty of wish lists contain hopes for a smartwatch or fitness tracker. These popular devices promise to help us run farther, sleep deeper, and keep better track of our health.

For many of us, wearable devices can be a great way to start monitoring our well-being.  But these little devices offer a wide variety of metrics—it can be confusing to know what data to trust and what to approach with caution.

MedStar Health cardiologists and primary care providers see data from these devices every day. Their perspective is clear: smartwatches are a valuable tool for promoting activity and heart-health awareness. But they should be used in addition to, not a replacement for, a medical evaluation. 

Here are some tips to help you get the most out of your wearable without compromising your health.

How a smart wearable can boost your heart health.

Wearable devices can provide useful information that encourages you to get interested about your health. They’re excellent for keeping an eye on your physical activity and sleep patterns, and many patients find that the buzzes, beeps, and movement reminders motivate them to achieve their fitness goals.

When reviewing data collected by your smartwatch, keep an eye out for what doctors call longitudinal trends. Tracking how your numbers change over weeks or months can give you a better sense of your health than a single measurement.

Ask yourself these types of questions about your data:
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• Am I walking more than I was last month?

• Has my average resting heart rate slowly dropped?

• Do I get 7-9 hours of sleep most nights?

Long-term trends can be the most meaningful indicators of improved heart health.
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Your doctor’s favorite wearable features.

Many of our cardiologists love getting heart rhythm data from patients’ wearables. These measurements often meet the strict accuracy requirements of the Food and Drug Administration (FDA). Here are some of our favorite rhythm-focused features.

Heart rate tracking.

Smartwatches use optical sensors, which use beams of light on your skin to keep track of your pulse. This technology is generally reliable for:
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• Resting heart rate: This measurement is a well-established indicator of your baseline cardiovascular conditioning and health.

• Heart rate during exercise: Monitoring this can help you gauge the intensity of your workouts and stay in your target training zone.

Irregular rhythm detection.

Many popular devices can record a single-lead electrocardiogram (ECG). This feature can be a big help if you suddenly feel symptoms like a rapid or irregular heartbeat. For example, if you have atrial fibrillation (Afib), the most common serious rhythm condition, some devices can capture signal of your rhythm that you can later share with your doctor.

The American College of Cardiology notes this function can be valuable, and the FDA has regulated and authorized these monitoring features for adults. 

View these smartwatch metrics with caution.

Some wearables substitute estimates of your long-term trends for accurate measurements. These can be good for tracking your personal progress but should never be used to guide medical care.

MedStar Health experts say these stats from wearables often aren’t accurate:
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• Blood oxygen saturation: Wrist-based optical sensors are easily disrupted and give highly variable readings.

• Blood pressure: You can’t get a reliable blood pressure reading without compressing your blood vessels, like with an inflatable cuff at the doctor’s office. 

• Sleep stage classification: Accurately assessing sleep stages requires brain wave monitoring, which a smartwatch can’t do. Instead, it estimates your sleep duration and patterns.

Other metrics, such as estimate VO2 max and cardio fitness zones can be useful for personal motivation. Keep in mind, data accuracy is heavily influenced by hydration, stress, and sleep. 

Related: Read "New Potential for GLP-1 RA Medications Unlocking Heart Health Benefits"

Safety first: When to call 911.

A smartwatch is no substitute for a doctor. Be sure to understand the limitations of your device before making it part of your routine. For example:
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• A smartwatch can’t detect a heart attack: If you feel chest pain, severe shortness of breath, lightheadedness, or other symptoms of a heart attack, ignore your watch and call 911 right away.

• The device can’t diagnose you: A smartwatch can’t replace a medical exam. If you are concerned about data on your watch, follow up with your doctor—they can use more sensitive tools to get to the source.

• Risk of False Positives: With a continuous stream of data, you can get non-critical alerts and false positives that cause unnecessary anxiety. Be sure to discuss any unusual readings with your doctor to find out if they reflect a cause of concern.

Related: Read "Patient-Centered Teamwork: The Power of Multidisciplinary Heart Care."

Partner with a doctor for your best health.

Used appropriately, smartwatches can meaningfully support your cardiovascular awareness and help you improve your overall health. A new wearable device can be a great way to start an informed conversation with your MedStar Health provider. 

If you get an alert about an irregular heart rhythm or notice worrying trends in your heart rate, talk with your primary care provider or cardiologist. They can help you determine if you need further testing.

Understanding the limitations and strengths of your new smartwatch can empower you to take a more active role in your heart health. Partner with your doctor to stay healthy long after the holiday season has come and gone.