In recent years we have witnessed an avalanche of new commercially available technologies for monitoring our health, specifically smart watches or smartwatches.
In the field of cardiology and especially in the study of heart rhythm disorders, the universal use of these watches stands out.
These devices allow us to assess our heart rate using two technologies: photoplethysmography and electrocardiography. The first uses the property of our blood to absorb and reflect certain wavelengths of light, allowing us to estimate our heart rate in a way similar to taking our pulse.
While the degree of correlation with the actual electrical activity of our heart is good, this technology is susceptible to errors due to artifacts caused by movement or in patients with frequent premature ventricular contractions (a common and generally benign condition in the general population). These are easily recognizable by the presence of green LED lights under the watch case. The electrocardiogram available in the most advanced smartwatches does allow for direct detection of the heart's electrical activity. The diagnostic applications developed by manufacturers have even led some health regulatory agencies to classify them as medical diagnostic devices.
The greatest benefit of these smartwatches, especially those with electrocardiogram capabilities, lies in the study of symptoms suspected of being arrhythmic in origin that occur briefly or intermittently. Until now, the diagnosis of these conditions has been delayed due to the difficulty of obtaining a high-quality electrocardiogram recording. Now, patients can obtain a recording within 30 seconds, which in many cases allows for confirmation or exclusion of an arrhythmic origin for their symptoms.
One of the most frequent inquiries we receive concerns extreme heart rate readings, both high (tachycardia) and low (bradycardia). While it's important to remember that many of these readings can be due to simple measurement errors (no matter how good or expensive your watch is), there is a wide range of heart rate variation under physiological conditions, which can be affected by countless factors such as age, level of physical fitness, sleep quality, and so on. Therefore, values up to 40 beats per minute during sleep or 100 beats per minute in stressful situations are perfectly within the realm of normal. Heart rate alone, especially in the absence of symptoms and outside of a context of high suspicion of pathology, rarely indicates significant health problems.
In short, smartwatches with electrocardiogram recording capabilities are a powerful tool for diagnosing and monitoring heart rhythm disorders , and those with photoplethysmography capabilities offer useful clinical information if interpreted in an appropriate clinical context, while being aware of the limitations of this technology.
Other related news of interest:
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Cardiovascular health: better safe than sorry