Smartwatches: a new technology that is an ally of our heart
In everyday clinical practice, the image of a patient coming to the doctor’s office holding their mobile phone in order to show recorded health data is no longer an exception but a common phenomenon.
Today, smartwatches are evolving into a particularly useful prevention and monitoring tool, as they provide the ability to continuously record basic biometric parameters and contribute substantially to the early detection of possible cardiac disorders.
A Global Trend with Medical Documentation
The technology of wearable devices (wearables) has shown impressive growth in recent years, with an increasingly larger percentage of the population incorporating smartwatches into their daily lives. International epidemiological data shows that approximately 3 in 10 people now own such a device, while the majority of users, at rates approaching 80%, use it specifically to monitor health parameters.
The initial philosophy behind the development of these devices was based on the idea that technology can act as a tool to prevent serious cardiovascular events, such as myocardial infarction and stroke. Today, this approach is not a theoretical scenario, but the subject of large international clinical studies, which investigate and document the role of wearables in the early detection of pathological conditions and in timely medical intervention.
The Reliability of Measurements: Sensitivity & Specificity
One of the key questions raised concerns whether smartwatch measurements can be considered reliable. This assessment is based on two fundamental concepts of medical statistics: sensitivity and specificity, terms that became more widely known during the pandemic.
- Sensitivity (94%–98%): It expresses the ability of the device to correctly detect an existing pathological finding, that is, to correctly identify and “not miss” a real problem, such as an arrhythmia.
- Specificity (>90%): It concerns the ability to avoid false positive results, that is, not to alert about a problem that does not exist, limiting unjustified “false alarms” that may cause unnecessary concern.
At the international level, the reliability of measurements is mainly based on the artificial intelligence algorithms that the devices incorporate. However, in Greek clinical practice, an additional advantage is observed: users are not limited to the automatic interpretation of the device, but transmit the recorded data, such as the electrocardiogram, to their treating physician for evaluation and final clinical confirmation.
This combined approach, where technology operates supportively and not autonomously, significantly enhances the accuracy and clinical reliability of the findings.
How does the technology work?
Modern smartwatches utilize two basic technologies to record cardiac function:
- Single-lead electrocardiogram (ECG)
To record an electrocardiogram, the creation of a closed electrical circuit is required. When the user touches the finger of the opposite hand to the special point on the device, the circuit is completed and the electrical activity of the heart is recorded.
Unlike the classic 12-lead hospital ECG, the smartwatch records a single lead. Although this is a more limited recording, it can highlight significant rhythm disturbances, such as atrial fibrillation. In cases where the recording on the wrist is not sufficiently clear and sharp, repositioning the device higher on the wrist or, rarely, on the ankle may improve the quality of the signal, facilitating medical evaluation.
- Photoplethysmography (PPG – the “green light”)
The sensor on the back of the device emits green light, which penetrates the skin and detects changes in blood flow in the capillaries. This technology, known as photoplethysmography, allows for continuous monitoring of:
- the frequency and regularity of heartbeats,
- the burden of arrhythmias (such as episodes of atrial fibrillation),
- indicators related to increased stress or sleep quality disorders.
Telemedicine and remote areas
One of the most important advantages of smartwatches is their contribution to telemedicine and in monitoring patients living in island or remote areas. The ability to send data in real time allows for early symptom assessment and, in some cases, reduces the need for Holter monitoring, as the device provides continuous recording on a 24-hour basis.
The Limitations of Technology
Despite progress, there are clear limits to the use of wearables:
- Blood pressure: Measuring blood pressure via smartwatch cannot currently replace the reliability of a conventional cuff blood pressure monitor. For the correct diagnosis and regulation of hypertension, the classic method remains the appropriate one.
- Psychological burden: Continuous monitoring and excessive preoccupation with measurements may cause anxiety in some users. Technology must operate supportively and discreetly, alerting only when there is a substantial indication that requires medical evaluation.
In conclusion, the smartwatch is a valuable complementary tool in cardiological monitoring. It does not replace medical practice nor does it function as an autonomous “diagnostician”. Its rational use, combined with the clinical assessment of the treating physician, is what maximizes the benefit for the patient and enhances prevention.
