In recent years, Smartwatches with advanced heart rate functions They have gone from being simple technological accessories to becoming a potential support tool for medicine. One of the fields where this change is most noticeable is in the detection of atrial fibrillation, a very common arrhythmia that can trigger serious strokes.
A series of recent investigations, led by a clinical trial conducted at the University Medical Center Amsterdam (Amsterdam UMC) The study, published in the Journal of the American College of Cardiology, suggests that the Apple Watch could play a significant role in screening for these arrhythmias in older people and those at high vascular risk, something particularly interesting for healthcare systems like Spain's and, in general, for Europe.
A clinical trial under real-world conditions with high-risk patients
The research was designed as a real-world randomized clinical trialThat is, outside the controlled environment of a laboratory. The Dutch researchers recruited 437 people aged 65 or older, all of whom were at high risk of stroke, a profile that closely matches many patients seen daily in primary care and cardiology in Spain and other European countries.
The participants were divided into two groups: 219 people received an Apple Watch They were asked to use it for about 12 hours a day, while the other 218 continued with standard care, based on regular medical visits, occasional electrocardiograms and additional tests only when there were symptoms or clinical suspicions.
The follow-up lasted for six full monthsDuring that time, the group with smartwatches had access to a virtually continuous monitoring of heart rate and rhythm, while the control group relied on traditional medical checks, which usually offer a very limited view over time.
The authors emphasize that this is a study with moderate sample size (437 participants) and a median age of around 75 yearsIn other words, the conclusions are mainly applicable to high-risk older people; a cohort with different characteristics could yield somewhat different figures, although the main trends are expected to remain.
Four times more arrhythmias detected with Apple Watch
After six months, the results were clear: in the group wearing the Apple Watch, A cardiac arrhythmia was diagnosed in 21 patientsmostly atrial fibrillation. In contrast, in the group that only received standard care, the following were identified: 5 cases of arrhythmia.
In other words, the doctors They detected arrhythmias about four times more often The difference was statistically significant among those using the Apple Watch compared to those who only followed conventional monitoring methods. This supports the idea that prolonged wrist-based monitoring can uncover problems that would otherwise remain hidden.
There is one particularly striking fact: of the 21 patients in the group with a watch, around 57% had no symptoms at the time of diagnosis. That is, these were people who felt well, had no palpitations or obvious discomfort, and probably would not have gone to the doctor on their own initiative.
In the standard care group the situation was very different: the five patients in whom an arrhythmia was detected Yes, they reported clear symptomsThis shows that, without continuous monitoring, there is a tendency to diagnose only those who already notice something unusual, while silent cases can go unnoticed for years.
If these data are translated into proportions, the group with Apple Watch reached a atrial fibrillation detection rate close to 9,6% during the six months, compared to approximately 2,3% in the control group, according to the detailed analysis of the trial.
Why atrial fibrillation escapes classic controls
The arrhythmia that is the main focus of this type of work is the atrial fibrillationThe most common rhythm disorder in older adults. In this condition, the atria—the upper chambers of the heart—stop contracting in an orderly fashion and begin to quiver uncoordinatedly, producing a chaotic heartbeat.
Cardiologists explain that the inside of the atrium is not a smooth surface, but rather has ridges, folds, and small pouchesWhen the ear wall no longer contracts properly and only vibrates, blood can pool in those spaces and form clots. If one of these clots breaks off and travels to the brain, it can block an artery and cause a stroke.
Scientific societies, such as the American Heart Association and its European counterparts, warn that atrial fibrillation can multiply the risk of stroke by fiveThe problem is that around half of the cases are intermittent and often do not produce striking symptoms, or these are mistaken for simple tiredness, nervousness, or lack of physical fitness.
When a person has a conventional electrocardiogram (ECG) in the doctor's office or in the emergency room, the professional only has access to a “snapshot” of a few seconds of the heart rateIf a fibrillation episode does not occur at that exact moment, the recording will be normal and the diagnosis will be postponed, even if the problem continues to appear sporadically at other times of the day or night.
This intermittent nature explains why, despite attending check-ups, Many patients with atrial fibrillation remain undiagnosed until they suffer a stroke or a serious complication. This is where devices capable of recording the pulse for hours on end can provide valuable information.
Key advantage of the Apple Watch: PPG, ECG, and continuous monitoring
Apple's commitment to heart health took a significant leap in 2018 with the arrival of the Apple Watch Series 4That model incorporated the electrocardiogram (ECG) app and irregular heart rhythm notifications, features that have been maintained and refined in later generations of the watch.
The device combines two main technologies: the photoplethysmography (PPG), which continuously measures heart rate using an optical sensor on the wrist, and a single-lead ECG, which the user can activate by placing a finger on the digital crown to obtain a basic electrical tracing of the heart.
PPG allows the watch to identify variations in pulse that don't fit a regular rhythm and, if it detects suspicious patterns, it can generate a notification of possible irregular rhythmFor its part, the ECG function offers a simple recording that, although it does not replace a complete clinical electrocardiogram, is useful for detecting atrial fibrillation and other common abnormalities.
Compared to other long-term monitoring systems, such as traditional Holter monitors with adhesive electrodes and bulky devices Unlike short-term implantable blood pressure monitors, smartwatches have the advantage of integrating into daily life with less inconvenience. Most users wear them for many hours a day almost without thinking, which increases the likelihood of capturing sporadic episodes.
The researchers at Amsterdam UMC themselves point out that devices capable of recording pulse and cardiac electrical activity already existed, but There was a lack of solid studies in real-world settings. that assessed its usefulness for screening people at higher risk of atrial fibrillation. The trial they have published contributes precisely to filling that gap.
More detection… but also false positives that need to be managed
In addition to the higher rate of confirmed diagnoses, detailed analysis of the study shows that the Apple Watch not infallibleAlmost half of the alerts generated by the watch during monitoring turned out to be false positives, that is, warnings that did not ultimately correspond to atrial fibrillation or another clinically relevant arrhythmia according to subsequent medical tests.
From a clinical perspective, these false positives primarily imply a increased workload of consultations and additional tests to check if there really is a problem. They can also generate some concern in users, who, upon receiving a warning about their heart, naturally tend to become alarmed.
However, the experts clarify that beyond this potential concern and the time invested in the evaluation, No direct adverse effects associated with the alerts have been observed.In other words, the balance tips towards greater sensitivity—more potential cases are detected—at the cost of losing some specificity.
In healthcare systems under high pressure, as is the case in much of Europe, this opens up an interesting debate: how Integrate notifications from smartwatches in an orderly manner in the care circuits, so that truly suspicious cases are prioritized without unnecessarily saturating the consultations.
The researchers also point out that, although the watch can accurately identify atrial fibrillation, Diagnostic confirmation should always be done in a medical setting.with higher quality records and expert evaluation. In this sense, the smartwatch acts as an "early detector" rather than a definitive diagnostic tool.
Potential impact on stroke, treatments and European healthcare systems
the cardiologist Michiel Winter, Amsterdam UMC, summarizes the scope of these findings by highlighting that the use of smartwatches with PPG and ECG functions helps diagnose arrhythmias in people who were unaware of having them, thus allowing speed up the diagnostic process and, in theory, reduce the associated risk of stroke.
When atrial fibrillation is confirmed, one of the main prevention strategies is the prescription of anticoagulant treatment In patients who need it, anticoagulation is used to reduce blood clot formation. However, several international studies indicate that up to 50% of those who should be anticoagulated are not, either due to lack of diagnosis or other factors.
If more patients—including asymptomatic ones—can be identified at relatively early stages, professionals have the opportunity to start these preventative therapies earlier This would reduce the incidence of strokes linked to atrial fibrillation. The benefit would not only be clinical but also economic, by avoiding prolonged hospitalizations, disabling sequelae, and the need for costly rehabilitation.
According to Winter and his team, in highly selected high-risk groups, such as those included in the trial, The reduction in complications could offset the initial cost of the deviceThis is especially relevant for public systems like the Spanish one, where any investment must be justified by its impact on health and sustainability.
In this context, the door is opened for some European healthcare systems to consider the use of smartwatches as part of their future healthcare systems. selective screening programs in older adults with high vascular riskprovided that the inclusion criteria, the protocols for action in the event of alerts, and the coordination with primary care and cardiology are well defined.
What does all this mean for users in Spain and Europe?
For the general public, and especially for those who already use an Apple Watch, the main message is that the watch can be a a useful ally for monitoring the heartHowever, it does not replace professional assessment or the periodic check-ups recommended by the doctor.
If the device repeatedly issues irregular rhythm warnings or displays unusual readings in the ECG app, the reasonable course of action is consult with the healthcare system for a complete evaluation, instead of relying solely on the interpretation of the watch itself, however advanced the algorithm may be.
At the same time, it is important not to fall into the opposite extreme: an apparently normal reading on the clock. It does not guarantee 100% the absence of heart problemsIf you experience symptoms such as intense palpitations, dizziness, shortness of breath, chest pain, or fainting spells, the recommendation remains to seek medical advice, regardless of what the screen displays.
European scientific societies insist that these devices should be viewed as complements within a cardiovascular prevention strategynot as substitutes for standard diagnostic methods. Their usefulness will be greater the better they are integrated into well-organized systems and the clearer the information received by both doctors and patients.
Taken together, the evidence provided by the Amsterdam UMC trial and other peer-reviewed studies reinforces the idea that the Apple Watch and similar smartwatches may play a significant role in the early detection of atrial fibrillation and in the prevention of strokeespecially in older people and those with risk factors. It remains to be seen how this will be reflected in clinical guidelines and daily practice in Spain and the rest of Europe, but everything suggests that the wrist will continue to gain importance as a strategic point for monitoring heart health.
