Smartwatches are increasingly present in our daily lives. It is estimated that in the United States of America one in three people use a smartwatch. In Europe (and in Portugal), the use of smartwatches is also growing. It is estimated that there were around 1.1 billion devices in use worldwide in 2022. Through different sensors , smartwatches can monitor health parameters , such as: Heart rate; Oxygen saturation; Sleep patterns; Physical activity levels. Regarding the heart and in addition to heart rate, several devices allow the detection of arrhythmias, namely atrial fibrillation and have received approval for this purpose from regulatory entities, namely the FDA (Food and Drug Administration) and CE (Conformité Européenne). Smartwatches that detect arrhythmias do so through the following technologies: Photoplethysmography Technology that allows the identification of alterations in the absorption of light by the tissues and that indirectly detects variations in the volume of blood in the blood capillaries. These variations are used to calculate heart rate and its regularity. Electrical activity sensors Through electrodes in contact with the skin, the sensors detect the electrical activity of the heart and, similarly to what is done in a conventional electrocardiogram, can record a heart rate strip. This rhythm strip only shows one lead and has a more limited interpretation than a conventional electrocardiogram that shows 12 leads. Artificial intelligence algorithms These integrate information from photoplethysmography and electrical activity sensors with motion sensors and other parameters measured by the smartwatch, to increase accuracy in identifying cardiac arrhythmias. The use of information from smartwatches to support the diagnosis of arrhythmias, namely atrial fibrillation, is a promising tool that should not be overlooked by doctors and by each one of us. However, there is a fundamental question to which it is important to know the answer: If a smartwatch indicates that you have atrial fibrillation, should you believe it or not? To answer this question, researchers from a hospital in Switzerland carried out a study in which the performance of five smartwatches was compared with that of the conventional electrocardiogram reported by physicians, in the diagnosis of atrial fibrillation. The population studied included: 201 patients who went to a cardiology consultation; Average age of 66.7 years; 31% women; 31% with atrial fibrillation. Each one of these patients used one of the following devices to record the electrocardiogram and detect the presence of atrial fibrillation: Apple Watch 6 Samsung Galaxy Watch 3 Withings Scanwatch Fitbit Sense AliveCor KardiaMobile In addition, all of them had a conventional 12-lead electrocardiogram interpreted by a physician. These were the main results of the BASEL Wearable Study Sensitivity, that is, the probability of detecting atrial fibrillation when it was actually present, ranged from 58% on the Withings Scanwatch to 85% on the Apple Watch 6 and Samsung Galaxy Watch 3; Specificity, that is, the probability that the detected atrial fibrillation actually corresponds to this arrhythmia, after confirmation by electrocardiogram, varied between 69% in AliveCor KardiaMobile, and 79% in Fitbit Sense; There were, on average, 20% of inconclusive results, that is, hearth rhythms that the automatic algorithms of the smartwatches were unable to interpret. When these inconclusive tracings were excluded, the sensitivity and specificity of the devices increased to over 90% across all devices, with 92% of interpretable tracings classified correctly. In addition to the aforementioned results, which are very interesting, the electrocardiographic tracings of the smartwatches were also analyzed by a doctor , without including the information from the automatic algorithms. In this case, medical analysis of all tracings, including the inconclusive ones, was possible, and in 99% of cases a diagnosis was established based on the analysis of the tracings. Study participants also completed a questionnaire about the comfort, ease of use, and other features of the smartwatches they used. The Apple Watch 6 was preferred in 39% of cases, with the remaining participants equally divided between the remaining devices. The conclusions The results obtained allow the conclusion that smartwatches were useful to detect atrial fibrillation in the studied population. When inconclusive tracings, which appear in 20% of cases, are excluded, the diagnostic accuracy of devices is very high. The review of the electrocardiographic tracings of the smartwatches, by the responsible physician, allows, in 99% of the cases, to confirm or exclude the presence of atrial fibrillation. Therefore, if your smartwatch indicates that you have atrial fibrillation, talk to your doctor as further investigations may be necessary. References Dagher L, Shi H, Zhao Y, Marrouche NF. Wearables in cardiology: Here to stay. Hearth Rhythm 2020;17:889-95. Mannhart D, Lischer M, Knecht S, et al. Clinical validation of 5 direct-to-consumer wearable smart devices to detect atrial fibrillation: BASEL Wearable Study. JACC Clin Electrophysiol 2023;9:232-42. Author: José Ferreira Santos Meet the cardiology clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
