Heart failure refers to a condition in which the heart's pumping capacity is weakened and is often difficult to treat. On the other hand, atrial fibrillation is a heart condition that arises when abnormal electrical impulses suddenly trigger irregular and often rapid heart rates in the upper chambers (atria) of the heart. This can limit a person's ability to carry out daily activities and lead to symptoms such as tiredness, dizziness, and shortness of breath, and is also linked to a fivefold increase in stroke risk. Now, a new study suggests that wearable devices like smart watches may have the potential to identify an elevated risk of developing heart failure and irregular heart rhythms later in life.

In the peer-reviewed study, researchers at University College London (London, UK) examined data from 83,000 individuals who had undergone a 15-second electrocardiogram (ECG) similar to the type used in smart watches and mobile devices. The study consisted of two groups: the first group comprised 54,016 participants with a median age of 58, who were monitored for an average of 11.5 years after their ECG was recorded; the second group was made up of 29,324 participants, with a median age of 64, who were monitored for 3.5 years. All ECG recordings analyzed were from individuals aged 50 to 70 with no known cardiovascular disease at the time. The researchers identified ECG recordings that contained extra heartbeats, typically harmless, but if frequent, could indicate conditions such as arrhythmia (irregular heartbeats) and heart failure.

During an electrocardiogram (ECG), sensors are affixed to the skin to detect the electrical impulses emitted by the heart during each contraction. In medical facilities, at least ten sensors are attached around the body, and the resulting recordings are examined by a specialist physician to detect any potential issues. In contrast, consumer-grade wearable devices utilize only a single device embedded with two sensors (known as a single-lead), making them less cumbersome but possibly less precise. For this particular study, the research team utilized automated computer software and machine learning techniques to identify recordings with extra heartbeats, which were classified as premature ventricular contractions (PVCs) originating from the lower chambers of the heart, or premature atrial contractions (PACs) originating from the upper chambers.

The ECG recordings that were identified as having additional heartbeats, along with some recordings that were not deemed to contain extra beats, were thoroughly evaluated by two specialists to validate the classification. The study's researchers discovered that after accounting for variables such as age and medication use, an additional beat originating from the lower chambers of the heart resulted in a twofold increase in the risk of future heart failure. Similarly, an extra beat emanating from the upper chambers (atria) was linked to a twofold increase in cases of atrial fibrillation.

“Our study suggests that ECGs from consumer-grade wearable devices may help with detecting and preventing future heart disease,” said lead author Dr. Michele Orini (UCL Institute of Cardiovascular Science). “The next step is to investigate how screening people using wearables might best work in practice. Such screening could potentially be combined with the use of artificial intelligence and other computer tools to quickly identify the ECGs indicating higher risk, as we did in our study, leading to a more accurate assessment of risk in the population and helping to reduce the burden of these diseases.” 

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