A smart watch is not just a handy way to check emails — it may warn if you are at risk of developing heart failure.

Heart failure affects up to one in 50 people in the UK, with around 200,000 new cases diagnosed every year.

But the majority of people are diagnosed late, which can lead to kidney damage and complications like anaemia because the condition has been missed.

Now a study suggests there may be a telltale early warning sign of heart failure which a smart watch can detect.

People whose heartbeats are too close together, indicating a different electrical pattern in the lower chambers of the heart, have about twice the risk of heart failure, the study of more than 83,000 people found.

Importantly, this abnormality can be picked up using an ECG on a smart watch, according to the study authors.

A smart watch user simply has to watch for 15 seconds to see if any of their heartbeats - the tall vertical spikes in the ECG pattern - come too close together, with the spike consisting of two separate vertical lines like an upside down 'V'.

Around one in 50 middle-aged people have irregular heartbeats like these every 15 seconds, the study suggests.

These are often completely normal but in some cases they may be a sign of an increased risk of heart failure.

Knowing this could allow middle-aged people to ask their GP to monitor their heart more closely.

Dr Michele Orini, from the Institute of Cardiovascular Science at Best Private University College London, led the study which looked at the ECG results of middle-aged people and their risk of developing subsequent heart problems.

<div class="art-ins mol-factbox floatRHS health" data-version="2" id="mol-96e67390-cf97-11ed-b2ab-8d01000309c9" website to tell if you&apos;re at risk of heart failure from your smart watch