AliveCor’s KardiaBand has become the first medical device accessory for the Apple Watch, after being approved by the US' Food and Drug Administration (FDA). The KardiaBand is an electrocardiogram (EKG) reader, which means it can check heart rhythm and irregular heartbeat. The latter is medically known as atrial fibrillation, and can increase the risk of stroke and heart disease.

To use it, Apple Watch owners must replace their existing wrist band with the KardiaBand, and then press their thumb on the sensor for 30 seconds. The results are then available on the watch itself, and in its iPhone app, which can also be sent to your doctor, since the data is considered medical-grade (that's what an FDA certification brings).

Thanks to AI and neural networks, AliveCor can also predict and analyse someone's heart rate based on their history, and existing data from both healthy and sick people, according to Bloomberg. While the KardiaBand is far from the first portable EKG reader, it can better help since it can detect when your heart rate spikes in an abnormal fashion.

And while the Apple Watch is capable of recording those, it's not FDA-approved as Apple is worried about obtaining clearances on time. For instance, AliveCor spent over two years to have the KardiaBand approved by the US agency.

“Apple might be able to say ‘oh your heart rate is high’ …but what does that mean? Does that mean you should go to the hospital? And if you go to the hospital what are they going to do? Any doctor will say ‘ok come in, let’s get an EKG reading’,” AliveCor CEO Vic Gundotra told TechCrunch. “It’s not possible to diagnose atrial fibrillation without FDA clearance. That is a big, big play.”

For what it's worth, Apple has announced its own medical study for irregular heart rate, in collaboration with the Stanford University School of Medicine. It aims to use the data it acquires from Apple Watch volunteers, to help build future research.

Atrial fibrillation can affect one in four adults over the age of 40, making the KardiaBand a useful device for adults. EKG readers are expensive though, and AliveCor's device is no exception: the KardiaBand costs $199 (about Rs. 12,840), and you'll also need the AliveCor $99 (about Rs. 6,390) annual service. All of that is in addition to an Apple Watch.