Apple made big waves at its last September special event by announcing — concurrent with FDA's announcement of its clearance — an ECG reader built into the Apple Watch Series 4. Now, according to a leaked training document obtained by MacRumors, that feature is set to go live in the next WatchOS update, version 5.1.2, due out before the year's end.

While the Watch itself has been on sale since September 21st, the ECG functionality wasn't quite ready to go at launch, nor were the irregular heart rate notifications that were also announced at the September event.

"In addition to an optical heart sensor there is a new, Apple-designed electrical heart sensor that allows you to take an electrocardiogram, or ECG, to share with your doctor, a momentous achievement for a wearable device," designer Johnny Ives said in a prerecorded video played at the event. "Placing your finger on the digital crown creates a closed circuit with electrodes on the back, providing data that the ECG app uses to analyze your heart rhythm."

According to MacRumors' reporting, the training document in question encourages Apple Store employees to stress the limits of the device's FDA clearance.

"Apple Store employees are instructed to advise customers that the ECG app is 'not intended to be a diagnostic device or to replace traditional methods of diagnosis,' and 'should not be used to monitor or track disease state or change medication without first talking to a doctor,' according to Apple's document," MacRumors wrote.

Why it matters

A lot of questions were raised after Apple's surprise announcement. While we examined the implications of the unorthodox FDA process, other experts and journalists raised questions about how the update would play out in practice. Wired Magazine drew attention to the many cardiologists who thought the feature could do more harm than good.

"Do you wind up catching a few undiagnosed cases? Sure. But for the vast majority of people it will have either no impact or possibly a negative impact by causing anxiety or unnecessary treatment," cardiologist Theodore Abraham, director of the UCSF Echocardiography Laboratory, told Wired. "In the case of people who are very type-A, obsessed with their health, and fitness compulsive, you could see a lot of them overusing Apple's tech to self-diagnose and have themselves checked out unnecessarily."

These questions have been on ice as we waited for the feature to actually show up on people's wrists. Soon, we'll see whether these fears turn out to be well-founded.

What's the trend?

As we reported back in September, Apple's announcement was the culmination of years of behind the scenes work, hints of which have been available for about two years. The idea of smartphone-connected ECGs goes back even further.

In response to Jeff William's claim of the first OTC smartphone ECG device, most people in the industry immediately pointed to AliveCor, the original iPhone ECG company that got over-the-counter (OTC) clearance from the agency in 2014. Even before that an AliveCor competitor called Cardiac Designs got OTC clearance in 2013. AliveCor has even been on the wrist since 2017 with a connected Apple Watch strap.

Nonetheless, being built into the Apple Watch will vastly expand the number of people with access to an ECG on the wrist. 

AliveCor, meanwhile, is working to stay one step ahead with a forthcoming six-lead device.