The majority of these devices are targeted to fitness junkies, who track their heart rate from the wrist as an alternative to a bulky chest strap. Many of these companies use terms like "optimizing performance" to describe their gadgets.
But can these devices support the millions of people who suffer from heart disease? Some 610,000 people die of heart disease in the United States every year, which accounts for one in four deaths.
What's preventing these companies from targeting their products to the sick? Could heart rate monitors eventually be used to alert people about potentially-fatal outcomes?
To answer these questions and more, KQED sat down with Euan Thomson, a health-technology investor, trained medical physicist and the chief executive of AliveCor, maker of the first device to win regulatory approval in the U.S. to detect a serious heart condition from electrocardiogram (ECG) readings via a mobile device. This interview has been edited for brevity.
We've seen a lot of hype around heart rate monitoring. Where are we with understanding how to measure heart health?
Today, we know very little about heart performance. Most of the measurements we take are under specific circumstances, like when your doctor takes your blood pressure. I'm hoping that we'll start measuring changes in someone's heart performance as well as the context of what they're doing: Did they sleep poorly, drink coffee, or gain some weight? When we start to gather this kind of longitudinal data, that will have an impact on how we treat heart disease in the long-term.
The way we treat heart disease today is akin to pulling everyone off the road because we know that traffic accidents kill a proportion of people.
What are the metrics that we should be measuring to better understand heart health?
We know that it's important to look at metrics like blood pressure, weight, sleep patterns, stress levels and alcohol consumption. The problem is that we know there are a lot of things that are generally bad for the heart, but that's very unspecific.
Ideally, we'll start measuring the ECG [the process of recording the electrical activity of the heart] three or four times a day; continuously track blood pressure, and compare that data to daily habits like diet and stress.
Many of the current heart rate monitors are worn on the wrist. What's the best part of the body for tracking the heart?
Chest straps are known to be less prone to noise, especially if you're running around a lot and moving your hands. But it's less comfortable on the chest. I think we have a lot of work to do to marry both comfort and accuracy.
Can wearable devices like the Apple Watch help to improve our clinical knowledge?
These devices are not intended for medical uses. None of these wearable tech companies that track heart rate are cleared by the FDA to give medical guidance. You wouldn't use them to find patterns that might be specific indicators of potentially-fatal abnormalities.
For example, if you just look at heart rate patterns using one of these monitors -- without the ECG -- you wouldn't know what's indicative of something being medically wrong, or whether it's because you've vigorously exercised, for instance.
So why bother using one of these heart rate monitors?
From a fitness standpoint, you may see that you've lowered your resting heart rate by exercising regularly. Heart rate is a wellness metric that I'd put in the same category of step-tracking.It's kind of useful for fitness, but it isn't a health care indicator.
There's been some talk of using heart rate monitors, like the Apple Watch, to assist patients with their rehab after heart surgeries. Is that a viable option?
I see huge potential for this approach. If someone is recovering from heart surgery, they are often enrolled in a rehab program, which involves steadily increasing exercise under controlled conditions. Their ECG is also observed while they're walking or jogging on the treadmill.
I could envision a program that uses smartwatches for remote monitoring, so patients don't need to go to a rehab facility. Their doctor could say something like, 'I want to measure your heart rate while you take 2,000 steps over the next few weeks. Then I want to increase your exercise to 6,000 steps. I don't want your heart rate going above 80 beats per minute.'
We don't have any specific guidance like this to give to patients at the moment. But we could come up with something over time. I could see that having a major positive impact because so few people actually finish their rehab. It's often very inconvenient for them.
Would smartwatch makers need to prove to regulators and doctors that the data is accurate?
The program itself probably would need regulatory approval. We could probably get away without regulating the devices themselves, but the companies would need to invest in clinical studies to show the heart rate and steps data they gather is accurate.
The wearable tech-makers with adequate cash should invest in the health care process. I've noticed a certain unwillingness. Many companies are opting instead to give these semi-meaningless metrics to people that give little more than high-level guidance.
So heart rate monitoring isn't regulated, but ECG-tracking is? Why is that?
ECGs are a regulated biometric as they are specialized, meaning most people can't look at them and detect abnormalities. If you want to display that data, you need to talk to the FDA. Unfortunately, not everyone wants to take on the job.
When it comes to regulation, it is more about the claims that companies make, rather than the device itself. When the company markets its heart rate monitor as the latest fitness gadget, it's not regulated. That's why you saw dozens of these low-cost performance monitors at the most recent Consumer Electronics Show.
It's a very small club that is monitoring the ECG. But that is the way these other companies should go. I hope Silicon Valley doesn't spend millions of dollars developing devices that aren't medically relevant. The amount of money being spent on useless metrics from a health care standpoint is stunning.
We are on the brink here of something very exciting. We have so much data, which would be useful when combined with the performance of the heart. We have the capability to understand for the first time how the heart actually works.
Can you provide any examples of how we might be able to intervene in the future?
We could send an alert to someone who is soon to have a stroke or heart attack if we do enough measurements of an ECG and we gather other data points about that person.
At my company, AliveCor, we are working to deskill the process of determining characteristics of Arrhythmia [an irregular heart beat]. On our app today, we have an FDA-approved algorithm that can detect the presence of Atrial fibrillation [an irregular, often rapid heart rate that can cause poor blood flow]. We are also logging the context around it: How is it linked to coffee consumption or stress?
In the next few years, I believe that the industry will be able to spot the characteristics of someone who's likely to have a heart attack in the next three days.
Ford recently put the brakes on a project to embed heart rate sensors in car seats. How pervasive do you think heart rate monitoring will be in our daily lives?
I think we are moving into an era where there will be a huge diversity of sensors. I am sure we'll have heart rate sensors, maybe ECGs, built into steering wheels of our cars in the future. And 'smart clothing' to track a variety of biometrics is already in existence.
The key is what people do with that data. There needs to be more focus on making it medically relevant, cool and appealing to people. I bet you'd be interested to learn, for instance, that a new job is prompting far more stress and a skyrocketing blood pressure.
Life insurer John Hancock recently announced that it will give discounts on its insurance to healthy people that track their steps using Fitbits, which raised the alarm from a privacy perspective. Should we be concerned about this data getting into the wrong hands?
Right now, many employers offer incentives to people who give up smoking. There's no reason why they shouldn't be more involved with specific measurements about our heart health -- and I suspect they will be.
That said, these measured biometrics belong to us and we should have a say about where the data goes. The key is that people shouldn't be forced to share this data, it should only be on a voluntary basis. If someone is generally fit and has a healthy lifestyle, they may wish to share this data to get a discount. But if people are penalized for unhealthy lifestyles, that's clearly taking it too far.