Regulatory experts say that it won't be easy to convince the FDA.

Apple is working with Stanford to study whether its Apple Watch can detect a heart rhythm disorder called atrial fibrillation.

Apple CEO Tim Cook speaks about the Apple Watch during an Apple special event at the Apple headquarters on March 21, 2016 in Cupertino, California. Justin Sullivan | Getty Images

Apple is moving ahead with a plan to screen for disease with its Apple Watch, starting with a clinical study. Earlier this month, the company announced it is partnering with clinicians at Stanford to assess whether the smartwatch's heart rate monitor can accurately pick up on an abnormal heart rhythm called atrial fibrillation. That health condition, associated with blood clots and strokes, can be treated if detected. One study might not seem like a big deal. But if the results are promising enough, it points to a future where Apple tweaks its product to screen users for potentially fatal outcomes. But some major challenges remain before Apple can get there. CNBC spoke to doctors and regulatory experts who are trying to figure out how to help users and help Apple sell more watches, without generating anxiety and adding cost to the already overburdened health-care system.

Challenges ahead

Apple hasn't spoken out about its reasons for conducting the study. But COO Jeff Williams did showcase some user stories where Apple Watch indicated a potential health problem before it was too late — and potentially saved lives. Other tech companies, like AliveCor and Cardiogram, have already commissioned studies that demonstrate high accuracy rates for using Apple Watch's heart rate monitor to detect atrial fibrillation compared to traditional hospital tests. But as is always the case with medicine, it's not as simple as it sounds. For starters, screening a general population with a wearable carries with it a high rate of false positives. For that reason, many health associations recommend screening seniors or people who have already had a stroke. "Otherwise, for every 20-year-old football player whose life we save, there are a 150 or more who go to the doctor and spend money for no reason," said Dr. Dave Albert, a cardiologist and co-founder of AliveCor, a mobile medical device that diagnoses problems with the electrical activity of the heart. And most insurance companies are not willing to bear the cost. A potentially more concerning outcome is the opposite: false negatives. Getting it wrong means that a user who does have a problem gets a false sense of security and avoids going to the doctor.

Targeting at-risk groups

For that reason, most of the cardiologists CNBC spoke with expect Apple to target high-risk groups. That might be a strategy shift for a consumer products giant, which has typically tried to get the broadest audience possible. But some analysts agree the company might make an exception and go narrow when it comes to health. CNBC reported earlier this year that it has a team working on noninvasive glucose monitoring, for instance, which is primarily a benefit for those with diabetes. "Most of what we see Apple doing is very broad, and on the health side, it has been tied to fitness," said Tim Bajarin, an analyst with the firm Creative Strategies. "But I don't think that specific audiences is out of the realm of possibility for them." Moreover, the company currently has a partnership with Aetna insurance company, which is looking to subsidize the cost of the watch for its members. Developing a screening tool for a targeted population might help Apple forge similar partnerships with other insurers, particularly those who cater to older populations and are looking for ways to prevent their members from getting serious and expensive health problems.

FDA hurdles