We are getting closer to the day when a smartphone app can detect atrial fibrillation in patients at high risk of a stroke or heart failure.

Researchers at Worcester Polytechnic Institute in Worcester, Mass., have submitted an application to the Food and Drug Administration for 510(k) approval of an Android app that can pick up subtle changes in skin color by scanning blood vessels, thanks to an algorithm developed at the school.

The yet-unnamed app measures heart rate, heart rhythm, respiration rate and, with the help of an external pulse oximeter, blood oxygen saturation, by scanning the patient's index finger for about a minute in front of the phone's video camera. A color bar on the screen turns red if the heartbeat is irregular, indicating possible atrial fibrillation.

"AFib is so common, but many people have no symptoms, or subtle symptoms like getting winded. This tool will be very helpful because AFib is so hard and expensive to diagnose," cardiologist Dr. David D. McManus of UMass Memorial Medical Center tells the Worcester Telegram & Gazette.

UMass Memorial clinicians tested the app on about 60 AFib patients, using Motorola Droid phones. Readings on the phone were just as accurate as those taken with traditional electrocardiograms. The WPI researchers published some of their findings last year in the journal IEEE Transactions on Biomedical Engineering. That article discussed some of the limitations of using a smartphone in place of an ECG, but also listed many of the positives.

"One of the advantages of mobile phone monitoring is that it allows patients to make baseline measurements at any time, building a database of normal cardiac function that could allow for improved detection of disease states," the WPI team wrote. "Current mobile phone technology extends beyond simply monitoring and measuring with ease for a patient; it could also be used to relay the information to medical professionals. This gives a patient the ability to carry an accurate physiological monitor anywhere, without additional hardware beyond what's already included in many consumer mobile phones."

However, McManus is not sure if the app would be sold directly to the public. He tells the Telegram & Gazette that there may be a market it among payer-supported preventive health and wellness programs. "It’s not intended to replace EKGs or doctor visits, but it’s a valuable piece of information," McManus adds.

The app should be available for Android and Apple's iPhone in three to six months, depending on FDA review, of course. While WPI engineers are said to be working on an iPad version, the iPad camera has a different kind of light source that it not compatible with the current smartphone software, according to the Worcester newspaper.