Washington-based Steth IO launched a new feature to its smartphone-based stethoscope application. Now, it uses an artificial intelligence to assist doctors in analyzing heart sounds.

“We want to reduce the number of heart related deaths,” Steth IO CEO Vikram Chalana said in a press release, according to Geek Wire. “The AI app release is a key milestone in our journey to update one of the oldest, most widely used and iconic tools in medicine. We believe that our stethoscope is the most practical way to screen patients for valve disease at scale.”

The smartphone attachment and app lets doctors listen to, see, and record patients’ heart sound waves on iPhones. The Steth IO team trained the AI tool by using recordings of patient heart sounds collected by doctors. The AI tool was built based on a type of machine learning called a convolution neural network. From this, Steth IO learned how to tell the difference between a normal heartbeat and one with a murmur.

The team tested Steth IO by having it analyze other recordings from doctors, and found it could accurately recognize abnormal heart sounds 73 percent of the time.

Although not a perfect record, Steth IO mentioned this percentage is much higher than the 20 percent accuracy of doctors who use an old-fashioned stethoscope.

Ultimately, the team said Steth IO is a supplement to a doctor, almost like a doctor’s assistant. The device allows doctors to get a solid ‘second opinion.’

Currently, the Steth IO smartphone attachment is only available for iPhones, and was launched in April. The attachment costs $229, and the app is free. Currently, the AI assistant is free of charge while it’s in beta testing.