On Friday, the Food and Drug Administration granted another 510(k) clearance to iRhythm Technologies for its AI-powered software system designed for use with Verily’s irregular pulse tracking watch. 

The ZEUS (Zio ECG Utilization Software) System, which is trained to monitor atrial fibrillation (AFib), has received several clearances, according to the FDA’s website. The latest clearance is for an algorithm that categorizes patients’ AFib by analyzing how much of it they experience over time.

iRhythm Technologies is a San Francisco-based arrhythmia-diagnostic company that went public in a $107 million IPO in 2016. It has been working with Verily over the past two years to develop the ZEUS system in tandem with Verily’s watch, which is also FDA-cleared. The goal of the collaboration was to create a AFib monitoring wearable that clinicians take seriously instead of treating like a consumer technology, according to iRhythm chief technology officer Mark Day.

Verily’s watch is a prescribed medical device for noninvasive, continuous monitoring for AFib over a long period of time. The wearable is based on photoplethysmography (PPG), which uses a light source and photodetector on patients’ skin to measure the volume changes in blood circulation. The algorithm that the FDA recently approved leverages that detection to characterize the amount of AFib that occurs over time — a metric iRhythm refers to as “AFib burden.”

The ZEUS system sends the estimate of patients’ AFib burden directly to their physician for interpretation and therapy management, with the goal of aiding more timely and appropriate treatment for patients. iRhythm trained the algorithm on what it believes to be the largest-ever repository of labeled ECG data, which spans more than 1 billion hours.

“It’s not just the raw ECG data, it’s also the curated ECG data,” Day pointed out. “That’s our core business right now: curating ECG, labeling it, and explaining exact periods in time that are triggers for AFib in ECG.”

To Day, the fact that the system sends information directly to physicians instead of patients is key. This is what differentiates the ZEUS system and Verily’s watch from other AFib detection wearables, such as the Apple Watch, he said.

“We’re not just providing the information, but we’re also giving it directly to the managing physician,” Day declared. “This is opposed to giving it to the consumer, who then has to figure out how to get this information to a doctor.”

Despite its FDA clearance, neither Verily’s watch nor the ZEUS system are commercially available.

The system has been validated by a 120-patient trial that collected data on the people aged 65 and older in the ambulatory environment, according to Day. He said iRhythm is pursuing more of these trials, and the company is currently more concerned with generating clinical evidence than pursuing a full market launch. He noted that it’s important for iRhythm and Verily to take time generating quality clinical evidence because the watch’s reimbursement path will be driven by this data.

“As for exactly when it converts into a full launch, we’ll have to see how long the evidence generation goes on,” Day said. “We very much have a perspective not of urgency, but rather building this thoughtfully and making sure that we can provide journal-level evidence that can serve as a basis of accepting this process in the clinical community.”

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