San Francisco-based iRhythm submitted two updates to the mobile cardiac telemetry device following an FDA warning letter last year. The letter, made public shortly after the company’s announcement, accused iRhythm of violations related to rules for labeling, quality systems and medical device reporting. The FDA said that, in at least two cases, iRhythm did not report patient deaths in the required 30-day window, and instead reported them the following year.

iRhythm received the first FDA clearance for design changes made to Zio AT last week. The system remains available to ship in the U.S. and the company plans to make the product enhancements cleared by the FDA available in 2025.