iRhythm Technologies (Nasdaq:IRTC) shares took a hit after hours today on mixed third-quarter results that compared to the consensus forecast.

Shares of IRTC nosedived 17.1% to $105.09 apiece after the market closed. MassDevice’s MedTech 100 Index — which includes stocks of the world’s largest medical device companies — finished the day up 2.1%. (UPDATE: After markets opened, IRTC shares were trading around $117 by mid-day, down about 7%. This may relate to a positive CMS ruling announced today.)

The San Francisco-based developer of wearable heart monitors posted losses of $21.5 million for the quarter. That comes to 71¢ per share on sales of $103.9 million for the three months ended Sept. 30, 2022.

iRhythm recorded a 9.2% bottom-line gain while remaining in the red on sales growth of 21.6%. Staffing and capacity challenges contributed to the company’s results.

Adjusted to exclude one-time items, losses per share totaled 63¢. That comes in 20¢ ahead of expectations on Wall Street. iRhythm failed to beat The Street on sales as analysts projected $106.1 million, though.

“Despite the ongoing staffing and capacity challenges, we grew registration volumes by more than 20% in the third quarter, achieving our highest daily registration volumes ever as we exited September,” iRhythm CEO and president Quentin Blackford said in a news release. “However, within the quarter, we also realized softness in returned devices — which impacted our ability to perform our services and realize revenue which muted our growth. We view this as persisting into the fourth quarter. These dynamics, as well as fourth-quarter trends in account staffing and capacity challenges as well as Zio AT utilization, have led to us reducing our full-year revenue guidance.”

iRhythm previously set its annual revenue guidance for between $415 million and $420 million. However, its updated guidance projects a reduced range between $407 million and $411 million.