iRhythm Technologies (NSDQ:IRTC) posted a classic beat-and-raise first quarter yesterday, topping the consensus forecasts on Wall Street and boosting its top-line outlook on the rest of the year.

The San Francisco-based wearable heart monitor maker cut its losses by -27.9% to -$8.0 million, or -33¢ per share, on sales growth of 54.5% to $47.2 million for the three months ended March 31, compared with Q1 2018.

Analysts on The Street were looking for losses-per-share of -48¢ on sales of $43.8 million.

“We are off to a great start in 2019 with strong first quarter revenue growth and continued gross margin improvement,” CEO Kevin King said in prepared remarks. “Our business continues to strengthen on all fronts. Zio’s proven clinical superiority, the completeness of our service, combined with the broad strength of our sales and support organization continues to create meaningful value for our customers both large and small. I am confident that the opportunities arising from the expansion of our market through our clinical research efforts along with the expected full commercial launch of ZioAT in the second half of this year position us for continued success in the near and long-term.”

iRhythm said it now expects to report full-year sales of $206 million to $211 million, up from $201 million to $206 million previously, and that it plans to increase its salesforce by as much as 25%, to 130 to 140 workers. Of 748 full-time employees as of Dec. 31, 2018, 112 were full-time-equivalent sales representatives.

IRTC shares were up 0.7% to $75.15 apiece today in mid-afternoon trading.