St. Paul-based Cardiovascular Systems, Inc., on Wednesday posted a 20 percent increase in first-quarter revenue and an improved net loss, beating analyst estimates.

Net loss for the quarter that ended September 30 totaled $4.3 million, or 28 cents per share, a 31 percent improvement over last year's first-quarter net loss of $6.2 million, or 43 cents per share.

Analysts polled by Thomson Reuters expected the company to post a loss of 35 cents per share.

First-quarter revenue increased 20 percent to $18.2 million from $15.2 million in the same period last year.

Revenue generated from customer reorders accounted for 95 percent of the company's total first-quarter revenue, up from 92 percent in last year's first quarter.

Operating expenses increased 2 percent to $17.9 million, largely due to $500,000 of net expenses related to a legal settlement with Ev3, Inc.

For the company's second quarter, which ends December 31, revenue is expected to range from $18.5 million to $19.5 million, which represents a growth of 23 percent to 29 percent over last year's second quarter. Net loss for the second quarter is expected to be between $2.7 million, or 17 cents per share, to $3.3 million, or 21 cents per share.

Shares of the company's stock were up 5 percent to $6.41 in Thursday morning trading.

Cardiovascular Systems, which develops and commercializes interventional treatment systems for vascular disease, is among Minnesota's 90-largest public companies based on revenue, which totaled $64.8 million in its most recent fiscal year, which ended in June.