First-quarter net losses for NMT Medical Inc. (NSDQ:NMTI) more than doubled on a write-down of warrants the company issued in February as part of a $5.8 million private placement.

The Boston-based cardiac implant maker posted net losses of $7.9 million, or 54 cents per share, during the three months ended March 31, compared with net losses of $3.8 million, or 29 cents per share, during the same period last year.

Absent that $4.7 million pre-tax charge, however, operating losses narrowed to $3.2 million, or 22 cents per share, compared with $3.8 million, or 29 cents per share, during Q1 2009. NMT posted sales of $3.0 million for the quarter, down 13.9 percent from $3.5 million during the year-ago quarter.

President and CEO Frank Martin said the global recession slowed sales, adding that the company believes "the growing anticipation in the medical community" for the results of NMT‘s Closure I clinical trial may be slowing referrals.

The study is examining whether the company’s StarFlex implant, used in a the catheter-based procedure to patch small holes between chambers of the heart, is more effective than standard drug treatments in preventing the re-occurrence of stroke. A portion of NMT’s $5.8 million private placement was used to fund the study, which is now in the data analysis phase, Martin said in prepared remarks. The trial will be complete this fall; if the results are positive the company plans to apply for pre-market approval from the Food & Drug Administration during the third quarter, he said.

COO Rick Davis said the company expects 2010 sales to "increase modestly" over 2009, pending results of the Closure I trial.