Shares of Edwards Lifesciences Corp. (NYSE:EW) were off by nearly 4 percent on Wall Street, despite a favorable FDA panel vote that should clear the way for the company to launch the Sapien transcatheter heart valve in the U.S.

Nine members of the FDA’s circulatory system devices advisory panel said the benefits of the Sapien transcatheter heart valve outweighed the risks, with one member of the committee abstaining. The panel vote means EW could win pre-market approval for the device as soon as the end of the summer (the FDA is not bound by its advisory panels’ recommendations, but usually follows their guidance).

“We are pleased with the panel’s strong recommendation for approval, and would like to thank them for their comprehensive and thoughtful review of the data presented from The PARTNER Trial. This represents another important step on the path to what we hope will lead to FDA approval of SAPIEN,” Michael Mussallem, Edwards’ chairman & CEO said in a prepared release.

The Street, however, seems unimpressed by the positive regulatory news of one of its favorite company’s. EW shares were down nearly 4 percent through mid-day trading to $84.15. The selloff is relatively surprising, considering that shares of Edwards have been on a hot streak for more than a year now, jumping nearly 60 percent since July 21, 2010.

Edwards will release Q2 2011 earnings results late this afternoon. Analysts on Wall Street expect the company to post a 50 cents per share profit on about $425 million in sales.

In documents released ahead of yesterday’s panel hearing, FDA reviewers said Sapien “substantially increases survival and improves patient function beginning at 30 days and thereafter, compared to best medical management” for patients suffering from aortic stenosis who are not candidates for conventional open-heart aortic valve replacement surgery.

Although the device performed well in clinical trials, the reviewers highlighted data showing that patients receiving the heart valve suffered a higher rate of stroke than the current standard of care. In clinical trials, incidents of neurologic events, including strokes, essentially doubled after 30 days and one year. In addition, the reviewers noted that patients who received transcatheter valve replacement had “more frequent vascular complications.”

Still, they wrote, the device’s benefits outweigh its risks.

Edwards, ranked 46th in the MassDevice Big 100 list of the world’s largest medical device makers, filed its PMA application in October 2010 and has staked its flag on an October 2011 release, sinking about $40 million into a launch that Mussallem said will allow the company to compete in 200 to 400 medical centers in the U.S. The Sapien heart valve is cleared for sale in 27 EU countries and in other countries that recognize the CE Mark.

Edwards now appears on track to have a healthy head start on rival Medtronic Inc. (NYSE:MDT) and its CoreValve system in the robust replacement heart valve market.

The companies have duked it out in court and the EU for more than four years. That market may be peanuts compared to the U.S., however, at least according to some estimates. About 100,000 U.S. patients mdash; roughly a third of the global market mdash; are candidates for the therapy, which involves replacing the diseased aortic valve with an implant inserted via catheter, rather than with open heart surgery.