Boston Scientific Corp. (BSX) issued on Tuesday second-quarter sales guidance for drug-coated stents that indicates improved world-wide sales from a year ago and potential growth from the first quarter.

The company, which beat its own coated-stent sales guidance for the first quarter, also set U.S. guidance targets that implied U.S. sales will move lower in the second quarter.

Additionally, Chief Financial Officer Samuel Leno issued second-quarter revenue targets for the company's implantable-defibrillator business while speaking on a conference call with analysts.

Coated stents are tiny scaffolds for clogged heart arteries that use medication to keep scar tissue from closing them off again. Boston Scientific sees its world-wide sales for the devices at $400 million to $440 million in the second quarter, Leno said. The forecasted range compares with the $382 million world-wide tally seen a year earlier, and it's mostly above the $445 million total just reported for the first-quarter.

In the U.S., Boston Scientific expects coated stent sales to range between $220 million and $240 million in the second quarter, Leno said. That would mark a big rise from a year ago, but it's below the $246 million in domestic sales posted in the first quarter.

Boston Scientific estimates its share of the roughly $2 billion U.S. coated-stent market improved to 50% in the first quarter, well ahead of Abbott Laboratories (ABT), Johnson & Johnson (JNJ) and Medtronic Inc. (MDT). But nearly half of Boston Scientific's market share comes from a device called Promus that is made by Abbott, and for which the companies share profits.

Leno noted that the profit contribution from Promus is half of the dollar contribution that Boston Scientific gets when it sells a home-grown Taxus stent.

"So the bad news is we have an adverse mix of Promus and Taxus compared to expectations year ago, but the good news that we have more total U.S. market share" than people outside the company expected, Leno said.

In the market for implantable cardioverter defibrillators, or ICDs, Leno said Boston Scientific anticipates world-wide sales will land in a $445 million to $480 million range in the second quarter, which implies gains from a year ago and the first quarter. U.S. sales are seen landing between $310 million and $330 million, which would be up from last year and is mostly above the first-quarter tally.

Boston Scientific competes with Medtronic and St. Jude Medical Inc. (STJ) in the market for ICDs, which shock hearts when needed to correct potentially deadly rhythm problems.

Boston Scientific shares were recently up a penny to $8.70.

-By Jon Kamp, Dow Jones Newswires; 617-654-6728; jon.kamp@dowjones.com