Updated from April 5Boston Scientific ( BSX) shares rose Tuesday after the company late Monday said that early sales of its Taxus drug-coated stent for heart disease patients have exceeded expectations. The Natick, Mass.-based company said after the bell that the stent -- which is inserted into arteries to facilitate blood flow and reduce the risk of arterial clogging -- produced $98 million in U.S. sales between March 8 and March 31, according to preliminary results. Official results will be published in two weeks when the company issues its financial report for the quarter ended March 31. Shares rose 54 cents, or 1.2%, to $46.35 in premarket trading. Boston Scientific had predicted in late February that U.S. Taxus sales would be between $54 million and $75 million for the period March 1 to March 31. But the Food and Drug Administrationslightly delayed the company's plans because the agency approved the device on March 4. Taxus is the second drug-coated stent to reach the U.S. market. The Cypher stent, made by the Cordis unit of Johnson & Johnson ( JNJ), has been sold here for nearly 12 months. Both stents are sold in many foreign markets. Several other companies are developing drug-coated stents; but their clinical tests are continuing and their products probably won't reach the market for perhaps two years or more. Analysts predict Cypher, Taxus and the other products -- also known as drug-eluting stents -- will render the existing bare metal stents a niche product in a few years. Bare metal stents have been available in the U.S. market for 10 years. They are inserted into arteries following angioplasty, a procedure by which doctors clear plaque and other deposits from arteries. The bare metal stent is a wire mesh tube which reduces the risk of arteries reclogging after angioplasty. But drug-eluting stents, which enable a drug to be released periodically into the artery, do a better job of reducing the reclogging risk than do bare metal stents.