Medical device maker Boston Scientific expects to sign a definitive agreement to acquire Guidant by the middle of the month, wresting the company from rival suitor Johnson & Johnson.

Boston Scientific also announced that Chief Executive Jim Tobin will stay in the post for another few years, laying to rest speculation that the 61-year-old could be planning to retire.

Both companies are hoping to win Guidant, the world's second-largest maker of implantable cardioverter defibrillators, and gain a stake in this fast-growing product segment. And Guidant is set to launch a range of cardiac rhythm management (CRM) systems, including wireless versions, which are tipped to be potential big sellers in a market currently valued at $10 billion.

Last week, Guidant recommended that its shareholders approve the offer by J&J at a meeting on January 31, although this is seen as a procedural matter that does not indicate that the firm is favouring the bid. Analysts suggested that Guidant is keeping both companies in the frame to make sure it receives fair value for the business, but Boston Scientific will be keen to have an offer agreed before this vote takes place.

Guidant suffered a string of bad news at the end of 2005, after it said fourth-quarter profit would not meet expectations because of a massive recall of ICDs last summer, while announcing 18 additional cases in which the devices had failed. It also said the US Food and Drug Administration found compliance problems at one of its manufacturing plants and could take regulatory action.

J&J offered to buy Guidant for $25.4 billion last year, but agreed a lower offer of around $21.5 billion with Guidant in November in the wake of the ICD recall. Boston Scientific then trumped this bid with its own $25 billion offer in early December.