As a courtroom showdown loomed, Medtronic Inc. and rival Abbott Laboratories apparently decided to settle their 12-year legal battle over heart stent technology with a handshake, a press release and a check for $400 million.

When the dust settles, it will be Fridley-based Medtronic forking over the cash.

The agreement announced Monday covers about a dozen legal cases worldwide between Medtronic and Illinois-based Abbott over coronary stent and stent delivery technology. It closes a chapter in a long, tangled legal tale.

Introduced by drug giant Johnson & Johnson in 2004, the drug-coated stent has proven to be a blockbuster device. Of the four major players in the market (which includes the Maple Grove-based cardiovascular division of Boston Scientific Corp.), both Abbott and Medtronic were relatively late to the game.

Medtronic received regulatory approval of its Endeavor stent in February 2008, then Abbott followed with its Xience stent the following July. Now, Xience and an identical stent called Promus made by Boston Scientific control roughly half the market, and Medtronic is last in the pack, according to one analyst.

Today, these tiny mesh struts are part of a highly competitive $2 billion market in the United States treating coronary artery disease -- the nation's leading killer, affecting some 13 million Americans. So it's no surprise the device would spur some serious legal wrangling over intellectual property and patent rights.

"Research is the lifeblood of the med-tech industry,'' said Ralph Hall, a law professor at the University of Minnesota and former deputy counsel for Guidant Corp., a medical device company now part of Boston Scientific.

"Companies are reluctant to allow others to benefit for free from their research and development, and that's why there's patent litigation" he said. "You tend to see it focused in larger markets with more profitable products.''

While $400 million may seem enormous, other med-tech patent settlements have been far larger -- such as the $1.3 billion Medtronic paid to Los Angeles surgeon Dr. Gary Michelson in 2005 to settle a patent dispute over devices used in spine surgery.

The market barely blinked on Medtronic's announcement Monday -- the company's stock closed at $34.81, down 24 cents. "The stock didn't move, nobody cares,'' said Tim Nelson, an analyst with FAF Advisors in Minneapolis.

Many analysts don't even factor potential patent settlements into their financial models because they're so unpredictable and litigation often drags on for decades. In Monday's settlement, Medtronic said it will record a special charge in its first fiscal quarter to cover the settlement.

Perhaps the most interesting element of Monday's settlement is an agreement that the two companies will refrain from suing each other in the stent field for the next 10 years.

Hall sees this as a positive. "Ten years gives everyone a level of certainty and time to focus attention and resources on new products, innovation and research, rather than being consumed by patent litigation," he said.

Meanwhile, other devicemakers in the stent field will continue to duke it out in the courts; Abbott still faces a legal dispute with Johnson & Johnson.

Hall says the decision to settle is complex, but the prospect of a trial can be a motivator. The trial of one of the Medtronic-Abbott cases was slated to begin Monday in federal court in San Francisco.

"Patent trials are very difficult to try because they involve very complex factual and legal issues," Hall said. "There's always a risk to both sides going to a trial. You can't predict how a jury will react. It's not a science. There's a lot of uncertainty.''

Janet Moore • 612-673-7752