ATLANTIC CITY, N.J. — Merck & Co. won a crucial legal victory yesterday, when jurors decided that the drugmaker’s Vioxx painkiller, now the subject of at least 16,000 product liability lawsuits, did not cause a 68-year-old woman’s heart attack.

The case was the first in which jurors considered whether Merck failed to warn patients about the drug’s cardiac risks, rather than just doctors as in prior trials.

The jury found that Merck properly warned doctors but did not warn the woman of the cardiac risks of the drug. The jury of five men and two women found that Vioxx was not a major factor in Elaine Doherty’s 2004 heart attack, however.

Merck will not have to pay compensatory or punitive damages in the case. The jury also found that Merck did not violate New Jersey’s consumer fraud law, meaning it met standards of honesty and good faith in its marketing of Vioxx and did not conceal information about the drug’s cardiovascular risks.

“Obviously, we’re extremely happy with the verdict,” an outside attorney speaking for Merck, Jim Fitzpatrick, said.

“This is the fourth case to go to verdict in New Jersey and on three out of four cases, the jury has found in Merck’s favor on the product liability claim,” Mr. Fitzpatrick added. “This really reinforces our strategy of defending (lawsuits) individually.”

The jurors, sitting in state Superior Court in Atlantic County, reached their decision after deliberating for 9 1/2 hours over two days. The victory was the fourth in seven Vioxx trials for Whitehouse Station, N.J.-based Merck, which plans to appeal the multimilliondollar verdicts against it in the other three cases.

Ms. Doherty’s husband, Daniel, clutched his wife’s hand as they rose before the verdict was read. Afterward, the couple spoke quietly with their attorneys but did not comment as they left the courtroom.

Lawyers for Ms. Doherty, a grandmother of six from Lawrenceville, N.J., alleged during the 5 1/2-week trial that Vioxx was a major cause of her heart attack and that Merck downplayed the risks of Vioxx both to doctors and to patients. Ms. Doherty, the first female Vioxx user whose case came to trial, had taken Vioxx for 2 1/2 years for arthritis before suffering a mild heart attack in January 2004.

Merck lawyers countered that company officials disclosed the drug’s risks appropriately and that Ms. Doherty’s own cardiac risk factors — including obesity, diabetes, high blood pressure and high cholesterol — were responsible for her heart attack.

In a 5–2 vote, a majority of the jurors agreed.

“Some of us believed that Vioxx truly hurt her and the rest didn’t,” juror Joseph Calabrese said afterward.

“It was another risk factor. I balanced it the same” as Ms. Doherty’s heart problems, said Richard Ozmore, one of the two jurors who voted that Vioxx was a substantial cause of the woman’s heart attack.

Mr. Calabrese described Ms. Doherty’s cardiac risk factors, which included severely blocked arteries, as “insurmountable” for the jury, and said a plaque rupture, not Vioxx, was likely the heart attack’s cause.

Gene Locks, head of the law firm representing Ms. Doherty, called the jury’s unanimous finding that Merck didn’t warn consumers a “major precedential victory in favor of plaintiffs,” although it resulted in no damage award in this case.

Merck’s lead attorney, Diane Sullivan, who successfully defended the company in both Ms.Doherty’s case and another New Jersey suit last fall, said having a jury decide whether a patient — not just a physician — was warned about such side effects was unprecedented. She said her team was surprised the judge made it part of the jury’s instructions, and would argue against including it in future Vioxx cases — even though she said consumers were adequately warned.

“Had we had notice this was going to be part of the case, we would have put on a defense to it,” Ms. Sullivan said. “The duty to warn … is really to the physician.You can’t get Vioxx at the supermarket.”

At its peak, Vioxx was a $2.5 billion-a-year blockbuster for Merck. It withdrew Vioxx from the market on Sept. 30, 2004, saying research showed it doubled the risk of heart attack and stroke after 18 months’ use. Data released since then indicate the heart risks started much sooner and persisted at least a year after people stopped taking Vioxx, although Merck has disputed that.

Merck has vowed to fight each Vioxx lawsuit individually and has set aside $970 million in reserve for its legal costs, of which $285 million had been spent as of the end of 2005.

Merck shares fell 4 cents to $36.66 in afternoon trading on the New York Stock Exchange.