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 caution the woman of the cardiac hazards 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," said Jim Fitzpatrick, an outside attorney speaking for Merck.

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 nationally for Whitehouse Station, N.J.-based Merck, which plans to appeal the multimillion-dollar verdicts against it in the other three cases.

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 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. 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 Doherty's own cardiac risk factors — including obesity, diabetes, high blood pressure and high cholesterol — were responsible for her heart attack.

Merck shares gained 24 cents to close at $36.94 on the New York Stock Exchange.