A New Jersey jury decided yesterday that Merck & Co. was not legally responsible for the heart attack suffered by an Idaho man taking the arthritis painkiller Vioxx -- concluding that the company had properly warned doctors of the drug's possible risks.

The victory followed an earlier loss in a Texas lawsuit. The trials are just the beginning of what is expected to be a long line of lawsuits, but the win lessened expectations that the company would have to settle thousands of cases filed after the drug's withdrawal last year.

Jurors in Atlantic City rejected claims by Frederick Humeston, 60, an Idaho postal worker who blamed his 2001 heart attack on Vioxx. The verdict didn't address whether the drug caused his heart attack, but jurors were clearly doubtful.

"Mr. Humeston had way too many other health issues to pinpoint it to Vioxx," said juror Vickie Heintz. "His medical records for the last 20 years were just riddled with many medicines and medical problems. Stress was a huge problem."

The company's lawyers said Humeston had other risk factors for a heart attack, including his high blood pressure, his weight and stress from a dispute he was having with his supervisors at the U.S. Postal Service.

The jury deliberated for less than eight hours over three days before clearing Merck of allegations that it hid the full risks of Vioxx from consumers and engaged in "unconscionable commercial practices" in marketing it to doctors and their patients.

In August, a Texas jury found Merck liable in a Vioxx user's death and awarded his widow $253 million in compensatory and punitive damages. That award will be cut under Texas law, but some observers predicted the company would have to settle the 6,500 outstanding lawsuits because it lost so decisively.

Yesterday's verdict clouded the picture and made clear that it will take several more cases to determine a precedent. Investors liked the verdict, which was followed by Merck shares increasing as much as $1.16 in heavy trading, and closing at $29.48, up 3.8 percent.

The next Vioxx liability case, the first federal trial, is scheduled to begin in Houston on Nov. 28.

Humeston claimed Merck neglected patient safety as it developed Vioxx, which eased pain without upsetting patients' stomachs. Approved by the Food and Drug Administration in 1999, Vioxx was a $2.5 billion-a-year blockbuster. Humeston's lawyer, Christopher Seeger, accused Merck of cutting corners in its research and of ignoring tests that suggested that Vioxx might cause heart attacks and strokes.

Humeston, who was awarded two Purple Hearts for service in Vietnam, testified that he was a healthy outdoorsman before the heart attack. But since then, he said, he no longer can hike and lead canoe trips as a wilderness guide.

Humeston said he took Vioxx to dull the pain in his left knee, which was damaged by shrapnel during his Vietnam tour as a Marine. Humeston said he took 54 Vioxx pills in the two months before his heart attack and two pills within hours of the incident.

Much of the seven-week trial relied on the testimony of medical experts. Witnesses for Merck testified that the company thought Vioxx was safe for the heart before the drug was pulled from the market a year ago, after a study showed it doubled the risk of heart attacks and strokes when taken for at least 18 months.

Merck repeatedly told jurors that the FDA had approved it as a safe and effective drug for use against different types of pain, the last a month before Merck recalled it.

Kenneth C. Frazier, senior vice president and general counsel of Merck, said in a statement: "[T]here will be other Vioxx trials, and we will vigorously defend them one by one over the coming years.

"Merck acted responsibly, from performing extensive clinical trials comparing Vioxx to [other painkillers] or placebo in almost 10,000 patients prior to approval, to monitoring the medicine while it was on the market, to voluntarily withdrawing the medicine when we did."

The Associated Press and Bloomberg News contributed to this story.

Plaintiff Frederick Humeston embraces his wife after the verdict, which didn't hold Merck liable for Humeston's 2001 heart attack while taking Vioxx.