Updated

Work-related stress and other risk factors caused a former postal worker's heart attack and not the withdrawn painkiller Vioxx, Merck & Co Inc.'s lead attorney said in closing arguments at the second Vioxx (search) trial on Monday.

"The best common-sense explanation for Mr. Humeston's heart attack is the stress he had in September of 2001," Merck attorney Diane Sullivan told the jury.

The suit was brought by Frederick "Mike" Humeston, a 60-year-old Idaho postal worker who blames Vioxx for his 2001 heart attack. Humeston had been taking Vioxx for about two months to relieve knee pain stemming from a Vietnam War (search) wound.

The case, which has featured seven weeks of testimony and several Merck motions to have a mistrial declared denied, is being keenly watched as an indicator of how the more than 6,500 pending lawsuits filed by users of Vioxx might play out.

Merck in August lost the first Vioxx case to go to trial as a Texas jury ordered the company to pay $253 million to the widow of a Vioxx user. That amount is expected to be cut to about $26 million under state caps on damages and Merck (MRK) is appealing the verdict.

Sullivan began her closing by listing factors that may have contributed to Humeston's heart attack.

She said Humeston was under "chronic stress" as a result of his knee pain and because of job-related pressure.

Humeston believed the postal service, where he had worked for 22 years, was attempting to force him to retire, Sullivan said.

Four days before the heart attack, Humeston had argued with his employer about whether his knee allowed him to perform his duties for the U.S. Postal Service (search), Sullivan said.

The day before the attack, he received a phone call from his doctor telling him that his employers had been conducting video surveillance at his house in an attempt to prove he was not as disabled from the injury as he claimed, Sullivan said.

She attempted to cast doubt on Humeston's account to another cardiologist that he had no work-related stress.

"It's up to you to decide whether he is playing it straight or not," Sullivan told the jury.

Sullivan said the plaintiff's age — he was 56 at the time of the attack — was a potential risk factor for heart attack.

Sullivan also argued that Humeston's blood pressure was borderline hypertensive and that his doctors had said that he was "borderline obese."

Humeston also had a "very low" level of HDL, or good cholesterol, Sullivan said. She cited evidence from cardiologist Nicolas DePace, a witness for the plaintiff, who told the court he could not eliminate low levels of HDL as a possible cause for Humeston's attack.

Humeston's heart attack was triggered by plaque tearing away from a coronary artery where it had built up. Sullivan told the jury there have been no clinical studies showing that Vioxx causes such plaque ruptures.

Merck withdrew the medicine from the market last year after studies showed increased heart risks following long-term use. The company has said it pulled the $2.5 billion-a-year drug as soon as it had definitive evidence of increased heart risks.

Humeston's lawyers contend that Merck hid the risks and recklessly marketed the drug to boost profits.

Sullivan said Merck went to great lengths to ensure the safety of its product and obtain FDA approval. She said the company published the results of its Vioxx studies in respected medical journals, consulted experts outside the company and went beyond required testing standards.

"Merck did what Merck is known for — rigorous science and following up on theories, not cutting corners."

Once Sullivan concludes, Humeston's attorneys will give their closing arguments before the jury gets the case to consider its verdict.