NEW YORK (CNNMoney.com) -- The latest lawsuit against Merck over its market-pulled painkiller Vioxx debuts this week in a California courtroom, while the drug giant continues to defend itself in a separate trial in New Jersey.

Plaintiff Stewart Grossberg blames Vioxx for his heart attack and is suing Merck in Los Angeles Superior Court. The trial began on Tuesday.

Merck lawyers dismissed Grossberg's claim that Vioxx, an anti-inflammatory drug that was withdrawn from the market in 2004, triggered his heart attack. Thomas Yoo, an outside counsel for Merck's defense, said the plaintiff's "health history is behind his heart attack, not Vioxx," and that his use of the drug was "sporadic and intermittent."

"The evidence will show that Mr. Grossberg was at high risk for a heart attack regardless of whether or not he was taking Vioxx," said Yoo, in a pre-trial statement provided by Merck. "His health and history also shows he has high cholesterol levels and a family history of cardiac problems."

Grossberg's lawyer Thomas Girardi was not immediately available for comment.

In the ongoing trial in New Jersey, plaintiff Elaine Doherty has sued Merck through New Jersey Superior Court in Atlantic City, N.J. Doherty took Vioxx for three years and, like the other plaintiffs, she blames the drug for her heart attack.

"We certainly feel that she is one of the many, many victims of the adverse effects of the drug," said Doherty's lawyer, Gene Locks.

Merck said closing arguments could begin this Friday, but the court is not expected to reconvene until next Wednesday because of Independence Day weekend.

Merck (up $0.50 to $35.21, Charts), the number 2 U.S. drugmaker, said it faces about 11,500 lawsuits from former Vioxx patients and their families. Based in Whitehouse Station, N.J., Merck faces more than 5,000 lawsuits filed in its home state under Judge Carol Higbee.

Merck pulled the arthritis painkiller off the market on Sept. 30, 2004, eliminating the drug's $2.5 billion in annual sales. Merck withdrew Vioxx after the company's "Approve" study showed an increased risk of blood clot-related heart attacks and strokes in patients who took the drug for at least 18 months.

So far, five cases have gone to trial, resulting in two wins and two losses for Merck, with a split verdict in the fifth case. As part of its defense, Merck has consistently said that the risk of using Vioxx increased only after 18 months of use.

But this last detail of the study has been a recent point of contention. The New England Journal of Medicine and Merck each both recently made corrections to the published Approve study.

NEJM's correction states that nothing in that study actually indicates anything about the safety of Vioxx during the first 18 months of its use, according to the journal. The study originally contended that Vioxx only posed a heightened heart attack risk after 18 months of use.

Peter Kim, president of Merck Research Laboratories, says the correction does not change the study's findings, but critics suspect that the risks of using Vioxx could emerge well before the 18 months cited by Merck.

This issue is sure to come up in current and upcoming trials, as lawyers from either side try to spin the data to their advantage.

The Vioxx withdrawal triggered a stock price plunge for Merck, but investor fears seem to be subsiding, as the price has climbed 9 percent this year. Shares were trading at $35.27 midday Wednesday.

Related: Is Merck winning or losing?