NEW YORK (CNNMoney.com) - Merck & Co. was held liable Wednesday by a New Jersey jury in the heart attack of a 77-year-old man who took the painkiller Vioxx, but not in the one suffered by a 60-year-old plaintiff.

Plaintiff John McDarby, 77, of Park Ridge, N.J., and his wife were awarded $4.5 million in their suit against Merck, the second-largest U.S. drug maker. But Tom Cona, 60, of Cherry Hill, N.J., received virtually no award. Both men blamed their non-fatal heart attacks on the arthritis painkiller.

The outcome in the fifth Vioxx case to reach a verdict could affect thousands of other cases filed against the company. In prior cases in state and federal court, Merck racked up three victories and one loss.

The jury also found that the drug company failed to provide warning of increased cardiovascular risk for both plaintiffs, but that the drug did not contribute to Cona's heart attack, Reuters reported.

The eight-person jury also found that Merck did not commit fraud in marketing Vioxx to either plaintiff, the news agency said.

Merck (Research) shares fell 3 percent in after-hours trading on the Inet electronic network after the verdict was announced.

In a statement about the verdict, and the forthcoming punitive phase of jury deliberations, Merck said it will "present evidence it believes shows that the company submitted to the U.S. Food and Drug Administration all relevant and material information concerning Vioxx. Merck will make further statements after the jury completes its deliberations after this phase of the trial."

Wednesday's outcome doesn't bode well for Merck, according to one analyst.

"There's no way that (Merck) is going to continue to pursue this strategy of trying every case. It would be foolhardy and very expensive," Sherwood Small, a fund manager with Boston Private Value, told Reuters after the decision. "This (split verdict) doesn't put Merck in a great position," he said.

Nearly 10,000 lawsuits have been filed against Merck by former Vioxx patients, or by surviving family members in cases alleging wrongful death. Most of the lawsuits have been filed in New Jersey Superior Court in Atlantic City under Judge Carol Higbee, or in federal district court in New Orleans under Judge Eldon Fallon.

Cona, who suffered a heart attack in 2003, and McDarby, who had one in 2004, are the first plaintiffs to sue who took Vioxx for more than 18 months.

That's a critical detail since the study that caused Merck to pull Vioxx off the market in September 2004 said the drug increased the risk of heart attacks and strokes in patients who took it for at least 18 months. Plaintiffs in previous cases all took the drug for shorter periods of time.

David Moskowitz, analyst for Friedman, Billings, Ramsey, has projected that damages against Merck could total $50 billion in a worst-case scenario. Merck, based in Whitehouse Station, N.J., has consistently denied accusations that it covered up the risks of Vioxx and has said its drug has killed no one.

Lawyer Mark Lanier of Houston, who represented Cona, was the only lawyer before Wednesday to defeat Merck in a Vioxx trial. In the first Vioxx trial in Texas state court last year, Lanier's client Carol Ernst was awarded $253 million by the jury for the death of her husband, a Vioxx patient, but state law will reduce the award by about 90 percent.

A sixth case is ongoing in Texas state court in Rio Grande City, a town of 12,000 near the border with Mexico.

The next trial is slated for New Jersey Supreme Court on June 5. In the U.S. court in New Orleans, a case scheduled to come to trial June 12 was dismissed Wednesday at the plaintiff's request.

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-- CNNMoney.com's Aaron Smith contributed to this report

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