A new study by Utah County researchers is illuminating the hazards of the banned weight-loss medication fen-phen and proving for the first time in large-scale research that women are more susceptible to consequent heart problems than men are.

The appetite suppressant fenfluramine -- the "fen" half of the drug -- was banned by the U.S. Food and Drug Administration in September 1997 over fears it damages the valves of the heart. The new review of heart scans of 5,743 former fen-phen users in Utah County suggested 19.6 percent of women experienced such problems, compared to 11.8 percent of men. Problems occur when the valves "regurgitate" -- or leak -- more than normal, putting stress on the heart and sometimes causing blood to flow backwards, said Dr. Charles Dahl, a cardiologist at Central Utah Clinic in Provo who led the study.

"Some of the medical world thinks that there never was a problem, and that's not true," Dahl said. "Almost as soon as it was banned I decided it would be interesting to keep track."

Dahl's group studied scans from patients of Central Utah Clinic and neighboring Utah Valley Regional Medical Center from 1997 to 2004. They also found that heart problems persisted in patients throughout the course of the study, but tended to diminish over time.

"We found more significant regurgitation before Jan. 1, 2000," he said. "It appears that the regurgitation is getting less somewhat."

That doesn't mitigate the severity of the problem as a whole, Dahl said. He said he suspects many people still experience problems related to the drug today, 11 years after it was outlawed. More than 120 deaths linked to fen-phen have been reported to the FDA.

Dahl said in his study that 0.44 percent of patients needed surgery to correct problems "directly because of the drugs."

"That's not a huge number, but if you would have told someone before taking the drug that one in 227 people would need surgery afterward, some might have opted out," he said.

The results are published in the latest issue of the journal BMC Medicine. The article is available online at www.biomedcentral.com/bmcmed.

• Ace Stryker can be reached at 344-2556 or astryker@heraldextra.com.