MONDAY, Dec. 8 (HealthDay News) -- Women who suffer the most severe form of heart attack are twice as likely as men to die in the hospital, a new study finds.

The study of more than 78,000 people treated for heart attacks at 420 U.S. hospitals between 2001 and 2006 found the same overall in-hospital death rate for men and women.

But 10.2 percent of women with a STEMI heart attack died, compared to 5.5 percent of men with the same diagnosis, said the report in the Dec. 9 issue of the journal Circulation.

"We believe that a part of it may be related to the fact that women are undertreated," said study lead author Dr. Hani Jneid, an assistant professor of cardiovascular medicine at Baylor College of Medicine in Houston. "There is evidence across the board of undertreatment."

"We obviously could not assess the appropriateness of the treatments," Jneid added. "But the results point to the fact that there might be some sex-related disparity in treatment that needs to be addressed by physicians."

STEMI is short for ST-elevation myocardial infarction, a name derived from the heartbeat pattern seen on an electrocardiogram. A STEMI heart attack usually is caused by complete blockage of a coronary artery, which means that more heart muscle dies than if there is only partial blockage.

While in theory "there is no intrinsic reason why there should be a difference" in survival rates between the sexes, there are several possible explanations, said Dr. Gregg C. Fonarow, a professor of cardiovascular medicine at the University of California, Los Angeles, and an author of the report. Those explanations may start with the symptoms reported by people having heart attacks and then go on to the treatment they receive, he said.

"Women when presenting with a heart attack tend to be older and have other comorbid conditions [health problems]," Fonarow said. "But even when we adjusted for that, we found a 12 percent difference."

Also, "women present more atypically," he said. "They are less likely to have sternal chest pain or pressure, just general symptoms like shortness of breath or other symptoms that are non-specific."