A new study has found surprising evidence of delays in getting women with heart trouble to the hospital.

Researchers at Tufts Medical Center in Boston examined 5,887 emergency calls about suspected cardiac symptoms in Dallas County, Tex. About half of the calls were made by women.

Ambulances arrived just as quickly for women as for men, the researchers found. Patients of both sexes spent an average of 34 minutes in the care of emergency medical workers, including about 19.9 minutes of care on the scene and 10.3 minutes spent traveling to the hospital.

But 647 patients, about 11 percent, were delayed, spending 45 minutes or longer in the care of emergency workers.