13 April 1999

Women Have the Edge in (some) Matters of the Heart

Women with advanced congestive heart failure (CHF) live twice as long as their male counterparts, according to a recent study in today's Circulation: Journal of the American Heart Association. CHF is the only form of cardiovascular disease that is increasing dramatically in the population. An estimated 4.6 million Americans have CHF, a condition in which the heart cannot pump enough blood to meet the demands of the body.

Lead researcher Kirkwood F. Adams Jr., M.D., at the University of North Carolina (UNC), says that a woman has a survival advantage even if her CHF is as severe as a man's and she has had the disease for the same duration.

The study challenges previous research findings that suggest that the survival advantage of women with heart failure over that of men might be due to differences between men and women in the type of treatment they received and the length of time they had the disease. "Our analysis also suggests that the trend for increased survival is strongest among a subset of patients -those with CHF that is not due to ischemia, or lack of blood supply to the heart," says Adams.

Ischemic heart disease results from atherosclerosis caused by fat-laden plaque obstructions that develop in blood vessels. Nonischemic heart failure results from high blood pressure or other factors that can weaken the heart muscle. Researchers compared groups that were similar in characteristics such as age, gender, race, weight, diabetes, duration of heart failure and high blood pressure. Other characteristics included the distance the patients walked in six minutes and dobutamine (Dobutrex) use - a drug used to increase the heart's blood output in patients with CHF. The study found other differences between the men and women with CHF. Men with CHF were more likely than females to be Caucasian, to have atherosclerosis as the primary cause of their condition, to have less severe CHF, and less dobutamine use. Men with nonischemic heart disease were three times more likely than females to die during the first year-and-a-half follow-up period. Men with ischemic heart disease were about one and a half times more likely to die during that period. Overall, males whose CHF was caused by high blood pressure and other factors were twice as likely to die as their female counterparts. "These are impressive differences," says Adams. "There are several unique aspects of the FIRST study population which enhance the likelihood that biological differences are an important cause of the survival difference we observed between males and females," Adams says. "A growing body of evidence points to fundamental gender-related differences in the nature and extent of heart failure." However, the researchers cautioned that larger studies are needed to further explore mechanisms of differences in survival rates between the sexes.