Sex And Survival: In Some Matters Of The Heart Women Have The Edge

Lead researcher Kirkwood F. Adams Jr., M.D., at the University of North Carolina (UNC), Chapel Hill, 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 is significant because it challenges previous research findings suggesting 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.

The only form of cardiovascular disease that is increasing dramatically in the population is congestive heart failure, a condition in which the heart cannot pump enough blood to meet the demands of the body. An estimated 4.6 million Americans have CHF.

"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.

Adams' study used data from the Flolan International Randomized Survival Trial (FIRST), which included 359 men and 112 women with "end-stage," or class IV, heart failure. After eliminating patients for whom baseline characteristics were not available, survival data on 331 men and 99 women were compared.

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-one-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, associate professor of medicine and radiology and director of UNC's Heart Failure Program.

"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.

Other researchers included Carla A. Sueta, Ph.D., Todd A. Schwartz, and Gary G. Koch, Ph.D., also of University of North Carolina; Mihai Gheorghiade, M.D., Northwestern University Medical School; Christopher M. O'Connor, M.D., and Robert M. Califf, M.D., Duke University Medical Center; Barry Uretsky, M.D., University of Texas Medical Branch at Galveston; Karl Swedberg, M.D., Ostra University Hospital; William McKenna, M.D., St. George's Hospital Medical School; and Jordi Soler-Soler, M.D., Hospital Universitari Vall D'Hebron in Barcelona.