Nov. 20, 2013 —
Science Daily/Emory Health Sciences
Researchers have found that women younger than 50 with a recent heart attack are more likely to experience restricted blood flow to the heart (myocardial ischemia) in response to psychological stress.
Among study participants older than 50, there were no significant sex differences in mental stress-induced ischemia;, however, men older than 50 had a rate of exercise-induced ischemia that was twice as high as women of a similar age.
"This is the first study to examine the cardiovascular effects of psychological stress as a possible mechanism for the greater mortality after myocardial infarction among younger women," says study leader Viola Vaccarino, MD, PhD, professor and chair of the Department of Epidemiology, Rollins School of Public Health.
"We saw a dramatic difference in mental stress-induced ischemia specifically in younger women. In addition, when ischemia was graded in a continuous way, we saw that it was twice as severe among the younger women."
Women who experience a heart attack before age 50 are relatively rare, suggesting that perhaps those who do simply have more severe heart disease. However, even when investigators adjusted for different rates of traditional heart disease risk factors such as smoking and diabetes, the disparity remained. In fact, women tended to have less severe coronary artery disease, measured by examining the degree of blockage in their coronary arteries.
One possible explanation the Emory investigators considered was a higher burden of psychosocial stress, Vaccarino says. In the study, the younger women were more often poor, of minority race, with a history of sexual abuse and with higher levels of depressive symptoms.
Heart rate goes up in response to physical or psychological stress, but the beats also become more evenly spaced. Heart rate variability is a measure of how much moment-to-moment fluctuation is present; higher heart rate variability is a marker of a more flexible, and thus healthier, autonomic system.
In the MIMS study, younger women had their heart rate variability dip more in response to stress, compared to men the same age. This is additional evidence that young women after a heart attack may be more vulnerable to the adverse effects of psychological stress on the heart.