Abstract 16170: Autonomic Effects of Acute Psychological Stress Are Greater in Young Women Than Men After Myocardial Infarction
Introduction: Young women suffer from a higher risk of adverse events after myocardial infarction and more psychosocial comorbidities than similarly-aged men. We hypothesized that an increased vulnerability in women may stem from a more adverse autonomic response to acute mental stress than men.
Methods: We studied 78 post-MI patients (39 women and 39 men) age 18-59 years. Women and men were matched for age, MI type, and months since MI. All patients underwent mental stress testing with a public speech stressor, as well as conventional exercise or pharmacological testing. Autonomic function was measured via heart rate variability [high frequency (HF) and low frequency (LF) HRV] from ambulatory ECG monitoring before and during mental stress. Linear mixed models were used to estimate the effect of sex on the change in HRV between rest and stress.
Results: The mean (SD) age was 50 (6) years, 45% had an ST-elevation MI, and 54% were black. The baseline mean HF HRV was higher for women than men, 5.9 (1.4) vs. 5.3 (1.0) ln(ms2), p=0.04, while baseline LF HRV was similar by sex. During the speech preparation and delivery, HF HRV decreased more in women (-83%) than men (-59%), p=0.005. LF HRV also decreased more in women (-69 % vs -37 %, p=0.046). After adjusting for race, CAD risk factors, ejection fraction, angiographic CAD severity, and medications (beta-blockers, ACE-inhibitors, and statins), this difference remained significant for both HF (p=0.01) and LF (p=0.03). Addition of depression and anti-depressants to the model did not change the relationship. The sex difference was more pronounced as age decreased, with sex-age interaction of p=0.01 for HF and 0.055 for LF. No sex differences in either HF or LF HRV were found during exercise stress.
Conclusion: In young adults with recent MI, women have greater reduction in HRV than men during acute psychological stress, denoting a more adverse autonomic response to stress. The younger the age, the more pronounced the sex difference. In contrast, no differences are observed during exercise stress. Given the prognostic value of HRV, these findings may help to explain sex-based differences in post-MI outcomes particularly for younger women.
- © 2013 by American Heart Association, Inc.