Women suffer from worse autonomic function after ACS

In the year following acute coronary syndrome (ACS), women tend to have higher heart rate (HR) and lower heart rate variability (HRV) than men, indicative of worse autonomic function, a recent study has shown.

A total of 416 ACS patients participated in the present study. Most were men (n=327; mean age, 58.37 years) and only 89 were women (mean age, 58.79 years). The study outcomes included HR and HRV, as expressed in time and frequency domains, such as the standard deviation of RR intervals (SDRR); the root mean square of successive differences; and very low (VLF), low (LF), and high (HF) frequency powers.

A month after ACS, women had greater resting HR than men (63 vs 60 bpm), which corresponded to a significant sex effect upon hierarchical linear regression analyses. Significance remained even after adjusting for age and clinical and psychological factors (coefficient, 4.03, 95 percent confidence interval [CI], 0.57–7.49).

This interaction persisted until 12 months after ACS, at which time point women had an even greater HR relative to men (66 vs 60 bpm; coefficient, 7.44, 95 percent CI, 3.58–11.30).

Moreover, HRV likewise differed between sexes over the post-ACS follow-up, with women demonstrating lower values than men.

One month after ACS, for example, sex emerged as a significant predictor of SDRR, and VLF, LF, and HF power. Complete model adjustment, however, only left VLF power as a correlate of sex (coefficient, –553.82, 95 percent CI, –1,207.25 to –80.40).

At 12 months, sex was significantly correlated with both VLF (coefficient, –817.50, 95 percent CI, –1,559.71 to –75.30) and SDRR (coefficient, –9.86, 95 percent CI, –18.95 to –0.76) in fully adjusted analyses.