Autonomic Function and Prothrombotic Activity in Women after an Acute Coronary Event

Background: The link between decreased heart rate variability (HRV) and atherosclerosis progression is elu-sive. We hypothesized that reduced HRV relates to increased levels of prothrombotic factors previously shown to predict coronary risk. Methods: We studied 257 women (aged 56 7 years) between 3 and 6 months after an acute coronary event and obtained very low frequency (VLF), low frequency (LF), and high frequency (HF) power, and LF/HF ra-tio from 24-hour ambulatory ECG recordings. Plasma levels of activated clotting factor VII (FVIIa), fibrinogen, von Willebrand factor antigen (VWF:Ag), and plasminogen activator inhibitor-1 (PAI-1) activity were deter-mined, and their levels were aggregated into a standardized composite index of prothrombotic activity. Results: In bivariate analyses, all HRV indices were inversely correlated with the prothrombotic index ex-plaining between 6 % and 14 % of the variance (p 0.001). After controlling for sociodemographic factors, in-dex event, menopausal status, cardiac medication, lifestyle factors, self-rated health, metabolic variables, and heart rate, VLF power, LF power, and HF power explained 2%, 5%, and 3%, respectively, of the variance in the prothrombotic index (p 0.012). There were also independent relationships between VLF power and PAI-1 ac-tivity, between LF power and fibrinogen, VWF:Ag, and PAI-1 activity, between HF power and FVIIa and fib-rinogen, and between the LF/HF power ratio and PAI-1 activity, explaining between 2 % and 3 % of the re-spective variances (p 0.05). Conclusions: Decreased HRV was associated with prothrombotic changes partially independent of covariates. Alteration in autonomic function might contribute to prothrombotic activity in women with coronary artery disease (CAD). 133