Subclinical atherosclerosis and risk factors in relation to autonomic indices in the general population

Orthostatic hypotension and resting heart rate (RHR) are associated with cardiovascular disease (CVD). However, it is unknown how these factors relate to subclinical CVD. We examined the relationship between orthostatic blood pressure (BP) response, RHR and cardiovascular risk factors, including coronary artery calcification score (CACS) and arterial stiffness, in the general population. METHODS: We included 5493 individuals (age 50–64 years; 46.6% men) from The Swedish CArdioPulmonary-bio-Image Study (SCAPIS). Anthropometric and haemodynamic data, biochemistry, CACS and carotid-femoral pulse wave velocity (PWV) were retrieved. Individuals were categorized into binary variables that manifest orthostatic hypotension and in quartiles of orthostatic BP responses and RHR, respectively. Differences across the various characteristics were tested using χ(2) for categorical variables and analysis of variance and Kruskal–Wallis test for continuous variables. RESULTS: The mean (SD) SBP and DBP decrease upon standing was -3.8 (10.2) and -9.5 (6.4) mmHg, respectively. Manifest orthostatic hypotension (1.7% of the population) associated with age (P = 0.021), systolic, diastolic and pulse pressure (P < 0.001), CACS (<0.001), PWV (P = 0.004), HbA1c (P < 0.001) and glucose levels (P = 0.035). Age (P < 0.001), CACS (P = 0.045) and PWV (P < 0.001) differed according to systolic orthostatic BP, with the highest values seen in those with highest and lowest systolic orthostatic BP-responses. RHR was associated with PWV (P < 0.001), SBP and DBP (P < 0.001) as well as anthropometric parameters (P < 0.001) but not CACS (P = 0.137). CONCLUSION: Subclinical abnormalities in cardiovascular autonomic function, such as impaired and exaggerated orthostatic BP response and increased resting heart rate, are associated with markers of increased cardiovascular risk in the general population.