Abstract 2096: Cardiovascular Risk Factors and Heart Rate Variability in an Older Cohort
Background: Lower heart rate variability (HRV) has been associated with CVD events in persons with CAD, diabetes and metabolic syndrome (MS). However, the role of HRV in predicting CVD risk in asymptomatic patients is not well elucidated. This study examines the relationship of HRV to CVD risk factors in healthy older adults who participated in the Atherosclerotic Disease VAscular FunctioN and GenetiC Epidemiology (ADVANCE study). Although free of CVD, subjects had traditional CVD risk factors.
Methods: Participants were recruited from a representative sample of adults aged 60 – 69 years who were enrolled in a large, integrated health care system in northern California and were free of clinical CVD and other major health problems. CVD risk factors and HRV were measured at the first study visit. Power spectral analysis was used to determine HRV in a 10-minute ECG recording using standard procedures. HRV data were edited and exclusions included irregular R-R intervals greater than 10% of tracing, artifact and sensing problems. HRV variables used in this analysis included SDNN (standard deviation of all N-N intervals - the best overall measure of HRV), HF (high frequency), LF (low frequency) and LF/HF ratio (a measure of autonomic nervous system (ANS) balance).
Results: In this cohort of 598 men and 365 women, the mean HRV (SDNN) was 39 (sd = 17.2) and is lower than data reported by some groups. In bivariate analysis, obesity (BMI), hypertension, family history of CVD, self-reported physical activity, triglycerides, insulin, and HDL were all correlated with SDNN (p < 0.05 for all). HRV differed by gender with women having lower SDNN, but a balanced LF/HF ratio. A forced stepwise linear regression analysis, adjusted for age, gender and beta-blocker use, demonstrated significantly lower HRV with higher insulin and triglyceride levels (both p < 0.01). HRV gender differences remained significant (p < 0.001).
Conclusions: These data suggest that lower HRV clusters with cardiovascular risk factors, especially those common in MS. MS adversely affects cardiac autonomic function and suggests that MS factors may play an important role in the development of CVD. This relationship highlights the importance of early identification and treatment of MS factors.