Impact of nocturnal heart rate variability on cerebral small-vessel disease progression: a longitudinal study in community-dwelling elderly Japanese

Recent evidence has shown an effect of ambulatory heart rate (HR) on cardiovascular events and mortality. Our objective was to determine whether ambulatory HR was related to the progression of cerebral small-vessel disease (SVD) or cognitive decline in community-dwelling elderly people. A cohort of 190 community-dwelling elderly people underwent an ambulatory blood pressure monitoring (ABPM), brain magnetic resonance imaging (MRI) and cognitive testing at baseline, with MRI and cognitive tests repeated 4 years later. HR variability in ABPM was quantified by the s.d. (s.d. and the root mean square of successive differences (RMSSD), and the relationship between HR variability and the progression of SVD/cognitive decline was investigated. We also assessed the association of nighttime HR variability and nocturnal HR dipping. The nighttime RMSSD of participants with the progression of SVD was significantly higher than that of those without progression of SVD (P<0.05). Moreover, nighttime RMSSD was independently associated with the progression of SVD (1 b.p.m. increment: odds ratio=1.13, 95% confidence interval=1.04-1.24, P<0.01). We failed to confirm an association between cognitive decline and nighttime HR variability. However, s.d. in the daytime and 24-h HR were independently related to cognitive decline (P<0.05). Nocturnal HR dipping was least in the top quartiles of nighttime HR variability, with a monotonic trend of nocturnal HR dipping that was dependent on the quartiles of nighttime HR variability indices (P<0.01). Increased HR variability during the night is a predictor of the progression of SVD in community-dwelling elderly people.