[Blood pressure variation and cardiovascular risk in hypertension]

Disruption of circadian rhythm of blood pressure (BP) is associated with advanced target organ damage and poor cardiovascular prognosis. We studied silent cerebrovascular disease and stroke events in older Japanese patients with different nocturnal BP dipping. There was a J-shaped relationship of nocturnal dipping status with silent cerebral infarcts detected by brain MRI at baseline, and with stroke incidence during the follow-up period. The extreme-dippers (with marked nocturnal BP dipping) and risers (with higher nocturnal BP than awake BP) had a higher prevalence of silent cerebral infarcts and poorer stroke prognosis than those with appropriate nocturnal BP dipping (dippers). Extreme-dippers tended to have predominant systolic hypertension and increased BP variability. Several factors are affecting the diurnal BP variation pattern. The non-dipping pattern is associated with autonomic nervous dysfunction and poor sleep quality due to nocturnal behavior and sleep apnea. Extreme-dippers might have increased arterial stiffness with reduced circulating blood volume in addition to an excessive morning surge due to alpha-adrenergic hyperactivity. Morning BP surge, which is partly associated with nocturnal BP dipping status, was a predictor of stroke event independently for ambulatory BP level and silent cerebral infarcts. Antihypertensive medication that normalize the disrupted circadian BP variation might improve cardiovascular prognosis in high-risk hypertensive patients.