Relationship among morning blood pressure surge, 24-hour blood pressure variability, and cardiovascular outcomes in a white population.

Abstract

Cardiovascular events have their greatest prevalence in the early morning period. Whether this is attributable to an arousal-dependent blood pressure (BP) increase is far from being clear. It is also not clear to what extent this phenomenon reflects overall 24-hour BP variability. In 2051 subjects (aged 25-74 years) representative of the population of Monza (Italy), we measured 24-hour ambulatory systolic BP (SBP) and calculated the difference between the 2-hour average values after morning arousal and the lowest 3 or average 2-hour values before arousal (morning BP surge 1 and 2, respectively). For either measure, we sought the relationship with a variety of indices of 24-hour SBP variability and collected information on (1) the occurrence of cardiovascular and all cause deaths during a follow-up of ≈16 years and (2) the appearance of echocardiographic left ventricular hypertrophy after 10 years from the baseline visit. Morning SBP surge 1 was directly related to indices of 24-hour SBP variability, including those made independent on the magnitude of the day-night SBP difference. There was a weak positive relationship between morning SBP surge 1 and the risk of cardiovascular and all-cause death, which disappeared after adjustment for confounders. This was the case also for development of left ventricular hypertrophy. Morning SBP surge 2 was smaller, inconsistently related to 24-hour SBP variability and not at all related to fatal events or new-onset left ventricular hypertrophy. In a white population, morning BP surge was not found to be an independent predictor of cardiovascular death, all-cause death, or development of high cardiovascular risk (as documented by new-onset cardiac damage) even when appropriately assessed by measures that reflect its association with 24-hour BP variability.