How important is blood pressure variability?

Abstract

Arterial blood pressure (BP) is a continuous variable, with a physiology characterized by significant variability stemming from the complex interaction among haemodynamic factors, neuronal reflexes, as well as hormonal, behavioural, and environmental stimuli. The homoeostatic response accounts for the physiologic variability in BP in normotensive individuals, which is more evident in hypertensive patients. Blood pressure variability is a complex phenomenon, which could be classified in various types: very short term (beat to beat), short term (during 24 h), mid-term (day by day), long term (<5 years), and very long term (>5 years). Accurate measurement of BP variability represents a complex and often controversial endeavour, despite several methodological approaches are available. Albeit a prognostic significance has been demonstrated for some indicators of BP variability, the clinical significance of this measurement is still uncertain. In fact, none of the indicators presently available for BP variability, including early morning BP rise, substantially affects, and redefines, the cardiovascular risk of the hypertensive patient, over and beyond the mere BP values. Accordingly, in defining the cardiovascular risk, the focus should be on the absolute BP values, which remain the most relevant risk factor, and the one more susceptible to modification with both non-pharmacologic and pharmacologic treatment.