Should reduction of increased short‐term blood pressure variability be a target of antihypertensive therapy?

Abstract

An extensive and highly consistent body of evidence indicates that the average level of 24-h ambulatory blood pressure (BP) correlates more closely than casual BP with the cardiovascular (CV) and renal complications of arterial hypertension. 1,2 However, average pressures neglect the temporal variation in BP, which may be also prognostically relevant. 1,[3][4][5][6][7] Since the pioneering observations ofStephen Hales, during the 18th century, BP has been recognized as a fluctuating parameter 2 ; indeed, it has been shown to be characterized by marked spontaneous oscillations over short-term (minutes to hours) and long-term (days to months) periods. Important BP variations from summer to winter have also been consistently reported (seasonal BP variability). Although in physiological conditions these variations may represent an adaptive humoral and neural response to environmental, behavioral, and emotional stimuli occurring in daily life, they may also reflect alterations in CV regulatory mechanisms. 1 Historically, variability in BP has been viewed as a factor inhibiting accurate measurement of mean BP and as a phenomenon to be overcome by improved monitoring. 1,2 Far from being a "background noise" that hinders the assessment of "true BP," 2 short-term BP variability (BPV) seems to be relevant to the pathophysiology of target organ damage and to the incidence of clinical events. 1,3-10 | IND I CE S OF S HORT-TERM B LOOD PRE SSURE VARIAB ILIT YAlthough the precise quantification of short-term BPV requires beat-to-beat BP recording, its assessment is also possible, even if less accurately, through the use of intermittent noninvasive 24hour ambulatory BP monitoring (ABPM), at intervals from 15 to 20 minutes. 1 This allows the straightforward estimation of shortterm BPV by calculating the 24-h BP standard deviation (SD) and the coefficient of variation (SD X 100/BP mean), which accounts for the dependence of the SD on mean BP levels. 1 Despite the