Blood Pressure Variability: Mechanisms, Measurement, Subtypes, and Clinical Implications

Abstract

The complex topic of short- and long-term blood pressure (BP) variability confounds the diagnosis, classification, and management of hypertension. True pathophysiologic BP variation (systematic and non-systematic deviations between- and within-individuals) is related to heart rate, respiration, complex responses of the sympathetic nervous system, vascular reactivity, and arterial stiffness. Measurement errors (systematic biases and random error) further compound the analysis. Most studies use serial clinic BP values, 24-hour ambulatory BP recordings, or home BP values with standard statistical indicators (standard deviation, variance, or coefficient of variation) or absolute real variability (mean difference of successive values). Clinical impact in retrospective secondary analyses includes a modest increase in cardiovascular disease (CVD) risk (equivalent to a few mmHg in mean systolic BP) yet questions remain whether adjustment for mean BP is needed. BP variability is reduced to a small degree by calcium antagonists and increased by ACE inhibitors, beta-blockers, and alpha-blockers but no interventional trial has addressed the question of whether reducing BP variability confers CVD risk protection. BP variability is not specifically discussed in practice guidelines but it is tacitly acknowledged by recommendations to repeat BP measurements, standardize technique, and confirm the hypertension diagnosis by home or ambulatory BP measurements to account for the “white coat effect.” There is no formal consensus on how to quantitate or manage BP variability despite a real-world need for better diagnostic and therapeutic guidance. Practitioners should thus focus on control of (mean) BP using combinations of agents that improve CVD outcomes. Future consensus guidance should directly address BP variability and should include educational materials for physicians, patient-contact staff, and patients.