Clinical Significance of 24-Hour Blood Pressure Variability
Blood pressure variability (BPV) measured over 24 hours is an independent predictor of cardiovascular mortality and morbidity, but current guidelines classify it as experimental with no routine clinical use recommended. 1
Guideline Position on BP Variability
The European Society of Hypertension/European Society of Cardiology explicitly states that BP variability indices—including average real variability (ARV), morning BP surge, blood pressure load, and ambulatory arterial stiffness index—should be regarded as experimental with no routine clinical use because their added predictive value beyond mean BP levels is not yet clear. 1
However, this conservative guideline stance contrasts sharply with emerging research evidence showing significant prognostic value.
Research Evidence Supporting Clinical Significance
Mortality and Cardiovascular Risk
The most recent and highest quality evidence demonstrates that BP variability independently predicts death and cardiovascular events:
In a 2024 study of 1,050 participants followed for 8.3 years, each 2 mmHg increase in 24-hour systolic ARV was associated with a 1.28-fold higher mortality risk and 1.24-fold higher risk of major adverse cardiovascular events (MACE). 2
Critically, after adjusting for absolute BP level, ARV remained independently associated with mortality (HR 1.17) and MACE (HR 1.16), proving that variability matters beyond the actual BP numbers. 2
A 2017 meta-analysis of 19 studies found that increased systolic BP variability measured by ARV was associated with an 18% increased risk of all cardiovascular events (HR 1.18,95% CI 1.09-1.27), independent of BP level. 3
Target Organ Damage
Seventeen of 19 studies in the meta-analysis reported significant associations between high ARV and both the presence and progression of subclinical organ damage, with ARV remaining a significant independent predictor after adjustment for BP and other clinical factors. 3
In pediatric populations, short-term BP variability (measured as standard deviation during 24-hour ABPM) is associated with left ventricular hypertrophy. 1
Comparison with Other Metrics
BP variability appears to provide prognostic information that BP load does not:
While both high ARV and high BP load (≥30% of readings above threshold) were associated with mortality and MACE, only ARV remained significant after adjusting for BP level. 2
This suggests that the pattern of BP fluctuation matters independently of how often BP exceeds thresholds. 2
Mechanisms and Clinical Implications
Why Variability Matters
BP variability may better reflect biological dysfunction in BP regulatory mechanisms, particularly alterations in the sympathetic nervous system, compared to mean BP values alone. 1
The American Heart Association/American Stroke Association notes that intraindividual BP variability confers risk beyond mean BP elevations, and calcium channel blockers may reduce variability more than beta-blockers, potentially providing additional stroke risk reduction benefits. 1
Measurement Considerations
Important caveats about measuring BP variability:
BP variability parameters like ARV, morning surge, and percent dip are highly sensitive to sampling rate, exhibiting more than 30% dispersion at 30-minute sampling intervals. 4
In contrast, 24-hour average BP is less sensitive to sampling rate. 4
For accurate BP variability assessment, higher sampling rates are needed around awakening time (~2 hours before and after), while lower rates may suffice at other times. 4
Practical Clinical Approach
When to Consider BP Variability
Despite guideline recommendations against routine use, consider assessing BP variability in:
- Patients with target organ damage disproportionate to their mean BP levels 3
- Those at high cardiovascular risk (diabetes, chronic kidney disease, prior cardiovascular events) 5
- Elderly patients, who may have greater BP variability 1
- Patients with suspected autonomic dysfunction 1
How to Interpret
- ARV is the preferred metric as it captures variability among consecutive BP readings and has the strongest evidence base. 2, 3
- An ARV >11 mmHg (mean + 1 SD from the 2024 study) suggests elevated variability warranting attention. 2
- Recognize that BP variability adds independent prognostic information beyond mean BP, dipping status, and BP load. 2
Common Pitfalls
- Do not ignore variability data when present on ABPM reports, even though guidelines say it's experimental—the research evidence for its prognostic value is strong. 2, 3
- Do not assume that controlling mean BP adequately addresses cardiovascular risk if variability remains high. 2
- Do not rely on BP variability measured with infrequent sampling (>30 minute intervals), as this significantly underestimates true variability. 4
- Do not use 24-hour BP mean alone for risk stratification, as it obscures important information about BP patterns and variability. 5