Blood Pressure Variability: A New Predicting Factor for Clinical Outcomes of Intracerebral Hemorrhage

Spontaneous primary intracerebral hemorrhage (ICH) is a stroke subtype associated with the highest mortality rate. High blood pressure (BP) is the most common cause of non-lobar ICH. Recent clinical trials have been inconclusive regarding the efficacy of aggressive BP lowering to improve ICH outcome. The association between high BP and ICH prognosis is rather complex and parameters other than absolute BP levels may be involved. In this regard, there is accruing evidence that BP variability (BPV) plays a major role in ICH outcome. Different BPV indices have been used to predict hematoma growth, neurological deterioration, and functional recovery. This review highlights the available evidence about the relationship between BPV and clinical outcomes among patients. We identified standard deviation (SD), residual SD, coefficient of variation, mean absolute change, average real variability, successive variation, spectral analysis using Fourier analysis, and functional successive variation (FSV) as indices to assess BPV. Most studies have demonstrated the association of BPV with ICH outcome, suggesting a need to monitor and control BP fluctuations in the routine clinical care of ICH patients. When large inter-subject variability exists, FSV is a viable alternative quantification of BPV as its computation is less sensitive to differences in the patient-specific observation schedules for BP than that of traditional indices.