Beat-to-Beat, Reading-to-Reading, and Day-to-Day Blood Pressure Variability in Relation to Organ Damage in Untreated Chinese

Whether target organ damage is associated with blood pressure (BP) variability independent of level remains debated. We assessed these associations from 10-minute beat-to-beat, 24-hour ambulatory, and 7-day home BP recordings in 256 untreated subjects referred to a hypertension clinic. BP variability indices were variability independent of the mean, maximum–minimum difference, and average real variability. Effect sizes (standardized &bgr;) were computed using multivariable regression models. In beat-to-beat recordings, left ventricular mass index (n=128) was not (P≥0.18) associated with systolic BP but increased with all 3 systolic variability indices (+2.97–3.53 g/m2; P<0.04); the urinary albumin-to-creatinine ratio increased (P⩽0.03) with systolic BP (+1.14–1.17 mg/mmol) and maximum–minimum difference (+1.18 mg/mmol); and pulse wave velocity increased with systolic BP (+0.69 m/s; P<0.001). In 24-hour recordings, all 3 indices of organ damage increased (P<0.03) with systolic BP, whereas the associations with BP variability were nonsignificant (P≥0.15) except for increases in pulse wave velocity (P<0.05) with variability independent of the mean (+0.16 m/s) and maximum–minimum difference (+0.17 m/s). In home recordings, the urinary albumin-to-creatinine ratio (+1.27–1.30 mg/mmol) and pulse wave velocity (+0.36–0.40 m/s) increased (P<0.05) with systolic BP, whereas all associations of target organ damage with the variability indices were nonsignificant (P≥0.07). In conclusion, while accounting for BP level, associations of target organ damage with BP variability were readily detectable in beat-to-beat recordings, least noticeable in home recordings, with 24-hour ambulatory monitoring being informative only for pulse wave velocity.