Association between the cumulative excessive systolic blood pressure and left ventricular mass index

Abstract

Abstract Background Ambulatory blood pressure (ABP) has been increasingly adopted in day-to-day clinical practices. Although clinicians can access an enormous amount of information regarding an individual’s blood pressures (BPs) through the ABP monitoring (ABPM), to date, only the mean BP is utilized as the diagnostic threshold of hypertension and the therapeutic target for BP control and no other indices were widely used to assess the burdens of high BP in the ABPM. Because elevated systolic BPs (SBPs) cumulatively damage the myocardium and induce hypertrophy and fibrosis, we hypothesized that the summated value of BP readings beyond a target level may be the better indicator of the overall BP loads than the mean BP value. Methods The Korean ABP registry is a multicenter prospective longitudinal cohort study performed in outpatients with hypertension. Among 5,965 patients enrolled in the registry, 951 patients with valid ABPM records and appropriate echocardiography measurements included in the study. The left ventricular mass (LVM) was normalized using the height2.7(m) (LVM index [LVMIH2.7] = LVM/Height2.7). The cumulative excessive SBP CE-SBP) was defined as the summation of the products of excessive SBPs (≥135 mmHg during wake, ≥10 mmHg during sleep) and the durations of the excessive SBP (Figure 1). Results The CE-SBP was non-linearly associated with both the office SBP and the mean SBP, but the association strength was much greater with the mean SBP than with the office SBP (R2=0.902 vs. R2=0.430). In linear regression models, the association of the CE-SBP with the LVMIH2.7 (R2=0.112 [0.074-0.149]) was greater than that of the office SBP (R2=0.072 [0.040-0.103]), the mean SBP (R2=0.082 [0.049-0.116]) or the mean SBP during sleep (R2=0.99 [0.063-0.134]). Non-linear regression models using restrictive cubic spline fits also showed that the association strength was greater with the CE-SBP (R2=0.117 [0.078-0.155]) than with the office SBP, mean SBP or mean SBP during sleep (Figure 2). Left ventricular hypertrophy (LVH) defined as the LVMIH27 ≥54 g/m2.7 was better predicted with the CE-SBP than with the other SBPs. The association between the CE-SBP and LVMIH27 was stronger in the patients not taking antihypertensive medications (R2=0.121) and strongest in those with the non-dipper pattern (R2=0.125). Combination with the variability indices (successive variation and average real variability) during sleep or the maximum SBP during sleep significantly improved the association strength of CE-SBP with LMMIH27, whereas the combination with the mean SBP or the variability indices during the entire period did not, in the linear models. Conclusion The CE-SBP was more strongly associated with the LVMIH27 than the office SBP and the mean SBP in the ABPM. This result suggests that the CE-SBP may be the better indicator of overall BP loads than the office SBP or the mean SBP in the ABPM, in patients with hypertension.Figure 1Figure 2