Which systolic blood pressure shows closest associations with left ventricular mass? the international 24 hour aortic blood pressure consortium (i24abc)

Objective: Central systolic blood pressure (cSBP) may be closer associated with hypertensive organ damage, namely left ventricular mass (LVM) and hypertrophy (LVH), as compared to brachial SBP (bSBP), and 24hour ambulatory SBP may be closer associated with LVM and LVH, as compared to office SBP. We sought to address this by pooling data from 21 centers worldwide. Design and method: In all centers, bSBP and cSBP was measured with the same validated oscillometric upper arm device (Mobil-O-Graph, I.E.M., Germany), using a transfer function for central pressure, and systolic/diastolic pressure (cSBPC1) or mean/diastolic pressure (cSBPC2) calibration. LVM was determined by echocardiography, and indexed to body surface area (LVMi). Results: We studied 2367 participants (45.5% women), 31.3% treated with antihypertensives. Mean age of 50.8 years (range 10-104 years). Average brachial office BP was 137/89 mm Hg, average brachial 24hour BP was 126/80 mm Hg. Average LVMi was 89.9 g/m 2 , and 24.1% had LVH. The correlation coefficients between LVMi and office bSBP, office cSBPC1, office cSBPC2, 24hour bSBP, 24hour cSBPC1, and 24hour cSBPC2 were 0.21, 0.20, 0.29, 0.31, 0.29, and 0.38, respectively. Based on z-statistics, the relationship between LVMi and office /24hour cSBPC2 was closer than with the other office/24hour SBPs (p = 0.0001 and 0.0002 for comparison with bSBPs, respectively). These findings were consistent in men and women, across all age groups, in lean, overweight and obese individuals, and in individuals with or without antihypertensives. In ROC analysis, the area under the curve (AUC) for detection of LVH was 0.626, 0.632, 0.668, 0.659, 0.653, and 0.687 for office bSBP, office cSBPC1, office cSBPC2, 24hour bSBP, 24hour cSBPC1, and 24hour cSBPC2, respectively – Figure). The AUC for office/24hour cSBPC2 was significantly larger, as compared to office/24hour bSBP (p < 0.0001 for both comparisons). Conclusions: In a large international research consortium, we observed that 24hour cSBP, measured with an oscillometric cuff, shows a significantly closer association with hypertensive cardiac organ damage than the related brachial SBPs. In addition, the method of waveform calibration is crucial.