A 'pressure-time index' for assessing the severity of essential hypertension

Objective A new derivative of 24 h ambulatory blood pressure monitoring (AB PM) is introduced and its association with left ventricular mass index (LVM I) in essential hypertension is examined. Patient population One hundred and fifty-three previously untreated essenti al hypertension patients. Methods Patients underwent casual blood pressure (BP) readings, 24 h ABPM a nd left ventricular echocardiographic assessment The following 24 h awake a nd sleep ABP variables were calculated: mean systolic and diastolic BP, sys tolic and diastolic BP loads (percentage of systolic readings > 140/120 mmH g (day/night) and diastolic readings > 90/80 mmHg (day/night), standard dev iation of systolic and diastolic ABP and nocturnal fall of systolic BP, as well as the integrated areas under the ABP curve. The area under the BP cur ve divided in horizontal slices was accurately modelled by a sigmoid curve. The parameters controlling the shape of the curve and in particular that r egarding its 'slope' is hereafter called the 'pressure-time index'. Results 'Systolic pressure-time index 24 h' (SPTI24) is related to left ven tricular mass index (multivariate analysis, P = 0.008). Using either partia l correlation coefficients or a multivariate analysis, SPTI24 is related to left ventricular mass index, independently of age, casual blood pressure, mean systolic and diastolic ABP, systolic and diastolic BP loads, BP variab ility (standard deviation (SD), nocturnal fall of systolic BP) and integrat ed area under the curve (multivariate analysis, P = 0.004). Conclusions In essential hypertension, the SPTI24 is related to LVMI indepe ndently of age, casual blood pressure, integrated area under the curve or a ny other derivative of 24 h ABPM, and might be used to assess the extent of hypertensive load. J Hypertens 1999, 17:1387-1393 (C) Lippincott Williams & Wilkins.