Ambulatory Arterial Stiffness Index As A Predictor Of Cardiovascular Diseases In Patients With Essential Hypertension

Objective Ambulatory arterial stiffness index (AASI) has been recently proposed to reflect the dynamic relation between diastolic and systolic blood pressure throughout the whole day. The aim of our study was to investigate the prognostic value of AASI in relation to cardiovascular outcomes in patients with essential hypertension.Methods 337 patients with essential hypertension and 156 healthy controls (control group) were enrolled. Detailed clinical data of these subjects were collected, including 24 hour ambulatory blood pressure monitoring recordings, mean arterial pressure (MAP), 24h heart rate (24h HR), 24h pulse pressure (24h PP) and so on. Then followed up 101 patients with hypertension alone, and the endpoint was occurring heart incidents (including myocardial infarction, angina pectoris, heart failure, sudden cardiac death) and stroke. Patients with essential hypertension were divided into three subgroups according to level of blood pressure, two groups according to whether complicating cardiovascular diseases, event group and non-event group according to the outcomes of following-up. The values of above indexes were compared between patients with essential hypertension and control group, and among subgroups of patients with essential hypertension. Then the correlation of AASI with age, MAP, 24hHR and 24hPP were analyzed. We calculated odds ratio (OR) by logistic regression in order to assess the prognostic value of AASI in relation to cardiovascular outcomes in patients with essential hypertension.Results (1). In 156 healthy individuals, AASI increased with age, and the correlation coefficient between AASI and 24h PP was 0.436(P<0.01). (2). The values of MAP, 24h PP and AASI of the patients with hypertension alone were significantly higher than those of the control group (P<0.01). But the age, BMI, 24h HR and AASI were not gradually blunted with the increment of blood pressure level (P>0.05). The value of AASI was significantly higher, the MAP was lower in the patients complicating cardiovascular diseases than in those of the hypertension alone (P<0.01). (3) There existed significant positive correlations between AASI and age (r=0.390, P<0.01), negative correlations between AASI and 24h HR (r=-0.176, P<0.01). There were curve correlation between 24h PP and age (correlation index R=0.69), linear correlation between 24h PP and 24h HR (r=-0.279, P<0.01). But AASI and 24h PP were not correlated with MAP (P>0.05). (4) The value of age, 24h PP, AASI in event group were higher than in non-event group, but 24h HR was lower than those in non-event group (P<0.05). (5) In univariate logistic regression analysis, age, 24h DBP, MAP, 24h PP and AASI had significant prognostic value for cardiovascular outcomes (P<0.05). In multivariate analysis, 24h PP and AASI had significant prognostic value for cardiovascular outcomes (OR=2.451, P=0.010 and OR=2.158, P=0.023, respectively).Conclusions The differences of AASI between patients with essential hypertension and control group or among subgroups of patients with hypertension were significant, indicating AASI as a new measure of arterial stiffness in essential hypertension. AASI is a significant and independent predictor of cardiovascular disease in patients with essential hypertension through logistic univariate and multivariate analysis.