Stratification of vascular risk in hypertension and therapeutic perspective

Abstract

Hypertension is a major risk factor for cardiovascular disease and atherosclerosis is the cause of most hypertensive complications. Therefore the detection of preclinical atherosclerosis may contribute to the better identification of hypertensive subjects at high risk of complications. Three main alterations are currently able to be diagnosed noninvasively: calcification, thickening, and stiffening of the arterial walls. Calcification of epicardial coronary arteries can be seen noninvasively by ultrafast computed tomography thanks to its rapid acquisition of image. Coronary calcification of epicardial coronary arteries can be seen noninvasively by ultrafast computed tomography thanks to its rapid acquisition of image. Coronary calcification is typical of atherosclerosis but not of stenosis. Conversely, the absence of calcification eliminates, practically, coronary artery disease as a diagnosis. Coronary calcification is present in only 63% of asymptomatic hypertensive men, suggesting that the degree of coronary atherosclerosis associated with high blood pressure varies among individuals. Wall thickening can be quantified in vivo by automated computerized analysis of ultrasonic images of the far wall intima-media complex of extracoronary vessels. Carotid and femoral wall thickening was observed in hypertensive subjects who had never been treated for hypertension compared to normotensive controls of similar age. Such vascular hypertrophy was not found in all patients, attesting to the disparity of the structural arterial changes within hypertensive subjects. Recent evidence from studies of essential hypertension suggests the lack of association between diffuse wall thickening of carotid or femoral arteries and the presence of atherosclerotic plaque (focal echogenic encroachment) in the same vessel. However, other studies in at-risk subjects suggest that extracoronary wall thickening could be related to the presence of coronary atherosclerosis, and to the incidence of coronary events. Wall stiffening is the third arterial alteration related to the sclerotic component of atherosclerosis. Its evaluation is based on the velocity of pulse wave propagation within the arterial tree or on the ultrasonic (echotracking) assessment of arterial wall distension during the cardiac cycle. Arterial stiffening is increased in the presence of hypertension, and such an increase is potentiated by the presence of other risk factors, such as smoking or hypercholesterolemia. Finally, the detection of early atherosclerosis with the above techniques optimizes the stratification of atherosclerotic risk, and may provide relevant information on comparative effectiveness of various classes of antihypertensive agents.