The smoothness index, but not the trough-to-peak ratio predicts changes incarotid artery wall thickness during antihypertensive treatment

Background It has recently been demonstrated that the smoothness index (SI) (the ratio between the average of the blood pressure changes computed for each hour of the recording and its standard deviation), a new and reproduci ble measure of the homogeneity of blood pressure reduction by antihypertens ive treatment, has evident advantages over trough-to-peak ratio (T/P) in th e prediction of the regression of left ventricular hypertrophy. Therefore w e considered it to be worthwhile to compare the ability of SI and T/P to pr edict changes of the carotid artery intima-media thickness (IMT) during pha rmacological treatment in patients with essential hypertension. Methods In 100 patients with essential hypertension, 24 h ambulatory blood pressure and carotid artery IMT were measured after 3 weeks of therapeutic wash-out and after 12 months of antihypertensive treatment (calcium antagon ists, diuretics, angiotensin converting enzyme (ACE) inhibitors or beta -bl ockers), The homogeneity of the effect of treatment over blood pressure was evaluated by computing T/P and SI. Results Twenty-four hour blood pressure was significantly reduced by therap y, while, on average, a small but significant increase in indices of caroti d artery wall thickness was observed, However, IMT was clearly reduced in p atients with high SI. Statistically significant correlations were observed between changes in indices of carotid artery IMT during therapy and SI. No significant correlation was observed between indices of carotid artery morp hology and T/P, basal 24 h blood pressure or changes in blood pressure duri ng therapy. Conclusions SI, but not T/P is the predictor of changes in carotid artery w all thickness. The information provided by SI is independent from basal blo od pressure values. For carotid artery morphology, the smoothness of blood pressure reduction is even more important than its absolute change. (C) 200 1 Lippincott Williams & Wilkins,