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(Hypertension. 1998;32:424-429.)
© 1998 American Heart Association, Inc.

Scientific Contributions

Reproducibility and Clinical Value of the Trough-to-Peak Ratio of the Antihypertensive Effect

Evidence From the Sample Study

Stefano Omboni; Roberto Fogari; Paolo Palatini; Alessandro Rappelli; Giuseppe Mancia; ; for the SAMPLE Study Group

From the Cattedra di Medicina Interna, Ospedale San Gerardo, Monza, Università di Milano, Centro di Fisiologia Clinica e Ipertensione, Ospedale Maggiore, and Istituto Scientifico Ospedale San Luca, Istituto Auxologico Italiano, Milano (S.O., G.M.); Dipartimento di Medicina Interna e Terapia Medica, Università di Pavia, Pavia (R.F.); Clinica Medica I, Università di Padova, Padova (P.P.); and Istituto di Patologia Medica, Ospedale Umberto I, Università di Ancona, Ancona (A.R.), Italy.

Correspondence to Giuseppe Mancia, MD, Cattedra di Medicina Interna, Ospedale San Gerardo dei Tintori, Università di Milano, Via Donizetti 106, 20052 Monza (Milano), Italy. E-mail mancia.g{at}imiucca.csi.unimi.it

Abstract—The objectives of our study were to assess the reproducibility of the trough-to-peak ratio (T/P) and to see whether a high T/P is accompanied by more organ protection or vice versa. The study included 175 (mean±SD age, 51±9 years) subjects with mild-moderate essential hypertension who had echocardiographic evidence of left ventricular (LV) hypertrophy taken from the SAMPLE study (Study on Ambulatory Monitoring of Blood Pressure and Lisinopril Evaluation), an open-label multicenter study. The study included a 3-week washout pretreatment period, a 12-month treatment period with lisinopril (n=84) or lisinopril plus hydrochlorothiazide (n=91) once daily, and a 4-week placebo follow-up period. Results of 24-hour ambulatory blood pressure monitoring and echocardiographic determination of left ventricular mass index (LVMI) were obtained before and after 3 and 12 months of treatment. T/Ps were computed in each patient by dividing the systolic and diastolic blood pressure changes at trough (changes in the last 2 hours of the monitoring period) by those at peak (average of the 2 adjacent hours with the maximal blood pressure reduction between the 2nd and 8th hour from drug intake) after 3 and 12 months of treatment. Average 24-hour blood pressure was similarly reduced at 3 and 12 months. Trough blood pressure changes at 3 and 12 months were closely correlated, as were the corresponding peak blood pressure changes. However, the 3- and 12-month T/Ps correlated to a lesser degree (r<0.42). Furthermore, the reduction of LVMI induced by treatment was similarly correlated with the treatment-induced reduction in 24-hour average, trough, and peak blood pressures but not with the T/Ps. This was also evident when the contribution to LV hypertrophy regression by 24-hour blood pressure changes and T/Ps was assessed in a multivariate regression analysis. In patients with a T/P 0.5 or <0.5, the regression of LVMI was similar. In conclusion, peak and trough blood pressure changes are reproducible and predict the regression of LVMI induced by treatment as well as average 24-hour blood pressure. T/Ps are less reproducible, and their value does not predict regression of organ damage by antihypertensive treatment.

Key Words: trough-to-peak ratio • blood pressure monitoring, ambulatory • hypertrophy, left ventricular • lisinopril • hydrochlorothiazide • antihypertensive agents