STATISTICAL EVALUATION OF CIRCADIAN BLOOD-PRESSURE RHYTHM DURING ISRADIPINE LONG-TERM THERAPY

In this study, using the two-step truncated Fourier series with four h armonics,we analysed the diurnal blood pressure profile in 13 mild-mod erate essential hypertensive patients during isradipine long-term ther apy. Circadian parameters such as the amplitudes and phases of the fou r harmonics and the overall amplitude and phase were obtained from the model. The total duration of the study was 26 weeks. Ambulatory blood pressure was measured at 15-min, intervals using a Takeda TM 2420 dev ice after 2 weeks of placebo and after 6 and 26 weeks of isradipine (5 mg daily) respectively. After 6 and 26 weeks therapy the blood pressu re values showed a significant decrease, although the daily blood pres sure curves obtained from Fourier analysis showed that the circadian r hythm was not altered by isradipine treatment. Both the night/day diff erences and the overall amplitude/acrophases were statistically signif icant at 0,6 and 26 weeks. According the nocturnal blood pressure fall , we found that long-term therapy with isradipine increased the number of patients with nocturnal blood pressure fall and reducing the early morning blood pressure rise. In conclusion, the two-step method Fouri er analysis represents a novel and useful statistical approach to eval uate the presence of a significant diurnal blood pressure rhythm and t o provide the circadian parameters of the 24-h blood pressure profile during pharmacological therapy.