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The objective of the MACH1 study (MEMS for the Assessment of Compliance of Hypertensives) was to evaluate the real behaviour of patients in relation to antihypertensive treatment administered as a single daily dose. After a 2-week period during which no other antihypertensive was allowed to be administered, 590 patients with mild-to-moderate hypertension received 2 mg of trandolapril as a single daily dose in the morning between 7:00 a.m. and 9:00 a.m. for 4 weeks. Treatment was packaged in electronic pillboxes recording the date and time of each opening. Various profiles were distinguished on the basis of the individual chronograms for the 501 patients able to be analysed in terms of compliance, and as a function of the deviations observed in relation to the treatment regimen prescribed. One hundred and two patients (20%) omitted more than 20% of the prescribed doses, either consecutive doses or scattered throughout the month of treatment; these patients were referred to as "omitters". The other patients were classified according to the scatter of openings in relation to the mean time of the dose: 10 "metronome" patients (2%), 126 "regular" patients (25%), 221 "irregular" patients (44%) and 42 "anarchic" patients (8%). Irregularities of dose times were more frequent on public holidays than on week days and in patients living in Paris or the Paris region. "Metronome" patients were older than the overall patient population. The use of an electronic pillbox could allow the attending physician to more adequately adapt his therapeutic approach and management of specific problems of compliance observed in hypertensive patients.

Clinical and 24-hour ambulatory measurements were made in 46 patients with mild to moderate essential hypertension in order to confirm that the efficacy and safety of sustained-release diltiazem LP 300 mg were the same regardless of the time of day at which it was taken. After two weeks of placebo, patients were randomly assigned double-blind to take diltiazem LP 300 mg either morning or evening for four weeks. Diltiazem LP 300 mg significantly lowered diastolic and systolic blood pressure in both groups by clinical or 24-hour ambulatory measurement, and without any difference according to whether diltiazem LP 300 mg was administered morning or evening. A lesser fall in blood pressure during the night in both groups led to study of the effect of diltiazem LP 300 mg according to initial ambulatory diastolic blood pressure level. Diltiazem brought about a greater fall in blood pressure when patients had an ambulatory diastolic pressure of 90 mmHg or more. Clinical, laboratory and electrocardiographic parameters were all satisfactory, regardless of the time at which the drug was taken.

Blood pressure (BP) is not a constant parameter, but exhibits variations, which involve a change in its value with time, and variability, which corresponds to the extent of this variation. A circadian pattern of BP, with higher values during the day than at night, is one expression of this variation in BP. This variation corresponding to the circadian pattern is dependent on both physical constraints and psychosensory factors. Investigation of variability implies consideration of both long-term and shorter term changes in BP. Long-term variability can be assessed by ambulatory determinations of BP, which can be carried out at intervals of 1/4 hour. This variability can be used to define the daytime/nighttime alteration of the circadian cycle, with the possible absence of the nocturnal reduction in BP or even a reversal of this circadian pattern. An abnormality of this type would be of prognostic importance, particularly in terms of impact on the left ventricle. Medium- or above all short-term variability can be assessed only from the change in beat/beat difference in BP and heart rate (HR) which depends on vagal tone and the orthosympathetic system. This variability can be detected by invasive methods and, more recently, using non-invasive methods (Finapres). It would seem that changes in this variability may reveal a defect in baroreceptor control which it is useful to identify for both diagnostic and therapeutic purposes.

Stress tests have been performed for a long time in patients with coronary disease. The study of blood pressure variations, under these circumstances, is also interesting in hypertension. Several types of stress tests, dynamic and static, may be performed. Dynamic tests on ergometric bicycles are the most frequently performed. The evolution of the BP during stress increases regularly and there is a linear correlation between the BP values and the level of work as well as the heart rate (HR). It is therefore possible to individualize a reference blood pressure profile, according to age and sex. The stress may find applications from a diagnostic, prognostic and therapeutic standpoint. First of all, in borderline HT, the stress test enables to confirm the HT and better differentiate between hyperemotional and hyperkinetic patients. In severe hypertension, the stress test permits to better define the magnitude of the haemodynamic disorder. In true hypertensive patients, undergoing major physical stress (work, sports...) the stress test permits to evaluate the tolerance to stress and the faculties of myocardial adaptation. From a prognostic standpoint, the incidence of permanent hypertension is 2 to 3 times higher in patients presenting an abnormal blood pressure profile. There is a significant correlation between the BP at maximum stress and the left ventricular mass index at all stages of the HT. The stress test makes it possible to better define the mode of action of antihypertensive medications, prescribe a personalized treatment according to these patients reactivity to stress and guarantee the correction of blood pressure abnormalities, since normalisation at rest does not necessarily imply a normalisation during stress.