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: Studies using ambulatory blood pressure (BP) monitoring have shown that BP during night-time sleep is a stronger predictor of cardiovascular outcomes than daytime ambulatory or conventional office BP. However, night-time ambulatory BP recordings may interfere with sleep quality because of the device cuff inflation and frequency of measurements. Hence, there is an unmet need for obtaining high quality BP values during sleep. In the last two decades, technological development of home BP devices enabled automated BP measurements during night-time. Preliminary data suggest that nocturnal home BP measurements yield similar BP values and show good agreement in detecting nondippers when compared with ambulatory BP monitoring. Thus, nocturnal home BP measurements might be a reliable and practical alternative to ambulatory BP monitoring to evaluate BP during sleep. As the use of home BP devices is widespread, well accepted by users and has relatively low cost, it may prove to be more feasible and widely available for routine clinical assessment of nocturnal BP. At present, however, data on the prognostic relevance of nocturnal BP measured by home devices, the optimal measurement schedule, and other methodological issues are lacking and await further investigation. This article offers a systematic review of the current evidence on nocturnal home BP, highlights the remaining research questions, and provides preliminary recommendations for application of this novel approach in BP management.

Background: The circadian rhythm of blood pressure (BP) is associated with a high span during the awake period and a low span during the sleep period. Of interest is that cardiovascular (CV) events occur more frequently in the early morning period, the time when BP and heart rate rise steeply., Objective: To provide an overview of circadian BP and its correlation with adverse clinical outcomes and to discuss strategies for optimizing BP control over 24 hours., Summary: Patients who have an excessive morning surge in BP and those who lack the normal nocturnal BP fall (nondippers) have been shown to have an excessive incidence of strokes, heart failure, and other CV events. While there are numerous pathophysiologic mechanisms underlying abnormalities in the 24-hour BP profile, including abnormalities in sympathetic nervous system activity, salt and volume balance, and activation of the renin-angiotensin aldosterone system, for many patients the mechanisms remain unclear. Nevertheless, several of these known abnormalities can be modified by clinical interventions, including proper timing of antihypertensive drug therapy and use of classes of antihypertensives for which a substrate exists to induce a pharmacologic effect. It is particularly important to use therapies that will provide control throughout a 24-hour dosing interval., Conclusion: While interventional strategies have not yet been shown to alter clinical outcomes, it is important to be cognizant of their physiologic basis and take them into consideration when making decisions regarding appropriate antihypertensive therapy.

In most individuals with hypertension, blood pressure (BP) shows a moderate to marked increase around the time of awakening, which has been linked to increases in cardiovascular complications occurring at this time of day. Many antihypertensive agents do not adequately control early morning BP, particularly when administered once daily in the morning. Points to consider in selecting an effective antihypertensive drug include pharmacokinetics and formulation of the agent and timing of administration. Agents with long pharmacologic half-lives, such as the angiotensin II receptor blocker telmisartan, the calcium antagonist amlodipine, and the beta-blocker bisoprolol, are examples of antihypertensive drugs with demonstrated efficacy in controlling early morning BP. Bedtime administration of chronotherapeutic preparations is also effective for controlling early morning BP. Given the association between early morning BP and cardiovascular risk, future clinical trials should focus on the efficacy of antihypertensive drugs during this important period of risk.

The circadian blood pressure (BP) rhythm is associated with worsened cardiovascular outcomes in patients who have an excessive morning BP surge and in those who lack the normal nocturnal BP fall (non-dippers). There are multiple pathophysiologic mechanisms underlying abnormalities in circadian BP, most importantly abnormalities in sympathetic nervous system activity, salt and volume balance, and activation of the renin-angiotensin system. Several of these factors can be modified by clinical interventions, either related to lifestyle changes and/or antihypertensive drug therapy. The timing of drug administration or specific drug delivery systems that lead to a greater effect at night and/or mitigate the early morning BP surge can correct abnormal circadian rhythms. Although these strategies have not yet been shown to alter clinical outcomes, it is reasonable to understand their biologic basis and take them into consideration when designing antihypertensive therapy.

Background: We conducted a large-scale, practice-based trial (MICCAT-2) to evaluate the effects of telmisartan alone and in combination with a diuretic on 24-h blood pressure (BP) profiles, including the early morning period, a time when cardiovascular risk is excessive., Methods: Patients with hypertension, either untreated or currently on treatment, were started on, or switched to, the angiotensin receptor blocker telmisartan 40 mg daily; after 2 weeks, if office blood pressure (BP) remained > or =140/85 mmHg, the dose was increased to 80 mg; and if necessary, hydrochlorothiazide 12.5 mg was added after a further 4 weeks and continued for a final 4-week period. Twenty-four-hour ambulatory blood pressure monitoring (ABPM) was performed at baseline and at the end of the treatment period. Baseline and treatment ABPM measurements were completed in 1619 patients., Results: There were highly significant reductions in both the daytime (-11.8/-7.2 mmHg) and night-time (-9.6/-5.7 mmHg) mean BP following telmisartan alone or in combination with the diuretic. Evaluation of the 24-h profiles showed evidence for sustained pharmacodynamic effects of telmisartan over the entire dosing period. Ninety-five (6%) patients had a marked surge in early morning BP defined as >30 mmHg post-awakening change in systolic BP. The average reduction of in the early morning (post-awakening) BP in the entire cohort was -11.5/-7.0 mmHg (P<0.001; reductions were similar for monotherapy and combination therapy groups. The early morning post-awakening BPs fell by an average of -17.2/-10.1 mmHg in patients with large morning BP surges (P<0.05 versus non-surge patients)., Conclusions: In a community based study using ambulatory BP monitoring, telmisartan-based therapy induced highly significant reductions in systolic and diastolic BP over 24 h and was particularly effective in reducing BP during the early morning period.

Background: Ambulatory blood pressure (BP) monitoring has shown that BP typically declines by 10% to 20% during sleep and increases fairly rapidly in the early morning period. Because the early morning period has been associated with both loss of hypertension control and increased rates of myocardial infarction and stroke, there has been interest in evaluating the effects of antihypertensive therapy at this particular time of the day. The purpose of this study was to assess the effects of a long half-life (telmisartan, 24 h) versus intermediate half-life (valsartan, 6 to 9 h) on early morning BP in two scenarios: after an active dose and after a missed dose of each agent., Methods: The study was a double-blind, randomized trial that compared telmisartan (40 to 80 mg once daily) versus valsartan (80 to 160 mg once daily) on early morning BP in 490 patients with hypertension. Ambulatory BP recordings were performed at baseline after a placebo period and again after 6 and 8 weeks of double-blind therapy in a randomized cross-over design. The monitoring patients received either an active dose or a placebo dose (to mimic a "missed" dose). The primary study end point was reduction in the BP in the early morning period (last 6 h of the dosing period)., Results: After the active dose, telmisartan reduced the BP during the last 6 h of the dosing period by -11/-7.6 +/- 0.8/0.6 mm Hg compared to -8.7/-5.8 +/- 0.8/0.6 mm Hg on valsartan (P = .02 for systolic BP and.01 for diastolic BP). On the day of the missed dose, telmisartan reduced the early morning BP by -9.0/-6.3 +/- 0.7/0.6 mm Hg versus -7.4/-5.1 +/- 0.7/0.4 mm Hg on valsartan (P = .09 for systolic BP and.06 for diastolic BP). On the day of the missed dose, reductions in 24-h average BP for the two antihypertensive agents were -10.3/-6.9 mm Hg for telmisartan versus -8.7/-5.9 mm Hg for valsartan (P = .06 for systolic BP and.056 for diastolic BP)., Conclusions: On a day of active therapy, telmisartan lowered both systolic and diastolic BP to a greater extent than valsartan for the last 6 h of the dosing interval. On a day in which a dose was missed, there was a notable trend for greater BP reduction during the latter part of the dosing interval on telmisartan versus valsartan. These results demonstrate that telmisartan achieved a greater effect than valsartan on BP during the early morning period in patients with hypertension.

Ambulatory blood pressure monitoring (ABPM) is a highly useful diagnostic tool as it can detect non-dipping and can distinguish masked hypertension, white-coat hypertension and sustained hypertension. Furthermore, measurement of blood pressure using ABPM has greater prognostic strength than single clinic blood pressure measurements. The Systolic Hypertension in Europe study, for example, found that elevation of ambulatory systolic blood pressure, but not conventional single cuff systolic blood pressure, by 10 mmHg was associated with adverse cardiovascular outcomes. Blood pressure follows a circadian rhythm, with peak levels during the morning hours. The morning period has also been associated with a greater risk for cardiovascular events compared with the rest of the 24 h. The morning surge in blood pressure, along with haemostatic changes that promote thrombosis, is believed to contribute to this heightened risk. Long-acting antihypertensive agents that provide blood pressure control throughout the 24-h dosing interval, including the morning hours, are the most appropriate therapeutic approach to hypertension. Direct comparative studies with telmisartan and other angiotensin-II receptor blockers and with amlodipine have shown that telmisartan has a long duration of action and controls blood pressure over the 24-h dosing period.

The incidence of most adverse cardiovascular events appears to follow a circadian pattern, reaching a peak in the morning shortly after wakening and arising. The activities of many physiologic parameters, including hemodynamic, hematologic and humoral factors, also fluctuate in a cyclical manner over the 24h. It has been suggested that, during the post-awakening hours, the phases of these cycles synchronize to create an environment that predisposes to atherosclerotic plaque rupture and thrombosis in susceptible individuals, thereby accounting for the heightened cardiovascular risk at this time of day. Blood pressure and heart rate are part of this physiologic process, following a clear circadian rhythm characterized by a fall during sleep and a sharp rise upon awakening. This so-called 'morning surge' in blood pressure may act as a trigger for cardiovascular events, including myocardial infarction and stroke. The clinical implication of these observations is that antihypertensive therapy should provide blood pressure control over the entire interval between doses. For agents taken once daily in the morning, the time of trough plasma drug level (and lowest pharmacodynamic effect) will often coincide with the early morning surge in blood pressure and heart rate. For these reasons, chronotherapeutic formulations of drugs and intrinsically long-acting antihypertensive agents provide the most logical approach to the treatment of hypertensive patients since they provide 24 h blood pressure control from a single daily dose as well as attenuating the early morning rise in blood pressure (and in some instances heart rate).

Ambulatory blood pressure monitoring (ABPM) has been increasingly used in hemodialysis (HD) practice and research; however, no study has evaluated the reproducibility of ABPM in this population. To address this question, we performed 48-hour interdialytic ABPM on 21 HD patients (mean age, 53 +/- 16 years; 7 women) on two different occasions 68 +/- 34 days (range, 30 to 154 days) apart. To qualify for the protocol, patients had to be at the same dry weight and on the same vasoactive drug regimen at both monitoring periods. BP was analyzed according to three different methods: isolated pre-HD and post-HD values, average pre-HD and post-HD values for the five HD sessions surrounding each monitoring period, and 48-hour interdialytic ABPM. Reproducibility was determined by analysis of the SD of the differences (SDD) between the two monitoring periods and the coefficient of variation of each method of BP determination. Our results show better reproducibility of ABPM (SDD, 10.6/6.6 mm Hg; coefficient of variation, 7.5%/8.1%) compared with isolated pre-HD BP (SDD, 24.4/11.3 mm Hg; coefficient of variation, 16.7%/14.1%) or post-HD BP (SDD, 16.8/14.5 mm Hg; coefficient of variation, 11.7%/17.8%), and averaged pre-HD BP (SDD, 14.7/7.2 mm Hg; coefficient of variation, 10.1%/9.1%) or post-HD BP (SDD, 12.4/8.7 mm Hg; coefficient of variation, 8.9%/11.1%). The reproducibility of the decrease in BP during sleep was poor, with up to 43% of the subjects changing dipping category within or between interdialytic periods. We conclude that ABPM is the most accurate method to study BP in HD patients over time. However, variability is significant, and there is poor reproducibility of the nocturnal decline in BP.

We studied how closely changes in electronically monitored physical activity are reflected in changes in blood pressure and heart rate in a group of untreated hypertensive subjects. Thirty-nine hypertensive patients (office blood pressure > 140/ 90 mm Hg) of mean age 57 +/- 10 years (mean +/-SD) wore an ambulatory blood pressure monitor and a wrist actigraph simultaneously. Both average and peak activity for 5 min before each valid blood pressure reading were determined, as was average activity for awake and sleep periods, determined by patient kept diaries. For the overall group, awake and 24-h activities were inversely correlated to age (n = 39, r = -0.42; P = 0.01 and n = 39, r = -0.38; P = 0.01, respectively). No correlation was found between group awake activity and group-average blood pressure or heart rate. For individual patients, there was marked variation in the degree of correlation between awake activity measures (both peak and average) and blood pressure and heart rate. The strongest positive correlation was between activity levels and the heart rate-pressure product. Nondipper profile hypertensives had higher sleep activity than dipper hypertensives (44 +/- 28 units/min v 25 +/- 20 units/min, df = 37, t = 2.12; P = 0.04), but awake activity levels were similar. The higher sleep activity remained after adjustment for age. These findings indicate that the relationship between actigraphic activity and hemodynamic parameters is highly variable and that the rate-pressure product is the strongest correlate of short-term activity. Furthermore, hypertensives with the nondipper profile have higher sleep activity than dipper hypertensives. These findings stress the need for further study into the role of day-to-day activity in determining ambulatory blood pressure and heart rate variability.

The time of administration of once-daily antihypertensive agents may have a significant impact on blood pressure control during awake and sleep periods. Using 24-h ambulatory monitoring, we compared the effects of morning and evening dosing of the long-acting dihydropyridine calcium channel blocker, nisoldipine extended-release (ER), on circadian blood pressure (BP) and heart rate in patients with mild-to-moderate hypertension. After completing a 3-week placebo run-in period, 85 patients were randomized to morning versus evening nisoldipine ER treatment at a fixed 20-mg dose. Patients were treated for 4 weeks, followed by crossover to the alternate dosing regimen for 4 additional weeks. Twenty-four-hour ambulatory monitoring was performed at baseline and at 4 and 8 weeks after randomization. Awake and sleep times were determined by electronic activity recorders (Actigraphy). Similar least-squares (+/-SE) mean changes from baseline in 24-h BP (systolic BP/diastolic BP: -11.9/-7.4 +/- 0.6/0.5 v -11.6/-6.5 +/- 0.6/0.5 mm Hg) and heart rate (1.0/1.7 +/- 0.4/0.4 beats/min) occurred with morning and evening administration, respectively. A significantly greater effect on awake diastolic BP (systolic BP/diastolic BP: -12.6/-8.1 +/- 0.7/0.4 v -11.3/-6.4 +/- 0.7/0.4 mm Hg; P = .16/.01) was observed with morning dosing compared with evening dosing. In addition, small increases in sleep and early morning heart rate were seen with evening compared with morning administration of nisoldipine (sleep, 3.1 +/- 0.4 v 0.4 +/- 0.4 beats/min; P < .001; early morning, 3.5 +/- 0.7 v 0.5 +/- 0.7 beats/min; P = .002). These differential effects on awake BP and sleep heart rate were also observed in patients who had normal (dippers) and elevated (nondippers) BP values during sleep. Appropriate evaluation of the efficacy and safety of long-acting antihypertensive agents is essential when evening administration is being considered. In the present study, the timing of nisoldipine ER administration had no effect on mean changes in BP and heart rate over a 24-h period. However, nisoldipine ER had some differential effects during sleep and awake periods with morning relative to evening dosing.

The inherent variability of activity and the awake-sleep cycle creates changes in hemodynamics that may influence the outcome of a variety of cardiovascular disorders. Recently, data suggest that increased variability of blood pressure may promote excessive hypertensive target organ disease. Several epidemiologic studies have demonstrated that myocardial ischemia, myocardial infarction and sudden cardiac death have an excess incidence in the first several hours post-awakening. Additionally, surveys of the incidence of stroke (both ischemic and hemorrhagic) have shown an excess for the hours between 8 a.m. and noon. The pathophysiologic bases for the increased number of cardiac and cerebrovascular events in the early morning hours may be both due to hemodynamic and hematorrheologic factors. During the past several years, therapeutic studies have evaluated the effects of antihypertensive therapies on blood pressure and heart rate during the circadian or 24 h period. There are a few studies that have evaluated nighttime dosing of conventional antihypertensive therapies but these have generally been statistically underpowered to demonstrate differences of morning versus evening dosing on circadian blood pressure. Since the timing of dosing (and hence the delivery of antihypertensive therapy) may be clinically relevant, prospective and well-performed clinical trials of chronotherapy are necessary. In this review, we evaluate new data on the clinical impact of cardiovascular chronotherapy and the importance of timing of dosing on pharmacodynamics.

Chronotherapeutics, or delivery of a medication in concentrations that vary according to physiological need at different times during the dosage period, is a relatively new practice in clinical medicine. Epidemiological studies document that the incidence of many cardiovascular diseases, including myocardial infarction and stroke, varies predictably in time over 24 hours (the circadian period). Advanced diagnostic technologies using ambulatory monitoring of the blood pressure and electrocardiogram have also demonstrated that there is marked variability in the level of pressure in hypertensive patients and the degree of myocardial ischaemia in patients with coronary disease. These diagnostic techniques also allow us to study the effects of varying the timing of administration or delivery of a concentration of a drug on end-points such as changes in blood pressure, heart rate or intensity of angina. The first chronotherapeutic agent for hypertension and angina pectoris, controlled onset, extended release (COER-24) verapamil, has recently been developed and registered in the US, Brazil, Canada and Mexico. The theoretical advantage of this formulation is that delivery of the active drug, verapamil, has been tailored to the typical circadian rhythm of blood pressure and heart rate in patients with hypertension and angina to better cover the early morning hours when cardiovascular need appears to be the greatest. An outcome study (CONVINCE) that evaluates primary prevention of cardiovascular events with this chronotherapy versus standard of care therapy is under way in several countries in North and South America and Europe.

A less-than-normal decline in nocturnal blood pressure (BP) has been associated with excessive hypertensive complications. This is concerning because secondary hypertension is often associated with this so-called nondipper BP profile. A nondipping pattern is more frequently found in the presence of pheochromocytoma, Cushing's syndrome, and sleep apnea syndrome, but the prevalence is unclear in patients with primary hyperaldosteronism. We therefore studied ambulatory BP profiles in 16 hypertensive patients with primary hyperaldosteronism and an equal number of essential hypertensive subjects. The awake-sleep BP difference of the hyperaldosteronism patients was similar to that of essential hypertensives (15/14 +/- 3/2 versus 14/9 +/- 3/2 mm Hg, P=NS). The prevalence of dippers and nondippers (according to two distinct criteria) in the two groups was similar. Repeat ambulatory BP monitoring in 12 subjects with primary hyperaldosteronism after specific intervention (3 after surgical removal of an adrenal adenoma and 9 after commencement and titration of spironolactone therapy) showed highly significant reductions in office BP (22/10 +/- 6/4 mm Hg, P<.05) and awake and sleep BP. However, the extent of nocturnal BP decline was unchanged between the two studies (17/16 +/- 3/3 versus 16/12 +/- 2/2 mm Hg, P=NS). There was no correlation between the awake-sleep difference and serum or urinary aldosterone levels or the aldosterone-to-renin ratio. In this study, we did not detect any differences in the awake-sleep differences between a group of hypertensives with primary hyperaldosteronism and a control group of essential hypertensives.

Approximately 1 in 4 patients with systemic hypertension have a 24-hour blood pressure (BP) profile characterized by a blunted or absent nocturnal decline in pressure. We evaluated the effects of a chronotherapeutic delivery system of controlled-onset extended-release (COER) verapamil hydrochloride and placebo in 257 hypertensive patients according to their circadian BP pattern in an 8-week prospective, multicenter, randomized, and double-blind clinical trial. Patients were stratified into 193 dippers (>10% decline in BP during the period of 10 P.M. to 5 A.M. compared with the hours of 5 A.M. to 10 P.M.) and 64 nondippers (<10% decline in BP during nighttime). During daytime, placebo-subtracted BP was similarly decreased in dippers and nondippers by COER verapamil. During nighttime, the placebo increased nocturnal BP in dippers (baseline nocturnal BP, 133/78 mm Hg) by 3/3 +/- 2/2 mm Hg and reduced BP by -5/-3 +/- 2/2 mm Hg in nondippers (baseline nocturnal BP, 152/94 mm Hg) (p = NS between groups). After controlling for age, gender, ethnicity, and the regression to the mean observed on placebo for all doses, COER verapamil reduced nocturnal BP more in nondippers than dippers -5.8/-2.4 mm Hg, p <0.0001 for systolic BP and p = 0.09 for diastolic BP). Additionally, a significant dose-related reduction in systolic and diastolic nocturnal BP (r = 0.56, p <0.0001 for systolic BP and r = 0.62, p <0.0001 for diastolic BP) was observed with COER verapamil after controlling for baseline covariates. These data demonstrate that nocturnal BP is decreased by a greater extent in nondipper hypertensives than in dipper hypertensives following treatment with COER verapamil HCL.

Patients with hypertension have a characteristic circadian pattern of blood pressure (BP) variability in a 24-h period, characterized by a wide range while awake and active, and a narrower range during sleep and inactivity. Blood pressure in the untreated hypertensive individual declines by approximately 10% to 20% during sleep compared with the mean awake BP values. Early in the morning (assuming a typical day-night activity cycle), the BP rises sharply on awakening, when physical and mental activities increase. Antihypertensive therapy has been traditionally dosed in the morning after awakening, and in recent years most of the newly developed antihypertensive agents have been once-daily, long-acting preparations. However, theoretically, this pattern of drug dosing may be suboptimal since pharmacodynamic activity is attenuated at the end of the dosing period, when a large rise in BP may occur. Presently, only a few studies have been performed to evaluate the effects of nocturnal dosing of standard long-acting drugs. Consequently, we undertook an assessment of the effects of a new formulation of verapamil--controlled onset extended release verapamil HCl (COER-24)--that is dosed nocturnally and has a controlled onset of delivery (4 to 5 h postdose) and an extended release for the remainder of the dosing period. Through ambulatory BP monitoring, evaluation revealed that this verapamil formulation produced changes in BP that followed the circadian rhythm of BP: lower reductions during sleep, when the BP is intrinsically lowest, and appropriately larger reductions during the early morning and daytime hours, when ambulatory BP values accelerate and plateau to their highest levels. These data demonstrate that it is possible to design antihypertensive therapy for once-nightly dosing, thereby providing a chronotherapeutic regimen for patients with hypertension.

Noninvasive 24-h blood pressure (BP) monitoring has demonstrated a diurnal blood pressure profile in most individuals that is characterized by higher arterial pressures during wakefulness and lower pressures at night during sleep. Recently, reports suggest that this typical diurnal variation is absent in syndromes of autonomic dysfunction and in some forms of secondary hypertension. We investigated the 24-h BP, BP variability, and adrenal steroid concentrations in a patient with deoxycorticosterone (DOC)-secreting adrenal adenoma prior to and following adrenalectomy. Preoperatively, when the patient had a ten-fold increase in serum concentrations of DOC, there was no fall in nocturnal BP despite a marked reduction in heart rate during sleep. Postoperatively, when the concentrations of DOC and other adrenal steroids returned to normal values, the 24-h BP profile normalized with restoration of the nocturnal reduction in pressure. These findings document the effects of mineralocorticoid overproduction on diurnal BP regulation. Intensive investigation of individuals with a well-defined etiology of hypertension and the absence of diurnal variation of BP may lead to further hypotheses that will define the role of both autonomic and nonautonomic factors in BP control.

Purpose: Ambulatory blood pressure monitoring has helped to identify different patterns of diurnal blood pressure variability in hypertensive patients. This review examines the available data, with special reference to diabetic hypertensives., Data Identification: The diurnal rhythm is absent or abnormal in certain disease states, including diabetes mellitus, Cushing's syndrome, hyperaldosteronism and renal failure. Lack of a nocturnal decline in blood pressure is clinically significant, as it is associated with a greater prevalence of hypertensive target-organ disease., Study Selection: Clinical studies were assessed, in which casual and 24-h blood pressure measurements were available from normotensive and hypertensive patients with insulin-dependent or non-insulin-dependent diabetes mellitus., Results of Data Analysis: Studies comparing the diabetic with the non-diabetic normotensive (based on casual, or office blood pressure measurements) have shown that 24-h mean blood pressures are higher in diabetics. In insulin-dependent diabetics, the incidence of elevated nocturnal pressure appears to be greater than in non-insulin-dependent diabetics. Furthermore, recent reports have shown that ambulatory blood pressure is more closely correlated than casual blood pressure with urinary albumin excretion in type 1 diabetic hypertensives., Conclusions: Ambulatory blood pressure monitoring reveals certain characteristic blood pressure variability in the diabetic patient with hypertension and allows an assessment of the effects of antihypertensive drug therapy in order to ensure blood pressure control.

The associations of age, blood pressure and cardiac structure with rapid left ventricular filling were assessed in 47 subjects (21 normotensives and 26 age-matched untreated hypertensives) by 24-h ambulatory blood pressure monitoring, sector-guided M-mode echocardiography and radionuclide ventriculography. Univariate analyses revealed strong negative correlations of the left ventricular filling rate with age, and 24-h systolic and diastolic blood pressure, and a moderate positive correlation with the left ventricular ejection fraction at rest. Multiple regression analysis was performed with these variables, left atrial size and left ventricular mass index. Left atrial size and the left ventricular mass index were dependent on 24-h blood pressure, indicating that these two cardiac structural variables were less important than left ventricular filling. Age was undoubtedly the most important correlate of left ventricular filling, since 88% of the subjects over 53 years of age had reduced left ventricular filling rates regardless of the blood pressure status. However, under the age of 53 years, only the hypertensives had reduced filling rates. Thus, our study shows that the left ventricular filling rate is more dependent on age and 24-h blood pressure than on the left ventricular mass index. Furthermore, in patients over 53 years of age, it is not possible to separate the effects of hypertension on the diastolic function of the heart from the physiological alterations associated with ageing.