Maria J. Fontao

Effects of Time of Day of Treatment on Ambulatory Blood Pressure Pattern of Patients With Resistant Hypertension

Patients with resistant hypertension present high prevalence of a non-dipper blood pressure pattern. Recent results indicate that non-dipping is related partly to the absence of 24-hour therapeutic coverage in patients treated with single morning doses. Accordingly, we investigated the impact of treatment time on the blood pressure pattern in 700 patients with resistant hypertension on the basis of clinic measurements who were studied by 48-hour ambulatory monitoring. Among them, 299 patients received all their medication on awakening, and 401 were taking ≥1 antihypertensive drug at bedtime. The percentage of patients with controlled ambulatory blood pressure was double in patients taking 1 drug at bedtime (P=0.008). Among the 578 patients with true resistant hypertension, subjects receiving 1 drug at bedtime showed a significant reduction in the 24-hour mean of systolic and diastolic blood pressure (3.1 and 1.6 mm Hg, respectively; P<0.011). This reduction was much more prominent during nighttime (5.1 and 3.0 mm Hg; P<0.001). Accordingly, the diurnal/nocturnal blood pressure ratio was significantly increased by 2.7 and the prevalence on non-dipping reduced (56.9 versus 81.9%; P<0.001) in patients taking 1 drug at bedtime. Compared with patients receiving all drugs on awakening, subjects with 1 drug at bedtime also showed significant reductions in the average values of glucose, cholesterol, fibrinogen, and urinary albumin excretion (P<0.011). In patients with resistant hypertension, pharmacological therapy should take into account when to treat with respect to the rest–activity cycle of each patient to improve control and to avoid the non-dipper pattern associated to higher cardiovascular risk.

Administration-Time-Dependent Effects of Doxazosin GITS on Ambulatory Blood Pressure of Hypertensive Subjects

Previous studies have shown that a single nighttime dose of standard doxazosin, an α-adrenergic antagonist, reduces blood pressure (BP) throughout the 24 h. We investigated the administration-time-dependent effects of the new doxazosin gastrointestinal therapeutic system (GITS) formulation. We studied 91 subjects (49 men and 42 women), 56.7 ± 11.2 (mean ± SD) yrs of age with grade 1–2 essential hypertension; 39 patients had been previously untreated, and the remaining 52 had been treated with two antihypertensive medications with inadequate control of their hypertension. The subjects of the two groups, the monotherapy and polytherapy groups, respectively, were randomly assigned to receive the single daily dose of doxazosin GITS (4 mg/day) either upon awakening or at bedtime. BP was measured by ambulatory monitoring every 20 min during the day and every 30 min at night for 48 consecutive hours just before and after 3 months of treatment. After 3 months of doxazosin GITS therapy upon awakening, there was a small and nonstatistically significant reduction in BP (1.8 and 3.2 mm Hg in the 24 h mean of systolic and diastolic BP in monotherapy; 2.2 and 1.9 mm Hg in polytherapy), mainly because of absence of any effect on nocturnal BP. The 24 h mean BP reduction was larger and statistically significant (6.9 and 5.9 mm for systolic and diastolic BP, respectively, in monotherapy; 5.3 and 4.5 mm Hg in polytherapy) when doxazosin GITS was scheduled at bedtime. This BP-lowering effect was similar during both the day and nighttime hours. Doxazosin GITS ingested daily on awakening failed to provide full 24 h therapeutic coverage. Bedtime dosing with doxazosin GITS, however, significantly reduced BP throughout the 24 h both when used as a monotherapy and when used in combination with other antihypertensive pharmacotherapy. Knowledge of the chronopharmacology of doxazosin GITS is key to optimizing the efficiency of its BP-lowering effect, and this must be taken into consideration when prescribing this medication to patients.

Circadian Pattern of Ambulatory Blood Pressure in Hypertensive Patients With and Without Type 2 Diabetes

There is strong association between diabetes and increased risk of end-organ damage, stroke, and cardiovascular disease (CVD) morbidity and mortality. Non-dipping (<10% decline in the asleep relative to awake blood pressure [BP] mean), as determined by ambulatory BP monitoring (ABPM), is frequent in diabetes and consistently associated with increased CVD risk. The reported prevalence of non-dipping in diabetes is highly variable, probably due to differences in the study groups (normotensive subjects, untreated hypertensives, treated hypertensives), relatively small sample sizes, reliance only on a single, low-reproducibility, 24-h ABPM evaluation per participant, and definition of daytime and nighttime periods by arbitrary selected fixed clock-hour spans. Accordingly, we evaluated the influence of diabetes on the circadian BP pattern by 48-h ABPM (rather than for 24 h to increase reproducibility of results) during which participants maintained a diary listing times of going to bed at night and awakening in the morning. This cross-sectional study involved 12 765 hypertensive patients (6797 men/5968 women), 58.1 ± 14.1 (mean ± SD) yrs of age, enrolled in the Hygia Project, designed to evaluate prospectively CVD risk by ABPM in primary care centers of northwest Spain. Among the participants, 2954 (1799 men/1155 women) had type 2 diabetes. At the time of study, 525/3314 patients with/without diabetes were untreated for hypertension, and the remaining 2429/6497 patients with/without diabetes were treated. Hypertension was defined as awake systolic (SBP)/diastolic (DBP) BP mean ≥135/85 mm Hg, or asleep SBP/DBP mean ≥120/70 mm Hg, or BP-lowering treatment. Hypertensive patients with than without diabetes were more likely to be men and of older age, have diagnoses of microalbuminuria, proteinuria, chronic kidney disease, obstructive sleep apnea, metabolic syndrome, and/or obesity, plus higher glucose, creatinine, uric acid, and triglycerides, but lower cholesterol and estimated glomerular filtration rate. In patients with diabetes, ambulatory SBP was significantly elevated (p < .001), mainly during the hours of nighttime sleep and initial hours after morning awakening, independent of presence/absence of BP-lowering treatment. Ambulatory DBP, however, was significantly higher (p < .001) in patients without diabetes, mainly during the daytime. Differing trends for SBP and DBP between groups resulted in large differences in ambulatory pulse pressure (PP), it being significantly greater (p < .001) throughout the entire 24 h in patients with diabetes, even after correcting for age. Prevalence of non-dipping was significantly higher in patients with than without diabetes (62.1% vs. 45.9%; p < .001). Largest difference between groups was in the prevalence of the riser BP pattern, i.e., asleep SBP mean greater than awake SBP mean (19.9% vs. 8.1% in patients with and without diabetes, respectively; p < .001). Elevated asleep SBP mean was the major basis for the diagnosis of hypertension and/or inadequate BP control among patients with diabetes; thus, among the uncontrolled hypertensive patients with diabetes, 89.2% had nocturnal hypertension. Our findings document significantly elevated prevalence of a blunted nocturnal BP decline in hypertensive patients with diabetes. Most important, prevalence of the riser BP pattern, associated with highest CVD risk among all possible BP patterns, was more than twice as prevalent in diabetes. Patients with diabetes also presented significantly elevated ambulatory PP, reflecting increased arterial stiffness and enhanced CVD risk. These collective findings indicate that diabetes should be included among the clinical conditions for which ABPM is recommended for proper CVD risk assessment. (Author correspondence: rhermida@uvigo.es)

Ambulatory Blood Pressure Monitoring: Importance of Sampling Rate and Duration—48 Versus 24 Hours—on the Accurate Assessment of Cardiovascular Risk

Independent prospective studies have found that ambulatory blood pressure (BP) monitoring (ABPM) is more closely correlated with target organ damage and cardiovascular disease (CVD) risk than clinic BP measurement. This is based on studies in which BP was sampled every 15–30 min for ≤24 h, without taking into account that reproducibility of any estimated parameter from a time series to be potentially used for CVD risk assessment might depend more on monitoring duration than on sampling rate. Herein, we evaluated the influence of duration (48 vs. 24 h) and sampling rate of BP measurements (form every 20–30 min up to every 2 h) on the prognostic value of ABPM-derived parameters. We prospectively studied 3344 subjects (1718 men/1626 women), 52.6 ± 14.5 yrs of age, during a median follow-up of 5.6 yrs. Those with hypertension at baseline were randomized to ingest all their prescribed hypertension medications upon awakening or ≥1 of them at bedtime. At baseline, BP was measured at 20-min intervals from 07:00 to 23:00 h and at 30-min intervals at night for 48 h, and physical activity was simultaneously monitored every min by wrist actigraphy to accurately derive the awake and asleep BP means. Identical assessment was scheduled annually and more frequently (quarterly) if treatment adjustment was required. ABPM profiles were modified to generate time series of identical 48-h duration but with data sampled at 1- or 2-h intervals, or shorter, i.e., first 24 h, time series with data sampled at the original rate (daytime 20-min intervals/nighttime 30-min intervals). Bland-Altman plots indicated that the range of individual differences in the estimated awake and asleep systolic (SBP) and diastolic BP (DBP) means between the original and modified ABPM profiles was up to 3-fold smaller for data sampled every 1 h for 48 h than for data sampled every 20–30 min for the first 24 h. Reduction of ABPM duration to just 24 h resulted in error of the estimated asleep SBP mean, the most significant prognostic marker of CVD events, in the range of −21.4 to +23.9 mm Hg. Cox proportional-hazard analyses adjusted for sex, age, diabetes, anemia, and chronic kidney disease revealed comparable hazard ratios (HRs) for mean BP values and sleep-time relative BP decline derived from the original complete 48-h ABPM profiles and those modified to simulate a sampling rate of one BP measurement every 1 or 2 h. The HRs, however, were markedly overestimated for SBP and underestimated for DBP when the duration of ABPM was reduced from 48 to only 24 h. This study on subjects evaluated prospectively by 48-h ABPM documents that reproducibility in the estimates of prognostic ABPM-derived parameters depends markedly on duration of monitoring, and only to a lesser extent on sampling rate. The HR of CVD events associated with increased ambulatory BP is poorly estimated by relying on 24-h ABPM, indicating ABPM for only 24 h may be insufficient for proper diagnosis of hypertension, identification of dipping status, evaluation of treatment efficacy, and, most important, CVD risk stratification. (Author correspondence: rhermida@uvigo.es)

Administration Time‐Dependent Effects of Valsartan on Ambulatory Blood Pressure in Elderly Hypertensive Subjects

Previous results have indicated that valsartan administration at bed‐time, as opposed to upon wakening, improves the diurnal/nocturnal ratio of blood pressure (BP) toward a normal dipping pattern, without loss of 24 h efficacy. This ratio is characterized by a progressive decrease with aging. Accordingly, we investigated the administration time‐dependent antihypertensive efficacy of valsartan, an angiotensin blocking agent, in elderly hypertensive patients. We studied 100 elderly patients with grade 1–2 essential hypertension (34 men and 66 women), 68.2±4.9 years of age, randomly assigned to receive valsartan (160 mg/d) as a monotherapy either upon awakening or at bed‐time. BP was measured for 48 h by ambulatory monitoring, at 20 min intervals between 07∶00 to 23∶00 h and at 30 min intervals at night, before and after 3 months of therapy. Physical activity was simultaneously monitored every minute by wrist actigraphy to accurately determine the duration of sleep and wake spans to enable the accurate calculation of the diurnal and nocturnal means of BP for each subject. There was a highly significant BP reduction after 3 months of valsartan treatment (p<0.001). The reduction was slightly larger with bed‐time dosing (15.3 and 9.2 mm Hg reduction in the 24 h mean of systolic and diastolic BP, respectively) than with morning dosing (12.3 and 6.3 mm Hg reduction in the 24 h mean of systolic and diastolic BP, respectively). The diurnal/nocturnal ratio, measured as the nocturnal decline of BP relative to the diurnal mean, was unchanged in the group ingesting valsartan upon awakening (−1.0 and −0.3 for systolic and diastolic BP; p>0.195). This ratio was significantly increased (6.6 and 5.4 for systolic and diastolic BP; p<0.001) when valsartan was ingested at bed‐time. The reduction of the nocturnal mean was doubled in the group ingesting valsartan at bed‐time, as compared to the group ingesting it in the morning (p<0.001). In elderly hypertensive patients, mainly characterized by a diminished nocturnal decline in BP, bed‐time valsartan dosing is better than morning dosing since it improves efficacy during the nighttime sleep span, with the potential reduction in cardiovascular risk that has been associated with a normalized diurnal/nocturnal BP ratio.

DOSE- AND ADMINISTRATION TIME-DEPENDENT EFFECTS OF NIFEDIPINE GITS ON AMBULATORY BLOOD PRESSURE IN HYPERTENSIVE SUBJECTS

Previous chronotherapy studies have shown that the circadian pattern of blood pressure (BP) remains unchanged after either morning or evening dosing of several calcium channel blockers (CCB), including amlodipine, isradipine, verapamil, nitrendipine, and cilnidipine. This trial investigated the antihypertensive efficacy and safety profile of the slow‐release, once‐a‐day nifedipine gastrointestinal therapeutic system (GITS) formulation administered at different times with reference to the rest‐activity cycle of each participant. We studied 80 diurnally active subjects (36 men and 44 women), 52.1±10.7 yrs of age, with grade 1–2 essential hypertension, who were randomly assigned to receive nifedipine GITS (30 mg/day) as a monotherapy for eight weeks, either upon awakening in the morning or at bedtime at night. Patients with uncontrolled BP were up‐titrated to a higher dose, 60 mg/day nifedipine GITS, for an additional eight weeks. BP was measured by ambulatory monitoring every 20 min during the day and every 30 min at night for 48 consecutive hours before and after therapy with either dose. The BP reduction after eight weeks of therapy with the lower dose of 30 mg/day was slightly, but not significantly, larger with bedtime dosing. The efficacy of 60 mg/day nifedipine GITS in non‐responders to the initial 30 mg/day dose was twice as great with bedtime as compared to morning dosing. Moreover, bedtime administration of nifedipine GITS reduced the incidence of edema as an adverse event by 91%, and the total number of all adverse events by 74% as compared to morning dosing (p=0.026). Independent of the time of day of administration, a single daily dose of 30 mg/day of nifedipine GITS provides full 24 h therapeutic coverage. The dose‐dependent increased efficacy and the markedly improved safety profile of bedtime as compared to morning administration of nifedipine GITS should be taken into account when prescribing this CCB in the treatment of essential hypertension.

Chronotherapy with valsartan/amlodipine fixed combination: improved blood pressure control of essential hypertension with bedtime dosing.

Administration of valsartan at bedtime as opposed to upon wakening improves the sleep-time relative blood pressure (BP) decline towards a more normal dipper pattern without loss of 24-h efficacy. Amlodipine, however, has been shown to be effective in reducing BP throughout the day and night, independent of dosing time. A large proportion of hypertensive subjects cannot be properly controlled with a single medication. However, no study has yet investigated the potential differing effects of combination therapy depending of the time-of-day of administration. Accordingly, the authors investigated the administration-time-dependent BP-lowering efficacy of valsartan/amlodipine combination. The authors studied 203 hypertensive subjects (92 men/111 women), 56.7 ± 12.5 yrs of age, randomized to receive valsartan (160 mg/day) and amlodipine (5 mg/day) in one of the following four therapeutic schemes: both medications on awakening, both at bedtime, either one administered on awakening and the other at bedtime. BP was measured by ambulatory monitoring for 48 consecutive hours before and after 12 wks of treatment. Physical activity was simultaneously monitored every min by wrist actigraphy to accurately determine the beginning and end of daytime activity and nocturnal sleep. BP-lowering efficacy (quantified in terms of reduction of the 48-h mean of systolic/diastolic BP) was highest when both hypertension medications were ingested at bedtime, as compared to any one of the three other tested therapeutic schemes (17.4/13.4 mm Hg reduction with both medications on awakening; 15.1/9.6 mm Hg with valsartan on awakening and amlodipine at bedtime; 18.2/12.3 mm Hg with valsartan at bedtime and amlodipine on awakening; 24.7/13.5 mm Hg with both medications at bedtime; p < .018 between groups). The sleep-time relative BP decline was significantly increased towards a more normal dipper pattern only when both medications were jointly ingested at bedtime (p < .001). Bedtime dosing of the combination of the two medications also resulted in the largest percentage of controlled subjects among all the assessed therapeutic schemes (p = .003 between groups). In subjects requiring combination therapy to achieve proper BP control, the association of amlodipine and valsartan efficiently reduces BP for the entire 24 h independent of dosing time. However, the greater proportion of controlled patients, improved efficacy on lowering asleep BP mean, and increased sleep-time relative BP decline suggest valsartan/amlodipine combination therapy should be preferably administered at bedtime. (Author correspondence: rhermida@uvigo.es).

Prevalence and Clinical Characteristics of Isolated-Office and True Resistant Hypertension Determined by Ambulatory Blood Pressure Monitoring

Hypertension is defined as resistant to treatment when a therapeutic plan including ≥3 hypertension medications failed to sufficiently lower systolic (SBP) and diastolic (DBP) blood pressures (BPs). Most individuals, including those under hypertension therapy, show a “white-coat” effect that could cause an overestimation of their real BP. The prevalence and clinical characteristics of “white-coat” or isolated-office resistant hypertension (RH) has always been evaluated by comparing clinic BP values with either daytime home BP measurements or the awake BP mean obtained from ambulatory monitoring (ABPM), therefore including patients with either normal or elevated asleep BP mean. Here, we investigated the impact of including asleep BP mean as a requirement for the definition of hypertension on the prevalence, clinical characteristics, and estimated cardiovascular (CVD) risk of isolated-office RH. This cross-sectional study evaluated 3042 patients treated with ≥3 hypertension medications and evaluated by 48-h ABPM (1707 men/1335 women), 64.2 ± 11.6 (mean ± SD) yrs of age, enrolled in the Hygia Project. Among the participants, 522 (17.2%) had true isolated-office RH (elevated clinic BP and controlled awake and asleep ambulatory BPs while treated with 3 hypertension medications), 260 (8.6%) had false isolated-office RH (elevated clinic BP, controlled awake SBP/DBP means, but elevated asleep SBP or DBP mean while treated with 3 hypertension medications), and the remaining 2260 (74.3%) had true RH (elevated awake or asleep SBP/DBP means while treated with 3 medications, or any patient treated with ≥4 medications). Patients with false, relative to those with true, isolated-office RH had higher prevalence of microalbuminuria and chronic kidney disease (CKD), significantly higher albumin/creatinine ratio (p < .001), significantly higher 48-h SBP/DBP means by 9.6/5.3 mm Hg (p < .001), significantly lower sleep-time relative SBP and DBP decline (p < .001), and significantly greater prevalence of a non-dipper BP profile (96.9% vs. 38.9%; p < .001). Additionally, the prevalence of the riser BP pattern, which is associated with highest CVD risk, was much greater, 40.4% vs. 5.0% (p < .001), among patients with false isolated-office RH. The estimated hazard ratio of CVD events, using a fully adjusted model including the significant confounding variables of sex, age, diabetes, chronic kidney disease, asleep SBP mean, and sleep-time relative SBP decline, was significantly greater for patients with false compared with those with true isolated-office RH (2.13 [95% confidence interval: 1.95–2.32]; p < .001). Patients with false isolated-office hypertension and true RH, however, were equivalent for the prevalence of obstructive sleep apnea, metabolic syndrome, obesity, diabetes, microalbuminuria, and chronic kidney disease, and they had an equivalent estimated hazard ratio of CVD events (1.04 [95% confidence interval: .97–1.12]; p = .265). Our findings document a significantly elevated prevalence of a blunted nighttime BP decline in patients here categorized as either false isolated-office RH and true RH, jointly accounting for 82.8% of the studied sample. Previous reports of much lower prevalence of true RH plus a nonsignificant increased CVD risk of this condition compared with isolated-office RH are misleading by disregarding asleep BP mean for classification. Our results further indicate that classification of RH patients into categories of isolated-office RH, masked RH, and true RH cannot be based on the comparison of clinic BP with either daytime home BP measurements or awake BP mean from ABPM, as so far customary in the available literature, totally disregarding the highly significant prognostic value of nighttime BP. Accordingly, ABPM should be regarded as a clinical requirement for proper diagnosis of true RH. (Author correspondence: rhermida@uvigo.es)

ADMINISTRATION-TIME-DEPENDENT EFFECTS OF SPIRAPRIL ON AMBULATORY BLOOD PRESSURE IN UNCOMPLICATED ESSENTIAL HYPERTENSION

The administration of most angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) at bedtime results in a greater reduction of nighttime blood pressure (BP) than dosing upon awakening. It has been proposed that this effect may be a consequence of a short half-life and duration of action. However, those findings were also documented for long-acting medications, such as the ARB telmisartan. Accordingly, we investigated the administration-time-dependent effects on ambulatory BP of spirapril, an ACEI with an elimination half-life of about 40 h. We studied 165 previously untreated hypertensive subjects, 42.5 ± 13.9 yrs of age, treated with spirapril (6 mg/day) as monotherapy for 12 weeks either upon awakening or at bedtime. BP was measured by ambulatory monitoring for 48 h before and after treatment. The BP reduction during diurnal activity was similar for both treatment times. Bedtime spirapril administration, however, was significantly more efficient than morning administration in reducing asleep BP. The awake/asleep BP ratio was decreased with the upon-awakening spirapril treatment schedule but significantly increased toward a more dipping pattern with the bedtime treatment schedule. The proportion of patients with controlled ambulatory BP increased from 23 to 59% (p < 0.001) with bedtime treatment. Sleep-time BP regulation is significantly better achieved with bedtime spirapril administration. This might be clinically important, as the sleep-time BP mean has been shown to be a more relevant marker of cardiovascular risk than the awake mean values. These administration-time-dependent effects of spirapril seem to be a class-related feature, and may be associated with the nocturnal activation of the renin-angiotensin-aldosterone system. (Author correspondence: rhermida@uvigo.es).

Association of Metabolic Syndrome and Blood Pressure Nondipping Profile in Untreated Hypertension

BACKGROUND There is a marked association between metabolic syndrome (MS) and increased cardiovascular risk. Moreover, nondipping (patients with <10% decline in the asleep relative to the awake blood pressure (BP) mean) has also been associated with increased cardiovascular morbidity and mortality. METHODS We investigated the association between MS and impaired nocturnal BP decline in 1,770 nondiabetic, untreated hypertensive patients (824 men and 946 women), 48.7 +/- 13.2 years of age. BP was measured by ambulatory monitoring for 48 h to increase reproducibility of the dipping pattern. Physical activity was simultaneously monitored every minute by wrist actigraphy. RESULTS MS was present in 42.4% of the patients. The prevalence of a nondipper BP profile was significantly higher in patients with MS (46.1% vs. 37.5% in patients without MS, P < 0.001). Patients with MS were characterized by significant elevations in uric acid (5.9 mg/dl vs. 5.2 mg/dl, P < 0.001), fibrinogen (314 mg/dl vs. 304 mg/dl, P = 0.021), and globular sedimentation rate (13.8 mm vs. 11.6 mm, P < 0.001). Nondipping was significantly associated to the presence of MS in a multiple logistic regression model adjusted by other significant confounding factors, including age, serum creatinine, and cigarette smoking. The single most relevant factor in the definition of MS associated to nondipping was elevated waist perimeter. CONCLUSIONS This study documents a significant increase of a blunted nocturnal BP decline in patients with MS. Patients with MS were also characterized by elevated values of relevant markers of cardiovascular risk, including fibrinogen and globular sedimentation rate.