Chronobiology international
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Randomized Controlled Trial
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. ⋯ 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.
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Some studies based on ambulatory blood pressure (BP) monitoring (ABPM) have reported a reduction in sleep-time relative BP decline towards a more non-dipping pattern in the elderly, but rarely have past studies included a proper comparison with younger subjects, and no previous report has evaluated the potential role of hypertension treatment time on nighttime BP regulation in the elderly. Accordingly, we evaluated the influence of age and time-of-day of hypertension treatment on the circadian BP pattern assessed by 48-h ABPM. This cross-sectional study involved 6147 hypertensive patients (3108 men/3039 women), 54.0 ± 13.7 (mean ± SD) yrs of age, with 2137 (978 men/1159 women) being ≥60 yrs of age. ⋯ The prevalence of a riser BP pattern, associated with highest cardiovascular risk among all possible BP patterns, was 4 times more prevalent in patients ≥60 yrs of age than those <60 yr of age. Most important, there was an attenuated prevalence of a blunted nighttime BP decline at all ages when ≥1 hypertension medications were ingested at bedtime as compared with when all of them were ingested upon awakening. These findings indicate that older age should be included among the conditions for which ABPM is recommended for proper cardiovascular risk assessment.
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Randomized Controlled Trial
Sleep-time blood pressure: prognostic value and relevance as a therapeutic target for cardiovascular risk reduction.
Correlation between blood pressure (BP) level and target organ damage, cardiovascular disease (CVD) risk, and long-term prognosis is greater for ambulatory BP monitoring (ABPM) than clinical BP measurements. Nevertheless, the latter continue to be the "gold standard" to diagnose hypertension, assess CVD risk, and evaluate hypertension treatment. Independent ABPM studies have found that elevated sleep-time BP is a better predictor of CVD risk than either the awake or 24-h BP mean. ⋯ The increased event-free survival associated with the progressive reduction in the asleep systolic BP mean during follow-up was significant for subjects with either normal or elevated BP at baseline. The ABPM-derived asleep BP mean was the most significant prognostic marker of CVD morbidity and mortality. Most important, the progressive decrease in asleep BP mean, a novel therapeutic target that requires proper patient evaluation by ABPM and best achieved by ingestion of at least one hypertension medication at bedtime, was the most significant predictor of event-free survival.
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Randomized Controlled Trial
Chronotherapy with low-dose aspirin for prevention of complications in pregnancy.
Preeclampsia and gestational hypertension are major contributors to perinatal morbidity and mortality. Several studies aimed to test the effects of low-dose aspirin (ASA) in the prevention of preeclampsia concluded that the beneficial effects of such treatment outweigh adverse ones. Such benefits have not been fully corroborated by larger randomized trials usually carried out in low-risk women, testing a dose of 60 mg/d ASA presumably ingested in the morning, and including women randomized as late as at 26-32 wks of gestation. ⋯ There was no increased risk of hemorrhage, either before or after delivery, with low-dose ASA relative to placebo (HR: .57, 95% CI: .25-1.33; p = .194). Results indicate that (i) 100 mg/d ASA should be the recommended minimum dose for prevention of complications in pregnancy; (ii) ingestion of low-dose ASA should start at ≤16 wks of gestation; and (iii) low-dose ASA ingested at bedtime, but not upon awakening, significantly regulates ambulatory BP and reduces the incidence of preeclampsia, gestational hypertension, preterm delivery, and IUGR. ABPM evaluation at the first trimester of pregnancy provides sensitive endpoints for identification of women at high risk for preeclampsia who might benefit most from the cost-effective preventive intervention with timed low-dose ASA.
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Randomized Controlled Trial
Cardiovascular risk of resistant hypertension: dependence on treatment-time regimen of blood pressure-lowering medications.
In resistant hypertension, ingesting one or more blood pressure (BP)-lowering medications at bedtime is associated with significant reduction of sleep-time BP, a sensitive prognostic marker of cardiovascular disease (CVD) risk. This randomized trial investigated if bedtime therapy with at least one hypertension medication exerts better BP control and CVD risk reduction than conventional, morning-time therapy with all medications. We conducted a prospective, open-label, blinded-endpoint trial on 776 patients (387 men/389 women) with resistant hypertension, 61.6 ± 11.2 (mean ± SD) yrs of age. ⋯ At the last evaluation, patients treated with the bedtime versus awakening-time-treatment regimen showed significantly lower sleep-time systolic/diastolic BP mean values (121.6/65.4 vs. 113.0/61.1 mm Hg; p < .001) and higher prevalence of controlled ambulatory BP (61% vs. 46%; p < .001). The progressive decrease in the sleep-time systolic BP mean during follow-up was the most significant predictor of event-free survival (15% risk reduction per 5 mm Hg decreased asleep systolic BP mean). Among patients with resistant hypertension, ingestion of at least one hypertension medication at bedtime, compared with all medications upon waking, resulted in improved ambulatory BP control and fewer hard and soft CVD events.