Relevance of blood pressure variation in the circadian onset of cardiovascular events

Examining the Pre- and Post-percutaneous Coronary Intervention Blood Pressure Variability Using Ambulatory Blood Pressure Monitoring in Patients With Stable and Unstable Coronary Artery Disease

Introduction The World Health Organization has drawn attention to the fact that coronary artery disease (CAD) is our modern "epidemic." Nowadays, sudden death during sleep has become prevalent due to a lack of oxygen supply to the heart. CAD causes more deaths and disabilities and incurs greater economic costs than any other illness in the developed world. The prevalence of cardiovascular disorders and heart disease is on the rise in India. Hypertension is one of the leading risk factors for all cardiovascular diseases. This study aims to compare blood pressure variability before and after percutaneous coronary intervention (PCI), using ambulatory blood pressure monitoring (ABPM) in patients with stable and unstable CAD. Materials and methods This prospective observational study was conducted among 52 patients with stable and unstable CAD, admitted to the medicine department, who required PCI at a tertiary care hospital. Before and after PCI, the same antihypertensive drugs were orally administered. ABPM was performed before PCI and one day after PCI. ABPM was conducted every 30 minutes during the day and every 60 minutes during the night over a 24-hour period using a mobil-o-graph (IEM, Germany). The results of the observed parameters were analyzed using the HMS Client-Server 4.0 system (Informer Technologies, Inc., Los Angeles, USA). The collected data were analyzed using SPSS Statistics version 21.0 software (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.). Results Out of 52 patients, 28 (53.8%) had stable CAD and 24 (46.2%) had unstable CAD. The mean age of patients with stable and unstable CAD was 56.64±9.44 and 57.04±12.36 years, respectively. The majority of patients with stable (67.9%) and unstable CAD (62.5%) were males. Various other variables were considered, such as lipid profile, blood sugar, cardiac troponin-I, and medical history, including hypertension and type 2 diabetes mellitus. Among stable CAD patients, a comparison between pre- and post-PCI systolic blood pressure (SBP) did not show a significant difference in all SBP measurements (p>0.05). However, the mean diurnal index was significantly lower following PCI compared to before PCI (p=0.019). Among unstable CAD patients, a comparison between pre- and post-PCI SBP showed a significant change in peak daytime, average daytime, and diurnal index (p<0.05). For all other SBP measurements, the difference between pre- and post-PCI measurements was not statistically significant (p>0.05). In patients with stable CAD, a statistically significant change in diastolic blood pressure (DBP) following PCI was observed for peak daytime, peak nighttime, and average nighttime values. In contrast, for patients with unstable CAD, a statistically significant change in DBP following PCI was observed for peak daytime, peak nighttime, and minimum daytime values (p<0.05). Statistically, post-PCI, there was no significant difference between the two groups for SBP and DBP measurements (p>0.05). Additionally, there was no significant difference between the two groups pre- and post-PCI in the pattern of dipping. Conclusion A comparison of the ABPM before and after PCI showed that, within 48 hours post-PCI, the ambulatory blood pressure indicators did not differ statistically from those before PCI.

Fragmented Ventricular Complexes and Blood Pressure Variability Assessed by Ambulatory Blood Pressure Monitoring in Patients With Metabolic Syndrome

Introduction Hypertension is a leading risk factor for the development of cardiovascular and metabolic derangements. In patients with metabolic syndrome (MetS), hypertension is one of the cornerstones showing high variability which is detected in ambulatory blood pressure monitoring. Fragmented ventricular complexes on ECG are seen as hypertensives and are a viable and easy measure of myocardial fibrosis even in the absence of obvious hypertrophy. Aim The present study was undertaken to study the blood pressure variability in patients of MetS with fragmented QRS (fQRS) versus normal ventricular complexes (QRS). Results Out of 100 patients, 22 (22%) had fQRS complexes. Hypertension and diabetes were the most prevalent associated in both groups but a difference was seen with coronary artery disease, which was significantly associated in the fQRS group (8.97% vs 95.45%, p<0.001) as compared to the non-fQRS group. Significant differences were observed in waist circumference (p=0.019), triglyceride (p=0.006) and left ventricular ejection fraction (p<0.001) between the two groups. There was a marked difference (p<0.05) between heart rate variability during day and night time between normal and fQRS sub-groups, being higher in the latter. A similar pattern of change was observed for systolic and diastolic blood pressures and associated dipping. Conclusion Significant differences exist between heart rate and blood pressure changes in patients with fQRS of MetS, thus making fQRS a potent indicator of cardiovascular status.

Clocks, Rhythms, Sex, and Hearts: How Disrupted Circadian Rhythms, Time-of-Day, and Sex Influence Cardiovascular Health

Cardiovascular diseases are the top cause of mortality in the United States, and ischemic heart disease accounts for 16% of all deaths around the world. Modifiable risk factors such as diet and exercise have often been primary targets in addressing these conditions. However, mounting evidence suggests that environmental factors that disrupt physiological rhythms might contribute to the development of these diseases, as well as contribute to increasing other risk factors that are typically associated with cardiovascular disease. Exposure to light at night, transmeridian travel, and social jetlag disrupt endogenous circadian rhythms, which, in turn, alter carefully orchestrated bodily functioning, and elevate the risk of disease and injury. Research into how disrupted circadian rhythms affect physiology and behavior has begun to reveal the intricacies of how seemingly innocuous environmental and social factors have dramatic consequences on mammalian physiology and behavior. Despite the new focus on the importance of circadian rhythms, and how disrupted circadian rhythms contribute to cardiovascular diseases, many questions in this field remain unanswered. Further, neither time-of-day nor sex as a biological variable have been consistently and thoroughly taken into account in previous studies of circadian rhythm disruption and cardiovascular disease. In this review, we will first discuss biological rhythms and the master temporal regulator that controls these rhythms, focusing on the cardiovascular system, its rhythms, and the pathology associated with its disruption, while emphasizing the importance of the time-of-day as a variable that directly affects outcomes in controlled studies, and how temporal data will inform clinical practice and influence personalized medicine. Finally, we will discuss evidence supporting the existence of sex differences in cardiovascular function and outcomes following an injury, and highlight the need for consistent inclusion of both sexes in studies that aim to understand cardiovascular function and improve cardiovascular health.

Narrative review of sleep and stroke

Sleep disorders, such as sleep-disordered breathing (SDB), insomnia or restless legs syndrome (RLS), are common in the general population and after stroke. In some cases, sleep disturbances are pre-existing, but can also appear de novo as a direct consequence of brain damage or due to stroke-related complications. Furthermore, some sleep conditions may act as a risk factor of stroke. This review explores the available evidence of the two-way relationship between sleep and stroke. Cardiovascular physiological changes during sleep are described, as well as the evidence on the relationship between stroke and sleep duration, SDB, RLS, insomnia, excessive daytime sleepiness (EDS), and circadian rhythm alterations. Potential changes on sleep architecture, and the links that may exist between sleep and functional outcomes after stroke are also discussed. Importantly, sleep-related disturbances may be associated with worse stroke recovery outcomes and increased cerebrovascular morbidity. It is therefore relevant that the bidirectional association between stroke and sleep is taken into consideration by clinicians taking care of these patients. Future research may focus on this mutual relationship for a better understanding of the impact of stroke on sleep, the importance of sleep in stroke incidence and recovery, and have further evidence on treatment strategies that may improve functional outcome after stroke.

Nocturnal blood pressure fluctuations measured by using pulse transit time in patients with severe obstructive sleep apnea syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is related to arterial hypertension. In the present study, we test the hypothesis that patients with severe OSAS have excessive apnea induced blood pressure (BP).

METHODS

We investigated 97 patients with an apnea/hypopnea index (AHI) greater than 30. Systolic BP (SBP) was continuously determined by using the pulse transit time (PTT). Apnea/hypopnea induced nocturnal BP fluctuations (NBPFs) were detected and showed phenomena of continuous increases of the SBP baseline. Such periods of SBP baseline elevations ≥ 10 mmHg were called superposition. Respiratory and cardiac parameters were obtained from the polysomnographic investigation.

RESULTS

Eighty-four periods of superposition were detected in 48 patients. They occurred mainly during REM sleep (76%). Apnea duration was increased and the time in respiration was reduced in periods of superposition compared to non-superposition periods. In superposition periods mean oxygen saturation (SpO₂) and the minimal SpO₂ were lower, desaturations were more pronounced, and the mean heart rate (HR) was increased. The maximum SBP during superposition was significantly increased (204 ± 32 vs.171 ± 28 mmHg). The clinic BP was higher in patients with superposition (SBP 149.2 ± 17.5 vs. 140 ± 19.1, DBP 91.5 ± 11.5 vs. 86.3 ± 11.8).

CONCLUSIONS

The study reveals that patients with severe OSAS can have periods of BP superposition during night with extremely high SBP and very low oxygen saturation, which may add to a high risk for cardiovascular events during the night.

Blood pressure effects of CPAP in nonresistant and resistant hypertension associated with OSA: A systematic review of randomized clinical trials

Obstructive sleep apnea (OSA) is a rather common chronic disorder, associated with increased prevalence of hypertension. The pathophysiological mechanisms for hypertension in OSA are at least in part linked to intermittent hypoxia developed during nightly hypopneas and apneas. Hypoxemia stimulates sympathetic overactivity, systemic inflammation, oxidative stress, and endothelial dysfunction. However, it appears that intermittent hypoxemia is not the only factor in the development of hypertension in OSA. Supplemental oxygen therapy that improved oxyhemoglobin saturation to similar levels to those achieved with CPAP treatment did not reduce BP. In this scenario, it could be proposed that hypoxemia acts as a trigger of sympathetic overdrive, which when set is the main factor in the development of hypertension in OSA. This review appraises evidence provided by randomized controlled trials on the BP-lowering effectiveness of continuous positive airway pressure (CPAP) treatment of OSA patients with nonresistant and resistant hypertension. It suggests that CPAP treatment is more effective in treating resistant hypertension than nonresistant hypertension. A possible explanation is that sympathetic overactivity and altered vascular reactivity in OSA could be more severe in resistant hypertension than in nonresistant hypertension. An intricate interaction among compliance, adherence, and their interaction with demographic characteristics, genetic factors, and comorbidities of the population included might explain the differences found between trials on their influence over the antihypertensive effectiveness of CPAP. Further long-term trials are needed in hypertensive OSA patients to assess whether CPAP treatment in OSA patients consistently restores physiological nocturnal BP fall and adjusts resting and circadian heart rate.

Novel Echocardiographic Indices as Predictors of Immediate Recurrence after Undersized Ring Annuloplasty for Ischemic Mitral Regurgitation

BACKGROUND AND AIM

Ischemic mitral regurgitation (IMR) is among the most serious complications of myocardial infarction which doubles the late mortality; mainly treated by undersizing ring annuloplasty. To find some preoperative echocardiographic indices that predict immediate failure of mitral valve annuloplasty (MVA), we designed the present study with more focusing on some novel parameters.

METHOD

Transthoracic echocardiography (TTE) indices of consecutive patients referred with 3+ or 4+ IMR were registered 24 hours before surgery. Thirty days later, a second TTE was performed. According to the results, the patients were categorized as the "successful" group (with 1+ or less mitral regurgitation) and the "unsuccessful" group (with 2+ or higher MR). Preoperative TTE indices were compared among the two groups using suitable statistical tests.

RESULTS

Of the total of 126 cases, 68 had successful and 58 had unsuccessful MVA. Statistically significant differences were found between the two groups for left ventricular ejection fraction (LVEF) (P = 0.007), left ventricular end systolic volume (LVESV) (P = 0.044), and basal-interpapillary muscle distance (IPMD) diastolic-to-systolic ratio (DSR) (P = 0.008). Receiver Operating Characteristic analysis demonstrated 37.5%, 3.85 cm(3) , and 1.25, as the best cutoff points for LVEF (P = 0.03, sensitivity: 81%, specificity: 69%), LVESV (P = 0.023, sensitivity: 83%, specificity: 57%), and basal-IPMD DSR (P = 0.001, sensitivity: 100%, specificity: 95%), respectively.

CONCLUSION

Among all TTE indices, LVEF, LVESV, and basal-IPMD DSR were helpful to differentiate between the successful and unsuccessful MVA results. We believe the basal-IPMD DSR as a novel index could be targeted in the future studies.

Independent association between symptom onset time and infarct size in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention

Recent studies have reported on circadian variation in infarct size in ST-elevation myocardial infarction (STEMI) patients. Controversy remains as to whether this finding indicates circadian dependence of myocardial tolerance to ischemia/reperfusion injury or that it can simply be explained by confounding factors such as baseline profile and ischemic time. We assessed the clinical impact and independent association between symptom onset time and infarct size, accounting for possible subgroup differences. From a multicenter registry, 6799 consecutive STEMI patients undergoing primary percutaneous coronary intervention (PCI) between 2004 and 2010 were included. Infarct size was measured using peak creatine kinase (CK). Infarct size exhibited circadian variation with largest infarct size in patients with symptom onset around 03:00 at night (estimated peak CK 1322 U/l; 95% confidence interval (CI): 1217-1436) and smallest infarct size around 11:00 in the morning (estimated peak CK 1071 U/l; 95% CI: 1001-1146; relative reduction 19%; p = 0.001). Circadian variation in infarct size followed an inverse pattern in patients with prior myocardial infarction (p-interaction <0.001) and prior PCI (p-interaction = 0.006), although the later did not persist in multivariable analysis. Symptom onset time remained associated with infarct size after accounting for these interactions and adjusting for baseline characteristics and ischemic time. Symptom onset time did not predict one-year mortality (p = 0.081). In conclusion, there is substantial circadian variation in infarct size, which cannot be fully explained by variations in baseline profile or ischemic time. Our results lend support to the hypothesis of circadian myocardial ischemic tolerance and suggest a different mechanism in patients with prior myocardial infarction.

Olmesartan vs. ramipril in elderly hypertensive patients: review of data from two published randomized, double-blind studies

Hypertension is a frequent condition among individuals over 65 years of age worldwide and is one of the most important risk factors for cardiovascular (CV) disease. Effective drug treatment of elderly hypertensives is usually associated with a marked reduction in CV morbidity and mortality. Among the different classes of antihypertensive agents, angiotensin receptor blockers (ARBs) and ACE-inhibitors are supposed to provide the best efficacy in lowering blood pressure (BP) and protecting target organ damage while featuring a good tolerability profile. However, up to date, few randomized clinical studies have directly compared the activity and safety of ARBs and ACE-inhibitors in elderly hypertensive patients. Aim of this review of published and unpublished pooled data from two recent randomized, double-blind, controlled trials, is to offer a comprehensive head-to-head comparison of the antihypertensive efficacy of the ARB olmesartan medoxomil vs. the ACE-inhibitor ramipril in a large study population including more than 1,400 hypertensive subjects aged 65-89 years with mild-to-moderate essential hypertension. The efficacy of the two drugs was separately evaluated in subgroups of patients classified according to the presence of metabolic syndrome, reduced renal function, CV risk level, gender, class of age, type of arterial hypertension and previous antihypertensive treatments. Olmesartan showed a greater efficacy than ramipril both in terms of clinic BP reduction and rate normalization. Olmesartan appeared significantly superior to ramipril in providing a more homogeneous and long-lasting 24-h BP control and maintaining an effective antihypertensive action in the last 6-h period from drug intake. In subgroups of patients with additional clinical conditions, olmesartan gave comparable, and in some cases greater, BP responses than those achieved with the ACE-inhibitor. The incidence of adverse events was similar for both drugs. Olmesartan may thus represent an effective alternative to ACE-inhibitors among first-line drug treatments for hypertension in older people.

Investigation on cardiovascular risk prediction using physiological parameters

Cardiovascular disease (CVD) is the leading cause of death worldwide. Early prediction of CVD is urgently important for timely prevention and treatment. Incorporation or modification of new risk factors that have an additional independent prognostic value of existing prediction models is widely used for improving the performance of the prediction models. This paper is to investigate the physiological parameters that are used as risk factors for the prediction of cardiovascular events, as well as summarizing the current status on the medical devices for physiological tests and discuss the potential implications for promoting CVD prevention and treatment in the future. The results show that measures extracted from blood pressure, electrocardiogram, arterial stiffness, ankle-brachial blood pressure index (ABI), and blood glucose carry valuable information for the prediction of both long-term and near-term cardiovascular risk. However, the predictive values should be further validated by more comprehensive measures. Meanwhile, advancing unobtrusive technologies and wireless communication technologies allow on-site detection of the physiological information remotely in an out-of-hospital setting in real-time. In addition with computer modeling technologies and information fusion. It may allow for personalized, quantitative, and real-time assessment of sudden CVD events.

Resistance exercise leading to failure versus not to failure: effects on cardiovascular control

BACKGROUND

The aim of the present study was to evaluate the acute effects of resistance exercise (RE) leading to failure and RE that was not to failure on 24 h blood pressure (BP) and heart rate variability (HRV) in sedentary normotensive adult women.

METHODS

Ten women (33.2 ± 5.8 years; 159.3 ± 9.4 cm; 58.0 ±6.4 kg; body fat 28.4 ± 2.8%) randomly underwent three experimental sessions: control (40 minutes of seated rest), RE leading to failure with 3 sets of 10 repetitions maximum (10-RM), and RE not to failure at 60% of 10-RM with 3 sets of 10 repetitions. Immediately post session BP and HRV were measured for 24 h.

RESULTS

Ratings of perceived exertion and heart rate were higher during the 10-RM session when compared with 60% of 10-RM (6.4 ± 0.5 vs 3.5 ± 0.8 and 123.7 ± 13.9 vs 104.5 ± 7.3 bpm, respectively). The systolic, diastolic and mean BP decreased at 07:00 a.m. after the 10-RM session when compared with the control session (-9.0 ± 7.8 mmHg, -16.0 ± 12.9 mmHg and -14.3 ± 11.2 mmHg, respectively). The root mean square of the squared differences between R-R intervals decreased after both the 60% of 10-RM and 10-RM sessions compared with the control session.

CONCLUSIONS

An acute RE session leading to failure induced a higher drop of BP upon awakening, while both RE sessions reduced cardiac parasympathetic modulation. RE may be an interesting training strategy to acutely decrease BP in adult women.

Characteristics of white coat hypertension in Chinese Han patients with type 2 diabetes mellitus

OBJECTIVES

This study documented the prevalence and clinical features of white coat hypertension (WCH) among Chinese Han patients with type 2 diabetes mellitus (T2DM).

METHODS

Clinic and ambulatory blood pressure (BP) measurements were compared in 856 patients with T2DM to determine the frequency of WCH (WCH was defined as clinical blood pressure ≥140/90 mmHg and daytime blood pressure <135/85 mmHg and/or 24-h ambulatory BP (ABP) mean value of <130/80 mmHg on ambulatory BP monitoring (ABPM). Weight, waist circumference (WC), body mass index (BMI), waist to height ratio (WHtR), fasting blood glucose, glycosylated hemoglobin level and circadian BP patterns were also measured to find clinical features predictive of WCH in T2DM.

RESULTS

The prevalence of WCH was 7.36% (63/856) in the overall population, 6.13% (29/473) in male and 8.88% (34/383) in female (p < 0.05). WCH accounted for 14.03% (63/449) of diagnosed hypertension. Age, course of T2DM, male WC were independent protective factors, whereas female sex, smoking and alcohol consumption were independent risk factors for WCH in T2DM. Non-dippers and reverse dippers made up larger proportion of the WCH group (p < 0.01).

CONCLUSION

WCH is relatively common among T2DM patients, it is a unique condition distinct from essential hypertension (EH), and WCH patients also exhibit significant differences in clinical parameters.

Women with metabolic syndrome present different autonomic modulation and blood pressure response to an acute resistance exercise session compared with women without metabolic syndrome

Metabolic syndrome (MetS) is a cluster of risk factors in individuals with high risk of diabetes and heart disease. Resistance training (RT) has been proposed to be a safe, effective and worthwhile method for the prevention and treatment of metabolic and cardiovascular diseases. However, no study has analysed the acute response of blood pressure (BP) and autonomic control of heart rate (HR) after a RT session in female patients with MetS. The aim of the present study was to analyse the response of laboratory assessed and ambulatory BP and cardiac autonomic modulation after a RT session in women with MetS. Nine women without MetS (35.0 ± 6.7 years) and 10 women with MetS (34.1 ± 9.4 years) completed one experimental exercise session and a control session. Laboratory BP, heart rate variability (HRV) and ambulatory BP of each subject were measured at rest, over 60 min, and for 24 h after the end of the sessions, respectively. There was a significant reduction in systolic blood pressure (SBP), night time diastolic blood pressure (DBP) and mean blood pressure (MBP) only for women with MetS, for all periods after the RT session when compared with the control session (P<0.05). Significantly lower laboratory values of SBP and DBP (10, 30 and 40 min postexercise) and MBP (10, 40 and 50 min postexercise) were observed in women with MetS (P<0.05). Patients with MetS exhibited significant lower basal HRV and a lower autonomic responsiveness during the 60 min of acute recovery. These results confirmed that an acute session of resistance exercise induced a lower BP during day time and sleeping hours in women with MetS that may offer a cardio-protective effect. Women with MetS exhibited an impaired autonomic modulation at rest and a lower acute autonomic responsiveness to a RT session. The dissociation between BP and HRV responses suggests that other factors than autonomic control could be involved in the hypotensive effect of a RT session in MetS patients.

Resistance training decreases 24-hour blood pressure in women with metabolic syndrome

BACKGROUND

The purpose of this study was to verify the effects of eight weeks of resistance training (RT) on 24 hour blood pressure (BP) in patients with and without metabolic syndrome (MetS).

METHODS

Seventeen women volunteered to participate in this study, 9 with MetS (37.0 ± 8.7 yrs; body mass 77.3 ± 9.7 kg; body mass index 30.3 ± 4.2 kg · m(-2)) and 8 without MetS (35.1 ± 7.2 yrs; body mass 61.3 ± 8.1 kg; body mass index 24.2 ± 2.5 kg · m(-2)). Individuals were subjected to eight weeks (3 times/week) of whole body RT comprised of one exercise for each main muscle group with three sets of 8-12 repetitions of each subject's maximal load . A rest interval of one minute was allowed between sets and exercises. Twenty-four hour BP was measured by ambulatory blood pressure monitoring.

RESULTS

Mean and diastolic night-time BP decreased (-3.9 mmHg, p = 0.04; -5.5 mmHg, p = 0.03, respectively) after eight weeks of training in MetS patients. This decrease was observed at 11:00 pm, 02:00 am (only diastolic), 07:00 am, and 6:00 pm. There was no training effect on BP in women without MetS.

CONCLUSIONS

Considering the elevation of BP as a contributor to the pathogenesis of MetS, and also to the increase of cardiovascular risk, this study supports RT as a non-pharmacological therapy in the management of BP control for MetS.

Are stroke occurrence and outcome related to weather parameters? Results from a population-based study in northern portugal

BACKGROUND

Changes in meteorological parameters have been associated with cardiovascular mortality and stroke. The high incidence of stroke in Portugal may be modelled by short- or long-term weather changes whose effect may be different across stroke types and severity.

METHODS

Data include all patients with a first-ever-in-a-lifetime stroke registered in a population of 86,023 residents in the city of Porto from October 1998 to September 2000. Specific stroke types were considered and ischaemic stroke (IS) subtype was defined according to the Oxfordshire Community Stroke Projet classification and the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Information on daily temperature, humidity and air pressure was obtained from the National Meteorological Office. The Poisson distribution was used to model the daily number of events as a function of each weather parameter measured over different hazard periods, and the binomial model to contrast effects across subgroups. Differential effects of meteorological parameters and hazard periods upon stroke occurrence and outcome were analysed in a stepwise model.

RESULTS

Among the 462 patients registered, 19.6% had a primary intracerebral haemorrhage (PICH) and 75.3% an IS. Among patients with IS, 21.6% were total anterior circulation infarcts (TACIs), 19.8% partial anterior circulation infarcts (PACIs), 19.5% posterior circulation infarcts (POCIs) and 39.1% were lacunar infarcts (LACIs). The aetiology of IS was large artery atherosclerosis in 6.9%, cardioembolism in 23.3% and small artery occlusion in 35.6%. The incidence of PICH increased by 11.8% (95% CI: 3.8-20.4%) for each degree drop in the diurnal temperature range in the preceding day. The incidence of IS increased by 3.9% (95% CI: 1.6-6.3%) and cardioembolic IS by 5.0% (95% CI: 0.2-10.1%) for a 1°C drop in minimum temperature in the same hazard period. The incidence of TACIs followed the IS pattern while for PACIs and POCIs there were stronger effects of longer hazard periods and no association was found for LACIs. The relative risk of a fatal versus a non-fatal stroke increased by 15.5% (95% CI: 6.1-25.4%) for a 1°C drop in maximum temperature over the previous day.

CONCLUSIONS

Outdoor temperature and related meteorological parameters are associated with stroke occurrence and severity. The different hazard periods for temperature effects and the absence of association with LACIs may explain the heterogeneous effects of weather on stroke occurrence found in community-based and hospital admission studies. Emergency services should be aware that specific weather conditions are more likely to prompt calls for more severe strokes.

The role of ambulatory blood pressure monitoring compared with clinic and home blood pressure measures in evaluating moderate versus intensive treatment of hypertension with amlodipine/valsartan for patients uncontrolled on angiotensin receptor blocker monotherapy

OBJECTIVES

Ambulatory blood pressure monitoring (ABPM) has greater predictive value than office blood pressure (BP) with respect to hypertension-related target-organ damage and morbidity. ABPM in a subset of 80 patients from the Exforge Target Achievement trial (N=728) was used to compare the efficacy of intensive-treatment and moderate-treatment regimens of amlodipine/valsartan, and to determine whether treatment differences could be better assessed with ABPM than with office or home BP. Home BP was measured on the morning of clinic visits to minimize differences that timing might have on home versus office BP measures.

METHODS

A 12-week randomized, double-blind study in which hypertensive patients earlier uncontrolled (mean sitting systolic BP≥150 and <200 mmHg) on angiotensin receptor blocker monotherapy (other than valsartan) after 28 days or more (N=728) were randomized to amlodipine/valsartan treatment [10/320 mg (intensive) or 5/160 mg (moderate)]. Treatment-naive patients (in previous 28 days) or patients who failed on a nonangiotensin receptor blocker agent underwent a 28-day run-in period with a 20-mg or 40-mg dose of olmesartan, respectively.

RESULTS

Significantly greater 24-h ABP reductions from baseline to week 4 (primary time point) were observed with intensive versus moderate treatment (least-square mean systolic/diastolic BP reduction of -16.2/-10.1 vs. -9.5/-6.5 mmHg; P=0.0024/P=0.010 for least-square mean difference). Similarly, a significantly greater proportion of patients receiving an intensive treatment achieved ambulatory BP goal (<130/80 mmHg) at week 4 than did those receiving a moderate treatment (P=0.040). Treatment-group differences did not reach statistical significance for these end points when measured by office and home BP.

CONCLUSION

In this first randomized trial evaluating the effects of intensive versus moderate dosing of the combination of amlodipine/valsartan, our data suggest that ABPM was a better method for assessing between-treatment differences than clinic or home BP recordings, although measurement of home BP as a single recording was a limitation of our trial.

Circadian variation in coronary stent thrombosis

OBJECTIVES

We sought to determine the circadian, weekly, and seasonal variation of coronary stent thrombosis.

BACKGROUND

Other adverse cardiovascular events such as acute myocardial infarction are known to have higher incidences during the early morning hours, Mondays, and winter months.

METHODS

The Mayo Clinic Percutaneous Coronary Intervention Registry was searched for patients admitted to our center who underwent repeat percutaneous coronary intervention in a previously stented coronary artery segment. Stent thrombosis was confirmed by angiographic review, and date and time of symptom onset were obtained from medical records.

RESULTS

We identified 124 patients with definite stent thrombosis and known date and time of symptom onset. In these patients, onset of stent thrombosis was significantly associated with time of day (p = 0.006), with a peak incidence around 7:00 am. When patients were subdivided into early stent thrombosis (0 to 30 days; n = 49), late stent thrombosis (31 to 360 days; n = 30), and very late stent thrombosis (>360 days; n = 45), only early stent thrombosis remained significantly associated with time of day (p = 0.030). No association with the day of the week was found (p = 0.509); however, onset of stent thrombosis did follow a significant seasonal pattern, with higher occurrences in the summer (p = 0.036).

CONCLUSIONS

Coronary stent thrombosis occurs more often in the early morning hours. Early stent thrombosis follows a circadian rhythm with a peak at 7:00 am. This pattern was not significant in late and very late stent thrombosis. Occurrences throughout the week were equally distributed, but stent thrombosis was more likely to occur in the summer months.

Sudden cardiac death: epidemiology, circadian variation, and triggers

Sudden cardiac death (SCD) remains a major health issue accounting for over 5% of annual mortality in the Western world. There are several causes of SCD, most commonly, coronary artery disease. Although identifying the prodrome of SCD has attracted considerable interest, a large proportion of patients die before any medical contact is established. SCD onset seems to follow a circadian pattern, most likely because of exposure to endogenous and exogenous triggers. The aim of the present report is to review the current knowledge of epidemiology, patterns of onset, and triggers of SCD and present directions for future research with a focus on coronary artery disease.

Twenty-four-hour ambulatory blood pressure measurement in clinical practice and research: a critical review of a technique in need of implementation

This review presents evidence that ambulatory blood pressure measurement (ABPM) should be used more widely in clinical practice and hypertension research. The technique, which should be mandatory in trials of antihypertensive drugs, is not being used in all studies of antihypertensive drug efficacy. ABPM is also being under-used in outcome studies. The failure to implement ABPM in primary care and hypertension research is impeding patient management and scientific advancement. ABPM offers so many advantages in assessing the efficacy of blood pressure (BP)-lowering drugs that it should be mandatory in pharmacological trials. Likewise, the technique provides a means of achieving BP control in clinical practice, which is essential if we are to halt the epidemic of the cardiovascular consequences of hypertension. However, if ABPM is to be implemented for these purposes, certain requirements will need to be fulfilled. These include the availability of accurate, patient-friendly and inexpensive devices; standardization of the presentation and plotting of data with summary statistics for day-to-day practice; provision of comprehensive data analysis for research; an interpretative report to facilitate use in busy clinical practice; a trend report to demonstrate efficacy or otherwise of treatment in clinical practice and online transmission of data to provide immediate real-time data analysis. The reasons why ABPM is not being implemented are reviewed, and proposals are made to make the technique more acceptable.

[Ambulatory blood pressure monitoring]

During the last decades non-invasive 24-hour ambulatory blood pressure monitoring has evolved from a research tool of limited clinical use into an important method for stratifying cardiovascular risk and guiding therapeutic decisions. Until recently, clinical use of ambulatory blood pressure monitoring focused on identifying patients with white-coat hypertension, but accumulated evidence now points to its greater prognostic significance in determining risk for target-organ damage compared with that of office blood pressure measurements. Ambulatory measurement of blood pressure using automated devices has also demonstrated benefit in other indications, such as treatment resistance and borderline hypertension, or in hypertension during pregnancy. Future directions for hypertension research and treatment will need to consider the circadian cycle of blood pressure, the effect of treatment on blood pressure variability, and the magnitude of blood pressure changes in daily life.

Efeito da inversão dos turnos de trabalho sobre capacidade aeróbia e respostas cardiovasculares ao esforço máximo

Os distúrbios do sono e alterações associadas atingem grande parte da população que trabalha no turno noturno, afetando a sua qualidade de vida. O objetivo do presente trabalho foi comparar a capacidade aeróbia e as respostas cardiovasculares ao exercício máximo em indivíduos com ciclo sono vigília fisiológico e com inversão dos turnos de trabalho. Foram analisados 18 indivíduos do sexo masculino, sedentários, com idade entre 23-35 anos, divididos em 2 grupos: a) grupo controle, formado por estudantes (n=9) e b) grupo experimental, composto por controladores de tráfego aéreo que trabalhavam com inversão dos turnos de trabalho (n=9). Para a medida da capacidade aeróbia, foi determinado o VO2máx. por meio do analisador de gases metabólicos (VO-2000, Aerosport, Medgraphics). Para o teste de esforço máximo foi realizado o protocolo de rampa em esteira (Millenniun ATL Inbramed) e as respostas cardiovasculares (FC, PAS e PAD) foram verificadas antes e após a realização do exercício. De acordo com os resultados, o grupo experimental apresentou valores inferiores de FC no repouso (79,8 ± 11,5 bpm vs. 70,3 ± 3,8 bpm), no 5º (112,7± 15,1 bpm vs. 98,7 ± 6,3 bpm) e no 7º minuto (108,7 ± 16,6 bpm vs. 93,9 ± 6,8 bpm) de recuperação. Quanto à PAS, foram observados valores superiores durante o repouso (110,0 ± 11,2 mmHg vs. 104,0 ± 5,7 mmHg), nos indivíduos do grupo controle. Já a PAD, mostrou níveis superiores no 5º minuto da recuperação no grupo experimental (67,0 ± 4,4 mmHg vs. 58,9 ± 6,0 mmHg). Por fim, foram verificados valores superiores de VO2máx. para os indivíduos do grupo controle (58,9 ± 6,1 ml/kg/min) em relação ao experimental (53,7 ± 2,5 ml/kg/min). Desta forma, podemos concluir que a inversão nos turnos de trabalho, afetando o ciclo sono-vigília, altera não apenas o ciclo circadiano das variáveis cardiovasculares no repouso e na recuperação do esforço, como também traz prejuízos à capacidade funcional, podendo comprometer o desempenho das atividades ocupacionais.

Influence of presentation at the weekend on treatment and outcome in ST-elevation myocardial infarction in hospitals with catheterization laboratories

BACKGROUND

Studies about the influence of various factors on clinical therapy and course in acute coronary syndromes have shown that the outcome is related to admission time to the hospital, with an impaired prognosis in patients admitted out of regular working hours. However little is known about the impact of admission on weekend in hospitals with catheterisation laboratories.

METHODS

We analyzed data of the prospective MITRA-PLUS registry of 11,516 patients with ST-elevation myocardial infarction (STEMI) admitted to hospitals with catheterization facilities for differences of in-hospital mortality between patients admitted during regular working hours, at night and on weekends.

RESULTS

The prehospital delay and "door-to-balloon"-time were significantly longer on weekends and at nights than at regular working hours (median 196 Vs. 240 Vs. 155 min; P < 0.0001; 60 Vs. 84 min at weekends, resp. 75 min at nights; P < 0.0001). Reperfusion therapy was performed in 72.8% (8,248/11,332) patients, and there were less patients treated on weekend versus "on"-hours (69.7 Vs. 77 %, P < 0.0001). On weekends we found a significant higher in-hospital mortality (11.1 Vs. 9.4%, P = 0.01) and at night there was a trend to higher in-hospital mortality when compared with regular working hours (10.6 Vs. 9.4%, P = 0.07).

CONCLUSION

In patients with STEMI admitted to hospitals with catheterization facilities, admission during the "off"-hours is associated with higher in-hospital mortality. This may be due to lower rates of revascularization therapy and longer prehospital and in-hospital delays as compared to "on"-hours.

Are overnight urinary indicators associated with morning blood pressure in the elderly?

Recent reports suggest that high blood pressure (BP) during the night is associated with hypertensive organ damage, and that increased BP in the morning is closely related to the incidence of stroke and ischemic heart disease. The aim of this study was to investigate the relationships between overnight urinary indicators and 24-hour (24-h) BP, especially in the morning and during sleep in the elderly. A total of 85 volunteers (males 43, females 42), aged between 51 and 76 years and not taking any antihypertensive medications, participated in this study. Their 24-h BP was measured by ambulatory BP monitoring every 30-minute using a TERUMO ES-H531 system. Overnight urine samples were collected using a proportional urine-sampling device, Urine mate P. Overnight sodium (UNa(n)) and potassium (UKn) excretions were measured by an ion electrode method. Simple linear regression analyses showed that systolic blood pressure (SBP) in the morning and diastolic blood pressure (DBP) during sleep were negatively related with overnight urinary weight standardized for body weight (UW(n)/BW). Multiple regression analyses showed that SBP during the morning and during sleep was positively related to UNa(n) and negatively related to UW(n)/BW. We also found a negative relationship between SBP during sleep and UK(n). The study suggested that urine weight adjusted for BW was negatively related with 24-h BP, especially morning BP. Sodium excretion combined with a large volume of urine proportional to body weight may prevent increases in BP, especially in the morning.

Circadian variation in cardiovascular emergencies among the elderly

Clarification of the cyclic pattern of emergency events is useful for identifying risk factors for emergency events. We attempted to characterize the circadian variation in emergency calls for the elderly (aged 65 years or older) because the use of emergency transportation by elderly patients is increasing rapidly. The study targeted mainly patients with cardiovascular disease. Additionally, the study analyzed circadian variability in the occurrence of cardiopulmonary arrest (CPA) and heat stroke. Data for this study were obtained from computerized records of ambulance transport from 1997 to 2003 (a total of 874,495 transported patients) managed by the Emergency Medical Division of the Yokohama Fire Bureau. A partial Fourier model was used to analyze circadian patterns of emergency calls for each disease category and determine the peak time of occurrence of disease events. A prominent peak of cardiovascular disease and CPA in the morning was observed among elderly patients, whereas amplitudes of the morning and evening peaks were almost the same among younger patients. Heat stroke among elderly patients occurred frequently from 10:00 AM to 3:00 PM, and the occurrence peaked around noon. The increase in cardiovascular disease events and CPA during the morning among elderly patients may be due to a natural fluctuation in blood pressure. A morning increase in hemoconcentration induced by dehydration during the night is thought to be another cause of the frequent occurrence of cardiovascular disease, CPA, and heat stroke events in the morning hours. In conclusion, there was a prominent peak in the morning in the occurrence of emergency events such as cardiovascular disease, CPA, and heat stroke events among the elderly.

The circadian nuances of hypertension: a reappraisal of 24-h ambulatory blood pressure measurement in clinical practice

Ambulatory blood pressure measurement has been in use in clinical practice for nearly half a century. However, despite the benefits the technique brings to managing patients with hypertension it is much under-used in practice. The purpose of this review is to examine critically the information that can be derived from the technique and to highlight the application of this evidence in clinical practice.

Does sleep protect against ischemic stroke? Less frequent ischemic strokes but more severe ones

BACKGROUND AND OBJECTIVE

Stroke occurrence follows a circadian curve, with a higher frequency in the morning. This curve changes if the hours of sleep also change. Our aim was to evaluate the characteristics, risk factors, and prognosis associated with sleep stroke.

METHODS

Patients with ischemic stroke (n = 813), consecutively assessed in our hospital for 2 years, were recorded with the time of clinical onset, pathological antecedents, severity (NIHSS), clinical classification, etiologic TOAST classification, and functional outcome at 3 months (modified Rankin scale). When clinical disturbance appeared during night sleep time it was considered as sleep stroke (SS). The rest were considered wakefulness stroke (WS). Differences SS-WS were analyzed with chi(2), t-student, Mann-Whitney U, and logistic regression tests.

RESULTS

From 813 patients included, 127 were SS (15.6%). The SS frequency was less than expected for the corresponding interval of hours. After the univariate analysis and posterior logistic regression, obesity was a factor associated with SS. Adjustment for age and gender revealed that atrial fibrillation (AF) was less frequent in the SS group. There were no differences for other risk factors or in the etiologic distribution. SS had a greater initial clinical severity and a worse functional outcome at 3 months. This functional outcome was dependent on the initial clinical severity.

CONCLUSIONS

Whilst sleep could be associated with a lesser stroke occurrence, it could also be associated with a higher severity. Obesity appears as a factor related to SS whilst AF appears related to WS.

Effect of Regular Phosphodiesterase Type 5 Inhibition in Hypertension

There are no published controlled clinical trials of regular phosphodiesterase type 5 inhibitor therapy as a long-term treatment of hypertension. In a randomized, double-blind, 2-way crossover study, 25 otherwise untreated hypertensive subjects were administered 50 mg of sildenafil or matched placebo 3 times daily for 16 days, and the effects on ambulatory blood pressure (BP), clinic BP, arterial wave reflection, carotid-femoral pulse wave velocity, and brachial artery flow-mediated dilatation were assessed. Three subjects were withdrawn because of adverse effects, and the data from the remaining 22 subjects were analyzed. Sildenafil reduced ambulatory BP (mean [SE] change from baseline for average daytime BP: systolic -8 [2] mm Hg versus 2 [2] mm Hg with placebo, P<0.01; diastolic -6 [1] mm Hg versus 0 [1] mm Hg, P<0.01) and clinic BP (change from baseline to 1 hour after drug administration on day 16: systolic -5 [2] mm Hg versus 4 [2] mm Hg, P<0.01; diastolic -5 [1] mm Hg versus 2 [2] mm Hg, P<0.01). Compared with baseline, sildenafil, but not placebo, reduced arterial wave reflection both acutely and after chronic treatment, but the chronic change in arterial wave reflection was not statistically different from the chronic change with placebo. Sildenafil did not affect pulse wave velocity or flow-mediated dilatation. The main adverse effects of sildenafil, which were generally transient and rated as mild or moderate in severity, were dyspepsia, headache, and myalgia. In conclusion, regular sildenafil constitutes effective antihypertensive therapy. Further studies are warranted to evaluate the role of longer-acting phosphodiesterase type 5 inhibitors as antihypertensive agents in clinical practice.

Impact of ramipril on the circadian periodicity of acute myocardial infarction

Onset of acute myocardial infarction (AMI) follows a diurnal periodicity, with a peak incidence between 6:00 a.m. and noon. Beta blockers and aspirin decrease the rate of AMI and blunt the peak incidence, but such an effect has not been evaluated for angiotensin-converting enzyme inhibitors. The effect of ramipril on onset of symptomatic AMI was evaluated in 4-hour periods over a 24-hour cycle in men and women who were > or =55 years of age, had cardiovascular disease or diabetes mellitus with > or =1 other risk factor, and participated in the Heart Outcomes Prevention Evaluation (HOPE) trial. During the 4.5-year follow-up, AMI was documented in 383 of 4,596 participants allocated to ramipril and in 491 of 4,598 participants allocated to placebo (8.3% vs 10.7%, p <0.001). Ramipril decreased rates of AMI at each period and attenuated, but did not blunt, the peak incidence. In conclusion, inhibiting angiotensin-converting enzyme decreased AMI over a 24-hour period, but this enzyme does not seem to play a major role in the circadian periodicity of this acute event.

The orphan Rev-erb nuclear receptors: a link between metabolism, circadian rhythm and inflammation?

Nuclear hormone receptors (NRs) function as ligand dependent DNA binding proteins that translate physiological/nutritional signals into gene regulation. Dysfunctional NR signaling leads to many disorders in reproduction, inflammation, and metabolism. The opportunity to identify novel regulatory pathways in the context of human health and disease drives the challenge to unravel the biological function of the “orphan nuclear hormone receptors”. For example, the Rev-erb (NR1D) subgroup (Rev-erbα/NR1D1 and Rev-erbβ/NR1D2) of orphan NRs are transcriptional silencers and negative regulators of RORα mediated trans-activation. The NR1D subgroup is highly enriched in peripheral tissues with onerous energy demands including skeletal muscle, brown and white adipose, brain, liver and kidney. This alludes to the involvement of this subgroup in metabolism. In this context, Rev-erbα-/- mice have a dyslipidemic phenotype. Recent studies in vascular smooth and skeletal muscle cells also suggest that the NR1D subgroup modulates inflammation by regulating IκBα/NFκB dependent gene expression. Rev-erbα has been identified as a critical regulator (and target) of circadian rhythm, a factor in blood pressure control and inflammation. Finally, two recent reports have demonstrated: (i) lithium mediated regulation of Rev-erbα stability and (ii) E75 (the Drosophila orthologue of human Rev-erbα) is tightly bound by heme, and functions as a “gas sensor” through interaction with CO/NO and interferes with the repression of DHR3 (the Drosophila orthologue of human RORα). In conclusion, the role of these receptors at the cross-roads of metabolism, inflammation, and circadian cycling underscores the importance of understanding the organ-specific function of the NR1D subgroup in homeostasis.