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Sudden cardiac death (SCD), the unexpected death due to acquired or genetic cardiovascular disease, follows distinct 24-hour patterns in occurrence. These 24-hour patterns likely reflect daily changes in arrhythmogenic triggers and the myocardial substrate caused by day/night rhythms in behavior, the environment, and endogenous circadian mechanisms. To better address fundamental questions regarding the circadian mechanisms, the National Heart, Lung, and Blood Institute convened a workshop, Understanding Circadian Mechanisms of Sudden Cardiac Death. We present a 2-part report of findings from this workshop. Part 1 summarizes the workshop and serves to identify research gaps and opportunities in the areas of basic and translational research. Among the gaps was the lack of standardization in animal studies for reporting environmental conditions (eg, timing of experiments relative to the light dark cycle or animal housing temperatures) that can impair rigor and reproducibility. Workshop participants also pointed to uncertainty regarding the importance of maintaining normal circadian rhythmic synchrony and the potential pathological impact of desynchrony on SCD risk. One related question raised was whether circadian mechanisms can be targeted to reduce SCD risk. Finally, the experts underscored the need for studies aimed at determining the physiological importance of circadian clocks in the many different cell types important to normal heart function and SCD. Addressing these gaps could lead to new therapeutic approaches/molecular targets that can mitigate the risk of SCD not only at certain times but over the entire 24-hour period.

Sudden cardiac death (SCD) is the sudden, unexpected death due to abrupt loss of heart function secondary to cardiovascular disease. In certain populations living with cardiovascular disease, SCD follows a distinct 24-hour pattern in occurrence, suggesting day/night rhythms in behavior, the environment, and endogenous circadian rhythms result in daily spans of increased vulnerability. The National Heart, Lung, and Blood Institute convened a workshop, Understanding Circadian Mechanisms of Sudden Cardiac Death to identify fundamental questions regarding the role of the circadian rhythms in SCD. Part 2 summarizes research gaps and opportunities in the areas of population and clinical research identified in the workshop. Established research supports a complex interaction between circadian rhythms and physiological responses that increase the risk for SCD. Moreover, these physiological responses themselves are influenced by several biological variables, including the type of cardiovascular disease, sex, age, and genetics, as well as environmental factors. The emergence of new noninvasive biotechnological tools that continuously measure key cardiovascular variables, as well as the identification of biomarkers to assess circadian rhythms, hold promise for generating large-scale human data sets that will delineate which subsets of individuals are most vulnerable to SCD. Additionally, these data will improve our understanding of how people who suffer from circadian disruptions develop cardiovascular diseases that increase the risk for SCD. Emerging strategies to identify new biomarkers that can quantify circadian health (eg, environmental, behavioral, and internal misalignment) may lead to new interventions and therapeutic targets to prevent the progression of cardiovascular diseases that cause SCD.

Abstract Background Temporal, i.e., 24-hour, weekly, and seasonal patterns in the occurrence of acute cardiovascular and cerebrovascular events are well documented; however, little is known about temporal, especially seasonal, variation in multiple sclerosis (MS) and its relapses. This study investigated, by means of a validated chronobiological method, whether severe relapses of MS, ones requiring medical specialty consultation, display seasonal differences, and whether they are linked with seasonal differences in local meteorological variables. Results We considered 96 consecutive patients with severe MS relapse (29 men, 67 women, mean age 38.5 ± 8.8 years), referred to the Multiple Sclerosis Center, Bellaria Hospital, Bologna, Italy, between January 1, 2007 and December 31, 2008. Overall, we analyzed 164 relapses (56 in men, 108 in women; 115 in patients aged < 40 years, 49 in patients ≥40 years). Relapses were more frequent in May and June (12.2% each) and the least frequent in September (3.7%). Chronobiological analysis showed a biphasic pattern (major peak in May-June, secondary peak in November-December, p = 0.030). Analysis of monthly mean meteorological data showed a significant seasonal pattern in ambient temperature (peak in July, p < 0.001), relative humidity (peak in January, p < 0.001), and wind speed (peak in June, p = 0.011). Conclusions In this Italian setting, we found a biphasic pattern (peaks in spring and autumn) in severe MS relapses requiring medical consultation by doctors of the MS specialty center, apparently unrelated to meteorological variables. Confirmations of the findings on larger multi-center populations residing in different climatic conditions are needed to further explore the potential seasonality of MS relapses and associated environmental triggers.

Abstract Background Previous studies have reported seasonal variation in peptic ulcer disease (PUD), but few large-scale, population-based studies have been conducted. Methods To verify whether a seasonal variation in cases of PUD (either compicated or not complicated) requiring acute hospitalization exists, we assessed the database of hospital admissions of the region Emilia Romagna (RER), Italy, obtained from the Center for Health Statistics, between January 1998 and December 2005. Admissions were categorized by sex, age (per se in the region. For statistical analysis, the χ2 test for goodness of fit and inferential chronobiologic method (Cosinor and partial Fourier series) were used. Results Of the total sample of PUD patients (26,848 [16,795 males, age 65 ± 16 yrs; 10,053 females, age 72 ± 15 yrs, p < 0.001)], 7,151 were p < 0.001), for total cases and rather all subgroups. Chronobiological analysis identified three major peaks of PUD hospitalizations (September-October, January-February, and April-May) for the whole sample (p = 0.035), and several subgroups, with nadir in July. Finally, analysis of the monthly prevalence proportions yielded a significant (p = 0.025) biphasic pattern with a main peak in August-September-October, and a secondary one in January-February. Conclusions A seasonal variation in PUD hospitalization, characterized by three peaks of higher incidence (Autumn, Winter, and Spring) is observed. When data corrected by monthly admission proportions are analyzed, late summer-autumn and winter are confirmed as higher risk periods. The underlying pathophysiologic mechanisms are unknown, and need further studies. In subjects at higher risk, certain periods of the year could deserve an appropriate pharmacological protection to reduce the risk of PUD hospitalization.

Chronotherapy is the timing of medications to circadian rhythms to optimize beneficial and minimize adverse outcomes. We reviewed the US Online Prescribers' Digital Reference for the specified administration schedule of medications prescribed to manage coronary heart disease (CHD) and its major risk factors. For arterial hypertension, dosing of terazosin and guanfacine is recommended in the evening and thiazide, thiazide-like, and sulfonamide diuretics morning; Verapamil (Verelan®) morning, its "PM" formulation evening, and long-acting diltiazem (Cardizem® LA), per clinical goal, morning or evening. Most hyperlipidemia medications are recommended in the evening. Many hyperglycemia medications are intended for morning ingestion, but, when indicated, some may be prescribed in unequal doses or intervals. For obesity, administration of appetite suppressant psychostimulants and sympathomimetics is stipulated for morning ingestion. Sleep insufficiency medications are to be taken before bedtime. For tobacco dependence, transdermal nicotine patch application is recommended in the morning, and bupropion early, but not late, during the wake span. For alcohol dependence, disulfiram is intended for morning ingestion. For thromboembolism prophylaxis, factor Xa inhibitor rivaroxaban is recommended at dinner and low-dose acetylsalicylic acid before bedtime. Medications for angina pectoris and edema of congestive heart failure are stipulated for morning administration. Overall, >200 medications prescribed to manage CHD and its risk factors qualify as chronotherapies. [ABSTRACT FROM AUTHOR]

BackgroundWearable sleep monitors are of high interest to consumers and researchers because of their ability to provide estimation of sleep patterns in free-living conditions in a cost-efficient way. ObjectiveWe conducted a systematic review of publications reporting on the performance of wristband Fitbit models in assessing sleep parameters and stages. MethodsIn adherence with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, we comprehensively searched the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane, Embase, MEDLINE, PubMed, PsycINFO, and Web of Science databases using the keyword Fitbit to identify relevant publications meeting predefined inclusion and exclusion criteria. ResultsThe search yielded 3085 candidate articles. After eliminating duplicates and in compliance with inclusion and exclusion criteria, 22 articles qualified for systematic review, with 8 providing quantitative data for meta-analysis. In reference to polysomnography (PSG), nonsleep-staging Fitbit models tended to overestimate total sleep time (TST; range from approximately 7 to 67 mins; effect size=-0.51, P

Major objectives of this work were to: (1) substantiate the 24‐hour pattern in the occurrence of childhood febrile seizures (CFSs) by a novel time series meta‐analysis of past reported time‐of‐day data and (2) discuss its potential circadian rhythm‐dependencies. Comprehensive search of the published literature retrieved eight articles that met inclusion criteria. Three investigations were conducted in Iran, two in Japan, and one each in Finland, Italy, and South Korea, representing a total of 2461 mostly simple febrile seizures of children who were on average about 2 years of age. Population‐mean cosinor analysis validated (p <.001) a 24‐hour pattern in the onset of CFSs, with an approximate four‐fold difference in the proportion of children expressing seizures at its peak at 18:04 h (95% confidence interval: 16:40–19:07 h) vs trough at 06:00 h, in the absence of meaningful time‐of‐day differences in mean body temeprarure. The CFS time‐of‐day pattern likely derives from the actions of multiple circadian rhythms, particularly the cytokines that comprise the pyrogenic inflammatory pathway and melatonin that influences the excitation level of central neurons and helps regulate body temperature. Past laboratory animal and patient investigations document that the vulnerability to a seizure by a provoking trigger of the same intensity is not the same but different in a predictable‐in‐time manner during the 24 h as a circadian susceptibility/resistance rhythm. Knowledge of the marked disparity in the time‐of‐day risk of CFSs can be translated into improved prevention, particularly during the late afternoon and early evening when highest, through proper timing of prophylactic interventions. [ABSTRACT FROM AUTHOR]

Atherosclerosis, a chronic inflammatory disease of the arteries that appears to have been as prevalent in ancient as in modern civilizations, is predisposing to life-threatening and life-ending cardiac and vascular complications, such as myocardial and cerebral infarctions. The pathogenesis of atherosclerosis involves intima plaque buildup caused by vascular endothelial dysfunction, cholesterol deposition, smooth muscle proliferation, inflammatory cell infiltration and connective tissue accumulation. Hypertension is an independent and controllable risk factor for atherosclerotic cardiovascular disease (CVD). Conversely, atherosclerosis hardens the arterial wall and raises arterial blood pressure. Many CVD patients experience both atherosclerosis and hypertension and are prescribed medications to concurrently mitigate the two disease conditions. A substantial number of publications document that many pathophysiological changes caused by atherosclerosis and hypertension occur in a manner dependent upon circadian clocks or clock gene products. This article reviews progress in the research of circadian regulation of vascular cell function, inflammation, hemostasis and atherothrombosis. In particular, it delineates the relationship of circadian organization with signal transduction and activation of the renin-angiotensin-aldosterone system as well as disturbance of the sleep/wake circadian rhythm, as exemplified by shift work, metabolic syndromes and obstructive sleep apnea (OSA), as promoters and mechanisms of atherogenesis and risk for non-fatal and fatal CVD outcomes. This article additionally updates advances in the clinical management of key biological processes of atherosclerosis to optimally achieve suppression of atherogenesis through chronotherapeutic control of atherogenic/hypertensive pathological sequelae. [ABSTRACT FROM AUTHOR]

Several prospective studies consistently report elevated asleep blood pressure (BP) and blunted sleep-time relative systolic BP (SBP) decline (non-dipping) are jointly the most significant prognostic markers of cardiovascular disease (CVD) risk, including heart failure (HF); therefore, they, rather than office BP measurements (OBPM) and ambulatory awake and 24 h BP means, seemingly are the most worthy therapeutic targets for prevention. Published studies of the 24 h BP pattern in HF are sparse in number and of limited sample size. They report high prevalence of the abnormal non-dipper/riser 24 h SBP patterning. Despite the established clinical relevance of the asleep BP, past as do present hypertension guidelines recommend the diagnosis of hypertension rely on OBPM and, when around-the-clock ambulatory BP monitoring (ABPM) is conducted to confirm the elevated OBPM, either on the derived 24 h or "daytime" BP means. Additionally, hypertension guidelines do not advise the time-of-day when BP-lowering medications should be ingested, in spite of known ingestion-time differences in their pharmacokinetics and pharmacodynamics. Between 1976 and 2020, 155 unique trials of ingestion-time differences in the effects of 37 different single and 14 dual-combination hypertension medications, collectively involving 23,972 patients, were published. The vast majority (83.9%) of them found the at-bedtime/evening in comparison to upon-waking/morning treatment schedule resulted in more greatly enhanced: (i) reduction of asleep BP mean without induced sleep-time hypotension; (ii) reduction of the prevalence of the higher CVD risk non-dipper/riser 24 h BP phenotypes; (iii) improvement of kidney function, reduction of cardiac pathology, and with lower incidence of adverse effects. Most notably, no single published randomized trial found significantly better BP-lowering, particularly during sleep, or medical benefits of the most popular upon-waking/morning hypertension treatment-time scheme. Additionally, prospective outcome trials have substantiated that the bedtime relative to the upon-waking, ingestion of BP-lowering medications not only significantly reduces risk of HF but also improves overall CVD event-free survival time. [ABSTRACT FROM AUTHOR]