Circadian Dependence of Infarct Size and Acute Heart Failure in ST Elevation Myocardial Infarction

Circadian biology of cardiac aging

The age of the U.S. population is increasing alongside a growing burden of age-related cardiovascular disease. Circadian rhythms are critical for human health and are disrupted with aging and cardiovascular disease. The goal of the present review is to summarize how cardiac circadian rhythms change with age and how this might contribute to the increasing burden of age-associated heart disease. Further, we will review what is known about interventions to slow aging and whether they impact cardiac clock function, as well as whether time-of-day or chronotherapy may improve cardiac function with age. Although much remains to be understood about the circadian biology of cardiac aging, we propose that altered circadian clock output should be considered a hallmark of aging and that efforts to fix the clock are warranted for healthy cardiac aging.

The chronobiology of human heart failure: clinical implications and therapeutic opportunities

Circadian variation in cardiovascular and metabolic dynamics arises from interactions between intrinsic rhythms and extrinsic cues. By anticipating and accommodating adaptation to awakening and activity, their synthesis maintains homeostasis and maximizes efficiency, flexibility, and resilience. The dyssynchrony of cardiovascular load and energetic capacity arising from attenuation or loss of such rhythms is strongly associated with incident heart failure (HF). Once established, molecular, neurohormonal, and metabolic rhythms are frequently misaligned with each other and with extrinsic cycles, contributing to HF progression and adverse outcomes. Realignment of biological rhythms via lifestyle interventions, chronotherapy, and time-tailored autonomic modulation represents an appealing potential strategy for improving HF-related morbidity and mortality.

Prediction of heart failure patients with distinct left ventricular ejection fraction levels using circadian ECG features and machine learning

Heart failure (HF) encompasses a diverse clinical spectrum, including instances of transient HF or HF with recovered ejection fraction, alongside persistent cases. This dynamic condition exhibits a growing prevalence and entails substantial healthcare expenditures, with anticipated escalation in the future. It is essential to classify HF patients into three groups based on their ejection fraction: reduced (HFrEF), mid-range (HFmEF), and preserved (HFpEF), such as for diagnosis, risk assessment, treatment choice, and the ongoing monitoring of heart failure. Nevertheless, obtaining a definitive prediction poses challenges, requiring the reliance on echocardiography. On the contrary, an electrocardiogram (ECG) provides a straightforward, quick, continuous assessment of the patient's cardiac rhythm, serving as a cost-effective adjunct to echocardiography. In this research, we evaluate several machine learning (ML)-based classification models, such as K-nearest neighbors (KNN), neural networks (NN), support vector machines (SVM), and decision trees (TREE), to classify left ventricular ejection fraction (LVEF) for three categories of HF patients at hourly intervals, using 24-hour ECG recordings. Information from heterogeneous group of 303 heart failure patients, encompassing HFpEF, HFmEF, or HFrEF classes, was acquired from a multicenter dataset involving both American and Greek populations. Features extracted from ECG data were employed to train the aforementioned ML classification models, with the training occurring in one-hour intervals. To optimize the classification of LVEF levels in coronary artery disease (CAD) patients, a nested cross-validation approach was employed for hyperparameter tuning. HF patients were best classified using TREE and KNN models, with an overall accuracy of 91.2% and 90.9%, and average area under the curve of the receiver operating characteristics (AUROC) of 0.98, and 0.99, respectively. Furthermore, according to the experimental findings, the time periods of midnight-1 am, 8-9 am, and 10-11 pm were the ones that contributed to the highest classification accuracy. The results pave the way for creating an automated screening system tailored for patients with CAD, utilizing optimal measurement timings aligned with their circadian cycles.

Investigating automated regression models for estimating left ventricular ejection fraction levels in heart failure patients using circadian ECG features

Heart Failure (HF) significantly impacts approximately 26 million people worldwide, causing disruptions in the normal functioning of their hearts. The estimation of left ventricular ejection fraction (LVEF) plays a crucial role in the diagnosis, risk stratification, treatment selection, and monitoring of heart failure. However, achieving a definitive assessment is challenging, necessitating the use of echocardiography. Electrocardiogram (ECG) is a relatively simple, quick to obtain, provides continuous monitoring of patient's cardiac rhythm, and cost-effective procedure compared to echocardiography. In this study, we compare several regression models (support vector machine (SVM), extreme gradient boosting (XGBOOST), gaussian process regression (GPR) and decision tree) for the estimation of LVEF for three groups of HF patients at hourly intervals using 24-hour ECG recordings. Data from 303 HF patients with preserved, mid-range, or reduced LVEF were obtained from a multicentre cohort (American and Greek). ECG extracted features were used to train the different regression models in one-hour intervals. To enhance the best possible LVEF level estimations, hyperparameters tuning in nested loop approach was implemented (the outer loop divides the data into training and testing sets, while the inner loop further divides the training set into smaller sets for cross-validation). LVEF levels were best estimated using rational quadratic GPR and fine decision tree regression models with an average root mean square error (RMSE) of 3.83% and 3.42%, and correlation coefficients of 0.92 (p<0.01) and 0.91 (p<0.01), respectively. Furthermore, according to the experimental findings, the time periods of midnight-1 am, 8-9 am, and 10-11 pm demonstrated to be the lowest RMSE values between the actual and predicted LVEF levels. The findings could potentially lead to the development of an automated screening system for patients with coronary artery disease (CAD) by using the best measurement timings during their circadian cycles.

Ruscogenin timing administration mitigates cerebral ischemia-reperfusion injury through regulating circadian genes and activating Nrf2 pathway

BACKGROUND

Ruscogenin (Rus), a steroidal sapogenin extracted from Ophiopogon japonicus (L. f.) Ker-Gawl., has the effect of alleviating cerebral ischemia-reperfusion injury (IRI), acute lung injury. At present, the chronopharmacological effects of Rus are still unknown.

PURPOSE

This study explored the alleviating effect and mechanism of Rus timing administration on mice cerebral IRI.

METHODS

The animals in different groups were administrated Rus (10 mg/kg) by gavage at four time points (23:00-01:00, 05:00-07:00, 11:00-13:00, 17:00-19:00) respectively for 3 days. On the 4th day, middle cerebral artery occlusion (MCAO) surgery was operated during 5:00-7:00. Behavioral tests were executed and the brain was collected for infarct volume, qPCR and immunoblot detection. The levels of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), interleukin-1beta (IL-1β) and inducible nitric oxide synthase (iNOS) were detected by qPCR. Glutathione (GSH), superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in serum and cerebral cortex were detected. The clock genes were tested by western blot. Based on these results, 17:00-19:00 was selected to administrate Rus for further mechanism study and Nrf2 blocker group was administrated all-trans-retinoic acid (ATRA) at 14:00 for 3 days.

RESULTS

Administration of Rus reduced cerebral infarcted volume, ameliorated the behavior score and upregulated the mRNA and protein expression of Per1, Bmal1, Clock, Rev-erbα, transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), quinone oxidoreductase 1 (NQO1). Administration of Rus during 17:00-19:00 had better preventive effect than other three time points. Combined administration of ATRA blunted the preventive effect of Rus.

CONCLUSION

The preventive effect of Rus is affected by the time of administration, which was regulated by Nrf2 pathway. Taken together, we provide solid evidence to suggest that different administration time point affect the effectiveness of Rus in alleviating IRI.

The Circadian Biology of Heart Failure

Driven by autonomous molecular clocks that are synchronized by a master pacemaker in the suprachiasmatic nucleus, cardiac physiology fluctuates in diurnal rhythms that can be partly or entirely circadian. Cardiac contractility, metabolism, and electrophysiology, all have diurnal rhythms, as does the neurohumoral control of cardiac and kidney function. In this review, we discuss the evidence that circadian biology regulates cardiac function, how molecular clocks may relate to the pathogenesis of heart failure, and how chronotherapeutics might be applied in heart failure. Disrupting molecular clocks can lead to heart failure in animal models, and the myocardial response to injury seems to be conditioned by the time of day. Human studies are consistent with these findings, and they implicate the clock and circadian rhythms in the pathogenesis of heart failure. Certain circadian rhythms are maintained in patients with heart failure, a factor that can guide optimal timing of therapy. Pharmacologic and nonpharmacologic manipulation of circadian rhythms and molecular clocks show promise in the prevention and treatment of heart failure.

The role of temporal changes of pro-inflammatory cytokines in the development of adverse cardiac remodeling after ST-elevation myocardial infarction

Introduction

Increasing evidence supports the view that pro-inflammatory cytokines play a role in fibrosis after myocardial infarction (MI). It has been suggested that interleukin (IL)-12p40, a pro-inflammatory cytokine, can induce interferon γ (IFN-γ) and matrix metalloproteinase (MMP). However, the role of IL-12p40 in adverse cardiac remodeling (AR) after ST-elevation MI (STEMI) is unclear.

Aim

To examine the role of temporal changes of pro-inflammatory cytokines in the development of post-STEMI AR.

Material and methods

A total of 43 patients with STEMI for the first time ever were prospectively analyzed. In cardiac magnetic resonance imaging at 6 months after STEMI, a decrease of left ventricular end-diastolic volume by ≥ 12% was defined as reverse cardiac remodeling (RR), and a 12% increase was defined as AR. Cytokine concentrations were measured on the first day (baseline) and 2 weeks after STEMI.

Results

Mean IL-12p40 (59.1 ±14.5 vs. 46.7 ±9.1 pq/ml, p = 0.001), median IFN-γ (20.4 vs. 16.2 pq/ml, p = 0.048) and median MMP-2 (33866 vs. 20691 pq/ml, p = 0.011) baseline concentrations were higher in AR than RR. In patients with AR, IL-12p40 level was lower at 2 weeks than baseline (p < 0.001). There was a positive correlation between the baseline concentrations of IL-12p40, IFN-γ, MMP-2, C-reactive protein and infarct size (p < 0.05). Increased IL-12p40 and MMP-2 baseline levels were independently associated with AR (OR = 1.14, p = 0.010; OR = 1.08, p = 0.035).

Conclusions

In the initial phase of MI, greater release of pro-inflammatory cytokines was associated with increased MMP-2 levels. Elevated expression of IL-12 and MMP-2 had an independent association with AR. This may be related to the excessive inflammatory response in the initial phase of MI.

Metabolic Pathway of Cardiospecific Troponins: From Fundamental Aspects to Diagnostic Role (Comprehensive Review)

Many molecules of the human body perform key regulatory functions and are widely used as targets for the development of therapeutic drugs or as specific diagnostic markers. These molecules undergo a significant metabolic pathway, during which they are influenced by a number of factors (biological characteristics, hormones, enzymes, etc.) that can affect molecular metabolism and, as a consequence, the serum concentration or activity of these molecules. Among the most important molecules in the field of cardiology are the molecules of cardiospecific troponins (Tns), which regulate the processes of myocardial contraction/relaxation and are used as markers for the early diagnosis of ischemic necrosis of cardiomyocytes (CMC) in myocardial infarction (MI). The diagnostic value and diagnostic capabilities of cardiospecific Tns have changed significantly after the advent of new (highly sensitive (HS)) detection methods. Thus, early diagnostic algorithms of MI were approved for clinical practice, thanks to which the possibility of rapid diagnosis and determination of optimal tactics for managing patients with MI was opened. Relatively recently, promising directions have also been opened for the use of cardiospecific Tns as prognostic markers both at the early stages of the development of cardiovascular diseases (CVD) (arterial hypertension (AH), heart failure (HF), coronary heart disease (CHD), etc.), and in non-ischemic extra-cardiac pathologies that can negatively affect CMC (for example, sepsis, chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), etc.). Recent studies have also shown that cardiospecific Tns are present not only in blood serum, but also in other biological fluids (urine, oral fluid, pericardial fluid, amniotic fluid). Thus, cardiospecific Tns have additional diagnostic capabilities. However, the fundamental aspects of the metabolic pathway of cardiospecific Tns are definitively unknown, in particular, specific mechanisms of release of Tns from CMC in non-ischemic extra-cardiac pathologies, mechanisms of circulation and elimination of Tns from the human body, mechanisms of transport of Tns to other biological fluids and factors that may affect these processes have not been established. In this comprehensive manuscript, all stages of the metabolic pathway are consistently and in detail considered, starting from release from CMC and ending with excretion (removal) from the human body. In addition, the possible diagnostic role of individual stages and mechanisms, influencing factors is analyzed and directions for further research in this area are noted.

The Importance of Cardiac Troponin Metabolism in the Laboratory Diagnosis of Myocardial Infarction (Comprehensive Review)

The study of the metabolism of endogenous molecules is not only of great fundamental significance but also of high practical importance, since many molecules serve as drug targets and/or biomarkers for laboratory diagnostics of diseases. Thus, cardiac troponin molecules have long been used as the main biomarkers for confirmation of diagnosis of myocardial infarction, and with the introduction of high-sensitivity test methods, many of our ideas about metabolism of these cardiac markers have changed significantly. In clinical practice, there are opening new promising diagnostic capabilities of cardiac troponins, the understanding and justification of which are closely connected with the fundamental principles of the metabolism of these molecules. Our current knowledge about the metabolism of cardiac troponins is insufficient and extremely disconnected from various literary sources. Thus, many researchers do not sufficiently understand the potential importance of cardiac troponin metabolism in the laboratory diagnosis of myocardial infarction. The purpose of this comprehensive review is to systematize information about the metabolism of cardiac troponins and during the discussion to focus on the potential impact of cTns metabolism on the laboratory diagnosis of myocardial infarction. The format of this comprehensive review includes a sequential consideration and analysis of the stages of the metabolic pathway, starting from possible release mechanisms and ending with elimination mechanisms. This will allow doctors and researchers to understand the significant importance of cTns metabolism and its impact on the laboratory diagnosis of myocardial infarction.

Biology of Cardiac Troponins: Emphasis on Metabolism

Understanding of the biology of endo- and exogenous molecules, in particular their metabolism, is not only of great theoretical importance, but also of high practical significance, since many molecules serve as drug targets or markers for the laboratory diagnostics of many human diseases. Thus, cardiac troponin (cTns) molecules have long been used as key markers for the confirmation of diagnosis of myocardial infarction (MI), and with the introduction of contemporary (high sensitivity) test methods, many of our concepts related to the biology of these cardiac markers have changed significantly. In current clinical practice, there are opening new promising diagnostic capabilities of cTns, the understanding and justification of which is closely connected with the theoretical principles of the metabolism of these molecules. However, today, the biology and metabolism of cTns have not been properly investigated; in particular, we do not know the precise mechanisms of release of these molecules from the myocardial cells (MCs) of healthy people and the mechanisms of circulation, and the elimination of cTns from the bloodstream. The main purpose of this manuscript is to systematize information about the biology of cTns, with an emphasis on the metabolism of cTns. The format of this paper, starting with the release of cTns in the blood and concluding with the metabolism/filtration of troponins, provides a comprehensive yet logically easy way for the readers to approach our current knowledge in the framework of understanding the basic mechanisms by which cTns are produced and processed. Conclusions. Based on the analysis of the current literature, the important role of biology and all stages of metabolism (release, circulation, removal) of cTns in laboratory diagnostics should be noted. It is necessary to continue studying the biology and metabolism of cTns, because this will improve the differential diagnosis of MI and i a new application of cTns immunoassays in current clinical practice.

Death and cardiovascular outcomes in end-stage renal failure patients on different modalities of dialysis

INTRODUCTION

Cardiovascular morbidity and mortality in end-stage renal failure (ESRF) patients are high. We examined the incidence and predictors of death and acute myocardial infarction (AMI) in ESRF patients on different modalities of dialysis.

METHOD

Data were obtained from a population-based database (National Registry Disease Offices) in Singapore. The study cohort comprised all adult patients initiated on dialysis between 2007 and 2012 who were closely followed for the development of death and AMI until September 2014. Cox regression methods were used to identify predictors of death and AMI.

RESULTS

Of 5,309 patients, 4,449 were on haemodialysis and 860 on peritoneal dialysis (PD). Mean age of the cohort was 61 (±13) years (44% women), of Chinese (67%), Malay (25%) and Indian (7%) ethnicities. By September 2014, the incidence of all-cause death was 34%; close to a third of the patients died from a cardiovascular cause. Age >60 years and the presence of ischaemic heart disease, diabetes, stroke, peripheral vascular disease and PD were identified as independent predictors of all-cause death. PD patients had lower odds of survival compared to patients on haemodialysis (hazard ratio 1.51, 95% confidence interval 1.35-1.70, P<0.0001). Predictors of AMI in this cohort were older age (>60 years) and the presence of ischaemic heart disease, diabetes, stroke, peripheral vascular disease and current/ex-smokers. There were no significant differences in the incidence of AMI between patients on PD and haemodialysis.

CONCLUSION

The short-term incidence of death and AMI remains high in Singapore. Future studies should investigate the benefits of a tighter control of cardiovascular risk factors among ESRF patients on dialysis.

Augmented early aged neutrophil infiltration contributes to late remodeling post myocardial infarction

Neutrophils oscillate in number and phenotype after being released from bone marrow. Myocardial infarction (MI) outcome is associated with the time-of-day of ischemia onset. However, the underlying contributive factors of neutrophils to cardiac remodeling post MI remain unknown. We examined neutrophil infiltration into the heart and cardiac function and remodeling in C57BL/6J MI model created by permanent coronary ligation at different zeitgeber times (ZT). We found that cell surface markers (CD62L, CXCR2, CXCR4) of neutrophils in peripheral blood lost diurnal oscillation 24 h post MI. Meanwhile, circadian gene Bmal1, Nr1d1, and Clock mRNA expression displayed disrupted diurnal patterns. Flow cytometry showed augmented aged neutrophil (CD11b+Ly6G+CD62Llow) infiltration into the heart along with increased circulating aged neutrophils in MI groups with more infiltration at ZT5 (p < 0.05), but no difference for aged neutrophil infiltration at different ZT points in late stage. Infiltrated neutrophils had significantly higher CXCL2 and CXCR2 but lower CXCR4 gene expression (p < 0.05). Mice that underwent ligation at ZT5 had high mortality rate and large infarct size. Echocardiography showed that those mice had significantly larger end diastolic and systolic volume and lower ejection fraction (p < 0.05). Immunohistology revealed that those mice displayed more fibrosis, cardiomyocyte hypertrophy, and less angiogenesis compared to ZT13 or ZT21 group (p < 0.05). However, treatment with anti-CXCL2 antibody significantly reduced LV dilatation, fibrosis, hypertrophy and improved cardiac function. These results indicate greater aged neutrophil infiltration into the heart contributes to cardiac hypertrophy, fibrosis, and dysfunction which suggests that blocking neutrophil aging may be a therapeutic alternative following acute myocardial infarction.

Period 2-Induced Activation of Autophagy Improves Cardiac Remodeling After Myocardial Infarction

Accumulating evidence indicates that the onset of myocardial infarction (MI) shows obvious circadian rhythmicity. Clinical studies have shown that MIs that occur in the early morning have a poor prognosis, but the mechanisms involved are still unknown. In this study, we showed that the expression level of Period 2 (per2) in the heart of mice is lower in the early morning than at noon and that increasing the expression of per2 in H9C2 cells and rat cardiomyocytes increases autophagy levels. Further studies indicated that overexpression of per2 after an MI improved cardiac function by increasing autophagy. In summary, this study has shown that the circadian clock protein, per2, may be a regulator of MI.

Cardiac Troponins: Contemporary Biological Data and New Methods of Determination

Laboratory diagnosis plays one of the key roles in the diagnosis of many diseases, including cardiovascular diseases (CVD). The methods underlying the in vitro study of many CVD biomarkers, including cardiac troponins (cTnI and cTnT), are imperfect and are continually being improved to enhance their analytical performance, with sensitivity and specificity being the most important. Recently developed improved cTnI and cTnT detection methods, referred to as highly sensitive methods (hs-cTnI, hs-cTnT), have changed many of our ideas about the biology of cardiac troponins and opened up a number of additional diagnostic capabilities for practical healthcare. This article systematizes some relevant data on the biology of cardiac troponins as well as on methods for determining cTnI and cTnT with an analysis of the diagnostic value of their analytical characteristics (limit of blank, limit of detection, 99th percentile, coefficient of variation, and others). Data on extracardiac expression of cTnI and cTnT, mechanisms of formation and potential clinical significance of gender, age, and circadian characteristics of hs-cTnI and hs-cTnT content in serum are discussed. Considerable attention is paid to the discussion of new diagnostic capabilities of hs-cTnI, hs-cTnT, including consideration of promising possibilities for their study in biological fluids that can be obtained by non-invasive methods. Also, some possibilities of using hs-cTnI and hs-cTnT as prognostic laboratory biomarkers in healthy people (for example, to assess the risk of developing CVD) and in patients suffering from a number of pathological conditions that cause damage to cardiomyocytes are examined, and the potential mechanisms underlying the increase in hs-cTnI and hs-cTnT are discussed.

Relationship between primary percutaneous coronary intervention time of day, infarct size, microvascular obstruction and prognosis in ST-segment elevation myocardial infarction

BACKGROUND

Whether the time of day of primary percutaneous coronary intervention (pPCI) in patients with ST-segment elevation myocardial infarction (STEMI) is associated with infarct size, microvascular obstruction (MVO), and prognosis is uncertain. We compared infarct size assessed by cardiac MRI (CMR) and clinical outcomes in STEMI patients according to the pPCI time of day from a large, individual patient-data pooled database.

METHODS

We pooled patient-level data from five randomized pPCI trials in which infarct size was measured within 1 month by CMR. Patients were categorized according to the pPCI time of day.

RESULTS

Among 1519 patients with STEMI, 794 (52.2%) underwent pPCI between 8:00 h and 15:59 h, 431 (28.4%) between 16:00 h and 23:59 h, and 294 (19.4%) between 24:00 h and 7:59 h. Infarct size was assessed in 1331 patients at a median of 3.0 days (interquartile range 2.0-5.0) after pPCI. Compared with patients who underwent PCI between 8:00 h and 15:59 h, infarct size was not significantly different for patients undergoing PCI from 16:00 h to 23:59 h [adjusted difference -0.7%, 95% confidence interval (CI) -3.1 to 1.7%, P = 0.46] or 24:00 h to 7:59 h (adjusted difference 0.9%, 95% CI -1.2 to 3.1%, P = 0.29). The time of day of pPCI was also unrelated to MVO and the 1-year risks of death or heart failure hospitalization.

CONCLUSION

In this large-scale, individual patient data pooled analysis, no association was found between the time of day of pPCI and infarct size, MVO, or prognosis after STEMI.

Impact of time of onset of symptom of ST-segment elevation myocardial infarction on 1-year rehospitalization for heart failure and mortality

Circadian patterns in ST-segment elevation myocardial infarction (STEMI) patients have been previously reported, but little is known about the impact of time dependence of symptom onset on long-term prognosis. Our study population consisted of 11,731 STEMI patients treated by primary percutaneous coronary intervention (PPCI), enrolled in the Singapore Myocardial Infarction Registry (SMIR). Analysis of STEMI incidence trends over the 24-hour period showed the highest rate of symptom onset in the morning, with the peak incidence at 09:00 am. Patients with symptom onset in between 00:00 am-5:59 am showed the highest prevalence of diabetes (P = .010) and anterior STEMI (P < .001) and had the longest ischemic time (P < .001). After adjusting for confounders, we found an association between time of symptom onset of STEMI and rehospitalization for heart failure (HF) at 1 year, with symptom onset between 06:00 pm-11:59 pm and 00:00 am-05:59 am having an estimated 30% to 50% higher risk of rehospitalization for HF at 1 year. Moreover, symptom onset remained a predictor of worse prognosis only in the subgroup of patients with symptoms lasting longer than 120 minutes. The results of this study demonstrate for the first time that rehospitalization for HF in STEMI patients treated with PPCI has a dependence on the time of onset of symptoms, with prolonged ischemia time playing a pivotal role. This may be an additional risk factor to identify those who warrant closer monitoring and more rigorous optimization of their treatment at follow-up, to improve their outcomes.

A Tissue-Specific Rhythmic Recruitment Pattern of Leukocyte Subsets

The circulating of leukocytes in the vasculature to reach various organs is a crucial step that allows them to perform their function. With a sequence of interaction with the endothelial cells, the leukocytes emigrate from the circulation either by firm attachment to vascular beds or by trafficking into the tissues. Recent findings reveal that the leukocyte recruitment shows time as well as tissue specificity depending on the cell type and homing location. This spatiotemporal distribution of leukocyte subsets is driven by the circadian expression of pro-migratory molecules expressed on the leukocytes and the endothelium. Both the systemic circadian signals and the cell's intrinsic molecule clock contribute to the oscillatory expression of pro-migratory molecules. The rhythmic recruitment of leukocytes plays an important role in the time-dependency of immune responses. It also helps to update blood components and maintain the tissue circadian microenvironment. In this review, we discuss the current knowledge about the mechanisms of the circadian system regulating the leukocyte rhythmic migration, the recruitment pattern of leukocyte subsets into different tissue/organs, and the time-dependent effects behind this process.

Vulnerability to cardiac arrest in patients with ST elevation myocardial infarction: Is it time or patient dependent? Results from a nationwide observational study

AIM

Cardiac arrest is a common complication of ST elevation myocardial infarction and is associated with high mortality. We evaluated whether vulnerability to cardiac arrest follows a circadian rhythm and whether it is related to specific patient characteristics.

METHODS

A total of 24,164 ST elevation myocardial infarction patients who were admitted to 60 Belgian hospitals between 2008-2017 were analysed. The proportion of patients with cardiac arrest before initiation of reperfusion therapy was calculated for different time periods (hour of the day, months, seasons) and related to patient characteristics using stepwise logistic regression analysis.

RESULTS

Cardiac arrest occurred in 10.8% of the ST elevation myocardial infarction patients at a median of 65 min (interquartile range 33-138 min) after onset of pain. ST elevation myocardial infarction patients with cardiac arrest showed a biphasic pattern with one peak in the morning and one peak in the late afternoon. Multivariate analysis identified the following independent factors associated with cardiac arrest: cardiogenic shock (odds ratio=28), left bundle branch block (odds ratio=3.7), short (<180 min) ischaemic period (odds ratio=2.2), post-meridiem daytime presentation (odds ratio=1.4), anterior infarction (odds ratio=1.3). Overall in-hospital mortality was 30% for cardiac arrest patients versus 3.7% for non-cardiac arrest patients (p<0.0001).

CONCLUSION

In the present study population, cardiac arrest in ST elevation myocardial infarction showed an atypical circadian rhythm with not only a morning peak but also a second peak in the late afternoon, suggesting that cardiac arrest and ST elevation myocardial infarction triggers are, at least partially, different. In addition, specific patient characteristics, such as short ischaemic period, cardiogenic shock and left bundle branch block, increase the vulnerability to cardiac arrest.

Time-of-day at symptom onset was not associated with infarct size and long-term prognosis in patients with ST-segment elevation myocardial infarction

Background

ST-segment elevation myocardial infarction (STEMI) displays circadian variability with the highest incidence in the morning hours. Data on whether the time-of-day at symptom onset affects infarct size or patients’ long-term prognosis are conflicting. We sought to investigate the association of time-of-day at symptom onset with infarct size or long-term mortality in patients with STEMI undergoing primary percutaneous coronary intervention (PPCI).

Methods

This study included 1206 STEMI patients undergoing PPCI. All patients underwent single photon emission computed tomography (SPECT) imaging with 99mTc-sestamibi before and 7–14 days after PPCI. The co-primary endpoints were final infarct size on day 10 after STEMI and all-cause mortality at 5-year follow-up. Time-of-day at symptom onset of STEMI was categorized in 6-h intervals.

Results

In patients presenting from 0 to 6 h, 6 to 12 h, 12 to 18 h, and 18 to 24 h, the infarct sizes (median [25th–75th percentiles]) were 10.0 [3.0–24.7], 10.0 [3.0–24.0], 10.0 [3.0–22.0], and 9.0 [3.0–21.0] of the left ventricle, respectively (p = 0.87); the Kaplan–Meier estimates of 5-year all-cause mortality were 13.6%, 8.7%, 13.7% and 9.3%, respectively (log-rank test p = 0.30). After adjustment, time-of-day was not associated with infarct size (p ≥ 0.76 for comparisons with infarct size from reference [6–12 h] time interval) or 5-year all-cause mortality (p ≥ 0.25 for comparisons with mortality from reference [6–12 h] time interval). Time-of-day at symptom onset of STEMI was not associated with differences in the recovery of left ventricular ejection fraction 6 months after STEMI.

Conclusions

In patients with STEMI undergoing PPCI, time-of-day at symptom onset was neither associated with scintigraphic infarct size, left ventricular ejection fraction recovery at 6 months nor with 5-year mortality.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1934-z) contains supplementary material, which is available to authorized users.

Cultural factors and the circadian rhythm of ST elevation myocardial infarction in patients in a Mediterranean island

INTRODUCTION

The circadian rhythm of onset of myocardial infarction shows an increased risk during the morning hours. However, it is not clear whether habits, culture and sunshine hours differentiate circadian rhythm. The aim of this study was to investigate the influence of cultural factors on the circadian rhythm of acute myocardial infarction with ST segment elevation in a Mediterranean island.

METHOD

The study was a retrospective correlational survey. It included 123 patients with ST elevation myocardial infarction (mean age 60.7±12.6; 82% men). The 24 h of a day were divided into four six-hour periods of time for study purposes (00:01-06:00; 06:01-12:00; 12:01-18:00; and 18:01-24:00) and the chi-square test was used for the analysis.

RESULTS

A morning peak of symptoms onset of ST-elevation myocardial infarction was detected during the period 06:01-12:00 (p=0.044). In patients who were smokers, a bimodal pattern involving a morning (06:01-12:00) and an afternoon-to-night peak (18:01-24:00) (p=0.005) was detected. For patients with a history of hypertension, a morning peak of their symptoms was also detected (p=0.028). Different circadian variations were found between patients over the age of 60 years old and patients under the age of 60 years old (p=0.025).

CONCLUSIONS

Patients with ST elevation myocardial infarction seem to follow a circadian rhythm with a peak of onset of symptoms in the morning. In the smokers' subgroup, a different circadian pattern was found. The habit of smoking is likely to affect the circadian rhythm of the onset of ST elevation myocardial infarction in the Mediterranean area and culture.

Neutrophils in Post-myocardial Infarction Inflammation: Damage vs. Resolution?

Inflammation not only plays a crucial role in acute ischemic cardiac injury, but also contributes to post-infarction repair and remodeling. Traditionally, neutrophils have been merely considered as detrimental in the setting of an acute myocardial infarction. However, recently published studies demonstrated that neutrophils might also play an important role in cardiac repair by regulating reparative processes. An emerging concept is that different neutrophil subsets exist, which might exhibit separate functional properties. In support of the existence of distinct neutrophil subsets in the ischemic heart, transcriptional changes in cardiac neutrophils have been reported within the first few days after myocardial infarction. In addition, there is an increasing awareness of sex-specific differences in many physiological and pathophysiological responses, including cardiovascular parameters and inflammation. Of particular interest in this context are recent experimental data dissecting sex-specific differences in neutrophil signaling after myocardial infarction. Unraveling the distinct and possibly stage-dependent properties of neutrophils in cardiac repair may provide new therapeutic strategies in order to improve the clinical outcome for myocardial infarction patients. This review will briefly discuss recent advances in our understanding of the neutrophil functional repertoire and emerging insights of sex-specific differences in post-myocardial infarction inflammatory responses.

Comparative analysis of recurrent events after presentation with an index myocardial infarction or ischaemic stroke

Aims

Acute myocardial infarction (AMI) and stroke are important causes of mortality and morbidity. Our aims are to determine the comparative epidemiology of AMI and ischaemic stroke; and examine the differences in cardiovascular outcomes or mortality occurring after an AMI or stroke.

Methods and results

The Singapore National Registry of Diseases Office collects countrywide data on AMI, stroke, and mortality. Index events of AMI and ischaemic stroke between 2007 and 2012 were identified. Patients were then matched for occurrences of subsequent AMI, stroke, or death within 1-year of the index event. There were 33 222 patients with first-ever AMI and 20 982 with first-ever stroke. AMI patients were significantly more likely to be men (66.3% vs. 56.9%), non-Chinese (32.1% vs. 24.1%), and smokers (43.1% vs. 38.6%), but less likely to have hypertension (65.6% vs. 79%) and hyperlipidaemia (61.1% vs. 65.5%), compared with stroke patients. In total 6.8% of the AMI patients had recurrent AMI, whereas 4.8% of the stroke patients had recurrent stroke within 1 year; 31.7% of the AMI patients died, whereas 17.1% of the ischaemic stroke patients died within 1 year. Older age, Malay ethnicity, and diabetes mellitus were statistically significant risk factors for all-cause mortality and for the composite endpoint of AMI, stroke, and all-cause mortality, at 1 year.

Conclusions

Risk profiles of patients with AMI and stroke are significantly different. Patients suffer recurrent events in vascular territories similar to the index event. Age and diabetes mellitus are significant predictors of recurrent vascular events and mortality.

Plasminogen activator inhibitor-1 activity and long-term outcome in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention: a prospective cohort study

AIM

To determine the relationship between plasminogen activator inhibitor-1 (PAI-1) activity rise during the first 24 hours of ST-elevation myocardial infarction (STEMI) treatment and death after 5 years.

METHODS

From May 1, 2009 to March 23, 2010, 87 STEMI patients treated with primary percutaneous coronary intervention (PCI) at the Sestre Milosrdnice University Hospital Center were consecutively enrolled in prospective single-center cohort study. PAI-1 activity was determined on admission and 24 hours later. The primary end-point was death after 5 years. The predictive value of PAI-1 activity variables as biomarkers of death was assessed using receiver operating characteristic (ROC) curve, independent predictors of death were assessed using multivariate Cox regression, and covariates independently related to higher PAI-1 activity rise were assessed using linear regression.

RESULTS

Two patients died during the hospital treatment and 11 during the follow-up. PAI-1 activity rise had the largest area under curve (0.748) for predicting death rate (optimal cut-off point 3.7 U/mL, sensitivity 53.8%, specificity 90.5%). Patients with PAI-1 activity rise higher than 3.7 U/mL had significantly higher mortality (P<0.001). Kaplan-Meier survival curve diverged within the first year after STEMI. Independent predictors of death were PAI-1 rise and final Thrombolysis in Myocardial Infarction flow. PAI-1 activity rise was independently related to heart failure, thrombus aspiration, and body weight.

CONCLUSION

PAI-1 activity rise higher than 3.7 U/mL is associated with higher 5-year death rate in STEMI patients treated with primary PCI.

"Summer Shift": A Potential Effect of Sunshine on the Time Onset of ST-Elevation Acute Myocardial Infarction

Background

ST‐elevation acute myocardial infarction (STEMI) represents one of the leading causes of death. The time of STEMI onset has a circadian rhythm with a peak during diurnal hours, and the occurrence of STEMI follows a seasonal pattern with a salient peak of cases in the winter months and a marked reduction of cases in the summer months. Scholars investigated the reason behind the winter peak, suggesting that environmental and climatic factors concur in STEMI pathogenesis, but no studies have investigated whether the circadian rhythm is modified with the seasonal pattern, in particular during the summer reduction in STEMI occurrence.

Methods and Results

Here, we provide a multiethnic and multination epidemiological study (from both hemispheres at different latitudes, n=2270 cases) that investigates whether the circadian variation of STEMI onset is altered in the summer season. The main finding is that the difference between numbers of diurnal (6:00 to 18:00) and nocturnal (18:00 to 6:00) STEMI is markedly decreased in the summer season, and this is a prodrome of a complex mechanism according to which the circadian rhythm of STEMI time onset seems season dependent.

Conclusions

The “summer shift” of STEMI to the nocturnal interval is consistent across different populations, and the sunshine duration (a measure related to cloudiness and solar irradiance) underpins this season‐dependent circadian perturbation. Vitamin D, which in our results seems correlated with this summer shift, is also primarily regulated by the sunshine duration, and future studies should investigate their joint role in the mechanisms of STEMI etiogenesis.

Coordination of cardiac rhythmic output and circadian metabolic regulation in the heart

Over the course of a 24-h day, demand on the heart rises and falls with the sleep/wake cycles of the organism. Cardiac metabolism oscillates appropriately, with the relative contributions of major energy sources changing in a circadian fashion. The cardiac peripheral clock is hypothesized to drive many of these changes, yet the precise mechanisms linking the cardiac clock to metabolism remain a source of intense investigation. Here we summarize the current understanding of circadian alterations in cardiac metabolism and physiology, with an emphasis on novel findings from unbiased transcriptomic studies. Additionally, we describe progress in elucidating the links between the cardiac peripheral clock outputs and cardiac metabolism, as well as their implications for cardiac physiology.

Circadian clocks: from stem cells to tissue homeostasis and regeneration

The circadian clock is an evolutionarily conserved timekeeper that adapts body physiology to diurnal cycles of around 24 h by influencing a wide variety of processes such as sleep-to-wake transitions, feeding and fasting patterns, body temperature, and hormone regulation. The molecular clock machinery comprises a pathway that is driven by rhythmic docking of the transcription factors BMAL1 and CLOCK on clock-controlled output genes, which results in tissue-specific oscillatory gene expression programs. Genetic as well as environmental perturbation of the circadian clock has been implicated in various diseases ranging from sleep to metabolic disorders and cancer development. Here, we review the origination of circadian rhythms in stem cells and their function in differentiated cells and organs. We describe how clocks influence stem cell maintenance and organ physiology, as well as how rhythmicity affects lineage commitment, tissue regeneration, and aging.

Circadian Periodicity of Ischemic Heart Disease: A Systematic Review of the Literature

The authors performed a MEDLINE search to identify reports, published during the last 20 years, focused on circadian variation of acute myocardial infarction (AMI), and prevalence and the ratios between the number of events per hour during the morning and the other hours of the day were calculated. Despite the optimization of interventional and medical therapy of AMI since the first reports of circadian patterns in AMI occurrence, it was found that such a pattern still exists and that AMI happens most frequently in the morning hours.

Variation within Variation: Comparison of 24-h Rhythm in Rodent Infarct Size between Ischemia Reperfusion and Permanent Ligation

The detrimental effects of myocardial infarction in humans and rodents have a 24-h rhythm. In some human cohorts however, rhythmicity was absent, while the time of maximum damage differs between cohorts. We hypothesized that the type of damage influences the 24-h rhythm in infarct size. Myocardial infarction was induced in 12-week-old C57BL/six mice at four different time-points during the day using either permanent ligation (PL) or 30-min of ischemia followed by reperfusion (IR), with a control group wherein no ligation was applied. Infarct size was measured by echocardiography and histology at a 1-month follow-up. Rhythmicity in infarct size was present in the PL group at the functional and histological level, with maximal damage occurring when the infarct was induced at noon. In the IR group, no circadian rhythm was found. The time of the coronary artery ligation determines the outcome of myocardial infarction. Our data showed that in rodents, the presence of circadian rhythmicity and time of peak infarct size varies between experimental setups.

Circadian networks in human embryonic stem cell-derived cardiomyocytes

Cell-autonomous circadian oscillations strongly influence tissue physiology and pathophysiology of peripheral organs including the heart, in which the circadian clock is known to determine cardiac metabolism and the outcome of for instance ischemic stress. Human pluripotent stem cells represent a powerful tool to study developmental processes in vitro, but the extent to which human embryonic stem (ES) cell-derived cardiomyocytes establish circadian rhythmicity in the absence of a systemic context is unknown. Here we demonstrate that while undifferentiated human ES cells do not possess an intrinsic functional clock, oscillatory expression of known core clock genes emerges spontaneously during directed cardiac differentiation. We identify a set of clock-controlled output genes that contain an oscillatory network of stress-related transcripts. Furthermore, we demonstrate that this network results in a time-dependent functional response to doxorubicin, a frequently used anti-cancer drug with known cardiotoxic side effects. Taken together, our data provide a framework from which the effect of oscillatory gene expression on cardiomyocyte physiology can be modeled in vitro, and demonstrate the influence of a functional clock on experimental outcome.

Circadian variation in acute myocardial infarct size assessed by cardiovascular magnetic resonance in reperfused STEMI patients

OBJECTIVE

Clinical studies using serum cardiac biomarkers to investigate a circadian variation in acute myocardial infarct (MI) size in ST-segment elevation myocardial infarction (STEMI) patients reperfused by primary percutaneous coronary intervention (PPCI) have produced mixed results. We aimed to investigate this phenomenon using acute MI size measured by cardiovascular magnetic resonance (CMR).

METHODS

Patient-level data was obtained from 4 randomized controlled trials investigating the MI-limiting effects of cardioprotective therapies in this pooled analysis. The primary analysis was performed in those patients with no pre-infarct angina; duration of ischemia >60min and <360min; Thrombolysis In Myocardial Infarction (TIMI) flow pre-PPCI ≤1; TIMI flow post-PPCI 3; and no collateral flow.

RESULTS

169 out of 376 patients with CMR data met the inclusion criteria for the primary analysis. A 24-hour circadian variation in acute MI size as a % of the area-at-risk (%AAR), after adjusting for confounders, was observed with a peak and nadir MI size in patients with symptom onset between 00:00 and 01:00 and between 12:00 and 13:00 respectively (difference from the average MI size 5.2%, 95%CI 1.1-9.4%; p=0.013). This was associated with a non-significant circadian variation in left ventricular ejection fraction (LVEF) (difference from the average LVEF 5.9%, 95%CI -0.6-2.2%, p=0.073). There was no circadian variation in MI size or LVEF in the whole cohort.

CONCLUSIONS

We report a circadian variation in acute MI size assessed by CMR in a subset of STEMI patients treated by PPCI, with the largest and smallest MI size occurring in patients with symptom onset between 00:00 and 01:00 and between 12:00 and 13:00 respectively.

Chronobiology of Takotsubo Syndrome and Myocardial Infarction: Analogies and Differences

Several pathophysiologic factors, not harmful if taken alone, are capable of triggering unfavorable events when presenting together within the same temporal window (chronorisk), and the occurrence of many cardiovascular events is not evenly distributed in time. Both acute myocardial infarction and takotsubo syndrome seem to exhibit a temporal preference in their onset, characterized by variations according to time of day, day of the week, and month of the year, although with both analogies and differences.