Circadian rhythms in patients with ST-elevation myocardial infarction

RPS27A as a potential clock-related diagnostic biomarker for myocardial infarction: Comprehensive bioinformatics analysis and experimental validation

BACKGROUND

The circadian system plays a crucial role in managing cardiovascular functions, with disturbances in this system associated with Myocardial Infarction (MI). Despite this connection, the exact mechanisms by which clock genes influence MI occurrence are not well-defined. This research focused on investigating the link between clock genes and MI.

METHODS

The authors examined MI microarray datasets (GSE151412 and GSE60993) from the GEO database, concentrating on Differentially Expressed Genes (DEGs) associated with the circadian system. To clarify critical biological functions and pathways, the authors performed enrichment analyses using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Through Lasso regression, the authors pinpointed hub genes and confirmed their relevance using both the GSE66360 dataset and quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). Furthermore, the authors conducted single-Gene Set Enrichment Analysis (GSEA) to reveal pathways linked to the hub gene. The analysis extended to exploring drug interactions and networks involving competing endogenous RNA (ceRNA).

RESULTS

The present analysis identified ten clock genes associated with circadian rhythms that showed differential expression between MI patients and healthy controls. Enrichment analysis suggested these genes' roles in pathways like the Gap junction and circadian rhythm pathways. Following Lasso regression and validation, RPS27A was identified as the main hub gene. GSEA further highlighted enriched pathways, such as mismatch repair. Additionally, immune infiltration analysis revealed notable differences in B-cell and CD4+ T-cell populations between the MI group and the control group.

CONCLUSION

The present findings suggest that the clock-related gene RPS27A is associated with MI, potentially influencing its development through circadian rhythm regulation. These results enhance the understanding of MI pathogenesis and may offer new avenues for therapeutic intervention.

The Prognostic Significance of Sleep and Circadian Rhythm for Myocardial Infarction Outcomes: Case-Control Study

BACKGROUND

Myocardial infarction (MI) is a medical emergency resulting from coronary artery occlusion. Patients with acute MI often experience disturbed sleep and circadian rhythm. Most previous studies assessed the premorbid sleep and circadian rhythm of patients with MI and their correlations with cardiovascular disease. However, little is known about post-MI sleep and circadian rhythm and their impacts on prognosis. The use of actigraphy with different algorithms to evaluate sleep and circadian rhythm after acute MI has the potential for predicting outcomes and preventing future disease progression.

OBJECTIVE

We aimed to evaluate how sleep patterns and disrupted circadian rhythm affect the prognosis of MI, using actigraphy and heart rate variability (HRV). Nonparametric analysis of actigraphy data was performed to examine the circadian rhythm of patients.

METHODS

Patients with MI in the intensive care unit (ICU) were enrolled alongside age- and gender-matched healthy controls. Actigraphy was used to evaluate sleep and circadian rhythm, while HRV was monitored for 24 hours to assess autonomic nerve function. Nonparametric indicators were calculated to quantify the active-rest patterns, including interdaily stability, intradaily variability, the most active 10 consecutive hours (M10), the least active 5 consecutive hours (L5), the relative amplitude, and the actigraphic dichotomy index. Follow-ups were conducted at 3 and 6 months after discharge to evaluate prognosis, including the duration of current admission, the number and duration of readmission and ICU admission, and catheterization. Independent sample t tests and analysis of covariance were used to compare group differences. Pearson correlation tests were used to explore the correlations of the parameters of actigraphy and HRV with prognosis.

RESULTS

The study included 34 patients with MI (mean age 57.65, SD 9.03 years) and 17 age- and gender-matched controls. MI patients had significantly more wake after sleep onset, an increased number of awakenings, and a lower sleep efficiency than controls. Circadian rhythm analysis revealed significantly lower daytime activity in MI patients. Moreover, these patients had a lower relative amplitude and dichotomy index and a higher intradaily variability and midpoint of M10, suggesting less sleep and wake activity changes, more fragmentation of the rest-activity patterns, and a more delayed circadian rhythm. Furthermore, significant correlations were found between the parameters of circadian rhythm analysis, including nighttime activity, time of M10 and L5, and daytime and nighttime activitySD, and patient prognosis.

CONCLUSIONS

Patients with acute MI experienced significantly worse sleep and disturbed circadian rhythm compared with healthy controls. Our actigraphy-based analysis revealed a disturbed circadian rhythm, including reduced daytime activities, greater fluctuation in hourly activities, and a weak rest-activity rhythm, which were correlated with prognosis. The evaluation of sleep and circadian rhythm in patients with acute MI can serve as a valuable indicator for prognosis and should be further studied.

Circadian rhythm pattern of symptom onset in patients with ST-segment elevation myocardial infarction in the Chinese population

Background

The peak incidence of cardiovascular diseases (CVD) usually occurs in the morning. This study aimed to investigate the exact distribution pattern of peak incidence of ST-segment elevation myocardial infarction (STEMI) in the Chinese population, and to explore whether it is associated with the prognosis.

Methods

This study included 7,805 patients with STEMI from the multicenter, prospective AMI cohort in China, for whom had a definite time of symptom onset. In the overall population and the predefined subgroup populations, the circadian rhythms of STEMI onset were statistically analyzed. Then patients were divided into four groups based on the time of onset (6 h interval) to assess the association of symptom onset time and major adverse cardiovascular and cerebrovascular events (MACCE) after discharge.

Results

The onset of STEMI had a bimodal distribution: a well-defined primary peak at 8:38 AM [95% confidence interval (CI): 7:49 to 9:28 AM], and a less well-defined secondary peak at 12:55 PM (95% CI: 7:39 AM to 18:10 PM) (bimodal: P < 0.001). A similar bimodal circadian rhythm pattern was observed in subgroups of patients with STEMI defined with respect to day of the week, age, sex, and coronary risk factors. Notedly, the two peaks on Sunday were significantly later than other days, and the secondary peaks became clear and concentrated. In addition, no significant difference was found in MACCE among the four groups (P = 0.905).

Conclusions

In the Chinese population, the onset of STEMI exhibited a bimodal circadian rhythm pattern, with a clear primary peak and a less clear secondary peak. One-year clinical outcomes were unrelated to the timing of STEMI onset.

Cardiovascular Implications of Sleep Disorders Beyond Sleep Apnea

PURPOSE OF REVIEW

Sleep is crucial for human health and life. There is still limited attention to the association between sleep disorders beyond sleep apnea and cardiovascular (CV) health. We investigated the current evidence between non-respiratory sleep disorders and CV health.

RECENT FINDINGS

Current evidence suggests an important association between sleep duration, circadian rhythm, insomnia, disorders of hypersomnolence and CV health. Sleep-related movement disorders exhibit a moderate association with CV health. Further research is needed to explore the effects of each sleep disorder on CV health.

SUMMARY

Given the close association between non-respiratory sleep disorders and CV health, it is crucial to recognize and address sleep disorders in patients with a high CV risk.

Dependence of clinical outcomes on time of hospital admission in patients with ST-segment elevation myocardial infarction

BACKGROUND

There are conflicting results in studies investigating the effects of percutaneous coronary intervention (PCI) on the prognosis of patients with ST-segment elevation myocardial infarction (STEMI) during or outside of usual hospital working hours. While some researchers have reported higher mortality rates in STEMI patients admitted outside of working hours, others did not find a statistically significant difference.

OBJECTIVES

Investigate the short-term endpoints and long-term outcomes of STEMI patients by time of admission.

DESIGN

Retrospective SETTING: Tertiary percutaneous coronary intervention center.

PATIENTS AND METHODS

Patients were grouped by admission, which consisted of four intervals: 06:00 to <12:00, 12:00 to <18:00, 18:00 to <24:00, and 24:00 to <06:00. We analyzed demographic, clinical and mortality by admission time interval and mortality by multivariate analyses, including the time intervals.

MAIN OUTCOME MEASURES

Clinical data and mortality SAMPLE SIZE: 735 patients; median (IQR) age 62 (22) years; 215 (29.3%) women.

RESULTS

Patients admitted at night were 1.37 times more likely to experience pulmonary edema than patients whose symptoms started in the daytime (P=.012); 32.9% of the patients whose symptoms started at night presented with Killip class II-IV, while during the daytime, 21.4% presented with Killip class II-IV (P=.001). Among the patients, the most common was inferior STEMI (38.6%). However, no-reflow was significantly higher during the daytime compared to the nighttime (P=.12). The risk of the cardiac arrest on admission was 1.2 times higher in patients admitted at night (P=.034). Neither time interval of admission nor several other variables had an effect on clinical outcome or mortality.

CONCLUSIONS

While patients admitted at night presented with pulmonary edema and cardiogenic shock more frequently, no reflow was observed during the day after the procedure. Although patients admitted at night with STEMI presented with worse clinical conditions, similar results were observed between the groups in clinical outcomes.

LIMITATIONS

More "real world" results might have been obtained if the study had replicated more typical referral conditions for PCI.

CONFLICT OF INTEREST

None.

Influence of Intermittent Fasting During Ramadan on Circadian Variation of Symptom-Onset and Prehospital Time Delay in Acute ST-Segment Elevation Myocardial Infarction

Ramadan interferes with circadian rhythms mainly by disturbing the routine patterns of feeding and smoking. The objective of this study was to investigate the circadian pattern of ST elevation acute myocardial infarction (STEMI) during the month of Ramadan. We studied consecutive STEMI patients 1 month before and after Ramadan (non-Ramadan group-NRG) and during Ramadan (Ramadan group-RG). The RG group was also divided into two groups, based on whether they chose to fast: fasting (FG) and non-fasting group (NFG). The time of STEMI onset was compared. A total of 742 consecutive STEMI patients were classified into 4 groups by 6 h intervals according to time-of-day at symptom onset. No consistent circadian variation in the onset of STEMI was observed both between the RG (P = .938) and NRG (P = .766) or between the FG (P = .232) and NFG (P = .523). When analyzed for subgroups of the study sample, neither smoking nor diabetes showed circadian rhythm. There was a trend towards a delay from symptom onset to hospital presentation, particularly at evening hours in the RG compared with the control group. In conclusion, there was no significant difference in STEMI onset time, but the time from symptom onset to hospital admission was significantly delayed during Ramadan.

Circadian and seasonal variation in onset of acute myocardial infarction

The aim was to investigate the circadian and seasonal variation of acute myocardial infarction (AMI). Clinical data of 3867 AMI patients hospitalized from November 2010 to October 2019 in the Border Yanbian Minority Autonomous Prefecture, China were collected, and 3158 patients with definite AMI onset times were analyzed. The clinical data analyzed included the time of onset, nationality, age, laboratory data. We divided the patients into 4 groups based on the timepoint of their AMI onsets: 00:00-05:59, 06:00-11:59, 12:00-17:59, and 18:00-23:59. We also divided the patients based on nationality: Chinese Korean and Han groups. We observed that there is a circadian rhythm in the incidence of AMI, and the peak of AMI is in the morning (7:00-9:00). Unexpectedly, the incidence of AMI was significantly lower in the cold winter than that of other 3 warm seasons (P < 0.01) and the peak of AMI presented at the months of the large contrast between day and night temperature difference (over 20°C) like May of Spring and October of Fall. Finally, there was no difference in circadian rhythm between Chinese Korean and Han, although these groups differed in age, body mass index, and the inflammatory cell level. These findings have shown a different seasonal and circadian variation in onset of AMI. Further studies are required to determine the pathophysiological mechanism(s) underlying these differences and to guide prevention of AMI for reducing its mortality and disability.

Contemporary impact of circadian symptom-onset patterns of acute ST-Segment elevation myocardial infarction on long-term outcomes after primary percutaneous coronary intervention

BACKGROUND

Daytime variation with regard to onset time of ST-elevation myocardial infarction (STEMI) symptoms has been observed. Nevertheless, with the advanced medical therapy, it is not uncertainty if a similar circadian pattern of STEMI symptom onset occurs, as well as its possible impact on clinical outcomes. Few long-term data are available. We assess the impact of circadian symptom-onset patterns of STEMI on major adverse cardiovascular events (MACE) in more contemporary patients treated with primary percutaneous coronary intervention (PPCI).

METHODS AND RESULTS

A total of 1099 consecutive STEMI patients undergoing PPCI ≤12h from symptom onset during 2013 to 2019 were classified into 4 groups by 6-h intervals according to time-of-day at symptom onset: night (0:00-5:59), morning (6:00-11:59), afternoon (12:00-17:59), and evening (18:00-23:59). Incidence of MACE including cardiovascular death and nonfatal MI during a median follow-up of 48 months was compared among the 4 groups. A morning peak of symptom onset of STEMI was detected during the period 06:00-11:59 (p < .001). Compared with other three 6-h intervals, the incidence of long-term MACE during night onset-time (18.8%, 10.1%, 10.7% and 12.4%, p = .020) was significant higher that was driven by more mortality (13.1%, 6.5%, 7.1%and 7.7%, p = .044). Night symptom-onset STEMI was independently associated with subsequent MACE (hazard ratio = 1.57, 95%CI: 1.09-2.27, p = .017) even after multivariable adjustment.

CONCLUSIONS

Circadian variation of STEMI symptom-onset with morning predominance still exists in contemporary practice. Night symptom-onset STEMI was independently associated with increased risk of MACE in Chinese patients treated with PPCI.

Bmal1 Regulates the Redox Rhythm of HSPB1, and Homooxidized HSPB1 Attenuates the Oxidative Stress Injury of Cardiomyocytes

Oxidative stress is the main cause of acute myocardial infarction (AMI), which is related to the disorder of the regulation of Bmal1 on the redox state. HSPB1 form homologous-oxidized HSPB1 (homooxidized HSPB1) to resist oxidative damage via S-thiolated modification. However, it is still unclarified whether there is an interaction between the circadian clock and HSPB1 in myocardial injury. A total of 118 AMI patients admitted and treated in our hospital from Sep. 2019 to Sep. 2020 were selected to detect the plasma HSPB1 expression and the redox state. We divided the AMI patients into three subgroups: morning-onset AMI (5 : 00 am to 8 : 00 am; Am-subgroup, n = 38), noon-onset AMI (12 : 00 pm to 15 : 00; Pm-subgroup, n = 45), and night-onset AMI (20 : 00 pm to 23 : 00 pm; Eve-subgroup, n = 35) according to the circadian rhythm of onset. The Am-subgroup had remarkably higher cardiac troponin I (cTnI), creatine kinase MB (CK-MB), and B-type natriuretic peptide (BNP) but lower left ventricular ejection fraction (LVEF) than the Pm-subgroup and Eve-subgroup. Patients complicated with cardiogenic shock were significantly higher in the Am-subgroup than in the other two groups. The homooxidized HSPB1 in plasma markedly decreased in the Am-subgroup. The HSPB1C141S mutant accelerated H9c2 cell apoptosis, increased reactive oxygen species (ROS), and decreased reduced-glutathione (GSH) and the ratio of reduced-GSH and GSSG during oxidative stress. Importantly, we found that the redox state of HSPB1 was consistent with the oscillatory rhythm of Bmal1 expression in normal C57B/L mice. The circadian rhythm disorder contributed to decrease Bmal1 and homooxidized HSPB1 in cardiomyocytes of C57BL/6 mice. In addition, Bmal1 and homooxidized HSPB1 decreased in neonatal rat cardiomyocytes exposed to H2O2. Knockdown of Bmal1 led to significant attenuation in homooxidized HSPB1 expression, whereas overexpression of Bmal1 increased homooxidized HSPB1 expression in response to H2O2. Our findings indicated that the homooxidized HSPB1 reduced probably the AMI patients' risk of shock and target organ damage, which was associated with Bmal1 regulating the redox state of HSPB1.

Identification of Key Genes Involved in Acute Myocardial Infarction by Comparative Transcriptome Analysis

Background

Acute myocardial infarction (AMI) is regarded as an urgent clinical entity, and identification of differentially expressed genes, lncRNAs, and altered pathways shall provide new insight into the molecular mechanisms behind AMI.

Materials and Methods

Microarray data was collected to identify key genes and lncRNAs involved in AMI pathogenesis. The differential expression analysis and gene set enrichment analysis (GSEA) were employed to identify the upregulated and downregulated genes and pathways in AMI. The protein-protein interaction network and protein-RNA interaction analysis were utilized to reveal key long noncoding RNAs.

Results

In the present study, we utilized gene expression profiles of circulating endothelial cells (CEC) from 49 patients of AMI and 50 controls and identified a total of 552 differentially expressed genes (DEGs). Based on these DEGs, we also observed that inflammatory response-related genes and pathways were highly upregulated in AMI. Mapping the DEGs to the protein-protein interaction (PPI) network and identifying the subnetworks, we found that OMD and WDFY3 were the hub nodes of two subnetworks with the highest connectivity, which were found to be involved in circadian rhythm and organ- or tissue-specific immune response. Furthermore, 23 lncRNAs were differentially expressed between AMI and control groups. Specifically, we identified some functional lncRNAs, including XIST and its antisense RNA, TSIX, and three lncRNAs (LINC00528, LINC00936, and LINC01001), which were predicted to be interacting with TLR2 and participate in Toll-like receptor signaling pathway. In addition, we also employed the MMPC algorithm to identify six gene signatures for AMI diagnosis. Particularly, the multivariable SVM model based on the six genes has achieved a satisfying performance (AUC = 0.97).

Conclusion

In conclusion, we have identified key regulatory lncRNAs implicated in AMI, which not only deepens our understanding of the lncRNA-related molecular mechanism of AMI but also provides computationally predicted regulatory lncRNAs for AMI researchers.

Circadian variations in pathogenesis of ST-segment elevation myocardial infarction: an optical coherence tomography study

Previous studies have reported a circadian variation in the onset of ST-segment elevation myocardial infarction (STEMI). However, underlying mechanisms for the circadian variation have not been fully elucidated. We investigated the relationship between onset of STEMI and the underlying pathology using optical coherence tomography (OCT). Patients with a diagnosis of STEMI were selected from a multicenter OCT registry. Patients were divided into 4 groups based on the estimated time of onset (00:00-05:59, 06:00-11:59, 12:00-17:59, or 18:00-23:59). Underlying pathologies of MI (plaque rupture, plaque erosion, and calcified plaque) were compared among the 4 groups. Among 648 patients, plaque rupture was diagnosed in 386 patients (59.6%), plaque erosion in 197 patients (30.4%), and calcified plaque in 65 patients (10.0%). A marked circadian variation was detected in the incidence of plaque rupture with a peak at 09:00, whereas it was not evident in plaque erosion or calcified plaque. The probability of plaque rupture significantly increased in the periods of 06:00-11:59 [odds ratio (OR) 2.13, 95% confidence interval (CI) 1.30-3.49, p = 0.002] and 12:00-17:59 (OR 2.10, 95% CI 1.23-3.58, p = 0.005), compared to the period of 00:00-05:59. This circadian pattern was observed only during weekdays (p = 0.010) and it was not evident during the weekend (p = 0.742). Plaque rupture occurred most frequently in the morning and this circadian variation was evident only during weekdays. Acute MI caused by plaque rupture may be related to catecholamine surge.

Comparison of clinical outcomes in STEMI patients treated with primary PCI according to day-time of medical attention and its relationship with circadian pattern

OBJECTIVE

Relationship between STEMI time of presentation, its circadian pattern and cardiovascular outcomes is unclear. Our objective is to analyze clinical outcomes of STEMI according to time of presentation and circadian pattern.

METHODS

We analyzed data from patients treated within the regional STEMI Network from January 2010 to December 2015. On-hour group included patients treated between 8:00 h and 19:59 h on weekdays, the rest were catalogued as off-hour group. The primary endpoint was 1-year all-cause mortality. Secondary endpoints were 30-day all-cause mortality and in-hospital complications.

RESULTS

A total of 8608 patients were included, 44.1% in the on-hour group and 55.9% in the off-hour group. We observed a shorter patient delay and longer system delay in the off-hour group compared to on-hour group with no difference in total ischemic time. At 30-day and 1-year follow-up there were no differences in adjusted all-cause mortality between groups [OR 0.91 (CI95%: 0.73-1.12; p = 0.35) and OR 0.99 (CI95%: 0.83-1.17; p = 0.87), respectively]. A circadian pattern was observed between 9:00 am and 12:30 pm, with no differences in 30-day and 1-year mortality between patients included in this time interval [OR 1.02 (IC95%: 0.81-1.30; p = 0.85) and OR 1.12 (IC95%: 0.92-1.36; p = 0.25) respectively].

CONCLUSIONS

Off-hour STEMI presentation was associated with a shorter patient delay and longer system delay without an increase in total ischemic time. The off-hour presentation was not related to an increase in 1-year all-cause mortality when compared to on-hour. A circadian pattern was found, without differences in 30-day and 1-year mortality.

Presentation Times of Myocardial Infarctions to the Emergency Department: Disappearance of the Morning Predominance

BACKGROUND

Previous studies show that myocardial infarctions (MIs) occur most frequently in the morning.

OBJECTIVES

We hypothesized that there no longer is a morning predominance of MI, and that the timing of ST-elevation myocardial infarction (STEMI) vs. non-ST-elevation myocardial infarction (NSTEMI) presentation differs.

METHODS

We reviewed MI, STEMI, and NSTEMI patients (2013-2017) from a multiple-hospital system, identified by diagnostic codes. Daily emergency department arrival times were categorized into variable time intervals for count and proportional analysis, then examined for differences.

RESULTS

There were 18,663 MI patients from 12 hospitals included in the analysis. Most MIs occurred between 12:00 pm and 5:59 pm (35.7%), and least between 12:00 am-5:59 am (16.3%). After subdividing all MIs into STEMIs and NSTEMIs, both groups continued to have the greatest presentation between 12:00 pm and 5:59 pm (33.1% and 36.0%, respectively). STEMIs (17.2%) and NSTEMIs (16.2%) were least frequent between 12:00 am and 5:59 am. We found the second most common presentation time for MIs was in the 6 pm-11:59 pm time period, which held true for both subtypes (MI 26.7%, STEMI 26.4%, NSTEMI 26.7%).

CONCLUSIONS

These data suggest a potential shift in the circadian pattern of MI, revealing an afternoon predominance for both STEMI and NSTEMI subtypes.

Outdoor environment management through air enthalpy analysis

With the ever-progressing urbanization of human society comes lingering public issues, primarily those related to human health and the need to provide environments where the population can be routinely frequent. Also, the effects of climatic changes tend to aggravate such public health issues, mainly respiratory and cardiac symptoms. As such, analyzing and studying those environments can be crucial for public administrations in the decision-making processes. One such method of analysis involves using an air enthalpy index to profile and provide a picture of stress situations, helping expedite preventive measures and hospital logistics. With that, this study used the enthalpy index as a tool to create a picture of the effect of seasonality on chronic health issues, such as respiratory and cardiac symptoms, for the city of Botucatu, a city with a characteristic tropical altitude climate. It was possible to determine that the air enthalpy profile is consistent throughout the year near the estimated thermal comfort boundaries, with peaks outside in hotter months. The hospitalizations tend to be more numerous during the transition from hot to cold seasons. Simple correlation analysis, along with a t test, provided further insight into the issue, showing strong correlation for pneumonia with the maximum enthalpy variation, which can relate to the heat amount variation in a given location. Also, an agreement was observed between enthalpy and an established thermal sensation index, the heat index, meaning that air enthalpy can be a reliable and simple index for environmental thermal comfort analysis. That being said, further studies are necessary to confirm these findings, considering a longer time frame, more diverse hospitalization data, and other meteorological parameters, like wind speed and precipitation.

Circadian clock genes and circadian phenotypes in patients with myocardial infarction

PURPOSE

Human physiological activities and diseases are under the control of the circadian rhythm. There are strong epidemiological associations between disrupted circadian rhythms, sleep duration and diseases. Sleep disorders are associated with vascular outcomes, such as myocardial infarction (MI).

METHODS

We conducted an association study of genotype-phenotype interaction, to determine which circadian clock gene variants might be associated with the circadian phenotypes in patients with MI. In the present study, we analyzed the allele frequencies of 10 single nucleotide polymorphisms in four circadian clock genes in two independent samples: MI patients and controls. Chronotype was assessed using the Morningness - Eveningness Questionnaire (MEQ) and daytime sleepiness using the Epworth Sleepiness Scale (ESS).

RESULTS

Chronotype was associated with the ARNTL genetic variant rs12363415 in MI patients. The polymorphisms rs11932595 of the CLOCK gene and rs934945 of the PER2 gene were associated with daytime sleepiness in the patient group.

CONCLUSION

Our data suggest that genetic variations in some circadian clock genes might be related to circadian phenotype (i.e., chronotype and daytime sleepiness) in patients with myocardial infarction.

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.

Plasminogen activator inhibitor 1 in acute coronary syndromes

Plasminogen activator inhibitor 1 (PAI-1) is the main regulator of endogenous fibrinolysis, overriding the impact of other constituents of fibrinolysis. In plasma, it can be found in three forms: active, latent and inactive. There are numerous commercially available tests, analysing the activity of PAI-1 or the antigen level, with variable correlations between the two. PAI-1 has been extensively studied regarding incidence and outcomes of acute coronary syndromes, and showed positive association with both in numerous studies. Higher PAI-1 has been associated with worse short- and long-term outcomes. Studies are more consistent in the primary percutaneous coronary intervention era. Higher rise of PAI-1 within the first 24 h of acute myocardial infarction has been linked to some of its high-risk features. The circadian pattern of PAI-1 kinetics has been previously described, and the mechanisms behind this phenomenon and its impact on the incidence of acute coronary syndromes are well known. Further investigations are needed to test the safety and efficacy of PAI-1 as a pharmacological target in cardiovascular diseases.

Circadian Rhythm and ST-Segment Elevation Myocardial Infarction: Insights From the Third Gulf Registry of Acute Coronary Events (Gulf RACE-3Ps)

Circadian rhythms have been identified in multiple physiological processes that may affect cardiovascular diseases, yet little is known about the impact of circadian rhythm on acute ST-segment elevation myocardial infarction (STEMI) onset and outcomes in the Middle East. The relationship between time of symptom onset during the 24-hour circadian cycle and prehospital delays and in-hospital death was assessed in 2909 patients with STEMI presenting in 6 Arabian Gulf countries. A sinusoidal smoothing function was used to show the average circadian trends. There was a significant association between time of symptom onset and the circadian cycle. The STEMIs were more frequent during the late morning and early afternoon hours ( P < .001). Patients with pain onset from 0.00 to 5:59 had median prehospital delays of 150 minutes versus 90 minutes from 6:00 to 11:59 and 12:00 to 17:59, respectively ( P < .001). Although there was no significant difference in mortality between the 4 groups ( P = .230), there was a significant association between time of symptom onset as sinusoidal function and in-hospital mortality ( P = .032). Patients with STEMI in the Middle East have significant circadian patterns in symptoms onset, prehospital delay, and timeliness of reperfusion. A circadian rhythm of in-hospital mortality was found over the 24-hour clock of symptom onset time.

ASSOCIATION OF CIRCADIAN RHYTHM WITH MYOCARDIAL INFARCTION

- Cardiovascular diseases are the world's leading cause of death. Human physiologic activities and state during illness are under the control of circadian rhythm. The aim of the study was to determine the potential association of chronotype and daytime sleepiness with susceptibility to myocardial infarction. We conducted a case-control study on 200 patients hospitalized due to myocardial infarction and 200 healthy controls. Systematic information on the past and present medical history was obtained from all participants. Chronotype was assessed using the Morningness-Eveningness Questionnaire (MEQ), and daytime sleepiness was assessed by the Epworth Sleepiness Scale (ESS). The mean age of the study population was 64±13 years, and 54.5% were male. There was no significant difference in MEQ (58.88±6.52 vs. 58.46±7.78, p=0.601) or ESS (5 (interquartile range, IQR 4-7.5) vs. 6 (IQR 3-8), p=0.912) score between patients and controls. Nevertheless, we found statistically significant differences related to risk factors for cardiovascular diseases, such as hypertension, dyslipidemia, and diabetes mellitus. However, there was no association of MEQ and ESS score with myocardial infarction in the study population.

"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.

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.

Seasonal and circadian variations of acute myocardial infarction: Findings from the Get With The Guidelines-Coronary Artery Disease (GWTG-CAD) program

BACKGROUND

Seasonal variation with winter preponderance of myocardial infarction incidence has been described decades ago, but only a few small studies have classified myocardial infarction based on ST-segment elevation. It is unclear whether seasonal and circadian variations are equally present in warmer and colder regions. We investigated whether seasonal and circadian variations in acute myocardial infarction (AMI) are more prominent in colder northern states compared with warmer southern states. We also investigated the peak time of admission to better understand the circadian rhythm.

METHODS

Data from the GWTG-CAD database were used. We analyzed 82,971 consecutive acute myocardial infarction (AMI) patients treated at 276 US centers from 2003 to 2008. The country was geographically divided into warmer southern and colder northern states using latitude 35 degrees for this purpose.

RESULTS

Overall, acute myocardial infarction (AMI) admissions varied across seasons (P < .01), and were higher in winter (winter vs. spring n = 21,483 vs. 20,291, respectively). When stratified based on type of AMI, non-ST-segment elevation myocardial infarction (NSTEMI) admissions varied across seasons (P < .01) and were highest in winter and lowest in spring. Seasonal variation was not significant in STEMI admissions (P = .30). Seasonal variation with winter predominance was noted in AMI patients in warmer southern states (P < .01), but not in colder states. The distributions of length of stay for AMI patients and door to balloon times for STEMI patients were minimally different across all four seasons (P < .01) with longest occurring in winter. Most patients with AMI presented during daytime with a peak close to 11 am and a nadir at approximately 4 am.

CONCLUSIONS

Seasonal variation with winter predominance exists in AMI admissions and was significant in NSTEMI admissions but not in STEMI admissions. Seasonal variation was only significant in warmer southern states.

Circadian clock-related genetic risk scores and risk of placental abruption

INTRODUCTION

The circadian clock plays an important role in several aspects of female reproductive biology. Evidence linking circadian clock-related genes to pregnancy outcomes has been inconsistent. We sought to examine whether variations in single nucleotide polymorphisms (SNPs) of circadian clock genes are associated with PA risk.

METHODS

Maternal blood samples were collected from 470 PA case and 473 controls. Genotyping was performed using the Illumina Cardio-MetaboChip platform. We examined 119 SNPs in 13 candidate genes known to control circadian rhythms (e.g., CRY2, ARNTL, and RORA). Univariate and penalized logistic regression models were fit to estimate odds ratios (ORs); and the combined effect of multiple SNPs on PA risk was estimated using a weighted genetic risk score (wGRS).

RESULTS

A common SNP in the RORA gene (rs2899663) was associated with a 21% reduced odds of PA (P < 0.05). The odds of PA increased with increasing wGRS (Ptrend < 0.001). The corresponding ORs were 1.00, 1.83, 2.81 and 5.13 across wGRS quartiles. Participants in the highest wGRS quartile had a 5.13-fold (95% confidence interval: 3.21-8.21) higher odds of PA compared to those in the lowest quartile. Although the test for interaction was not significant, the odds of PA was substantially elevated for preeclamptics with the highest wGRS quartile (OR = 14.44, 95%CI: 6.62-31.53) compared to normotensive women in the lowest wGRS quartile.

DISCUSSION

Genetic variants in circadian rhythm genes may be associated with PA risk. Larger studies are needed to corroborate these findings and to further elucidate the pathogenesis of this important obstetrical complication.

Circadian pattern of symptoms onset in patients ≤35 years presenting with ST-segment elevation acute myocardial infarction

BACKGROUND

There are scarce data regarding the circadian pattern of symptoms onset in young patients presenting with acute myocardial infarction (AMI). We explored whether young patients with ST-segment elevation AMI exhibit a circadian variation in symptoms onset.

METHODS

We recruited prospectively 256 consecutive patients who had survived their first ST-segment elevation AMI ≤35 years of age. Patients were categorized into 4 groups by 6-h intervals over 24 h.

RESULTS

In 49 patients (19.1%) the clinical presentation of AMI was atypical. The symptoms onset was as follows: 00:01 to 06:00, 19.1%, 06:01 to 12:00, 32.4%; 12:01 to 18:00, 28.1%; and 18:01 to 24:00, 20.3%. There was a significant association between the time of day and the likelihood of symptoms onset (Rayleigh test, p<0.001). Between 00:01 and 06:00 the incidence of AMI onset was lower than expected and between 06:01 and 12:00 was higher (p=0.034 and p=0.011, respectively), whereas in the other 6-h period groups no difference was found between expected and observed AMI incidence (p=0.280 and p=0.131). No significant differences were found regarding clinical characteristics, i.e. traditional risk factors, reperfusion treatment of AMI, ejection fraction of left ventricle, time interval from pain onset to hospital arrival, dietary habits and physical activity, among the 6-h period groups.

CONCLUSIONS

ST-segment elevation AMI in individuals ≤35 years of age follows a circadian pattern with a morning peak. This information might be useful for the prompt diagnosis and treatment of AMI in very young patients which occurs rarely and frequently with atypical clinical presentation.

Myocardial infarct size and mortality depend on the time of day-a large multicenter study

BACKGROUND

Different studies have shown circadian variation of ischemic burden among patients with ST-Elevation Myocardial Infarction (STEMI), but with controversial results. The aim of this study was to analyze circadian variation of myocardial infarction size and in-hospital mortality in a large multicenter registry.

METHODS

This retrospective, registry-based study was based on data from AMIS Plus, a large multicenter Swiss registry of patients who suffered myocardial infarction between 1999 and 2013. Peak creatine kinase (CK) was used as a proxy measure for myocardial infarction size. Associations between peak CK, in-hospital mortality, and the time of day at symptom onset were modelled using polynomial-harmonic regression methods.

RESULTS

6,223 STEMI patients were admitted to 82 acute-care hospitals in Switzerland and treated with primary angioplasty within six hours of symptom onset. Only the 24-hour harmonic was significantly associated with peak CK (p = 0.0001). The maximum average peak CK value (2,315 U/L) was for patients with symptom onset at 23:00, whereas the minimum average (2,017 U/L) was for onset at 11:00. The amplitude of variation was 298 U/L. In addition, no correlation was observed between ischemic time and circadian peak CK variation. Of the 6,223 patients, 223 (3.58%) died during index hospitalization. Remarkably, only the 24-hour harmonic was significantly associated with in-hospital mortality. The risk of death from STEMI was highest for patients with symptom onset at 00:00 and lowest for those with onset at 12:00.

DISCUSSION

As a part of this first large study of STEMI patients treated with primary angioplasty in Swiss hospitals, investigations confirmed a circadian pattern to both peak CK and in-hospital mortality which were independent of total ischemic time. Accordingly, this study proposes that symptom onset time be incorporated as a prognosis factor in patients with myocardial infarction.

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.

Association of lifestyle-related factors with circadian onset patterns of acute myocardial infarction: a prospective observational study in Japan

OBJECTIVE

The onset of acute myocardial infarction (AMI) shows characteristic circadian variations involving a definite morning peak and a less-defined night-time peak. However, the factors influencing the circadian patterns of AMI onset and their influence on morning and night-time peaks have not been fully elucidated.

DESIGN, SETTING AND PARTICIPANTS

An analysis of patients registered between 1998 and 2008 in the Osaka Acute Coronary Insufficiency Study, which is a prospective, multicentre observational study of patients with AMI in the Osaka region of Japan. The present study included 7755 consecutive patients with a known time of AMI onset.

MAIN OUTCOMES AND MEASURES

A mixture of two von Mises distributions was used to examine whether a circadian pattern of AMI had uniform, unimodal or bimodal distribution, and the likelihood ratio test was then used to select the best circadian pattern among them. The hierarchical likelihood ratio test was used to identify factors affecting the circadian patterns of AMI onset. The Kaplan-Meier method was used to estimate survival curves of 1-year mortality according to AMI onset time.

RESULTS

The overall population had a bimodal circadian pattern of AMI onset characterised by a high and sharp morning peak and a lower and less-defined night-time peak (bimodal p<0.001). Although several lifestyle-related factors had a statistically significant association with the circadian patterns of AMI onset, serum triglyceride levels had the most prominent association with the circadian patterns of AMI onset. Patients with triglyceride ≥150 mg/dL on admission had only one morning peak in the circadian pattern of AMI onset during weekdays, with no peaks detected on weekends, whereas all other subgroups had two peaks throughout the week.

CONCLUSIONS

The circadian pattern of AMI onset was characterised by bimodality. Notably, several lifestyle-related factors, particularly serum triglyceride levels, had a strong relation with the circadian pattern of AMI onset.

TRIAL REGISTRATION NUMBER

UMIN000004575.

Inconsistent measurement of acute coronary syndrome patients' pre-hospital delay in research: a review of the literature

BACKGROUND

Patients' treatment-seeking delay remains a significant barrier to timely initiation of reperfusion therapy. Measurement of treatment-seeking delay is central to the large body of research that has focused on pre-hospital delay (PHD), which is primarily patient-related. This research has aimed to quantify PHD and its effects on morbidity and mortality, identify contributing factors, and evaluate interventions to reduce such delay. A definite time of symptom onset in acute coronary syndrome (ACS) is essential for determining delay, but difficult to establish. This literature review aimed to explore the variety of operational definitions of both PHD and symptom onset in published research.

METHODS AND RESULTS

We reviewed the English-language literature from 1998-2013 for operational definitions of PHD and symptom onset. Of 626 papers of possible interest, 175 were deemed relevant. Ninety-seven percent reported a delay time and 84% provided an operational definition of PHD. Three definitions predominated: (a) symptom onset to decision to seek help (18%); (b) symptom onset to hospital arrival (67%), (c) total delay, incorporating two or more intervals (11%). Of those that measured delay, 8% provided a definition of which symptoms triggered the start of timing.

CONCLUSION

We found few and variable operational definitions of PHD, despite American College of Cardiology/American Heart Association recommendations to report specific intervals. Worryingly, definitions of symptom onset, the most elusive component of PHD to establish, are uncommon. We recommend that researchers (a) report two PHD delay intervals (onset to decision to seek care, and decision to seek care to hospital arrival), and (b) develop, validate and use a definition of symptom onset. This will increase clarity and confidence in the conclusions from, and comparisons within and between studies.

Circadian patterns of ST elevation myocardial infarction in the new millennium

OBJECTIVE

Nearly four decades ago, a circadian pattern of acute myocardial infarction (AMI) with a peak in the early morning waking hours was described. The goal of the present study was to determine whether major changes in lifestyle and significant advances in medical therapy have altered this pattern in the intervening years.

DESIGN

Retrospective chart review.

SETTING

Tertiary care hospital in central Wisconsin.

METHODS

We examined circadian patterns of ST elevation myocardial infarction (STEMI) in 519 patients diagnosed with STEMI over a 5-year period. Time of symptom onset was obtained from patient self-reports in the medical record and was recorded over 24 hours.

RESULTS

We observed a circadian pattern of STEMI occurrence with a morning peak at approximately 11:30 AM. This pattern was highly significant in patients who were not using beta-blockers (P <0.0001) and had no history of diabetes (P <0.0001), but was otherwise absent. The circadian pattern appeared to be attenuated in patients of a younger age, female gender, or who used statins or aspirin. Peak STEMI occurrence was earlier in smokers than non-smokers.

CONCLUSIONS

Despite significant lifestyle changes and medical advances in the nearly four decades since a circadian pattern of AMI occurrence was first described, patients with STEMI had a circadian pattern of symptom onset with a morning peak. Use of beta-blockers and a history of diabetes mellitus abolished this pattern. Other modifying factors, including medications, age, and gender attenuated, but did not abolish, the circadian pattern.

Twenty-four-hour patterns in occurrence and pathophysiology of acute cardiovascular events and ischemic heart disease

The scientific literature clearly establishes the occurrence of cardiovascular (CV) accidents and myocardial ischemic episodes is unevenly distributed during the 24 h. Such temporal patterns result from corresponding temporal variation in pathophysiologic mechanisms and cyclic environmental triggers that elicit the onset of clinical events. Moreover, both the pharmacokinetics and pharmacodynamics of many, though not all, CV medications have been shown to be influenced by the circadian time of their administration, even though further studies are necessary to better clarify the mechanisms of such influence on different drug classes, drug molecules, and pharmaceutical preparations. Twenty-four-hour rhythmic organization of CV functions is such that defense mechanisms against acute events are incapable of providing the same degree of protection during the day and night. Instead, temporal gates of excessive susceptibility exist, particularly in the morning and to a lesser extent evening (in diurnally active persons), to aggressive mechanisms through which overt clinical manifestations may be triggered. When peak levels of critical physiologic variables, such as blood pressure (BP), heart rate (HR), rate pressure product (systolic BP × HR, surrogate measure of myocardial oxygen demand), sympathetic activation, and plasma levels of endogenous vasoconstricting substances, are aligned together at the same circadian time, the risk of acute events becomes significantly elevated such that even relatively minor and usually harmless physical and mental stress and environmental phenomena can precipitate dramatic life-threatening clinical manifestations. Hence, the delivery of CV medications needs to be synchronized in time, i.e., circadian time, in proportion to need as determined by established temporal patterns in risk of CV events, and in a manner that averts or minimizes undesired side effects.

A common polymorphism near PER1 and the timing of human behavioral rhythms

OBJECTIVE

Circadian rhythms influence the timing of behavior, neurological diseases, and even death. Rare mutations in homologs of evolutionarily conserved clock genes are found in select pedigrees with extreme sleep timing, and there is suggestive evidence that certain common polymorphisms may be associated with self-reported day/night preference. However, no common polymorphism has been associated with the timing of directly observed human behavioral rhythms or other physiological markers of circadian timing at the population level.

METHODS

We performed a candidate gene association study with replication, evaluating associations between polymorphisms in homologs of evolutionarily conserved clock genes and the timing of behavioral rhythms measured by actigraphy. For validated polymorphisms, we evaluated associations with transcript expression and time of death in additional cohorts.

RESULTS

rs7221412, a common polymorphism near period homolog 1 (PER1), was associated with the timing of activity rhythms in both the discovery and replication cohorts (joint p = 2.1 × 10(-7) ). Mean activity timing was delayed by 67 minutes in rs7221412(GG) versus rs7221412(AA) homozygotes. rs7221412 also showed a suggestive time-dependent relationship with both cerebral cortex (p = 0.05) and CD14+ CD16- monocyte (p = 0.02) PER1 expression and an interesting association with time of death (p = 0.015) in which rs7221412(GG) individuals had a mean time of death nearly 7 hours later than rs7221412(AA/AG) .

INTERPRETATION

A common polymorphism near PER1 is associated with the timing of human behavioral rhythms, and shows evidence of association with time of death. This may be mediated by differential PER1 expression. These results may facilitate individualized scheduling of shift work, medical treatments, or monitoring of vulnerable patient populations.

Circadian variations of ischemic burden among patients with myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

Several parameters of cardiovascular physiology and pathophysiology exhibit circadian rhythms. Recently, a relation between infarct size and the time of day at which it occurs has been suggested in experimental models of myocardial infarction. The aim of this study is to investigate whether circadian rhythms could cause differences in ischemic burden in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

METHODS

In 353 consecutive patients with STEMI treated by PPCI, time of symptom onset, peak creatine kinase (CK), and follow-up at 30 days were obtained. We divided 24 hours into 4 time groups based on time of symptom onset (00:00-05:59, 06:00-11:59, 12:00-17:59, and 18:00-23:59).

RESULTS

There was no difference between the groups regarding baseline patients and management's characteristics. At multivariable analysis, there was a statistically significant difference between peak CK levels among patients with symptom onset between 00:00 and 05:59 when compared with peak CK levels of patients with symptom onset in any other time group (mean increase 38.4%, P < .05). Thirty-day mortality for STEMI patients with symptom onset occurring between 00:00 and 05:59 was significantly higher than any other time group (P < .05).

CONCLUSION

This study demonstrates an independent correlation between the infarct size of STEMI patients treated by PPCI and the time of the day at which symptoms occurred. These results suggest that time of the day should be a critical issue to look at when assessing prognosis of patients with myocardial infarction.

The Editors. Circulation: Cardiovascular Quality and Outcomes Editors' Picks

The following are highlights from the new series, Circulation: Cardiovascular Quality and Outcomes Topic Review. This series will summarize the most important manuscripts, as selected by the editors, that have published in the Circulation portfolio. The objective of this new series is to provide our readership with a timely, comprehensive selection of important papers that are relevant to the quality and outcomes and general cardiology audience. The studies included in this article represent the most significant research in the area of ST-segment elevation myocardial infarction care and address improvements in the timeliness of care, strategies for initial treatment—particularly with respect to reperfusion therapies—and trends.

Circadian dependence of infarct size and left ventricular function after ST elevation myocardial infarction

RATIONALE

In rodents, infarct size after ischemia/reperfusion exhibits a circadian dependence on the time of coronary occlusion. It is not known if a similar circadian dependence of infarct size occurs in humans.

OBJECTIVE

To determine if humans exhibit a circadian dependence of infarct size in the setting of ST elevation myocardial infarction (STEMI).

METHODS AND RESULTS

A retrospective analysis of 1031 patients with STEMI referred for primary percutaneous coronary intervention with known ischemic times between 1 and 6 hours identified 165 patients with occluded arteries on presentation without evidence of preinfarction angina or collateral blood flow. Both ischemic duration and angiographic area at risk were not dependent on time of infarct onset. We observed that the extent of infarct size measured by creatine kinase release was significantly associated with time of day onset of infarction (P<0.0001). The greatest myocardial injury occurred at 1:00 am onset of ischemia and 5:00 am onset of reperfusion, with the peak creatine kinase measured at the peak of the curve being 82% higher than that recorded at the trough. Similarly, left ventricular ejection fraction measured within 2 days of infarction was also dependent on time of onset of STEMI with the absolute left ventricular ejection fraction at peak >7% higher than at trough (43% vs 51%; P<0.03). These findings were supported by a subgroup of patients (n = 45) who underwent cardiac MRI measurements of infarct size and area-at-risk measurements.

CONCLUSIONS

The results of this study demonstrate for the first time in humans that myocardial infarct size and left ventricular function after STEMI have a circadian dependence on the time of day onset of ischemia.