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Concept: Troponin

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Background The clinical effect of routine oxygen therapy in patients with suspected acute myocardial infarction who do not have hypoxemia at baseline is uncertain. Methods In this registry-based randomized clinical trial, we used nationwide Swedish registries for patient enrollment and data collection. Patients with suspected myocardial infarction and an oxygen saturation of 90% or higher were randomly assigned to receive either supplemental oxygen (6 liters per minute for 6 to 12 hours, delivered through an open face mask) or ambient air. Results A total of 6629 patients were enrolled. The median duration of oxygen therapy was 11.6 hours, and the median oxygen saturation at the end of the treatment period was 99% among patients assigned to oxygen and 97% among patients assigned to ambient air. Hypoxemia developed in 62 patients (1.9%) in the oxygen group, as compared with 254 patients (7.7%) in the ambient-air group. The median of the highest troponin level during hospitalization was 946.5 ng per liter in the oxygen group and 983.0 ng per liter in the ambient-air group. The primary end point of death from any cause within 1 year after randomization occurred in 5.0% of patients (166 of 3311) assigned to oxygen and in 5.1% of patients (168 of 3318) assigned to ambient air (hazard ratio, 0.97; 95% confidence interval [CI], 0.79 to 1.21; P=0.80). Rehospitalization with myocardial infarction within 1 year occurred in 126 patients (3.8%) assigned to oxygen and in 111 patients (3.3%) assigned to ambient air (hazard ratio, 1.13; 95% CI, 0.88 to 1.46; P=0.33). The results were consistent across all predefined subgroups. Conclusions Routine use of supplemental oxygen in patients with suspected myocardial infarction who did not have hypoxemia was not found to reduce 1-year all-cause mortality. (Funded by the Swedish Heart-Lung Foundation and others; DETO2X-AMI ClinicalTrials.gov number, NCT01787110 .).

Concepts: Oxygen, Epidemiology, Clinical trial, Myocardial infarction, Atherosclerosis, Randomness, Troponin, Oxygen therapy

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Financial barriers to health care are associated with worse outcomes following acute myocardial infarction (AMI). Yet, it is unknown whether the prevalence of financial barriers and their relationship with post-AMI outcomes vary by sex among young adults.

Concepts: Health care, Myocardial infarction, Atherosclerosis, Infarction, Troponin, Necrosis

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BACKGROUND: Approximately 2/3 of Veterans admitting to Veterans Health Administration (VHA) facilities present >12 hours after symptom onset of acute myocardial infarction (AMI) (“late presenters”). Veterans admitted to VHA facilities with AMI may delay hospital presentation for different reasons compared to their general population counter parts. Despite the large descriptive literature on factors associated with delayed presentation in the general population, the literature describing these factors among the Veteran AMI population is limited. The purpose of this analysis is to identify predictors of late presentation in the Veteran population presenting with AMI to VHA facilities. Identifying predictors will help inform and target interventions for Veterans at a high risk of late presentation. METHODS: In our cross-sectional study, we analyzed a cohort of 335 male Veterans from nine VHA facilities with physician diagnosed AMI between April 2005 and December 2006. We compared demographics, presentation characteristics, medical history, perceptions of health, and access to health care between early and late presenting Veterans. We used standard descriptive statistics for bivariate comparisons and multivariate logistic regression to identify independent predictors of late presentation. RESULTS: Our cohort was an average of 64 +/- 10.5 years old and was 88% white. Sixty-eight percent of our cohort were late presenters. Bivariate comparisons found that fewer late presenters had attended at least some college or vocational school (late 53.2% vs. early 66%, p = 0.02). Multivariate analysis showed that presentation with ST-elevation myocardial infarction (STEMI) was associated with early presentation (OR = 0.43 95%CI [0.2, 0.9]) and >=2 angina episodes in the prior 24 hours (versus 0-1 episode) was associated with late presentation (OR = 7.5 95%CI [3.6,15.6]). CONCLUSIONS: A significant majority of Veterans presenting to VHA facilities with AMI were late presenters. We found few differences between early and late presenters. Having a STEMI was independently associated with early presentation and reporting >=2 angina episodes in the 24 hours prior to hospital admission was independently associated with late presentation. These independent predictors of early and late presentation are similar to what has been reported for the general population. Despite these similarities to the general population, there may be untapped opportunities for patient education within the VHA to decrease late presentation.

Concepts: Myocardial infarction, Atherosclerosis, Coronary artery disease, Infarction, Troponin, United States Department of Veterans Affairs, Veterans Health Administration, Cardiac stress test

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Loss of cardiomyocytes is a major cause of heart failure, and while the adult heart has a limited capacity for cardiomyogenesis, little is known about what regulates this ability or whether it can be effectively harnessed. Here we show that 8 weeks of running exercise increase birth of new cardiomyocytes in adult mice (~4.6-fold). New cardiomyocytes are identified based on incorporation of 15N-thymidine by multi-isotope imaging mass spectrometry (MIMS) and on being mononucleate/diploid. Furthermore, we demonstrate that exercise after myocardial infarction induces a robust cardiomyogenic response in an extended border zone of the infarcted area. Inhibition of miR-222, a microRNA increased by exercise in both animal models and humans, completely blocks the cardiomyogenic exercise response. These findings demonstrate that cardiomyogenesis can be activated by exercise in the normal and injured adult mouse heart and suggest that stimulation of endogenous cardiomyocyte generation could contribute to the benefits of exercise.

Concepts: Mass spectrometry, Myocardial infarction, Heart, Muscle, Cardiac muscle, Circulatory system, Mammal, Troponin

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Early myocardial reperfusion therapy ( < 12 h) in patients with acute myocardial infarction (AMI) can significantly improve their prognosis. However, the effect of late reperfusion ( > 12 h) remains controversial. In this study, the effects of late reperfusion versus standard drug therapy on the outcomes of patients with AMI were evaluated by systematic review and meta-analysis.

Concepts: Myocardial infarction, Atherosclerosis, Medical terms, Systematic review, Infarction, Troponin, Meta-analysis, Acute coronary syndrome

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Previous research has found that patients with acute cardiovascular conditions treated in teaching hospitals have lower 30-day mortality during dates of national cardiology meetings.

Concepts: Myocardial infarction, Atherosclerosis, Hospital, Cardiology, Cardiovascular disease, Coronary catheterization, Interventional cardiology, Troponin

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Background Acute myocardial infarction can be triggered by acute respiratory infections. Previous studies have suggested an association between influenza and acute myocardial infarction, but those studies used nonspecific measures of influenza infection or study designs that were susceptible to bias. We evaluated the association between laboratory-confirmed influenza infection and acute myocardial infarction. Methods We used the self-controlled case-series design to evaluate the association between laboratory-confirmed influenza infection and hospitalization for acute myocardial infarction. We used various high-specificity laboratory methods to confirm influenza infection in respiratory specimens, and we ascertained hospitalization for acute myocardial infarction from administrative data. We defined the “risk interval” as the first 7 days after respiratory specimen collection and the “control interval” as 1 year before and 1 year after the risk interval. Results We identified 364 hospitalizations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza. Of these, 20 (20.0 admissions per week) occurred during the risk interval and 344 (3.3 admissions per week) occurred during the control interval. The incidence ratio of an admission for acute myocardial infarction during the risk interval as compared with the control interval was 6.05 (95% confidence interval [CI], 3.86 to 9.50). No increased incidence was observed after day 7. Incidence ratios for acute myocardial infarction within 7 days after detection of influenza B, influenza A, respiratory syncytial virus, and other viruses were 10.11 (95% CI, 4.37 to 23.38), 5.17 (95% CI, 3.02 to 8.84), 3.51 (95% CI, 1.11 to 11.12), and 2.77 (95% CI, 1.23 to 6.24), respectively. Conclusions We found a significant association between respiratory infections, especially influenza, and acute myocardial infarction. (Funded by the Canadian Institutes of Health Research and others.).

Concepts: Myocardial infarction, Atherosclerosis, Virus, Influenza, Transmission and infection of H5N1, Troponin, Human respiratory syncytial virus, Orthomyxoviridae

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Physical exertion, anger, and emotional upset are reported to trigger acute myocardial infarction (AMI). In the INTERHEART study, we explored the triggering association of acute physical activity and anger or emotional upset with AMI to quantify the importance of these potential triggers in a large, international population.

Concepts: Myocardial infarction, Atherosclerosis, Obesity, Infarction, Troponin, Necrosis

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Tissue engineering approaches have the potential to increase the physiologic relevance of human iPS-derived cells, such as cardiomyocytes (iPS-CM). However, forming Engineered Heart Muscle (EHM) typically requires >1 million cells per tissue. Existing miniaturization strategies involve complex approaches not amenable to mass production, limiting the ability to use EHM for iPS-based disease modeling and drug screening. Micro-scale cardiospheres are easily produced, but do not facilitate assembly of elongated muscle or direct force measurements. Here we describe an approach that combines features of EHM and cardiospheres: Micro-Heart Muscle (μHM) arrays, in which elongated muscle fibers are formed in an easily fabricated template, with as few as 2,000 iPS-CM per individual tissue. Within μHM, iPS-CM exhibit uniaxial contractility and alignment, robust sarcomere assembly, and reduced variability and hypersensitivity in drug responsiveness, compared to monolayers with the same cellular composition. μHM mounted onto standard force measurement apparatus exhibited a robust Frank-Starling response to external stretch, and a dose-dependent inotropic response to the β-adrenergic agonist isoproterenol. Based on the ease of fabrication, the potential for mass production and the small number of cells required to form μHM, this system provides a potentially powerful tool to study cardiomyocyte maturation, disease and cardiotoxicology in vitro.

Concepts: Heart, Muscle, Cardiac muscle, Skeletal muscle, Smooth muscle, Muscular system, Sarcomere, Troponin