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

Objectives

There are conflicting data on the relationship between the time of symptom onset during the 24-hour cycle (circadian dependence) and infarct size in ST-elevation myocardial infarction (STEMI). Moreover, the impact of this circadian pattern of infarct size on clinical outcomes is unknown. We sought to study the circadian dependence of infarct size and its impact on clinical outcomes in STEMI.

Methods

We studied 6,710 consecutive patients hospitalized for STEMI from 2006 to 2009 in a tropical climate with non-varying day-night cycles. We categorized the time of symptom onset into four 6-hour intervals: midnight–6:00 A.M., 6:00 A.M.–noon, noon–6:00 P.M. and 6:00 P.M.–midnight. We used peak creatine kinase as a surrogate marker of infarct size.

Results

Midnight–6:00 A.M patients had the highest prevalence of diabetes mellitus (P = 0.03), more commonly presented with anterior MI (P = 0.03) and received percutaneous coronary intervention less frequently, as compared with other time intervals (P = 0.03). Adjusted mean peak creatine kinase was highest among midnight–6:00 A.M. patients and lowest among 6:00 A.M.–noon patients (2,590.8±2,839.1 IU/L and 2,336.3±2,386.6 IU/L, respectively, P = 0.04). Midnight–6:00 A.M patients were at greatest risk of acute heart failure (P<0.001), 30-day mortality (P = 0.03) and 1-year mortality (P = 0.03), while the converse was observed in 6:00 A.M.–noon patients. After adjusting for diabetes, infarct location and performance of percutaneous coronary intervention, circadian variations in acute heart failure incidence remained strongly significant (P = 0.001).

Conclusion

We observed a circadian peak and nadir in infarct size during STEMI onset from midnight–6:00A.M and 6:00A.M.–noon respectively. The peak and nadir incidence of acute heart failure paralleled this circadian pattern. Differences in diabetes prevalence, infarct location and mechanical reperfusion may account partly for the observed circadian pattern of infarct size and acute heart failure.     

Longitudinal Strain Is a Marker of Microvascular Obstruction and Infarct Size in Patients with Acute ST-Segment Elevation Myocardial Infarction

Objectives

We assessed the value of speckle tracking imaging performed early after a first ST-segment elevation myocardial infarction (STEMI) in order to predict infarct size and functional recovery at 3-month follow-up.

Methods

44 patients with STEMI who underwent revascularization within 12 h of symptom onset were prospectively enrolled. Echocardiography was performed 3.9±1.2 days after myocardial reperfusion, assessing circumferential (CGS), radial (RGS), and longitudinal global (GLS) strains. Late gadolinium-enhanced cardiac magnetic imaging (CMR), for assessing cardiac function, infarct size, and microvascular obstruction (MVO), was conducted 5.6±2.5 days and 99.4±4.6 days after myocardial reperfusion.

Results

GLS was evaluable in 97% of the patients, while CGS and RGS could be assessed in 85%. Infarct size significantly correlated with GLS (R = 0.601, p<0.001), RGS (R = −0.405, p = 0.010), CGS (R = 0.526, p = 0.001), ejection fraction (R = −0.699, p<0.001), wall motion score index (WMSI) (R = 0.539, p = 0.001), and left atrial volume (R = 0.510, p<0.001). Baseline ejection fraction and GLS were independent predictors of 3-month infarct size. MVO mass significantly correlated with GLS (R = 0.376, p = 0.010), WMSI (R = 0.387, p = 0.011), and ejection fraction (R = −0.389, p = 0.011). In multivariate analysis, GLS was the only independent predictor of MVO mass (p = 0.015). Longitudinal strain >−6.0% within the infarcted area exhibited 96% specificity and 61% sensitivity for predicting the persistence of akinesia (≥3 segments) at 3-month follow-up.

Conclusions

Speckle-tracking strain imaging performed early after a STEMI is easy-to-use as a marker for persistent akinetic territories at 3 months. In addition, GLS correlated significantly with MVO and final infarct size, both parameters being relevant post-MI prognostic factors, usually obtained via CMR.     

Circulatory and Metabolic Effects of Oxygen in Myocardial Infarction

The circulatory and metabolic effects of inhalation of oxygen in high concentration were investigated in 50 patients with acute myocardial infarction. The heart rate, arterial blood pressure, cardiac out-put, blood gas tensions, pH, and lactate and pyruvate levels were measured. In general, oxygen inhalation produced a fall in cardiac output and stroke volume and a rise in blood pressure and systemic vascular resistance. In a small number of patients with very low cardiac out-puts there was a rise in output. A substantial rise in arterial oxygen tension was obtained even in patients with low initial values. The raised arterial blood lactate levels which were frequently present were reduced after oxygen. The therapeutic implications of these effects are discussed.     

Exogenous Galanin Reduces Hyperglycemia and Myocardial Metabolic Disorders Induced by Streptozotocin in Rats

International Journal of Peptide Research and Therapeutics - Middle East respiratory syndrome coronavirus (MERS-CoV) has caused a high mortality rate since its emergence in 2012 in the Middle East....     

Exercise Training Reduces Cardiac Dysfunction and Remodeling in Ovariectomized Rats Submitted to Myocardial Infarction

The aim of this study was to evaluate whether exercise training (ET) prevents or minimizes cardiac dysfunction and pathological ventricular remodeling in ovariectomized rats subjected to myocardial infarction (MI) and to examine the possible mechanisms involved in this process. Ovariectomized Wistar rats were subjected to either MI or fictitious surgery (Sham) and randomly divided into the following groups: Control, OVX+SHAM_SED, OVX+SHAM_ET, OVX+MI_SED and OVX+MI_ET. ET was performed on a motorized treadmill (5x/wk, 60 min/day, 8 weeks). Cardiac function was assessed by ventricular catheterization and Dihydroethidium fluorescence (DHE) was evaluated to analyze cardiac oxidative stress. Histological analyses were made to assess collagen deposition, myocyte hypertrophy and infarct size. Western Blotting was performed to analyze the protein expression of catalase and SOD-2, as well as Gp91phox and AT1 receptor (AT1R). MI-trained rats had significantly increased in +dP/dt and decreased left ventricular end-diastolic pressure compared with MI-sedentary rats. Moreover, oxidative stress and collagen deposition was reduced, as was myocyte hypertrophy. These effects occurred in parallel with a reduction in both AT1R and Gp91phox expression and an increase in catalase expression. SOD-2 expression was not altered. These results indicate that ET improves the functional cardiac parameters associated with attenuation of cardiac remodeling in ovariectomized rats subjected to MI. The mechanism seems to be related to a reduction in the expression of both the AT1 receptor and Gp91phox as well as an increase in the antioxidant enzyme catalase, which contributes to a reduction in oxidative stress. Therefore, ET may be an important therapeutic target for the prevention of heart failure in postmenopausal women affected by MI.     

Riociguat Reduces Infarct Size and Post-Infarct Heart Failure in Mouse Hearts: Insights from MRI/PET Imaging

Aim

Stimulation of the nitric oxide (NO) – soluble guanylate (sGC) - protein kinase G (PKG) pathway confers protection against acute ischaemia/reperfusion injury, but more chronic effects in reducing post-myocardial infarction (MI) heart failure are less defined. The aim of this study was to not only determine whether the sGC stimulator riociguat reduces infarct size but also whether it protects against the development of post-MI heart failure.

Methods and Results

Mice were subjected to 30 min ischaemia via ligation of the left main coronary artery to induce MI and either placebo or riociguat (1.2 µmol/l) were given as a bolus 5 min before and 5 min after onset of reperfusion. After 24 hours, both, late gadolinium-enhanced magnetic resonance imaging (LGE-MRI) and ¹⁸F-FDG-positron emission tomography (PET) were performed to determine infarct size. In the riociguat-treated mice, the resulting infarct size was smaller (8.5±2.5% of total LV mass vs. 21.8%±1.7%. in controls, p = 0.005) and LV systolic function analysed by MRI was better preserved (60.1%±3.4% of preischaemic vs. 44.2%±3.1% in controls, p = 0.005). After 28 days, LV systolic function by echocardiography treated group was still better preserved (63.5%±3.2% vs. 48.2%±2.2% in control, p = 0.004).

Conclusion

Taken together, mice treated acutely at the onset of reperfusion with the sGC stimulator riociguat have smaller infarct size and better long-term preservation of LV systolic function. These findings suggest that sGC stimulation during reperfusion therapy may be a powerful therapeutic treatment strategy for preventing post-MI heart failure.     

Evaluation of Left Ventricle Function by Regional Fractional Area Change (RFAC) in a Mouse Model of Myocardial Infarction Secondary to Valsartan Treatment

Aim

Left ventricle (LV) regional fractional area change (RFAC) measured by cardiac magnetic resonance (CMR) allows the non-invasive localization and quantification of the degree of myocardial infarction (MI), and could be applied to assess the effectiveness of pharmacological or regenerative therapies. Here we investigate the ability of RFAC to identify regional dysfunction and discriminate the effect of pharmacological treatment with valsartan, a selective antagonist of angiotensin II type 1 receptor, in a model of MI.

Methods and Results

C57BL/6N mice, undergoing coronary artery ligation, were divided into two groups: untreated (MI) or treated with valsartan (MI+Val). Sham-operated mice were used as a control. Cardiac dimensions and function were assessed at baseline, 24 hours, 1 and 4 weeks post surgery by CMR and echocardiography. At sacrifice histology and whole-genome gene expression profiling were performed. RFAC was able to detect significant differences between treatment groups whereas the global ejection fraction was not. RFAC showed greater loss of regional contraction in remote non-infarcted myocardium in MI group than in MI+Val group. Consistently, in the same region MI+Val mice showed reduced myocyte hypertrophy, fibroblast proliferation, and fibrosis and modulation of target genes; in addition, left atrium volumes, appendage length and duct contraction were preserved.

Conclusion

In this study, RFAC effectively estimated the degree of systolic dysfunction and discriminated the regions preserved by pharmacological treatment. RFAC index is a promising tool to monitor changes in LV contraction and to assess the effectiveness of therapeutic regimens in clinical settings.     

猪冠状动脉前降支结扎位点和左室功能的线性回归

目的探讨猪冠状动脉前降支(LAD)结扎百分位点和心梗体积、左室射血分数的关系,以期指导研究者能够根据急性心肌梗死模型的心功能要求选择合适的LAD结扎百分位点。方法将47只小型猪开胸结扎心脏LAD中远段约30%~75%的不同百分位点,分别于术前、术后1 h心脏超声检查左室射血分数(LVEF),术后3 d进行常规冠状动脉造影,4周处死测量前降支结扎位点和梗死体积,最后用简单直线回归模型分析LAD结扎百分位点和心梗体积、左室射血分数回归方程和相关系数。结果47例动物手术过程中死亡8只,剩余39只存活动物冠状动脉造影均显示LAD中远段结扎部位处完全闭塞,表明手术成功。LAD结扎百分位点和术后1 h LVEF、术后1 hLVEF下降值、梗死心肌体积均明显相关(相关系数r分别为0.87、0.78和0.90,P均<0.001),其回归方程分别为:术后LVEF(%)=65.88-0.55x结扎百分位点;术后LVEF下降值(%)=0.12 0.59x结扎百分位点;心肌梗死体积(%)=0.53x结扎百分位点-5.43。结论猪LAD结扎百分位点和术后左室功能、梗死心肌体积均存在显著的相关性,可根据实验目的和对心功能的要求选择合适的结扎百分位点。     

Association of Left Ventricular Mass with All-Cause Mortality,Myocardial Infarction and Stroke

Background

Our aim was to assess the association of left ventricular mass with mortality and nonfatal cardiovascular events.

Methodology/Principal Findings

Left ventricular mass was measured by echocardiography in 40138 adult patients (mean age 61.1±16.4 years, 52.5% male). The primary endpoint was all-cause mortality. Secondary endpoints included nonfatal myocardial infarction and nonfatal stroke. During a mean follow-up period of 5.6±3.9 years, 9181 patients died, 901 patients had a nonfatal myocardial infarction, and 2139 patients had a nonfatal stroke. Cumulative 10-year mortality was 26.8%, 31.9%, 37.4% and 46.4% in patients with normal, mildly, moderately and severely increased left ventricular mass, respectively (p<0.001). Ten-year rates of nonfatal myocardial infarction and stroke ranged from 3.2% and 6.7% in patients with normal left ventricular mass to 5.3% and 12.7% in those with severe increase in left ventricular mass, respectively. After multivariate adjustment, left ventricular mass remained an independent predictor of all-cause mortality (hazard ratio [HR] per 100 g increase 1.21, 95% confidence interval [CI] 1.14–1–27, p<0.001 in women, and HR 1.09, 95% CI 1.04–1–13, p<0.001 in men), myocardial infarction (HR 1.60, 95% CI 1.31–1.94, p<0.001 in women and HR 1.15, 95% CI 1.02–1.29, p = 0.019 in men) and stroke (HR 1.26, 95% CI 1.13–1.40, p<0.001 in women and HR 1.19, 95% CI 1.09–1.30, p<0.001 in men).

Conclusions/Significance

Left ventricular mass has a graded and independent association with all-cause mortality, myocardial infarction and stroke.     

Ghrelin对心肌梗死大鼠恶性心律失常和早期左室重构的影响(英文)

目的:本文主要研究ghrelin对心肌梗死大鼠恶性心律失常和早期左室重构的影响。方法:心肌梗死大鼠模型每天两次注射ghrelin(100μg/kg)或生理盐水。通过超声心动图评估大鼠的心脏重量并且观察大鼠的血流动力学。使用酶免疫分析法测定血清胰岛素生长因子I(IGF-1)、血浆肾上腺素、去甲肾上腺素和多巴胺的浓度。注射药物前后分析大鼠的神经功能。结果:与对照组相比,ghrelin治疗的心肌梗死模型大鼠生存率显著增加(P0.05),心脏功能增强,但心肌梗死面积差异不大(P0.05)。结论:Ghrelin能够提高心肌梗死模型大鼠的生存率、缓解心肌梗死大鼠心率失常、改善心肌梗死大鼠左心室重构。     

Alteration in Metabolic Signature and Lipid Metabolism in Patients with Angina Pectoris and Myocardial Infarction

Lipid metabolites are indispensable regulators of physiological and pathological processes, including atherosclerosis and coronary artery disease (CAD). However, the complex changes in lipid metabolites and metabolism that occur in patients with these conditions are incompletely understood. We performed lipid profiling to identify alterations in lipid metabolism in patients with angina and myocardial infarction (MI). Global lipid profiling was applied to serum samples from patients with CAD (angina and MI) and age-, sex-, and body mass index-matched healthy subjects using ultra-performance liquid chromatography/quadruple time-of-flight mass spectrometry and multivariate statistical analysis. A multivariate analysis showed a clear separation between the patients with CAD and normal controls. Lysophosphatidylcholine (lysoPC) and lysophosphatidylethanolamine (lysoPE) species containing unsaturated fatty acids and free fatty acids were associated with an increased risk of CAD, whereas species of lysoPC and lyso-alkyl PC containing saturated fatty acids were associated with a decreased risk. Additionally, PC species containing palmitic acid, diacylglycerol, sphingomyelin, and ceramide were associated with an increased risk of MI, whereas PE-plasmalogen and phosphatidylinositol species were associated with a decreased risk. In MI patients, we found strong positive correlation between lipid metabolites related to the sphingolipid pathway, sphingomyelin, and ceramide and acute inflammatory markers (high-sensitivity C-reactive protein). The results of this study demonstrate altered signatures in lipid metabolism in patients with angina or MI. Lipidomic profiling could provide the information to identity the specific lipid metabolites under the presence of disturbed metabolic pathways in patients with CAD.     

Assessment of Recanalization of Chronic Total Occlusions on Left Ventricular Function in Patients With or Without Previous Myocardial Infarction by Real-time Three-Dimensional Echocardiography

The changes of left ventricular ejection fraction (LVEF) were assessed after successful recanalization of chronic total occlusions (CTO) with or without previous myocardial infarction (MI) by real-time three-dimensional echocardiography (RT3DE). 32 patients with a successfully recanalyzed CTO were included in the present prospective study. The patients were divided into group 1 without previous MI and group 2 with previous MI in the territories of total occlusion vessel that was recanalized. In addition, there was a subgroup composed of 14 patients with collateral flow or retrograde flow in group 2. In all patients, LVEF was determined by RT3DE at baseline and after 6 weeks. In group 1, the evolution of LVEF increased significantly from 59.9 ± 7.2–67.5 ± 8.7% (P < 0.05). In group 2, the evolution of LVEF increased from 48.6 ± 6.1–50.1 ± 6.4%, however, it was without statistic significance (P > 0.05). The evolution of LVEF increased from 46.8 ± 7.1–53.0 ± 7.2% (P < 0.05) in the subgroup of group 2. Left ventricular function in patients with CTO can be feasibility and actually evaluated by RT3DE. The influence of recanalization of CTO on the improvement of left ventricular function was different between MI and non-MI patients. The left ventricular function did not improve in MI patients, but improved significantly in the patients having rich collateral circulation.     

Long-Term Prognosis of Acute Myocardial Infarction Associated With Metabolic Health and Obesity Status

ObjectiveEmerging evidence supports the favorable cardiovascular health in nonobese subjects with healthy metabolism. However, little is known regarding the prognosis across the range of metabolic phenotypes once cardiovascular disease is established. We examined the prognosis of patients with acute myocardial infarction (AMI) stratified according to metabolic health and obesity status.MethodsThis is a retrospective study on consecutive patients with AMI admitted to a tertiary hospital between 2014 and 2021. Patients were allocated into the following 4 groups based on metabolic and obesity profile: (1) metabolically healthy obese (MHO), (2) metabolically healthy nonobese (MHNO), (3) metabolically unhealthy obese (MUO), and (4) metabolically unhealthy nonobese (MUNO). Metabolic health was defined in accordance to the Biobank Standardisation and Harmonisation for Research Excellence in the European Union Healthy Obese Project. The primary outcome was all-cause mortality. The Cox regression analysis examined the independent association between mortality and metabolic phenotypes, adjusting for age, sex, AMI type, chronic kidney disease, smoking status, and left ventricular ejection fraction.ResultsOf 9958 patients, the majority (68.5%) were MUNO, followed by MUO (25.1%), MHNO (5.6%), and MHO (0.8%). MHO had the lowest mortality (7.4%), followed by MHNO (9.7%), MUO (19.2%), and MUNO (22.6%) (P < .001). Compared with MHNO, MUO (hazard ratio [HR], 1.737; 95% confidence interval [CI], 1.282-2.355; P < .001) and MUNO (HR, 1.482; 95% CI, 1.108-1.981; P = .008) had a significantly higher mortality risk but not MHO (HR, 1.390; 95% CI, 0.594-3.251; P = .447), after adjusting for confounders. The Kaplan-Meier curves showed favorable survival in the metabolically healthy and obesity groups, with the highest overall survival in the MHO, followed by MHNO, MUO, and MUNO (P < .001).ConclusionMetabolically healthy and obese patients with AMI have favorable prognosis compared with metabolically unhealthy and nonobese patients. It is equally important to prioritize intensive metabolic risk factor management to weight reduction in the early phase after AMI.     

心肌梗死患者择期行PCI治疗对左心室重构和收缩功能的影响

目的:研究心肌梗死患者择期行经皮冠状动脉介入(PCI)治疗对左心室重构和收缩功能的影响。方法:选取2009年12月到2014年12月我院收治的心肌梗死择期行PCI治疗的患者60例(研究组),另选同期单纯心绞痛行PCI治疗的患者60例(对照组)。比较治疗前、后两组左心室舒张末期容积(LVEDV)、收缩末期容积(LVESV)、每搏量(SV)、左室射血分数(LVEF)、左室收缩末期压(LVESP)和左心室舒张末压(LVEDP)。结果:治疗后研究组LVEDV、LVESV、SV、LVEF、LVESP和LVEDP均显著优于治疗前,比较差异均具有统计学意义(P0.05),对照组治疗前、后LVEDV、LVESV、SV、LVEF、LVESP和LVEDP比较差异均无统计学意义(P0.05)。结论:心肌梗死患者行PCI治疗具有较好的效果,能显著改善患者的左心室重构和收缩功能。     

N-乙酰半胱氨酸改善大鼠心肌梗死后心室结构重塑的研究

目的：探讨N-乙酰半胱氨酸（N-acetylcysteine,NAC）对大鼠心肌梗死（myocardial infarction,MI）后心室结构重塑的影响及其潜在机制。方法：Sprague-Dawley（SD）大鼠96只,随机分为空白对照组（blank control,BC组）6只,余90只制作心肌梗死模型,成功存活24小时后随机分为NAC干预组（NAC）34只,生理盐水对照组（NS）32只,NAC组腹腔注射NAC[0.2 mg·kg-1.2d-1],NS组腹腔注射同等剂量的生理盐水。连续干预4周后,超声心动图检测大鼠收缩期左室后壁厚度（systolic left ventricular posterior wallthickness,LVPW;s）,舒张期左室后壁厚度（diastolic left ventricular posterior wall thickness,LVPW;d）,收缩期室间隔厚度（systolicinterventricular septal thickness,IVS;s）,舒张期室间隔厚度（diastolic interventricular septal thickness,IVS;d）,左室质量指数（LV Mass）及校正后的左室质量指数（LV Mass Corrected）等,还原型谷胱甘肽（glutathione,GSH）和氧化型谷胱甘肽（glutathione disulfide,GSSG）检测试剂盒检测心肌组织中GSH的含量,并计算大鼠的存活率。结果：与BC组相比,NS组左室后壁厚度明显变薄,室间隔厚度显著减小,GSH含量明显减少,存活率明显下降,左室质量指数及校正后的左室质量指数明显增大,差异均具有显著统计学意义（P〈0.05）;NAC组左室后壁厚度、室间隔厚度等未见明显减小,左室质量指数及校正后的左室质量指数未见明显增大GSH含量未见明显降低,差异均不具有统计学意义（P〈0.05）,但存活率明显下降,差异具有统计学意义（P〈0.05）;与NS组相比,NAC组左室后壁厚度增厚,室间隔厚度显著提高,左室质量指数及校正后的左室质量指数明显减小,GSH含量明显增高,差异均具有统计学意义（P〈0.05）,但存活率无明显统计学差异（P〉0.05）。结论：NAC能改善大鼠心肌梗死后心室结构的重塑,可能与抑制氧化应激,增加GSH的含量有关,但其对心肌梗死后大鼠的存活率无明显影响。     

Temporal Changes in Sequential Quantitative Thallium-201 Imaging Following Myocardial Infarction in Dogs: Comparison of Four and Twenty-Four Hour Infarct Images

Thallium-201 (²⁰¹T1) myocardial perfusion imaging allows definition of zones of myocardial infarction and ischemia. The temporal changes in sequential quantitative ²⁰¹T1 infarct imaging was studied 4 and 24 hours in dogs subjected to closed-chest anterior wall myocardial infarction. A temporal decrease in ²⁰¹T1 imaged infarct areas was noted in 10 of 13 animals. In no animal did the infarct area increase. The imaged infarct area decreased by an average of 30% from 12.9 ± 6.2 cm² at 4 hours to 9.1 ± 5.1 cm² at 24 hours (p < 0.001), and involved 34 ± 16% of the total ²⁰¹T1 left ventricular distribution at 4 hours and 22 ± 14% at 24 hours (p < 0.001). The magnitude of temporal change in imaged infarct area was not predicted by initial image defect or final histopathologic infarct size. Thus, the results of ²⁰¹T1 infarct imaging in the early period of infarction are clearly dependent upon the time at which the procedure is performed.     

结扎兔冠状动脉前降支与左室支的急性心肌梗塞比较

本文比较了结扎兔冠状动脉前降支（ＬＡＤ组）和左室支（ＬＶＡ组）两种方法建立的急性心肌梗塞模型。结果发现１：ＥＣＧ标测,三天内不同时间ＬＶＡ组∑△ＳＴ升高毫伏数均高于ＬＡＤ组（Ｐ＜０．０１或Ｐ＜０．０５）;２：Ｎ－ＢＴ染色,ＬＶＡ组心肌梗塞占心室重的百分率为１７．３％±０．５６％,而ＬＡＤ组为８．２％±２．４２％,两者相差非常显著（Ｐ＜０．０１）,证实了ＬＶＡ组心梗面积较ＬＡＤ组大且相对稳定。采用增强（Ｇｄ－ＤＴＰＡ）磁共振成像（ＭＲＩ）扫描发现ＬＶＡ组急性心梗范围在三天内基本稳定。作者认为,兔急性心梗模型采用结扎ＬＶＡ优于结扎ＬＡＤ。