Acute Myocardial Infarct Size Research Articles

Effect of Cangrelor on Infarct Size in ST-Segment-Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention: A Randomized Controlled Trial (The PITRI Trial).

The administration of intravenous cangrelor at reperfusion achieves faster onset of platelet P2Y12 inhibition than oral ticagrelor and has been shown to reduce myocardial infarction (MI) size in the preclinical setting. We hypothesized that the administration of cangrelor at reperfusion will reduce MI size and prevent microvascular obstruction in patients with ST-segment-elevation MI undergoing primary percutaneous coronary intervention. This was a phase 2, multicenter, randomized, double-blind, placebo-controlled clinical trial conducted between November 2017 to November 2021 in 6 cardiac centers in Singapore. Patients were randomized to receive either cangrelor or placebo initiated before the primary percutaneous coronary intervention procedure on top of oral ticagrelor. The key exclusion criteria included presenting <6 hours of symptom onset; previous MI and stroke or transient ischemic attack; on concomitant oral anticoagulants; and a contraindication for cardiovascular magnetic resonance. The primary efficacy end point was acute MI size by cardiovascular magnetic resonance within the first week expressed as percentage of the left ventricle mass (%LVmass). Microvascular obstruction was identified as areas of dark core of hypoenhancement within areas of late gadolinium enhancement. The primary safety end point was Bleeding Academic Research Consortium-defined major bleeding in the first 48 hours. Continuous variables were compared by Mann-Whitney U test (reported as median [first quartile-third quartile]), and categorical variables were compared by Fisher exact test. A 2-sided P<0.05 was considered statistically significant. Of 209 recruited patients, 164 patients (78%) completed the acute cardiovascular magnetic resonance scan. There were no significant differences in acute MI size (placebo, 14.9% [7.3-22.6] %LVmass versus cangrelor, 16.3 [9.9-24.4] %LVmass; P=0.40) or the incidence (placebo, 48% versus cangrelor, 47%; P=0.99) and extent of microvascular obstruction (placebo, 1.63 [0.60-4.65] %LVmass versus cangrelor, 1.18 [0.53-3.37] %LVmass; P=0.46) between placebo and cangrelor despite a 2-fold decrease in platelet reactivity with cangrelor. There were no Bleeding Academic Research Consortium-defined major bleeding events in either group in the first 48 hours. Cangrelor administered at the time of primary percutaneous coronary intervention did not reduce acute MI size or prevent microvascular obstruction in patients with ST-segment-elevation MI given oral ticagrelor despite a significant reduction of platelet reactivity during the percutaneous coronary intervention procedure. URL: https://www.clinicaltrials.gov; Unique identifier: NCT03102723.

MYOCARDIAL INFARCTION DUE TO LEFT CIRCUMFLEX ARTERY OCCLUSION: A SUBTLE TROJAN HORSE

Abstract A 47–year–old man presented to the emergency department complaining of recurrent chest pain (CP) since the previous day. His medical history included active smoking and dyslipidemia. The ECG revealed sinus bradycardia (56 bpm) with widespread ST elevation, consistent with benign early repolarization, and hyperacute and broad–based T waves in V2–V3 (Fig. A). The echocardiography showed normal left and right ventricular systolic function and no valvular abnormalities. A low but abnormal initial high–sensitivity cardiac troponin I value (40 pg/mL, normal range: 1.7– 34,2 pg/mL) and a slightly and early increase after two hours (52 pg/ml) were seen. Therefore, the patient was admitted to our intensive cardiac care unit (ICCU) with a working diagnosis of non–ST–segment elevation myocardial infarction (NSTEMI). No sign or symptoms of heart failure on physical examination were recorded. GraceScore 2.0 was calculated as 68 points and coronary angiography was organized within 24h. Two hours after admission to the ICCU, the patient experienced a new episode of CP. Consequently, ECG and echo were repeated. Compared to the previous results, ECG showed dynamic changes in V2–V3, with the resolution of hyperacute T waves (Fig B); bedside echo remained unchanged. Considering the unresponsiveness to nitrate therapy, the cath lab was activated for a time–dependent coronary angiography. The exam showed an acute total thrombotic occlusion of the mid–segment of the circumflex branch (LCx) in the setting left–sided dominant circulation. A drug eluting stent was deployed into the culprit lesion (Fig. C), and the coronary flow was restored completely (TIMI Flow 3). The subsequent hospital stay proceeded without complications. The peak troponin level was 60’000 pg/ml. The patient was discharged on the fifth day, asymptomatic and hemodynamically stable, with instructions to continue dual antiplatelet therapy. The case report focuses on the electrocardiographic and angiographic expression of LCx total occlusion. Despite acute myocardial infarction (AMI) size was large, as confirmed by the abnormal troponin I values and the angiographic total occlusion, the first and the repeated ECGs showed only vague repolarization changes without clear ST–segment modifications. LCx occlusion is often characterized by the absence of significant ST–elevation, therefore categorized as NSTEMI. Greater awareness of the presentation of LCx–related AMI can be crucial to avoid delays in reperfusion.

Fabrication of blended nanofibrous cardiac patch transplanted with TGF-β3 and human umbilical cord MSCs-derived exosomes for potential cardiac regeneration after acute myocardial infarction

Acute myocardial infarction (AMI) is a common cardiovascular condition that progressively results in heart failure. In the present study, we have designed to load transforming growth factor beta 3 (TGF-β3) and cardio potential exosomes into the blended polycaprolactone/type I collagen (PCL/COL-1) nanofibrous patch (Exo@TGF-β3@NFs) and examined its feasibility for cardiac repair. The bioactivity of the developed NFs towards the migration and proliferation of human umbilical vein endothelial cells was determined using in vitro cell compatibility assays. Additionally, Exo@TGF-β3/NFs showed up-regulation of genes involved in angiogenesis and mesenchymal differentiations in vitro. The in vivo experiments performed 4 weeks after transplantation showed that the Exo@TGF-β3@NFs had a higher LV ejection fraction and fraction shortening functions. Subsequently, it has been determined that Exo@TGF-β3@NFs significantly reduced AMI size and fibrosis and increased scar thickness. The developed NFs approach will become a useful therapeutic approach for the treatment of AMI.

Remote ischemic preconditioning and hypoxia-induced biomarkers in acute myocardial infarction: study on a porcine model

Objectives. Remote ischemic preconditioning (RIPC) mitigates acute myocardial infarction (AMI). We hypothesized that RIPC reduces the size and severity of AMI and explored molecular mechanisms behind this phenomenon. Design. In two series of experiments, piglets underwent 60 min of the circumflex coronary artery occlusion, resulting in AMI. Piglets were randomly assigned into the RIPC groups (n = 7 + 7) and the control groups (n = 7 + 7). The RIPC groups underwent four 5-min hind limb ischemia-reperfusion cycles before AMI. In series I, the protective efficacy of RIPC was investigated by using biomarkers and echocardiography with a follow-up of 24 h. In series II, the heart of each piglet was harvested for TTC-staining to measure infarct size. Muscle biopsies were collected from the hind limb to explore molecular mechanisms of RIPC using qPCR and Western blot analysis. Results. The levels of CK-MBm (p = 0.032) and TnI (p = 0.007) were lower in the RIPC group. Left ventricular ejection fraction in the RIPC group was greater at the end of the follow-up. The myocardial infarct size in the RIPC group was smaller (p = 0.033). Western blot indicated HIF1α stabilization in the skeletal muscle of the RIPC group. PCR analyses showed upregulation of the HIF target mRNAs for glucose transporter (GLUT1), glucose transporter 4 (GLUT4), phosphofructokinase 1 (PFK1), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), enolase 1 (ENO1), lactate dehydrogenase (LDHA) and endothelial nitric oxidate synthase (eNOS). Conclusions. Biochemical, physiologic, and histologic evidence confirms that RIPC decreases the size of AMI. The HIF pathway is likely involved in the mechanism of the RIPC.

Research progress on the effects of novel hypoglycemic drugs in diabetes combined with myocardial ischemia/reperfusion injury.

Acute myocardial infarction (AMI) reperfusion is associated with ischemia/reperfusion (I/R) injury, which leads to enlarged myocardial infarction size, poor healing of the infarcted myocardium, and poor left ventricular remodeling, thus increasing the risk of major adverse cardiovascular events (MACEs). Diabetes increases myocardial susceptibility to I/R injury, decreases myocardial responsiveness to cardioprotective strategies, exacerbates myocardial I/R injury, and expands the infarct size of AMI, thereby increasing the incidence of malignant arrhythmias and heart failure. Currently, evidence regarding pharmacological interventions for diabetes combined with AMI and I/R injury is lacking. Traditional hypoglycemic drugs have a limited role in the prevention and treatment of diabetes combined with I/R injury. Current evidence suggests that novel hypoglycemic drugs may exert a preventive effect on diabetes combined with myocardial I/R injury, especially glucagon-like peptide-1 receptor agonists (GLP-1 RA) and sodium-dependent glucose transporter protein 2 inhibitors (SGLT2i), which may increase coronary blood flow, reduce acute thrombosis, attenuate I/R injury, decrease myocardial infarction size, inhibit structural and functional remodeling of the ischemic heart, improve cardiac function, and reduce the occurrence of MACEs of diabetes patients combined with AMI via mechanisms such as reduction of inflammatory response, inhibition of oxidative stress, and improvement of vascular endothelial function. This paper will systematically elaborate the protective role and molecular mechanisms of GLP-1 RA and SGLT2i in diabetes combined with myocardial I/R injury, aiming to provide clinical assistance.

A Noncontrast CMR Risk Score for Long-Term Risk Stratification in Reperfused ST-Segment Elevation Myocardial Infarction

ObjectivesThis study compared the prognostic value of a noncontrast CMR risk score for the composite of all-cause death, nonfatal myocardial infarction, and new congestive heart failure. BackgroundA cardiovascular magnetic resonance (CMR) risk score including left ventricular ejection fraction (LVEF), myocardial infarct (MI) size, and microvascular obstruction (MVO) was recently proposed to risk-stratify patients with ST-segment elevation myocardial infarction (STEMI). MethodsThe Eitel CMR risk score and GRACE (Global Registry of Acute Coronary Events) score were used as a reference (Score 1: acute MI size ≥19% LV, LVEF ≤47%, MVO >1.4% LV and GRACE score). MVO was replaced by intramyocardial hemorrhage (IMH) in Score 2 (acute MI size ≥19% LV, LVEF ≤47%, IMH, and GRACE score). Score 3 included only LVEF ≤45%, IMH, and GRACE score. ResultsThere were 370 patients in the derivation cohort and 234 patients in the validation cohort. In the derivation cohort, the 3 scores performed similarly and better than GRACE score to predict the 1-year composite endpoint with C-statistics of 0.83, 0.83, 0.82, and 0.74, respectively. In the validation cohort, there was good discrimination and calibration of score 3, with a C-statistic of 0.87 and P = 0.71 in a Hosmer-Lemeshow test for goodness of fit, on the 1-year composite outcome. Kaplan-Meier curves for 5-year composite outcome showed that those with LVEF ≤45% (high-risk) and LVEF >45% and IMH (intermediate-risk) had significantly higher cumulative events than those with LVEF >45% and no IMH (low-risk), log-rank tests: P = 0.02 and P = 0.03, respectively. The HR for the high-risk group was 2.3 (95% CI: 1.1-4.7) and for the intermediate-risk group was 2.0 (95% CI: 1.0-3.8), and these remained significant after adjusting for the GRACE score. ConclusionsThis noncontrast CMR risk score has performance comparable to an established risk score, and patients with STEMI could be stratified into low risk (LVEF >45% and no IMH), intermediate risk (LVEF >45% and IMH), and high risk (LVEF ≤45%). (A Trial of Low-dose Adjunctive alTeplase During prIMary PCI [T-TIME]; NCT02257294) (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction [BHF MR-MI]; NCT02072850)

Effect of remote ischaemic conditioning on infarct size and remodelling in ST-segment elevation myocardial infarction patients: the CONDI-2/ERIC-PPCI CMR substudy

The effect of limb remote ischaemic conditioning (RIC) on myocardial infarct (MI) size and left ventricular ejection fraction (LVEF) was investigated in a pre-planned cardiovascular magnetic resonance (CMR) substudy of the CONDI-2/ERIC-PPCI trial. This single-blind multi-centre trial (7 sites in UK and Denmark) included 169 ST-segment elevation myocardial infarction (STEMI) patients who were already randomised to either control (n = 89) or limb RIC (n = 80) (4 × 5 min cycles of arm cuff inflations/deflations) prior to primary percutaneous coronary intervention. CMR was performed acutely and at 6 months. The primary endpoint was MI size on the 6 month CMR scan, expressed as median and interquartile range. In 110 patients with 6-month CMR data, limb RIC did not reduce MI size [RIC: 13.0 (5.1–17.1)% of LV mass; control: 11.1 (7.0–17.8)% of LV mass, P = 0.39], or LVEF, when compared to control. In 162 patients with acute CMR data, limb RIC had no effect on acute MI size, microvascular obstruction and LVEF when compared to control. In a subgroup of anterior STEMI patients, RIC was associated with lower incidence of microvascular obstruction and higher LVEF on the acute scan when compared with control, but this was not associated with an improvement in LVEF at 6 months. In summary, in this pre-planned CMR substudy of the CONDI-2/ERIC-PPCI trial, there was no evidence that limb RIC reduced MI size or improved LVEF at 6 months by CMR, findings which are consistent with the neutral effects of limb RIC on clinical outcomes reported in the main CONDI-2/ERIC-PPCI trial.

Size of Acute Myocardial Infarction Correlates with Earlier Time of Initiation of Reperfusion Therapy with Cardiac Perfusion Scintigraphy: A National Single-Center Study

BackgroundThe aim of this study was to determine the correlation between the size of acute myocardial infarction (AMI) and the time of initiation of reperfusion therapy with cardiac perfusion scintigraphy.Material/MethodsOverall, 80 patients with acute ST elevation myocardial infarction (STEMI) were examined. All patients were treated with primary percutaneous coronary intervention (pPCI). Data on patient and system delay expressed in minutes were recorded and compared with recommended timelines. Cardiac scintigraphy was performed with 99m Tc-sestamibi single-photon emission computed tomography (SPECT). The median time of cardiac scintigraphy was 20 days. The correlation between the size of infarction and the time of initiation of reperfusion therapy was evaluated.ResultsThe mean age of patients was 60.5±11.5 years, and 72.5% were male. The average system delay was 348 min, and the average patient delay was 173 min. The mean total ischemic time was 800 min. There was a correlation between time delays of reperfusion therapy and infarct size. Patients with a shorter time delay to patent artery after FMC showed smaller infarct size when compared to the patients with longer delay times. Multiple linear regression analysis showed that FMC, being male, and smokers had statistical significance when predicting infarct size.ConclusionsThere is a correlation between the size of myocardial infarction and the time of initiation of reperfusion therapy determined by perfusion myocardial scintigraphy. The study showed that there are time delays in starting the treatment of AMI with pPCI when compared to the recommended time, which requires an action plan in the near future to ensure earlier treatment for our patients.

High Triglyceride-Glucose Index is Associated with Poor Cardiovascular Outcomes in Nondiabetic Patients with ACS with LDL-C below 1.8 mmol/L.

Aim: To evaluate the prognostic value of triglyceride-glucose (TyG) index in nondiabetic patients with acute coronary syndrome (ACS) with low-density lipoprotein cholesterol (LDL-C) below 1.8 mmol/L. Methods: A total of 1655 nondiabetic patients with ACS with LDL-C below 1.8 mmol/L were included in the analysis. Patients were stratified into two groups. The incidence of acute myocardial infarction (AMI), infarct size in patients with AMI, and major adverse cardiac and cerebral event during a median of 35.6-month follow-up were determined and compared between the two groups. The TyG index was calculated using the following formula: ln [fasting triglycerides (mg/dL)×fasting plasma glucose (mg/dL)/2]. Results: Compared with the TyG index ＜8.33 group, the TyG index ≥ 8.33 group had a significantly higher incidence of AMI (21.2% vs. 15.2%, p =0.014) and larger infarct size in patients with AMI [the peak value of troponin I: 10.4 vs. 4.8 ng/ml, p =0.003; the peak value of Creatine kinase MB: 52.8 vs. 22.0 ng/ml, p =0.006; the peak value of myoglobin: 73.7 vs. 46.0 ng/ml, p =0.038]. Although there was no significant difference in mortality between the two groups, the incidence of revascularization of the TyG index ≥ 8.33 group was significantly higher than that of the TyG index ＜8.33 group (8.9% vs. 5.0%, p =0.035). A multivariable Cox regression revealed that the TyG index was positively associated with revascularization [hazard ratio, 1.67; 95% confidence interval, 1.02–2.75; p =0.043]. Conclusions: In nondiabetic patients with ACS with LDL-C below 1.8 mmol/L, a high TyG index level was associated with higher incidence of AMI, larger infarct size, and higher incidence of revascularization. A high TyG index level might be a valid predictor of subsequent revascularization.

Abstract 13780: Effects of Op2113 on Myocardial Infarct Size and No Reflow in a Rat Myocardial Ischemia/reperfusion Model

Background: Despite advances in early reperfusion therapy for acute ST elevation myocardial infarction (MI), mortality rates and prevention of heart failure after the MI are not optimal. There have been many attempts to further reduce the size of acute MI and to limit the no reflow phenomenon after reperfusion, with mixed results. One promising approach may be to target the mitochondria. The purpose of the present study was to determine whether OP2113 and its active principle ATT (Anethol-TriThione, named also 5-(4-Methoxyphenyl)-3H-1,2-dithiole-3-thione; CAS 532-11-6 ), a pharmaceutical that has been shown to decrease mitochondrial reactive species production from complex I of the mitochondrial respiratory chain, could limit MI size and the no reflow phenomenon in a standardized rat model of 30 minutes of proximal coronary artery occlusion and reperfusion. Methods and Results: Anesthetized rats were exposed to MI and received OP2113 as an intravenous infusion starting either 5 minutes prior to coronary artery occlusion (preventive), or 5 minutes prior to reperfusion (curative), or received vehicle starting 5 minutes prior to coronary artery occlusion. Infusions continued until the end of the study (3 hours of reperfusion). MI size ( triphenyl tetrazolium chloride staining technique) , expressed as a percentage of the ischemic risk zone ( blue dye technique) was significantly lower in the OP2113 treated preventive group at 44.5 ± 2.9% versus 57.0 ± 3.6% ( p&lt;0.05) in the vehicle group, with a nonsignificant trend toward a smaller infarct size in the curative group ( 50.8 ± 3.9%). Area of no reflow ( thioflavin S technique) as a percentage of the risk zone was significantly smaller in both the OP2113 treated preventive (28.8 ± 2.4%; p =0.026 vs vehicle) and curative groups ( 30.1 ± 2.3%; p=0.04 vs vehicle) compared to the vehicle group ( 38.9 ± 3.1%). OP2113 was not associated with any hemodynamic changes. Conclusions: These results suggest that OP2113 is a promising agent to reduce no-reflow as well as to reduce MI size, especially if it is on board early in the course of the MI. It appears to have benefit on no-reflow even when administered relatively late in the course of ischemia.

Left Ventricular Assist Devices for Acute Myocardial Infarct Size Reduction: Meta-analysis.

We conducted a meta-analysis of preclinical studies that tested left ventricular assist device (LVAD) therapy for reducing myocardial infarct size in experimental acute myocardial infarction (AMI). Twenty-six articles were included with a total of 488 experimental animal subjects. The meta-analysis showed that infarct size was significantly decreased by LVAD support compared to control animals (SDM, - 2.19; 95% CI, - 2.70 to - 1.69; P < 0.001). The meta-regression analysis demonstrated a high degree of heterogeneity associated with time from coronary artery occlusion to LVAD support, which correlated positively with infarct size. Subgroup analysis suggested smaller infarct size in LVAD therapies that withdrew blood from left heart than those from right heart. The proportion of left ventricular support relative to total cardiac output was positively correlated with infarct size reduction in Impella studies. Thus, early initiation of LVAD after ischemia and effective left ventricular venting may be important factors to reduce infarct size in AMI.

Symptoms Predictive of Acute Myocardial Infarction in the Troponin Era: Analysis From the TRAPID-AMI Study.

The TRAPID-AMI (High Sensitivity Cardiac Troponin T assay for rapid Rule-out of Acute Myocardial Infarction) study evaluated a rapid "rule-out" acute myocardial infarction (AMI). We evaluated what symptoms were associated with AMI as part of a substudy of TRAPID-AMI. There were 1282 patients evaluated from 12 centers in Europe, the United States of America, and Australia from 2011 to 2013. Multiple symptom variables were prospectively obtained and evaluated for association with the final diagnosis of AMI. Multivariate logistic regression analysis was done, and odds ratios (OR) were calculated. There were 213/1282 (17%) AMIs. Four independent predictors for the diagnosis of AMI were identified: radiation to right arm or shoulder [OR = 3.0; confidence interval (CI): 1.8-5.0], chest pressure (OR = 2.5; CI: 1.3-4.6), worsened by physical activity (OR = 1.7; CI: 1.2-2.5), and radiation to left arm or shoulder (OR = 1.7; CI: 1.1-2.4). In the entire group, 131 (10%) had radiation to right arm or shoulder, 897 (70%) had chest pressure, 385 (30%) worsened with physical activity, and 448 (35%) had radiation to left arm or shoulder. Duration of symptoms was not predictive of AMI. There were no symptoms predictive of non-AMI. Relationship between AMI size and symptoms was also studied. For 213 AMI patients, cardiac troponins I values were divided into 4 quartiles. Symptoms including pulling chest pain, supramammillary right location, and right arm/shoulder radiation were significantly more likely to occur in patients with larger AMIs. In a large multicenter trial, only 4 symptoms were associated with the diagnosis of AMI, and no symptoms that were associated with a non-AMI diagnosis.

Mineralocorticoid receptor antagonist pre-treatment and early post-treatment to minimize reperfusion injury after ST-elevation myocardial infarction: The MINIMIZE STEMI trial

BackgroundMineralocorticoid receptor antagonist (MRA) therapy has been shown to prevent adverse left ventricular (LV) remodeling in ST-segment elevation myocardial infarction (STEMI) patients with heart failure. Whether initiating MRA therapy prior to primary percutaneous coronary intervention (PPCI) accrues additional benefit of reducing myocardial infarct size and preventing adverse LV remodeling is not known. We aimed to investigate whether MRA therapy initiated prior to reperfusion reduces myocardial infarct (MI) size and prevents adverse LV remodeling in STEMI patients.MethodsSTEMI patients presenting within 12 hours and with a proximal coronary artery occlusion with Thrombolysis In Myocardial Infarction flow grade 0 were consented and randomized to either an intravenous bolus of potassium canrenoate, followed by oral spironolactone for 3 months or matching placebo. The primary endpoint was MI size by cardiovascular magnetic resonance at 3 months.ResultsSixty-seven patients completed the study. There was no significant difference in the final MI size at 3 months between the 2 groups (placebo: 17 ± 11%, MRA: 16 ± 10%, P = .574). There was also no difference in acute MI size (26 ± 16% versus 23 ± 14%, P = .425) or myocardial salvage (26 ± 12% versus 24 ± 8%, P = .456). At follow-up, there was a trend towards an improvement in LVEF (placebo: 49 ± 8%, MRA: 54 ± 11%, P = .053), and the MRA group had significantly greater percentage decrease in LVEDV (mean difference: −12.2 (95% CI −20.3 to −4.4)%, P = .003) and LVESV (mean difference: −18.2 (95% CI −30.1 to −6.3)%, P = .003).ConclusionThis pilot study showed no benefit of MRA therapy in reducing MI size in STEMI patients when initiated prior to reperfusion, but there was an improvement in LV remodeling at 3 months. Adequately powered studies are warranted to confirm these findings.

Size of Anterior Wall Acute Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention in United States Versus Europe/Australia Versus India (from the CRISP-AMI Randomized Controlled Trial)

International variability in infarct size following acute anterior ST-elevation myocardial infarction without shock treated with primary percutaneous coronary intervention (PCI) has been little studied. Patients enrolled in the Counterpulsation to Reduce Infarct Size pre-PCI for Acute Myocardial Infarction international randomized trial were analyzed according to their region of enrollment: United States (US) (n = 60), Europe/Australia (EU/AU) (n = 104), or India (n = 123). Cardiac magnetic resonance imaging was performed 3-5 days after PCI to assess infarct size, expressed as percentage of left ventricular mass, and analyzed by an imaging core laboratory. The relation between infarct size and region was modelled using multivariable linear regression adjusting for time from symptom onset to first hospital contact, myocardial infarction severity, and baseline characteristics. Infarct size was 36.4% of left ventricular mass in US patients (95% confidence interval [CI] 31.5 to 41.4), 36.5% (95% CI 32.6 to 40.4) in EU/AU patients, and 44.7% (95% CI 41.1 to 48.2) in patients from India (p = 0.01). In multiplicity-adjusted regression analysis, mean infarct size in patients from India was higher than in US patients (mean difference of 8.3%; 95% CI 0.7 to 15.8; p = 0.03), and EU/AU patients (mean difference of 8.2%; 95% CI 1.6 to 14.8; p = 0.01). There was no significance difference in infarct size between patients from the EU/AU and the US (mean difference of 0.1%; 95% CI -7.5 to 7.4; p = 0.99). ln conclusion, in patients with anterior ST-elevation myocardial infarction without cardiogenic shock treated with primary PCI, infarct size was larger in India compared to the United States and EU/AU, even after adjustment for performance metrics, including time to treatment, and other potential confounders. Future studies are needed to better elucidate this discrepancy.

Cardiometabolic efficacy and toxicological evaluation of a pharmacological galanin receptor agonist

The goal of this study was to examine effects of a novel galanin receptor agonist GalR1-3 [bAla14, His15]-galanine 2-15 (G), obtained by automatic solid-phase synthesis, on the metabolic state of the area at risk and the size of acute myocardial infarction (MI) in rats in vivo and evaluate its toxicity in BALB /c mice. In anesthetized rats, regional ischemia was simulated by coronary artery occlusion and then coronary blood flow was restored. The peptide G was administered intravenously (i.v.) with a bolus after a period of regional ischemia in the dose range of 0.25-3.0 mg/kg. The sizes of MI and the activities of creatine kinase-MB (СK-MB) and lactate dehydrogenase (LDH) in blood plasma were estimated. The effect of administration of the optimal dose of G (1.0 mg/kg) on myocardial content of adenine nucleotides (AN), phosphocreatine (PCr), creatine (Cr) and lactate was studied. I.v. administration of G to rats at a dose of 1.0 mg/kg slightly affected hemodynamic parameters, but reduced MI size by 40% and decreased plasma LDH and CK-MB activity by the end of reperfusion compared to control. These effects were accompanied by a significant improvement in energy state of area at risk (AAR) - an increase in myocardial content of ATP, åAN, PCr and åCr, and combined with a decrease in myocardial lactate level compared with the control. Toxicity of peptide G was studied with a single intraperitoneal injection of 0.5-3.0% solution of the peptide substance to mice. The absence of signs of intoxication and death of animals after G injection in the maximum possible dose did not allow determining the value of the average lethal dose. The results indicate therapeutic potential of the peptide G for preventing myocardial ischemia and reperfusion injury and feasibility for further study of its pharmacological properties and mechanisms of action.

Mimicking Preconditioning by Vagal Stimulation. Effects on Ventricular Function in a Chronic Experimental Model

Background: Previous studies have shown that preischemic vagal electrostimulation (pVS) reduces acute myocardial infarctsize, without a significant improvement on ventricular function within the two-hour reperfusion period. It is unknown whichare the long-term effects of pVS on left ventricular function (LVF).Objectives: The aim of this study was to analyze whether the protective effects of brief pVS on acute infarct size improvesLVF in a chronic myocardial ischemia-reperfusion model.Methods: FVB mice were subjected to 45-minutes regional myocardial ischemia followed by 2 hours of reperfusion or 28-daypost-reperfusion follow-up with or without 10-minutes pVS. Infarct size (IS) was measured with 2,3,5-triphenyltetrazoliumchloride, and LVF was assessed by echocardiography and left ventricular catheterization.Results: Preischemic vagal stimulation reduced IS from 66.8±3.2% to 43.2±1.6% (p <0.001) at 2 hours of reperfusion, without afavorable LVF response. At 28 days, the pVS group exhibited LVF improvement, with lower left ventricular end-diastolic pressure(4.44±1 vs. 6.91±1 mmHg in the control group; p<0.05), higher ejection fraction (69.7±2.8% vs. 59.3±3.2; p<0.05), greatershortening fraction (33.4±2.23 vs. 25.8±1.8%; p<0.05) and lower isovolumic relaxation time (25±0.8 ms vs. 30.3±1.2 ms; p<0.05)Conclusions: In a mice model of myocardial ischemia and reperfusion, mimicking ischemic preconditioning by VS improvesthe chronic outcome of infarction, resulting in greater LVF recovery

Local sympathetic denervation attenuates myocardial inflammation and improves cardiac function after myocardial infarction in mice.

AimsCardiac inflammation has been suggested to be regulated by the sympathetic nervous system (SNS). However, due to the lack of methodology to surgically eliminate the myocardial SNS in mice, neuronal control of cardiac inflammation remains ill-defined. Here, we report a procedure for local cardiac sympathetic denervation in mice and tested its effect in a mouse model of heart failure post-myocardial infarction.Methods and resultsUpon preparation of the carotid bifurcation, the right and the left superior cervical ganglia were localized and their pre- and postganglionic branches dissected before removal of the ganglion. Ganglionectomy led to an almost entire loss of myocardial sympathetic innervation in the left ventricular anterior wall. When applied at the time of myocardial infarction (MI), cardiac sympathetic denervation did not affect acute myocardial damage and infarct size. In contrast, cardiac sympathetic denervation significantly attenuated chronic consequences of MI, including myocardial inflammation, myocyte hypertrophy, and overall cardiac dysfunction.ConclusionThese data suggest a critical role for local sympathetic control of cardiac inflammation. Our model of myocardial sympathetic denervation in mice should prove useful to further dissect the molecular mechanisms underlying cardiac neural control.

The relationship between fasting blood glucose variability and coronary artery collateral formation in type 2 diabetes patients with coronary artery disease.

Coronary collaterals are an alternative source of blood supply to ischemic myocardium. Well-developed coronary collateral arteries in patients with coronary artery disease (CAD) limit the size of acute myocardial infarction and improves survival. The aim of this study was to investigate the relationship between glycemic variability and coronary collateral formation in patients with type 2 diabetes mellitus and CAD. Consecutive patients undergoing percutaneous coronary intervention or coronary artery bypass grafting procedures were studied. Multivariate logistic regression models were used to examine the association between coronary artery collateral formation graded by Rentrope classification and glycemic variability, measured by coefficient variation of fasting blood glucose. In our study, we retrospectively enrolled 300 patients, of whom 239 were diabetic (age: 70.1±11.9, 56% men) and 61 were nondiabetic (age: 71.5±11.5, 72% men). Diabetic patients were further stratified as follows: those with poor coronary collateral artery development (n=171, age: 69.7±12.4, 55% men) and those with good coronary collateral artery development (n=68, age 71.1±10.8, 59% men) according to the Rentrope classification. Our findings did not show association between glycemic variability and coronary collateral vessels development after controlling for potential confounders (odds ratio: 2.51; 95% confidence interval: 0.57-11.03; P=0.22). The culprit lesion (≥75% stenosis) in the left anterior descending artery and the right coronary artery was more frequent in the good collateral group compared with the poor collateral group (66 vs. 50%, P=0.02; 63 vs. 45%, P=0.01 respectively). Glycemic variability is not associated with coronary collateral artery formation in patients with type 2 diabetes mellitus and CAD.

The challenge of magnetic vagal nerve stimulation for myocardial infarction -preliminary clinical trial.

Numerous studies have shown in animal models that vagal nerve stimulation (VNS) strikingly reduces infarct size of acute myocardial infarction (AMI) and prevents heart failure. However, the lack of techniques to noninvasively stimulate the vagal nerve hinders VNS from clinical applications. Transcranial magnetic stimulation is noninvasive and capable of stimulating central neurons in patients. In this study, we examined whether the magnetic stimulation could noninvasively activate the cervical vagal nerve in healthy human. Sixteen healthy males and 4 females were enrolled in this study. We used Magstim Rapid2 with a 70-mm double coil in the right neck. We randomly assigned the subjects to 5 Hz or 20 Hz stimulation. We defined the maximum intensity of stimulation (MAX) which is the intensity just below the threshold of adverse effects. We defined HALF as a half of MAX. Protocols comprised 2 sets of MAX and 2 sets of HALF. Each stimulation continued for 3 minutes. We monitored heart rate (HR) and assessed the bradycardic response as an index of successful VNS. Nineteen subjects completed all protocols. They had no problematic adverse events during and/or after magnetic VNS. The magnetic VNS induced transient bradycardic responses in some subjects, whereas failed to induce sustained bradycardia in pooled data in any settings. Arterial pressure did not change either. Successful magnetic stimulation requires technical improvements including narrowing the magnetic focus and optimization of stimulation site. These improvements may enable us to apply magnetic VNS in the management of AMI.

Human Umbilical Cord Blood Stem Cells and Chitosan Hydrogels Produce Similar Beneficial Effects in Acute Myocardial Infarctions and Ischemic Cardiomyopathies

We utilized two separate techniques, human Umbilical Cord Blood Stem Cells (hUCBC) and chitosan hydrogels, to limit acute myocardial infarction size and LV remodeling. Human Umbilical Cord Blood Mononuclear Cells (hUCBC), contain hematopoietic and mesenchymal stem cells. Chitosan is a polysaccharide and chitosan hydrogels are approved by the United States Food and Drug Administration for human use in drug delivery and are used in repair of skin, nerve, cartilage, and bone.