Therapies to prevent heart failure post-myocardial infarction

Stromal cell-derived factor-1 alpha improves cardiac function in a novel diet-induced coronary atherosclerosis model, the SR-B1ΔCT/LDLR KO mouse

BACKGROUND AND AIMS

There are a limited number of pharmacologic therapies for coronary artery disease, and few rodent models of occlusive coronary atherosclerosis and consequent myocardial infarction with which one can rapidly test new therapeutic approaches. Here, we characterize a novel, fertile, and easy-to-use HDL receptor (SR-B1)-based model of atherogenic diet-inducible, fatal coronary atherosclerosis, the SR-B1ΔCT/LDLR KO mouse. Additionally, we test intramyocardial injection of Stromal Cell-Derived Factor-1 alpha (SDF-1α), a potent angiogenic cytokine, as a possible therapy to rescue cardiac function in this mouse.

METHODS

SR-B1ΔCT/LDLR KO mice were fed the Paigen diet or standard chow diet, and we determined the effects of the diets on cardiac function, histology, and survival. After two weeks of feeding either the Paigen diet (n = 24) or standard chow diet (n = 20), the mice received an intramyocardial injection of either SDF-1α or phosphate buffered saline (PBS). Cardiac function and angiogenesis were assessed two weeks later.

RESULTS

When six-week-old mice were fed the Paigen diet, they began to die as early as 19 days later and 50% had died by 38 days. None of the mice maintained on the standard chow diet died by day 72. Hearts from mice on the Paigen diet showed evidence of cardiomegaly, myocardial infarction, and occlusive coronary artery disease. For the five mice that survived until day 28 that underwent an intramyocardial injection of PBS on day 15, the average ejection fraction (EF) decreased significantly from day 14 (the day before injection, 52.1 ± 4.3%) to day 28 (13 days after the injection, 30.6 ± 6.8%) (paired t-test, n = 5, p = 0.0008). Of the 11 mice fed the Paigen diet and injected with SDF-1α on day 15, 8 (72.7%) survived to day 28. The average EF for these 8 mice increased significantly from 48.2 ± 7.2% on day 14 to63.6 ± 6.9% on day 28 (Paired t-test, n = 8, p = 0.003).

CONCLUSIONS

This new mouse model and treatment with the promising angiogenic cytokine SDF-1α may lead to new therapeutic approaches for ischemic heart disease.

Butyrate attenuates sympathetic activation in rats with chronic heart failure by inhibiting microglial inflammation in the paraventricular nucleus

Sympathetic activation is a hallmark of heart failure and the underlying mechanism remains elusive. Butyrate is generated by gut microbiota and influences numerous physiological and pathological processes in the host. The present study aims to investigate whether the intestinal metabolite butyrate reduces sympathetic activation in rats with heart failure (HF) and the underlying mechanisms involved. Sprague-Dawley rats (220‒250 g) are anaesthetized with isoflurane, and the left anterior descending artery is ligated to model HF. Then, the rats are treated with or without butyrate sodium (NaB, a donor of butyrate, 10 g/L in water) for 8 weeks. Blood pressure and renal sympathetic nerve activity (RSNA) are recorded to assess sympathetic outflow. Cardiac function is improved (mean ejection fraction, 22.6%±4.8% vs 38.3%±5.3%; P<0.05), and sympathetic activation is decreased (RSNA, 36.3%±7.9% vs 23.9%±7.6%; P<0.05) in HF rats treated with NaB compared with untreated HF rats. The plasma and cerebrospinal fluid levels of norepinephrine are decreased in HF rats treated with NaB. The infusion of N-methyl-D-aspartic acid (NMDA) into the paraventricular nucleus (PVN) of the hypothalamus of HF model rats increases sympathetic nervous activity by upregulating the NMDA receptor. Microglia polarized to the M2 phenotype and inflammation are markedly attenuated in the PVN of HF model rats after NaB administration. In addition, HF model rats treated with NaB exhibit enhanced intestinal barrier function and increased levels of GPR109A, zona occludens-1 and occludin, but decreased levels of lipopolysaccharide-binding protein and zonulin. In conclusion, butyrate attenuates sympathetic activation and improves cardiac function in rats with HF. The improvements in intestinal barrier function, reductions in microglia-mediated inflammation and decreases in NMDA receptor 1 expression in the PVN are all due to the protective effects of NaB.

Association Between Myocardial Infarction and Triglyceride-Glucose Index: A Study Based on NHANES Database

Objective

To investigate differences in levels of the triglyceride-glucose (TyG) index between individuals with myocardial infarction (MI) and those without MI, as well as the association between TyG index and risk of MI.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) for US adults from 2013 to 2018 were included in this study. Using MI as an outcome variable and TyG index as an exposure variable, logistic regression models were employed to analyze relationship between MI and TyG index.

Results

The study included 6,695 participants. Compared to the non-MI group, patients with MI had significantly higher TyG index (8.89 vs. 8.63, P = 0.003). Higher TyG index was significantly associated with an increased risk of MI in US adults (OR: 1.69, 95% CI: 1.26-2.26, P < 0.001). Race, smoking status, and history of chronic obstructive pulmonary disease (COPD) had significant impacts on the association between TyG index and risk of MI (P for interaction < 0.05). Subgroup analysis demonstrated a significant positive correlation between TyG index and MI risk in non-Hispanic Black individuals, non-smokers, and individuals without COPD across multiple models (OR > 1.0, P < 0.05).

Conclusion

US adults with higher TyG index were more susceptible to MI, and TyG index may be used to identify individuals at high risk of MI in the US population.

Spacial and Temporal Patterns of Gene Expression After Cardiac MEK1 Gene Transfer Improve Post-Infarction Remodeling Without Inducing Global Hypertrophy

Alteration of mitogen activated protein (MAP) kinase signaling in transgenic mice can ameliorate post-myocardial infarction (MI) remodeling. However, pre-existing changes in transgenic hearts and clinically unrealistic transgene expression likely affect the response to injury; it is unknown whether clinically relevant induction of transgene expression in an otherwise normal heart can yield similar benefits. Constitutively active MEK1 (aMEK1) or LacZ adeno-associated virus 9 (AAV9) vectors were injected into the left ventricular (LV) chambers of mice either just before or after coronary ligation. Hearts were evaluated via Western blot, quantitative polymerase chain reaction, histology, and echocardiography. AAV9-mediated aMEK1 delivery altered ERK1/2 expression/activation as in transgenic mice. Transgene expression was not immediately detectable but plateaued at 17 days, and therefore did not likely impact acute ischemia as it would in transgenics. With AAV9-aMEK1 injection just prior to MI, robust expression in the infarct border zone during post-MI remodeling increased border zone wall thickness and reduced infarct size versus controls at 4 weeks, but did not induce global hypertrophy. Significant improvements in local and global LV function were observed, as were trends toward a preservation of LV volume. Delivery after ligation significantly lowered transgene expression in the infarct border zone and did not yield structural or functional benefits. The primary benefits observed in transgenic mice, ameliorated remodeling, and reduced chronic infarct size, were achievable via clinically relevant gene transfer of aMEK1, supporting ongoing translational efforts. Important differences, however, were observed, and consideration must be given to the timing and distribution of transgene delivery and expression. J. Cell. Biochem. 118: 775-784, 2017. © 2016 Wiley Periodicals, Inc.

Rapid predictors for the occurrence of reduced left ventricular ejection fraction between LAD and non-LAD related ST-elevation myocardial infarction

BACKGROUNDS

Reduced left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI), which implies the occurrence of cardiac dysfunction, impacts cardiac prognosis, even after primary percutaneous coronary intervention (PCI). This study was designed to clarify the difference of clinical and angiographic predictors for reduced LVEF in ST-elevation myocardial infarction (STEMI) patients with left anterior descending artery (LAD) or non-LAD vessel as culprit artery.

METHODS

This was a retrospective study to review a total of 553 patients of STEMI underwent primary PCI in our hospital. All patients underwent echocardiography. Univariate analysis, multivariate analysis and classification and regression tree (CART) were performed between LAD related AMI and non-LAD related STEMI. The primary outcome was the occurrence of reduced LVEF 4-6 days after PCI.

RESULTS

In this study, culprit arteries of STEMI were 315 in LAD system (6 in left main artery, 309 in LAD) and 238 in non-LAD system (63 in left circumflex and 175 in right coronary artery). Compared with non-LAD group, post-MI LVEF was significantly reduced in LAD related STEMI group (52.4 ± 9.3% vs. 57.1 ± 7.8%, P < 0.01). Multivariate analysis indicated that elder (>65 years), time to hospital and proximal occlusion were associated with reduced LVEF (<55%) in LAD related STEMI patients. However, in non-LAD patients, time to hospital, multivessel stenosis and post-PCI blood pressure predicted the occurrence of reduced LVEF. Furthermore, CART analysis also obtained similar findings.

CONCLUSIONS

Patients with LAD or non-LAD related STEMI could suffer reduced LVEF, while the clinical and angiographic predictors for the occurrence were different.

Biomechanics of Cardiac Function

The heart pumps blood to maintain circulation and ensure the delivery of oxygenated blood to all the organs of the body. Mechanics play a critical role in governing and regulating heart function under both normal and pathological conditions. Biological processes and mechanical stress are coupled together in regulating myocyte function and extracellular matrix structure thus controlling heart function. Here, we offer a brief introduction to the biomechanics of left ventricular function and then summarize recent progress in the study of the effects of mechanical stress on ventricular wall remodeling and cardiac function as well as the effects of wall mechanical properties on cardiac function in normal and dysfunctional hearts. Various mechanical models to determine wall stress and cardiac function in normal and diseased hearts with both systolic and diastolic dysfunction are discussed. The results of these studies have enhanced our understanding of the biomechanical mechanism in the development and remodeling of normal and dysfunctional hearts. Biomechanics provide a tool to understand the mechanism of left ventricular remodeling in diastolic and systolic dysfunction and guidance in designing and developing new treatments.

ECG quantification of myocardial scar and risk stratification in MADIT-II

BACKGROUND

Low left ventricular ejection fraction (LVEF) increases risk for both sudden cardiac death (SCD) and for heart failure (HF) death; however, implantable cardioverter-defibrillators (ICDs) reduce the incidence of SCD, not HF death. Distinguishing individuals at risk for HF death (non-SCD) versus SCD could improve ICD patient selection.

OBJECTIVE

This study evaluated whether electrocardiogram (ECG) quantification of myocardial infarction (MI) could discriminate risk for SCD versus non-SCD.

METHODS

Selvester QRS scoring was performed on 995 MADIT-II trial subjects' ECGs to quantify MI size. MIs were categorized as small (0-3 QRS points), medium (4-7) or large (≥ 8). Mortality, SCD and non-SCD rates in the conventional medical therapy (CMT) arm and mortality and ventricular tachycardia/fibrillation (VT/VF) rates in the ICD arm were analyzed by QRS score group. Both arms were analyzed to determine ICD efficacy by QRS score group.

RESULTS

In the CMT arm, mortality, SCD and non-SCD rates were similar across QRS score groups (P = 0.73, P = 0.92, and P = 0.77). The ICD arm showed similar rates of mortality (P = 0.17) and VT/VF (P = 0.24) across QRS score groups. ICD arm mortality was lower than CMT arm mortality across QRS score groups with greatest benefit in the large scar group.

CONCLUSION

Recently, QRS score was shown to be predictive of VT/VF in the SCD-HeFT population consisting of both ischemic and nonischemic HF and having a maximum LVEF of 35% versus 30% for MADIT-II. Our study found that QRS score did not add prognostic value in the MADIT-II population exhibiting relatively more severe cardiac dysfunction.

Scirica B. Risk of Heart Failure Complication During Hospitalization for Acute Myocardial Infarction in a Contemporary Population

Background—

Patients with acute myocardial infarction (MI) complicated by heart failure (HF) are subject to higher mortality during the index hospitalization. Early risk prediction and intervention may help prevent HF-related morbidity and mortality.

Methods and Results—

We examined 77 675 ST-elevation MI and 110 128 non-ST-elevation patients with MI without cardiogenic shock or HF at presentation treated at 609 hospitals in Acute Coronary Treatment and Intervention Outcomes Network Registry (ACTION) Registry-Get With The Guidelines between January 1, 2007, and March 31, 2011. Logistic regression identified patient characteristics associated with development of in-hospital HF. Overall, 3.8% of patients with MI developed in-hospital HF, which was associated with higher mortality in both ST-elevation MI and non-ST elevation MI. In multivariable logistic regression, left ventricular ejection fraction ≤30%, prior HF, diabetes mellitus, female sex, ST-elevation MI, and hypertension (all P <0.005) were independently associated with in-hospital HF. Patients who developed HF during non-ST-elevation MI were more likely to be medically managed without catheterization (30% versus 13% with HF, P <0.0001) or had longer delays to surgical or percutaneous revascularization. Patients with ST-elevation MI and HF were less likely to receive primary percutaneous coronary revascularization (84% versus 79% with HF, P <0.0001), and more likely to receive thrombolytic therapy (14% versus 11%; P =0.0001).

Conclusions—

Patients with MI who develop HF during hospitalization have a higher risk clinical profile and greater mortality, but may be less likely to receive revascularization in a timely fashion. Targeting these highest risk patients may improve outcome post-MI.

Early development of hyponatremia implicates short- and long-term outcomes in ST-elevation acute myocardial infarction

BACKGROUND

Clinical importance of hyponatremia in ST-elevation acute myocardial infarction (STEMI) in the era of primary intervention has not been fully understood. The aim of this study was to investigate the impact of hyponatremia on outcomes in patients with STEMI and secondarily to investigate the contribution of arginine vasopressin (AVP) to hyponatremia in STEMI.

METHODS AND RESULTS

Hyponatremia was defined as a sodium concentration <136 mmol/L at 72h after hospitalization. First, the short-term (in-hospital mortality or congestive heart failure (CHF)) and long-term prognosis (cardiac death, re-admission for CHF) in STEMI patients was conducted. Second, the relationship between serum sodium level and plasma AVP was investigated. In hyponatremic patients the incidence of in-hospital heart failure was significantly greater (P=0.0018), long-term cardiac death was a higher trend (17.2% vs. 6.3%, P=0.19) and re-admission due to CHF was significantly more frequent (20.7% vs. 4.5%, P=0.0024). Plasma AVP level was higher in the hyponatremia group (4.5 vs. 2.7 pg/ml, P=0.003), and it had a negative correlation with serum sodium level (r=-0.28, P=0.02).

CONCLUSIONS

Hyponatremia was frequently found in the early phase of STEMI, and associated with heart failure in both short- and long-term outcomes. Non-osmotic secretion of AVP could be involved in hyponatremia in STEMI patients.

Single administration of the CXC chemokine-binding protein Evasin-3 during ischemia prevents myocardial reperfusion injury in mice

OBJECTIVE

Evasins (chemokine-binding proteins) have been shown to selectively neutralize chemokine bioactivity. We investigated the potential benefits of Evasin-3 on mouse myocardial ischemia/reperfusion injury.

METHODS AND RESULTS

In vivo and ex vivo (Langendorff model) left coronary artery ligature was performed in C57Bl/6 mice. Coronary occlusion was maintained for 30 minutes, followed by different times (up to 24 hours) of reperfusion. Five minutes after coronary occlusion, mice received 1 intraperitoneal injection of Evasin-3 or vehicle. Infarct size was assessed histologically and by serum cardiac troponin I ELISA. In vitro neutrophil chemotaxis, immunohistology, oxidative stress quantification, real-time RT-PCR analysis of leukocyte chemoattractants, and Western blots for cardioprotective intracellular pathway activation were performed. Evasin-3 reduced infarct size and cardiac troponin I levels compared with vehicle. This effect was associated with the reduction of neutrophil infiltration and reactive oxygen species production within the infarcted myocardium. Evasin-3 did not reduce infarct size in the absence of circulating neutrophils (Langendorff model). Evasin-3 did not influence the activation of intracellular cardioprotective pathways or the expression of leukocyte chemoattractants during early phases of reperfusion.

CONCLUSIONS

Single administration of Evasin-3 during myocardial ischemia significantly reduced infarct size by preventing CXC chemokine-induced neutrophil recruitment and reactive oxygen species production in myocardial ischemia/reperfusion.

Canadian Cardiovascular Society Consensus Conference recommendations on heart failure update 2007: Prevention, management during intercurrent illness or acute decompensation, and use of biomarkers

Heart failure is common, yet it is difficult to treat. It presents in many different guises and circumstances in which therapy needs to be individualized. The Canadian Cardiovascular Society published a comprehensive set of recommendations in January 2006 on the diagnosis and management of heart failure, and the present update builds on those core recommendations. Based on feedback obtained through a national program of heart failure workshops during 2006, several topics were identified as priorities because of the challenges they pose to health care professionals. New evidence-based recommendations were developed using the structured approach for the review and assessment of evidence adopted and previously described by the Society. Specific recommendations and practical tips were written for the prevention of heart failure, the management of heart failure during intercurrent illness, the treatment of acute heart failure, and the current and future roles of biomarkers in heart failure care. Specific clinical questions that are addressed include: which patients should be identified as being at high risk of developing heart failure and which interventions should be used? What complications can occur in heart failure patients during an intercurrent illness, how should these patients be monitored and which medications may require a dose adjustment or discontinuation? What are the best therapeutic, both drug and nondrug, strategies for patients with acute heart failure? How can new biomarkers help in the treatment of heart failure, and when and how should BNP be measured in heart failure patients? The goals of the present update are to translate best evidence into practice, to apply clinical wisdom where evidence for specific strategies is weaker, and to aid physicians and other health care providers to optimally treat heart failure patients to result in a measurable impact on patient health and clinical outcomes in Canada.

Diabetes and heart failure in the post-myocardial infarction patient

Diabetes mellitus, a disease which is increasing in prevalence, is a major risk factor for coronary heart disease. In patients following acute myocardial infarction, the presence of diabetes is a powerful risk factor for the development of heart failure, and this intersection of heart failure and diabetes following myocardial infarction carries substantial risk. The poor prognosis associated with heart failure in diabetic patients following myocardial infarction is likely multifactorial. Aggressive strategies for prevention and treatment of heart failure are crucial to reducing the risk associated with diabetes and heart failure following myocardial infarction. This review summarizes epidemiologic, pathophysiologic, and therapeutic data related to diabetes and heart failure in the post-myocardial infarction setting.