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.

Protective or Inhibitory Effect of Pharmacological Therapy on Cardiac Ischemic Preconditioning: A Literature Review

Ischemic preconditioning (IP) is an innate phenomenon, triggered by brief, non-lethal cycles of ischemia/reperfusion applied to a tissue or organ that confers tolerance to a subsequent more prolonged ischemic event. Once started, it can reduce the severity of myocardial ischemia associated with some clinical situations, such as percutaneous coronary intervention (PCI) and intermittent aortic clamping during coronary artery bypass graft surgery (CABG). Although the mechanisms underlying IP have not been completely elucidated, several studies have shown that this phenomenon involves the participation of cell triggers, intracellular signaling pathways, and end-effectors. Understanding this mechanism enables the development of preconditioning mimetic agents. It is known that a range of medications that activate the signaling cascades at different cellular levels can interfere with both the stimulation and the blockade of IP. Investigations of signaling pathways underlying ischemic conditioning have identified a number of therapeutic targets for pharmacological manipulation. This review aims to present and discuss the effects of several medications on myocardial IP.

Rethinking pioglitazone as a cardioprotective agent: a new perspective on an overlooked drug

Since 1985, the thiazolidinedione pioglitazone has been widely used as an insulin sensitizer drug for type 2 diabetes mellitus (T2DM). Although fluid retention was early recognized as a safety concern, data from clinical trials have not provided conclusive evidence for a benefit or a harm on cardiac function, leaving the question unanswered. We reviewed the available evidence encompassing both in vitro and in vivo studies in tissues, isolated organs, animals and humans, including the evidence generated by major clinical trials. Despite the increased risk of hospitalization for heart failure due to fluid retention, pioglitazone is consistently associated with reduced risk of myocardial infarction and ischemic stroke both in primary and secondary prevention, without any proven direct harm on the myocardium. Moreover, it reduces atherosclerosis progression, in-stent restenosis after coronary stent implantation, progression rate from persistent to permanent atrial fibrillation, and reablation rate in diabetic patients with paroxysmal atrial fibrillation after catheter ablation. In fact, human and animal studies consistently report direct beneficial effects on cardiomyocytes electrophysiology, energetic metabolism, ischemia–reperfusion injury, cardiac remodeling, neurohormonal activation, pulmonary circulation and biventricular systo-diastolic functions. The mechanisms involved may rely either on anti-remodeling properties (endothelium protective, inflammation-modulating, anti-proliferative and anti-fibrotic properties) and/or on metabolic (adipose tissue metabolism, increased HDL cholesterol) and neurohormonal (renin–angiotensin–aldosterone system, sympathetic nervous system, and adiponectin) modulation of the cardiovascular system. With appropriate prescription and titration, pioglitazone remains a useful tool in the arsenal of the clinical diabetologist.

Novel Findings and Therapeutic Targets on Cardioprotection of Ischemia/ Reperfusion Injury in STEMI

Acute ST-segment elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality around the world. A large number of STEMI patients after the infarction gradually develop heart failure due to the infarcted myocardium. Timely reperfusion is essential to salvage ischemic myocardium from the infarction, but the restoration of coronary blood flow in the infarct-related artery itself induces myocardial injury and cardiomyocyte death, known as ischemia/reperfusion injury (IRI). The factors contributing to IRI in STEMI are complex, and microvascular obstruction, inflammation, release of reactive oxygen species, myocardial stunning, and activation of myocardial cell death are involved. Therefore, additional cardioprotection is required to prevent the heart from IRI. Although many mechanical conditioning procedures and pharmacological agents have been identified as effective cardioprotective approaches in animal studies, their translation into the clinical practice has been relatively disappointing due to a variety of reasons. With new emerging data on cardioprotection in STEMI over the past few years, it is mandatory to reevaluate the effectiveness of "old" cardioprotective interventions and highlight the novel therapeutic targets and new treatment strategies of cardioprotection.

Relationship Between Glucose Fluctuations and ST-Segment Resolution in Patients With ST-Elevation Acute Myocardial Infarction

This study was conducted to assess whether any relationships exist between glucose fluctuations and electrocardiographic surrogate markers of reperfusion injury in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).We prospectively studied 63 consecutive patients with STEMI undergoing primary PCI. Patients had either diabetes (n = 30), impaired glucose tolerance (n = 26), impaired fasting glucose (n = 1), or normal glucose tolerance (n = 6). STsegment resolution (STR, %) was measured using electrocardiograms recorded 60 minutes after PCI. STR was categorized as ≥ 30% and < 30%. Glucose fluctuations were assessed by the following parameters obtained from a continuous glucose monitoring system: mean amplitude of glucose excursion (MAGE, mg/dL); and area under curve with reference to mean blood glucose (AUC_MBG, mg/ dL/day).Both MAGE and AUC_MBG were significantly higher in STR < 30%. In univariate analysis, MAGE ≥ 70 mg/dL (OR = 17.0; 95%CI, 1.93-150.12; P < 0.01), AUC_MBG ≥ 20 mg/dL/day (OR = 10.9; 95%CI, 1.92-61.77; P < 0.01), and reperfusion arrhythmias (OR = 7.6; 95%CI, 1.32-44.29; P < 0.05) were significantly associated with suboptimal STR. Multiple logistic regression analysis showed only MAGE ≥ 70 mg/dL was predictive of suboptimal STR (OR = 22.5; 95%CI, 2.43-208.66, P < 0.01).Parameters of glucose fluctuations correlated with electrocardiographic surrogate markers of impaired myocardial salvage in STEMI after reperfusion therapy. Our results suggest that glucose fluctuations may represent a potential therapeutic target to reduce myocardial reperfusion injury in STEMI.

The Role of Peroxisome Proliferator-Activated Receptor γ in Mediating Cardioprotection Against Ischemia/Reperfusion Injury

Myocardial infarction (MI) is a serious cardiovascular disease resulting in high rates of morbidity and mortality. Although advances have been made in restoring myocardial perfusion in ischemic areas, decreases in cardiomyocyte death and infarct size are still limited, attributing to myocardial ischemia/reperfusion (I/R) injury. It is necessary to develop therapies to restrict myocardial I/R injury and protect cardiomyocytes against further damage after MI. Many studies have suggested that peroxisome proliferator-activated receptor γ (PPARγ), a ligand-inducible nuclear receptor that predominantly regulates glucose and lipid metabolism, is a promising therapeutic target for ameliorating myocardial I/R injury. Thus, this review focuses on the role of PPARγ in cardioprotection during myocardial I/R. The cardioprotective effects of PPARγ, including attenuating oxidative stress, inhibiting inflammatory responses, improving glucose and lipid metabolism, and antagonizing apoptosis, are described. Additionally, the underlying mechanisms of cardioprotective effects of PPARγ, such as regulating the expression of target genes, influencing other transcription factors, and modulating kinase signaling pathways, are further discussed.

Improving myocardial injury, infarct size, and myocardial salvage in the era of primary PCI for STEMI

ST-segment elevation myocardial infarction (STEMI) is a major cause of mortality and disability worldwide. Reperfusion therapy by thrombolysis or primary percutaneous coronary intervention (PPCI) improves survival and quality of life in patients with STEMI. Despite the proven efficacy of timely reperfusion, mortality from STEMI remains high, particularly among patients with suboptimal reperfusion. Reperfusion injury following opening of occluded coronary arteries mitigates the efficacy of PPCI by further accentuating ischemic damage and increasing infarct size (IS). On the basis of experimental studies, it is assumed that nearly 50% of the final IS is because of the reperfusion injury. IS is a marker of ischemic damage and adequacy of reperfusion that is strongly related to mortality in reperfused patients with STEMI. Many therapeutic strategies including pharmacological and conditioning agents have been proven effective in reducing reperfusion injury and IS in preclinical research. Mechanistically, these agents act either by inhibiting reperfusion injury cascades or by activating cellular prosurvival pathways. Although most of these agents/strategies are at the experimental stage, some of them have been tested clinically in patients with STEMI. This review provides an update on key pharmacological agents and postconditioning used in the setting of PPCI to reduce reperfusion injury and IS. Despite intensive research, no strategy or intervention has been shown to prevent reperfusion injury or enhance myocardial salvage in a consistent manner in a clinical setting. A number of novel therapeutic strategies to reduce reperfusion injury in the setting of PPCI in patients with STEMI are currently under investigation. They will lead to a better understanding of reperfusion injury and to more efficient strategies for its prevention.

Pioglitazone prevents the endothelial dysfunction induced by ischemia and reperfusion in healthy subjects

BACKGROUND

No study has investigated whether pioglitazone (an agonist of peroxisome proliferator-activated receptor gamma) protects against ischemia and reperfusion (IR)-induced endothelial dysfunction in humans.

METHODS AND RESULTS

In the first crossover study, 20 volunteers were randomized to 1 week of pioglitazone (30 mg/d, postoperatively) or control (no treatment). In the second single-arm study, 15 volunteers received pioglitazone and the cyclooxygenase-2 inhibitor meloxicam for 1 week. On day 7, endothelium-dependent flow-mediated dilation (FMD) of the distal brachial artery was measured before and after IR (15 minutes of ischemia followed by 15 minutes of reperfusion in the proximal upper arm). Pre-IR brachial-artery diameter and FMD were similar across the 2 sessions (control, pioglitazone) in protocol 1 and between the 2 protocols. IR significantly blunted FMD after no treatment (pre-IR FMD: 10.2% ± 2.6%; post-IR FMD: 3.5% ± 1.9%, P < 0.01) but not after pioglitazone administration (pre-IR FMD: 9.7% ± 2.5%; post-IR FMD: 8.8% ± 2.9%, P = 0.11). This protective effect was accompanied by an increase in serum levels of the antioxidant enzyme extracellular superoxide dismutase and was not affected by concomitant administration of the cyclooxygenase-2 inhibitor meloxicam (P = 0.10).

CONCLUSIONS

In humans, pioglitazone provides potent protection against IR-induced endothelial dysfunction.

Combination therapy reduces the incidence of no-reflow after primary per-cutaneous coronary intervention in patients with ST-segment elevation acute myocardial infarction

Background

No-reflow is associated with an adverse outcome and higher mortality in patients with ST-segment elevation acute myocardial infarction (STEMI) who undergo percutaneous coronary intervention (PCI) and is considered a dynamic process characterized by multiple pathogenetic components. The aim of this study was to investigate the effectiveness of a combination therapy for the prevention of no-reflow in patient with acute myocardial infarction (AMI) undergoing primary PCI.

Methods

A total of 621 patients with STEMI who underwent emergency primary PCI were enrolled in this study. Patients with high risk of no-reflow (no-flow score ≥ 10, by using a no-flow risk prediction model, n = 216) were randomly divided into a controlled group (n = 108) and a combination therapy group (n = 108). Patients in the controlled group received conventional treatment, while patients in combination therapy group received high-dose (80 mg) atorvastatin pre-treatment, intracoronary administration of adenosine (140 µg/min per kilogram) during PCI procedure, platelet membrane glycoprotein IIb/IIIa receptor antagonist (tirofiban, 10µg/kg bolus followed by 0.15 µg/kg per minute) and thrombus aspiration. Myocardial contrast echocardiography was performed to assess the myocardial perfusion 72 h after PCI. Major adverse cardiac events (MACE) were followed up for six months.

Results

Incidence of no-reflow in combination therapy group was 2.8%, which was similar to that in low risk group 2.7% and was significantly lower than that in control group (35.2%, P < 0.01). The myocardial perfusion (A × β) values were higher in combination therapy group than that in control group 72 h after PCI. After 6 months, there were six (6.3%) MACE events (one death, two non-fatal MIs and three revascularizations) in combination therapy group and 12 (13.2%) (four deaths, three non-fatal MIs and five revascularizations, P < 0.05) in control group.

Conclusions

Combination of thrombus aspiration, high-dose statin pre-treatment, intracoronary administration of adenosine during PCI procedure and platelet membrane glycoprotein IIb/IIIa receptor antagonist reduce the incidence of no-reflow after primary PCI in patients with acute myocardial infarction who are at high risk of no-reflow.

Effect of peroxisome proliferator-activated receptor gamma agonist on heart of rabbits with acute myocardial ischemia/reperfusion injury

OBJECTIVE

To explore protective effect of rosiglitazone on myocardial ischemia reperfusion injury.

METHODS

A total of 48 male SD rats were randomly divided into control group (A), I/R group(B), high dose of rosiglitazone (C), low dose of rosiglitazone (D). Plasm concentration of creatine kinase (CK), CK-MB, hsCRP, Superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), nitric oxide (NO) and endothelin (ET) were measured 1 h later after I/R. 24 h after I/R hearts were harvested to observe pathological and ultrastructural changes. Immunohistochemistry and western blotting was used to test CD40 expression in myocardial tissue. Area of myocardial infarction were tested, arrhythmia rate during I/R was recorded.

RESULTS

Plasm concentration of creatine kinase (CK), CK-MB, hsCRP, NO, MDA and ET were decreased in group C, D compared with group B. Plasm concentration of T-SOD and GSH-Px was increased significantly in group C, D compared with group B. Compared with group B, pathological and ultrastructural changes in group C, D were slightly. Myocardial infarction area and arrhythmia rate were lower in group C, D compare with group B.

CONCLUSIONS

Rosiglitazone can protect myocardium from I/R injury by enhancing T-SOD and GSH-Px concentration, inhibit inflammatory reaction, improve endothelial function, reduce oxidative stress and calcium overload.

A Comparison of the Performance of Myocardial Videodensitometry, Tissue Velocity Imaging and Tissue Tracking in Discrimination Between ST-Segment Elevation Ischemic Reperfusion Injury and Normal Reperfusion State After Non-Beating Cardiac Operation

Background:

The timely diagnosis of presence or absence of reperfusion injury after cardiac operation is critical for the patient’s outcome. Whether transesophageal echocardiography (TEE) acquisition of regional grayscale intensity (TI), velocity, and displacement (D) after cardiac operation can discriminate between patients with ST-segment elevation ischemic reperfusion injury (STEIRI) and normal reperfusion state remains unknown.

Objectives:

In this study, we investigated whether these parameters can effectively reflect the situation of ST-segment elevation ischemic reperfusion injury (STEIRI) in patients after cardiac operation and which has a higher performance of discrimination between patients with and without STEIRI.

Patients and Methods:

The maximal and minimal grayscale intensity in the cardiac cycle [TI (max), TI (min)], the difference of TI (max) and TI (min) [TI (max-min)], the cyclic variation index of TI [TI (CVI)], the systolic velocity (Vs), the early diastolic velocity (Ve), the late diastolic velocity (Va) and the peak displacement in the cardiac cycle (D) at the lateral side of the mitral annulus were measured and compared between patients with and without STEIRI. The performance of these parameters in discriminating between patients with and without STEIRI was analyzed.

Results:

Compared with the patients without STEIRI, the patients with STEIRI had significantly smaller TI (max-min), TI (CVI), Vs, Ve, Va and D (P<0.05). With the use of these parameters as the criteria to distinguish patients with STEIRI from patients without STEIRI, the areas under the receiver operating characteristic curve were 0.86 for TI (max-min), 0.99 for TI (CVI), 0.89 for Vs, 0.71 for Ve, 0.85 for Va and 0.82 for D. For the best cut-off value of TI (CVI) of less than 34.45%, the sensitivity, specificity and accuracy for the prediction of patients with STEIRI were 94.74%, 97.05%, and 96.22%, respectively.

Conclusion:

The myocardial grayscale intensity, velocity and displacement can effectively reflect the situation of STEIRI in patients after cardiac operation, and TI (CVI) has a higher performance in discriminating between patients with and without STEIRI.

Pharmacologic Therapy for Reducing Myocardial Infarct Size in Clinical Trials

In patients with acute ST-segment elevation myocardial infarction, early, successful, and durable reperfusion therapy optimizes the likelihood of favorable outcomes. Fibrinolysis and primary percutaneous coronary intervention improve survival compared to no reperfusion therapy in large part by reducing infarct size (IS) and preserving left ventricular ejection fraction. There is direct correlation between IS and clinical outcomes. In this article, we will review some of the more promising pharmacological agents geared toward reduction in IS, discuss the major pathways that can lead to this desirable outcome, and evaluate the results of clinical trials performed with these and other compounds.

Current state of clinical translation of cardioprotective agents for acute myocardial infarction

There is continued interest in the concept of limiting myocardial infarct size with adjunctive agents administered along with reperfusion injury; however, there remains considerable controversy in the literature. The purpose of this article is to review the medical literature on clinical trials performed during the past 3 years that have attempted to reduce myocardial infarct size by administration of adjunctive therapies along with reperfusion therapy. A PubMed-driven literature search revealed a host of clinical trials focusing on the following prominent types of therapies: endogenous conditioning (postconditioning and remote ischemic conditioning); rapid cooling; pharmacological therapy (cyclosporine, abciximab, clopidogrel, tirofiban, erythropoietin, thrombus aspiration, adenosine, glucose-insulin-potassium, statins, antidiabetic agents, FX06, iron chelation, and ranolazine). Although there remains some controversy, quite a few of these studies showed that adjunctive therapy further reduced myocardial infarct size when coupled with reperfusion. Antiplatelet agents are emerging as some of the newest agents that seem to have cardioprotective capabilities. Postconditioning has become a bit more controversial in the clinical literature; remote conditioning, early and rapid cooling, adenosine, and ranolazine are intriguing therapies deserving of larger studies. Certain agents and maneuvers, such as erythropoietin, protein kinase C δ inhibitors, iron chelation, and intra-aortic balloon counterpulsation, perhaps should be retired. The correct adjunctive therapy administered along with reperfusion has the capability of further reducing myocardial injury during ST-segment-elevation myocardial infarction.

Peroxisome proliferator-activated receptors modulate cardiac dysfunction in diabetic cardiomyopathy

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus (DM). Chronic inflammation and derangement of myocardial energy and lipid homeostasis are common features of DM. The transcription factors of peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily, which are important in regulating energy and lipid homeostasis. There are three PPAR isoforms, α, γ, and δ, and their roles have been increasingly recognized to be important in CVD. These three isoforms are expressed in the heart and play pivotal roles in myocardial lipid metabolism, as well as glucose and energy homeostasis, and contribute to extra metabolic roles with effects on inflammation and oxidative stress. Moreover, regulation of PPARs may have significant effects on cardiac electrical activity and arrhythmogenesis. This review describes the roles of PPARs and their agonists in DM cardiomyopathy, inflammation, and cardiac electrophysiology.

MiRNA-711-SP1-collagen-I pathway is involved in the anti-fibrotic effect of pioglitazone in myocardial infarction

Although microRNAs (miRNAs) have been intensively studied in cardiac fibrosis, their roles in drug-mediated anti-fibrotic therapy are still unknown. Previously, Pioglitazone attenuated cardiac fibrosis and increased miR-711 experimentally. We aimed to explore the role and mechanism of miR-711 in pioglitazone-treated myocardial infarction in rats. Our results showed that pioglitazone significantly reduced collagen-I levels and increased miR-711 expression in myocardial infarction heart. Pioglitazone increased the expression of miR-711 in cardiac fibroblasts, and overexpression of miR-711 suppressed collagen-I levels in angiotensin II (Ang II)-treated or untreated cells. Transfection with antagomir-711 correspondingly abolished the pioglitazone-induced reduction in collagen-I levels. Bioinformatics analysis identified SP1, which directly promotes collagen-I synthesis, as the putative target of miR-711. This was confirmed by luciferase assay and western blot analysis. Additionally, increased SP1 expression was attenuated by pioglitazone in myocardial infarction heart. Furthermore, transfection of antagomir-711 attenuated pioglitazone-reduced SP1 expression in cardiac fibroblasts with or without Ang II stimulation. We conclude that pioglitazone up-regulated miR-711 to reduce collagen-I levels in rats with myocardial infarction. The miR-711-SP1-collagen-I pathway may be involved in the anti-fibrotic effects of pioglitazone. Our findings may provide new strategies for miRNA-based anti-fibrotic drug research.