Effects of Liraglutide on Reperfusion Injury in Patients With ST-Segment-Elevation Myocardial Infarction

Impact of intravenous exenatide infusion for perioperative blood glucose control on myocardial ischemia-reperfusion injuries after coronary artery bypass graft surgery: sub study of the phase II/III ExSTRESS randomized trial

BACKGROUND

The aim of the study was to investigate whether intravenous (iv) infusion of exenatide, a synthetic GLP-1 receptor agonist, could provide a protective effect against myocardial ischemia-reperfusion injury after coronary artery bypass graft (CABG) surgery.

METHODS

A sub study analysis of patients > 18 years admitted for elective CABG and included in the ExSTRESS trial was conducted. Patients were randomized to receive either iv exenatide (1-h bolus of 0.05 µg min^-1 followed by a constant infusion of 0.025 µg min^-1) (exenatide group) or iv insulin therapy (control group) for blood glucose control (target range 100-139 mg dl^-1) during the first 48 h after surgical incision. All serum levels of troponin I measured during routine care in the Cardiac Surgery ICU were recorded. The primary outcome was the highest value of plasma concentration of troponin I measured between 12 and 24 h after ICU admission. The proportion of patients presenting an echocardiographic left ventricular ejection fraction (LVEF) > 50% at the follow-up consultation was compared between the two groups.

RESULTS

Finally, 43 and 49 patients were analyzed in the control and exenatide groups, respectively {age: 69 [61-76] versus 71 [63-75] years; baseline LVEF < 50%: 6 (14%) versus 16 (32%) patients; on-pump surgery: 29 (67%) versus 33 (67%) patients}. The primary outcome did not significantly differ between the two groups (3.34 [1.06-6.19] µg l^-1 versus 2.64 [1.29-3.85] µg l^-1 in the control and exenatide groups, respectively; mean difference (MD) [95% confidence interval (95% CI)] 0.16 [- 0.25; 0.57], p = 0.54). The highest troponin value measured during the first 72 h in the ICU was 6.34 [1.36-10.90] versus 5.04 [2.39-7.18] µg l^-1, in the control and exenatide groups respectively (MD [95% CI] 0.20 [- 0.22; 0.61], p = 0.39). At the follow-up consultation, 5 (12%) versus 8 (16%) patients presented a LVEF < 50% in the control and in the exenatide groups respectively (relative risk [95% CI] 0.68 [0.16; 2.59], p = 0.56).

CONCLUSIONS

Postoperative iv exenatide did not provide any additional cardioprotective effect compared to iv insulin in low-risk patients undergoing scheduled CABG surgery. Trial registration ClinicalTrials.gov Identifier NCT01969149, date of registration: January 7th, 2015; EudraCT No. 2009-009254-25 A, date of registration: January 6th, 2009.

Cardiovascular outcomes in patients who experienced a myocardial infarction while treated with liraglutide versus placebo in the LEADER trial

OBJECTIVE

Animal studies demonstrated that glucagon-like peptide-1 receptor agonists reduce myocardial necrosis following regional ischaemia induction. This effect may improve cardiovascular outcomes after myocardial infarction. Risk of cardiovascular death or hospitalisation for heart failure after myocardial infarction was evaluated in patients with type 2 diabetes at high cardiovascular risk in the LEADER trial.

METHODS

Data from patients randomised to liraglutide or placebo, in addition to standard of care, in Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) (NCT01179048) were analysed post hoc. Cox regression, with myocardial infarction as a time-dependent covariate, was used to analyse time from randomisation to a composite of cardiovascular death or hospitalisation for heart failure.

RESULTS

Patients who experienced myocardial infarction had a sevenfold higher risk of the composite endpoint (with myocardial infarction: n = 148, 25.0%; without myocardial infarction: n = 716, 8.2%; hazard ratio: 7.0; 95% confidence interval: 5.8, 8.4). The risk of the composite endpoint after myocardial infarction was not significantly lower in the liraglutide group ( n = 63, 23.0%) compared with placebo ( n = 85, 26.7%; hazard ratio: 0.91; 95% confidence interval: 0.66, 1.26).

CONCLUSION

The data demonstrated that having myocardial infarction significantly increased the risk of subsequent cardiovascular death or hospitalisation for heart failure. However, we did not find evidence for a reduced risk in these cardiovascular outcomes following myocardial infarction in patients treated with liraglutide versus placebo.

No-reflow phenomenon in the heart and brain

The no-reflow phenomenon refers to the observation that when an organ is made ischemic by occlusion of a large artery supplying it, restoration of patency in that artery does not restore perfusion to the microvasculature supplying the parenchyma of that organ. This has been observed after prolonged arterial occlusions in the heart (30–90 min), brain, skin, and kidney. In experimental models, zones of no reflow in the heart are characterized by ultrastructural microvascular damage, including focal endothelial swelling obstructing the lumen of small vessels. Blood elements such as neutrophil plugs, platelets, and stacking of erythrocytes have also been implicated. No reflow is associated with poor healing of the myocardial infarction. In patients, no reflow is associated with a poor clinical outcome independent of infarct size, suggesting that therapy for no reflow may be an important approach to improving outcome for ST elevation myocardial infarction. No reflow occurs after reperfusion of experimental cerebral ischemia and may be observed after only 5-min episodes of ischemia. Aggregation of blood elements may play a greater role than in cardiac no reflow. No reflow in the brain may involve cortical spreading depression with disturbed local vascular control and high, vasculotonic levels of extracellular K+ concentration, postischemic swelling in endothelial cells and abutting end feet of pericytes, pericyte contraction and death, interstitial edema with collapse of cerebral capillaries, and inflammatory reaction. New guidelines suggesting that reperfusion for stroke may be considered as late as 24 h after the onset of symptoms suggest that clinicians may be seeing more no reflow in the future.

New therapies for acute myocardial infarction: current state of research and future promise

Progress has been made into research on new therapies, mechanical and pharmacological approaches and repair/regenerative cellular therapy to treat irreversible cardiovascular pathologies, such as acute myocardial infarction. Research into cellular therapies is exploring the use of new cellular types. Although the therapeutic effects of cell therapy remain modest, results from clinical trials are encouraging. To expand this improvement, advances are being made that involve the paracrine function of stem cells, the use of growth factors, miRNA and new biomaterials. In the near future, these therapies should become part of routine clinical practice.

Myocardial Infarction Subtypes in Patients With Type 2 Diabetes Mellitus and the Effect of Liraglutide Therapy (from the LEADER Trial)

Diabetes mellitus (DM) is a known risk factor for myocardial infarction (MI); however, data regarding MI subtypes in people with diabetes are limited. In the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) trial (n = 9,340), liraglutide significantly reduced the risk of major adverse cardiovascular (CV) events (composite of CV death, nonfatal MI, or nonfatal stroke) versus placebo in patients with type 2 DM and high CV risk. Liraglutide also reduced risk of first MI (292 events with liraglutide vs 339 with placebo). This post hoc analysis characterized MIs (first and recurrent) occurring in LEADER, by treatment arm and regarding incidence, outcome, subtype, and troponin levels. A total of 780 MIs (first and recurrent) were reported, with fewer in the liraglutide-treatment group than in the placebo-treatment group (359 vs 421, p = 0.022). Numerically fewer MIs were associated with CV death with liraglutide than with placebo (17 vs 28 fatal MIs, p = 0.28). Symptomatic MIs in both arms were mainly non-ST-segment elevation MI (555/641) and spontaneous MI (518/641). Numerically greater proportions of symptomatic MIs were associated with troponin levels ≤5× or ≤10× the upper reference limit with liraglutide versus placebo (p = 0.16 and p = 0.42, respectively). At baseline, more liraglutide-treated patients than placebo-treated patients with MI during the trial had a history of coronary artery bypass graft (p = 0.008), and fewer had peripheral arterial disease in the lower extremities (p = 0.005) and >50% stenosis of the coronary artery, the carotid artery, or other arteries (p = 0.044). In conclusion, this analysis showed that liraglutide reduces the incidence of MIs in patients with type 2 DM at high CV risk and may impact the clinical outcomes of MI.

Protective role of melatonin in cardiac ischemia-reperfusion injury: From pathogenesis to targeted therapy

Acute myocardial infarction (MI) is a major cause of mortality and disability worldwide. In patients with MI, the treatment option for reducing acute myocardial ischemic injury and limiting MI size is timely and effective myocardial reperfusion using either thombolytic therapy or primary percutaneous coronary intervention (PCI). However, the procedure of reperfusion itself induces cardiomyocyte death, known as myocardial reperfusion injury, for which there is still no effective therapy. Recent evidence has depicted a promising role of melatonin, which possesses powerful antioxidative and anti-inflammatory properties, in the prevention of ischemia-reperfusion (IR) injury and the protection against cardiomyocyte death. A number of reports explored the mechanism of action behind melatonin-induced beneficial effects against myocardial IR injury. In this review, we summarize the research progress related to IR injury and discuss the unique actions of melatonin as a protective agent. Furthermore, the possible mechanisms responsible for the myocardial benefits of melatonin against reperfusion injury are listed with the prospect of the use of melatonin in clinical application.

Liraglutide repairs the infarcted heart: The role of the SIRT1/Parkin/mitophagy pathway

Liraglutide is glucagon‑like peptide‑1 receptor agonist used for treating patients with type 2 diabetes mellitus. The present study aimed to investigate the role and mechanism of liraglutide in repairing the infarcted heart following myocardial infarction. The results of the present study demonstrated that amplification of the dose of liraglutide for ~28 days was able to reduce cardiac fibrosis, inflammatory responses and myocardial death in the post‑infarcted heart. In vitro, liraglutide protected cardiomyocyte mitochondria against the chronic hypoxic damage, inhibiting the mitochondrial apoptosis pathways. Mechanistically, liraglutide elevated the expression of NAD‑dependent protein deacetylase sirtuin‑1 (SIRT1), which increased the expression of Parkin, leading to mitophagy activation. Protective mitophagy reversed cellular adenosine 5'‑triphosphate production, reduced cellular oxidative stress and balanced the redox response, sustaining mitochondrial homeostasis. Notably, following blockade of glucagon‑like peptide 1 receptor or knockdown of Parkin, the beneficial effects of liraglutide on mitochondria disappeared. In conclusion, the results of the present study illustrated the protective role of liraglutide in repairing the infarcted heart via regulation of the SIRT1/Parkin/mitophagy pathway.

GLP-1 Receptor Agonists and Cardiovascular Disease in Patients with Type 2 Diabetes

Diabetes mellitus is a chronic disease prevalence of which is high and continually growing. Cardiovascular disease continues to be the leading cause of death in patients with T2DM. The prevention of cardiovascular complications and the cardiovascular safety of treatments should be a primary objective when selecting treatment. Among all the drugs available, the compounds known as glucagon-like peptide-1 receptor agonists (GLP-1 RAs) appear to be not just innocuous in terms of CVD but indeed to be beneficial. GLP-1 RA actions not only translate on an improvement of well-known cardiovascular risk factors such as glycaemic control, dyslipidaemia, weight, or arterial hypertension but also might show benefits on endothelial function, coronary ischaemia, and heart failure. On the other hand, recent clinical trials aimed at studying cardiovascular episodes have been conducted with GLP-1 RAs. Only liraglutide and semaglutide have shown superiority in cardiovascular benefit compared with placebo. Although many of the mechanisms by which liraglutide and semaglutide produce a cardiovascular benefit are still unknown it would be desirable for these benefits to be incorporated into the therapeutic algorithms routinely used in clinical practice. The purpose of this review is to explore GLP-1 RA actions not only in cardiovascular risk factors (glucose, weight, and hypertension) but also the possible effects on established cardiovascular disease.

DUSP1 alleviates cardiac ischemia/reperfusion injury by suppressing the Mff-required mitochondrial fission and Bnip3-related mitophagy via the JNK pathways

Mitochondrial fission and selective mitochondrial autophagy (mitophagy) form an essential axis of mitochondrial quality control that plays a critical role in the development of cardiac ischemia-reperfusion (IR) injury. However, the precise upstream molecular mechanism of fission/mitophagy remains unclear. Dual-specificity protein phosphatase1 (DUSP1) regulates cardiac metabolism, but its physiological contribution in the reperfused heart, particularly its influence on mitochondrial homeostasis, is unknown. Here, we demonstrated that cardiac DUSP1 was downregulated following acute cardiac IR injury. In vivo, compared to wild-type mice, DUSP1 transgenic mice (DUSP1^TG mice) demonstrated a smaller infarcted area and the improved myocardial function. In vitro, the IR-induced DUSP1 deficiency promoted the activation of JNK which upregulated the expression of the mitochondrial fission factor (Mff). A higher expression level of Mff was associated with elevated mitochondrial fission and mitochondrial apoptosis. Additionally, the loss of DUSP1 also amplified the Bnip3 phosphorylated activation via JNK, leading to the activation of mitophagy. Increased mitophagy overtly consumed mitochondrial mass resulting into the mitochondrial metabolism disorder. However, the reintroduction of DUSP1 blunted Mff/Bnip3 activation and therefore alleviated the fatal mitochondrial fission/mitophagy by inactivating the JNK pathway, providing a survival advantage to myocardial tissue following IR stress. The results of our study suggest that DUSP1 and its downstream JNK pathway are therapeutic targets for conferring protection against IR injury by repressing Mff-mediated mitochondrial fission and Bnip3-required mitophagy.

Protective effect of glucagon-like peptide-1 agents on reperfusion injury for acute myocardial infarction: a meta-analysis of randomized controlled trials

BACKGROUND

The cardioprotective properties of glucagon-like peptide-1 (GLP-1) receptor agonists in acute myocardial infarction (AMI) patients against reperfusion injury remain unclear. We performed a meta-analysis to assess their role in the acute phase of AMI.

METHODS AND RESULTS

Randomized controlled trials (RCTs) comparing GLP-1 agents with placebo in AMI patients undergoing percutaneous coronary intervention were identified by searching PubMed, Embase and Cochrane libraries. Six RCTs with 800 patients were included in the meta-analysis. Compared with placebo, GLP-1 agents improved left ventricular ejection fraction (LVEF) by 2.46 [95% confidence interval (CI): 0.23-4.70%] and reduced the infarct size in grams as well as in percentage of the area at risk [weighted mean difference (WMD) - 5.29, 95% CI: -10.39 to -0.19; WMD -0.08, 95% CI: -0.12 to -0.04, respectively]. The incidence of cardiovascular events appeared to be lower with GLP-1 therapy, but the statistical significance was not reached [relative risk (RR): 0.78; 95% CI: 0.58-1.06]. In terms of safety evaluation, GLP-1 treatment increased the risk of gastrointestinal adverse events (RR: 5.50, 95% CI: 2.85-10.60).

CONCLUSIONS

Our analysis shows that in patients with AMI undergoing PCI, GLP-1 treatment is associated with improved LVEF and reduced infarct size.

Liraglutide Preserves Intracellular Calcium Handling in Isolated Murine Myocytes Exposed to Oxidative Stress

In ischemic/reperfusion (I/R) injured hearts, severe oxidative stress occurs and is associated with intracellular calcium (Ca2+) overload. Glucagon-Like Peptide-1 (GLP-1) analogues have been shown to exert cardioprotection in I/R heart. However, there is little information regarding the effects of GLP-1 analogue on the intracellular Ca2+ regulation in the presence of oxidative stress. Therefore, we investigated the effects of GLP-1 analogue, (liraglutide, 10 µM) applied before or after hydrogen peroxide (H2O2, 50 µM) treatment on intracellular Ca2+ regulation in isolated cardiomyocytes. We hypothesized that liraglutide can attenuate intracellular Ca2+ overload in cardiomyocytes under H2O2-induced cardiomyocyte injury. Cardiomyocytes were isolated from the hearts of male Wistar rats. Isolated cardiomyocytes were loaded with Fura-2/AM and fluorescence intensity was recorded. Intracellular Ca2+ transient decay rate, intracellular Ca2+ transient amplitude and intracellular diastolic Ca2+ levels were recorded before and after treatment with liraglutide. In H2O2 induced severe oxidative stressed cardiomyocytes (which mimic cardiac I/R) injury, liraglutide given prior to or after H2O2 administration effectively increased both intracellular Ca2+ transient amplitude and intracellular Ca2+ transient decay rate, without altering the intracellular diastolic Ca2+ level. Liraglutide attenuated intracellular Ca2+ overload in H2O2-induced cardiomyocyte injury and may be responsible for cardioprotection during cardiac I/R injury by preserving physiological levels of calcium handling during the systolic and diastolic phases of myocyte activation.

Cardiovascular Actions and Clinical Outcomes With Glucagon-Like Peptide-1 Receptor Agonists and Dipeptidyl Peptidase-4 Inhibitors

Potentiation of glucagon-like peptide-1 (GLP-1) action through selective GLP-1 receptor (GLP-1R) agonism or by prevention of enzymatic degradation by inhibition of dipeptidyl peptidase-4 (DPP-4) promotes glycemic reduction for the treatment of type 2 diabetes mellitus by glucose-dependent control of insulin and glucagon secretion. GLP-1R agonists also decelerate gastric emptying, reduce body weight by reduction of food intake and lower circulating lipoproteins, inflammation, and systolic blood pressure. Preclinical studies demonstrate that both GLP-1R agonists and DPP-4 inhibitors exhibit cardioprotective actions in animal models of myocardial ischemia and ventricular dysfunction through incompletely characterized mechanisms. The results of cardiovascular outcome trials in human subjects with type 2 diabetes mellitus and increased cardiovascular risk have demonstrated a cardiovascular benefit (significant reduction in time to first major adverse cardiovascular event) with the GLP-1R agonists liraglutide (LEADER trial [Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Ourcome Results], -13%) and semaglutide (SUSTAIN-6 trial [Trial to Evaluate Cardiovascular and Other Long-term Outcomes with Semaglutide], -24%). In contrast, cardiovascular outcome trials examining the safety of the shorter-acting GLP-1R agonist lixisenatide (ELIXA trial [Evaluation of Lixisenatide in Acute Coronary Syndrom]) and the DPP-4 inhibitors saxagliptin (SAVOR-TIMI 53 trial [Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus-Thrombolysis in Myocardial Infarction 53]), alogliptin (EXAMINE trial [Examination of Cardiovascular Outcomes With Alogliptin Versus Standard of Care in Patients With Type 2 Diabetes Mellitus and Acute Coronary Syndrome]), and sitagliptin (TECOS [Trial Evaluating Cardiovascular Outcomes With Sitagliptin]) found that these agents neither increased nor decreased cardiovascular events. Here we review the cardiovascular actions of GLP-1R agonists and DPP-4 inhibitors, with a focus on the translation of mechanisms derived from preclinical studies to complementary findings in clinical studies. We highlight areas of uncertainty requiring more careful scrutiny in ongoing basic science and clinical studies. As newer more potent GLP-1R agonists and coagonists are being developed for the treatment of type 2 diabetes mellitus, obesity, and nonalcoholic steatohepatitis, the delineation of the potential mechanisms that underlie the cardiovascular benefit and safety of these agents have immediate relevance for the prevention and treatment of cardiovascular disease.

Effects of prostaglandin E1 on reperfusion injury patients: A meta-analysis of randomized controlled trials

BACKGROUND

Prostaglandin E1 (PGE1) is widely used as a pretreatment for myocardial reperfusion injury in animal experiments. However, the cardioprotective effects of PGE1 in patients have not been established. We performed a meta-analysis to investigate whether PGE1 is cardioprotective, based on the reduction of correlative reperfusion injury events (CRIE), major adverse cardiac events (MACE), and biomarker release in patients with ischemia reperfusion injury.

METHODS

The Medline, EMBASE, and Cochrane databases were searched for randomized clinical trials confirming the effects of PGE1. Two investigators independently selected suitable trials, assessed trial quality, and extracted data.

RESULTS

Six studies in patients undergoing percutaneous coronary intervention (4 studies) and cardiac surgery (2 studies), comprising a total of 445 patients, were included in this review. The results showed that PGE1 reduced the incidence of CRIE (relative ratio 0.4 [95% confidence interval 0.43, 0.95]), the incidence of MACE (0.35 [0.17, 0.70]), and the level of troponin T (standardized mean difference 20.28 [20.47, 20.09]), creatine kinase-MB (-1.74 [-3.21, - 0.27]), interleukin-6 (-1.37 [-2.69, - 0.04]), and interleukin-8 (-2.05 [-2.75, - 1.34]).

CONCLUSION

PGE1 may have beneficial effects on myocardial reperfusion injury in the clinic.