Limit Infarct Size Research Articles

Abstract 13594: Cyclosporine-A Reduces Myocardial Damage in Donation After Circulatory Death Hearts

Background: Mitochondria contribute to ischemia and reperfusion injury (IRI) in donation after circulatory death (DCD) donor hearts. Cyclosporine A (CyA), an inhibitor of mitochondrial permeability transition pore (MPTP) opening, limits IRI. CyA administration at the onset of reperfusion is essential for therapeutic efficacy. DCD heart transplantation (HTx) is a unique setting for controlled administration of CyA. Hypothesis: CyA administered to DCD hearts during reperfusion is cardioprotective. Methods: Under general anesthesia Sprague Dawley rats underwent simulated clinical DCD setup with a global ischemia of 25 minutes. Control beating-heart donor (CBD) hearts served as controls (n=10). Hearts were reanimated ex-vivo with Krebs-Henseleit buffer (KH) perfusion at 37 o C for 90 minutes. DCD hearts were randomly assigned to receive CyA (0.5mM) or DMSO added to KH buffer for the first 15 minutes of perfusion (n=10 each). The hearts were collected to measure oxidative phosphorylation (OXPHOS) and calcium retention capacity (CRC). Additional CBD (n=5) and DCD (with or without CyA, n=15) hearts underwent heterotopic HTx in recipient rats to measure developed pressure (DP) and rate pressure product (RPP) at 48 hours. Results: Compared to CBD hearts, OXPHOS in DCD hearts was significantly reduced. CyA improved OXPHOS and was similar to CBD hearts. CRC was reduced in DCD hearts compared to CBD hearts (317 vs.578nM/mg) and was increased with CyA treatment (413 vs. 317nM/mg; p<0.05, Figure). Infarct size decreased significantly with CyA treatment (15% vs. 25%). In transplanted DCD hearts, DP and RPP were significantly reduced compared to CBD hearts (80 vs.153mmHg and 17639 vs. 29545mmHg*bpm). CyA treatment improved DP (124vs.80mmHg; p<0.05) and RPP (35491vs.17639mmHg*bpm; p<0.05) which was comparable to CBD hearts. Conclusions: CyA administered at reperfusion reduces mitochondrial damage, limits infarct size, and preserves function in transplanted DCD hearts.

Acute administration of the olive constituent, oleuropein, combined with post-conditioning mechanism exerts cardioprotective effects by modulating oxidative defense

Abstract Background/Introduction Oleuropein (oleu), the main polyphenolic constituent of olive, has cardioprotective effects against ischemia (I) – reperfusion (R) injury (IRI) when administered chronically. Purpose We aimed to assess the cardioprotection afforded by acute administration of oleu, to evaluate the underlying mechanism and whether it could enhance or imbed the cardioprotective manifestation of ischemic postconditioning (PostC). Methods Male rabbits were subjected to I/R (30/180 min) and randomized to 7 groups: (i) Control (ii) PostC: 8 cycles of 30-sec I/R at the onset of R; (iii) Oleu (100 mg/kg, iv bolus) at the 20th min of I; (iv) Oleu+NOS inhibitor (L-NAME, 10mg/kg); (v) Oleu+PI3K/Akt inhibitor (wortmannin, 60 μg/kg); (vi) Oleu+JAK2 inhibitor (AG490, 6μg/kg/min) and (vii) Oleu+PostC. Additionally, male C57BL6/J mice, subjected to I/R (30/180 min) and randomized to 4 groups: (i) Control; (ii) PostC: 3 cycles of 10-sec I/R at the onset of R; (iii) Oleu (350 mg/kg, iv bolus) at the 20th min of I; (iv) Oleu+PostC. In both animal models, infarct size (IS) expressed as percentage of infarct to area at risk ratio (I/R, %) was determined. Oleu's effect on cardiomyocytes was measured by MTT assay in adult rat cardiomyocytes exposed to simulated I (SI) and reoxygenation. We also assessed the effect of oleu on mitochondrial permeability transition pore (mPTP) through calcium retention capacity (CRC) assay and on cGMP accumulation in rat aortic smooth muscle cells. In a mouse model of IRI, we explored the effect of oleu on the recruitment of inflammatory monocytes and neutrophils in the IR heart using flow cytometry, whereas the effect of oleu on Nrf-2 signaling pathway-related genes was analyzed by western blot. Results In both animal models acute oleu administration reduced significantly the IS compared to the control group. None of the inhibitors of the classic cardioprotective pathways influence its IS limiting effects in rabbits. Combination of oleu with PostC caused further limitation of IS compared to PostC in both animal models (I/R Rabbits: 14.6±0.9 vs. 26.7±2.7%, p<0.01 and I/R mice: 11.5±1.8 vs. 20.3±1.8%, p<0.01). Oleu had a direct protective effect on cardiomyocytes since it significantly increased their viability following SI-reoxygenation injury as compared to non-treated cells. Oleu did not inhibit the calcium induced mPTP opening in isolated mitochondria and did not increase cGMP production. Oleu, PostC and their combination reduced inflammatory monocytes infiltration into the heart and the circulating monocytes. Oleu conferred additive cardioprotection on top of PostC, via increasing the expression of Nrf-2 and its downstream targets (HO-1 and SOD-2). Conclusion(s) Acute oleu administration combined with PostC provides robust and synergistic cardioprotection in experimental models of IRI by inducing antioxidant defense genes through Nrf-2 axis and independently of the classic cardioprotective signaling pathways. Funding Acknowledgement Type of funding sources: None.

Peoniflorin Preconditioning Protects Against Myocardial Ischemia/Reperfusion Injury Through Inhibiting Myocardial Apoptosis: RISK Pathway Involved.

Preconditioning with Peoniflorin, a component of traditional Chinese prescriptions, was proposed to be a potential strategy for cardioprotection against ischemia/reperfusion (I/R) injury. However, the cardioprotective effect of Peoniflorin preconditioning has not been thoroughly confirmed, and the underlying mechanism remains unclear. Here, we examined the cardioprotective effect and its mechanism of Peoniflorin preconditioning against myocardial I/R injury. Rats were subjected to 30min of transient ischemia followed by 2h of reperfusion with or without Peoniflorin (100mg/kg) prior to reperfusion. Peoniflorin preconditioning significantly limited myocardial infarct size and reperfusion arrhythmias, as well as obviously attenuated the histomorphological and micromorphological damages induced by I/R injury. The reduced myocardial injury was also associated with the anti-apoptotic effect of Peoniflorin, as evidence by decreased TUNEL-positive cells, upregulation of BCL-2 expression, and downregulation of Bax and caspase-3 expression. In an effort to evaluate the mechanism responsible for the observed cardioprotective and anti-apoptotic effect, Western blot of phosphorylated protein was performed after 20min of reperfusion. Results showed that Peoniflorin preconditioning activated both the Akt and ERK1/2 arm of the reperfusion injury salvage kinase (RISK) pathway. To further confirm this mechanism, the PI3K signaling inhibitor LY294002 and ERK1/2 signaling inhibitor PD98059 were administered in vivo. The cardioprotective and anti-apoptotic effects of Peoniflorin preconditioning were diminished but not abolished by pretreatment with LY294002 or PD98059. Taken together, these results indicate that Peoniflorin preconditioning protects the myocardial against I/R injury and inhibits myocardial apoptosis via the activation of the RISK pathway, highlighting the potential therapeutic effects of Peoniflorin on reducing myocardial I/R injury.

Effects of three types of bariatric interventions on myocardial infarct size and vascular function in rats with type 2 diabetes mellitus

AimsThe effects of three types of bariatric interventions on myocardial infarct size were tested in the rat model of type 2 diabetes mellitus (T2DM). We also evaluated the effects of bariatric surgery on no-reflow phenomenon and vascular dysfunction caused by T2DM. Main methodsRats with T2DM were assigned into groups: without surgery, sham-operated, ileal transposition, Roux-en-Y gastric bypass, and sleeve gastrectomy. Oral glucose tolerance, glucagon-like peptide-1, and insulin levels were measured. Six weeks after surgery, the animals were subjected to myocardial ischemia-reperfusion followed by histochemical determination of infarct size (IS), no-reflow zone, and blood stasis area size. Vascular dysfunction was characterized using wire myography. Key findingsAll bariatric surgery types caused significant reductions in animal body weight and resulted in T2DM compensation. All bariatric interventions partially normalized glucagon-like peptide-1 responses attenuated by T2DM. IS was significantly smaller in animals with T2DM. Bariatric surgery provided no additional IS limitation compared with T2DM alone. Bariatric surgeries reversed T2DM-induced enhanced contractile responses of the mesenteric artery to 5-hydroxytryptamine. Sleeve gastrectomy normalized decreased nitric oxide synthase contribution to the endothelium-dependent vasodilatation in T2DM. SignificanceT2DM resulted in a reduction of infarct size and no-reflow zone size. Bariatric surgery provided no additional infarct-limiting effect, but it normalized T2DM-induced augmented vascular contractility and reversed decreased contribution of nitric oxide to endothelium-dependent vasodilatation typical of T2DM. All taken together, we suggest that this type of surgery may have a beneficial effect on T2DM-induced cardiovascular diseases.

Donor Heart Preservation with Hydrogen Sulfide: A Systematic Review and Meta-Analysis.

Preclinical studies have shown that postconditioning with hydrogen sulfide (H2S) exerts cardioprotective effects against myocardial ischemia-reperfusion injury (IRI). The aim of this study was to appraise the current evidence of the cardioprotective effects of H2S against IRI in order to explore the future implementation of H2S in clinical cardiac transplantation. The current literature on H2S postconditioning in the setting of global myocardial ischemia was systematically reviewed and analyzed, performing meta-analyses. A literature search of the electronic databases Medline, Embase and Cinahl identified 1835 studies that were subjected to our pre-defined inclusion criteria. Sixteen studies were considered eligible for inclusion. Postconditioning with H2S showed significant robust effects with regard to limiting infarct size (standardized mean difference (SMD) = −4.12, 95% CI [−5.53–−2.71], p < 0.00001). Furthermore, H2S postconditioning consistently resulted in a significantly lower release of cardiac injury markers, lower levels of oxidative stress and improved cardiac function. Postconditioning with slow-releasing H2S donors offers a valuable opportunity for novel therapies within cardiac preservation for transplantation. Before clinical implication, studies evaluating the long-term effects of H2S treatment and effects of H2S treatment in large animal studies are warranted.

Door-to-unload: left ventricular unloading before reperfusion in ST-elevation myocardial infarction.

ST-elevation myocardial infarction treatment in the modern era has focused on minimizing time of ischemia by reducing door-to-balloon time to limit infarct size and improve survival. Although there have been significant improvements in minimizing time to coronary reperfusion, the incidence of heart failure following a myocardial infarction has remained high. Preclinical studies have shown that unloading the left ventricle for 30min prior to coronary reperfusion can reduce infarct size and promote myocardial recovery. The DTU-STEMI randomized prospective trial will test the hypothesis that left ventricular unloading for at least 30min prior to coronary reperfusion will improve infarct size and heart failure-related events as compared with the current standard of care.

Remote ischemic conditioning: Feeling the squeeze

Key Points Adjunctive strategies to primary percutaneous coronary intervention (pPCI) that limit infarct size represent an unmet clinical need. The ability of remote ischemic conditioning to improve clinical outcomes in acute myocardial infarction treated with pPCI is not supported by clinical trials. The current study is consistent and found no improvement in myocardial salvage index by MRI at 6 months in patients with pPCI for anterior STEMI randomized to remote ischemic per‐postconditioning versus sham.

Acute administration of the olive constituent, oleuropein, combined with ischemic postconditioning increases myocardial protection by modulating oxidative defense

Oleuropein, one of the main polyphenolic constituents of olive, is cardioprotective against ischemia reperfusion injury (IRI). We aimed to assess the cardioprotection afforded by acute administration of oleuropein and to evaluate the underlying mechanism. Importantly, since antioxidant therapies have yielded inconclusive results in attenuating IRI-induced damage on top of conditioning strategies, we investigated whether oleuropein could enhance or imbed the cardioprotective manifestation of ischemic postconditioning (PostC). Oleuropein, given during ischemia as a single intravenous bolus dose reduced the infarct size compared to the control group both in rabbits and mice subjected to myocardial IRI. None of the inhibitors of the cardioprotective pathways, l-NAME, wortmannin and AG490, influence its infarct size limiting effects. Combined oleuropein and PostC cause further limitation of infarct size in comparison with PostC alone in both animal models. Oleuropein did not inhibit the calcium induced mitochondrial permeability transition pore opening in isolated mitochondria and did not increase cGMP production. To provide further insights to the different cardioprotective mechanism of oleuropein, we sought to characterize its anti-inflammatory potential in vivo. Oleuropein, PostC and their combination reduce inflammatory monocytes infiltration into the heart and the circulating monocyte cell population. Oleuropein's mechanism of action involves a direct protective effect on cardiomyocytes since it significantly increased their viability following simulated IRI as compared to non-treated cells. Οleuropein confers additive cardioprotection on top of PostC, via increasing the expression of the transcription factor Nrf-2 and its downstream targets in vivo. In conclusion, acute oleuropein administration during ischemia in combination with PostC provides robust and synergistic cardioprotection in experimental models of IRI by inducing antioxidant defense genes through Nrf-2 axis and independently of the classic cardioprotective signaling pathways (RISK, cGMP/PKG, SAFE).

Targeting the Endothelium to Achieve Cardioprotection.

Despite considerable improvements in the treatment of myocardial infarction, it is still a highly prevalent disease worldwide. Novel therapeutic strategies to limit infarct size are required to protect myocardial function and thus, avoid heart failure progression. Cardioprotection is a research topic with significant achievements in the context of basic science. However, translation of the beneficial effects of protective approaches from bench to bedside has proven difficult. Therefore, there is still an unmet need to study new avenues leading to protecting the myocardium against infarction. In line with this, the endothelium is an essential component of the cardiovascular system with multiple therapeutic targets with cardioprotective potential. Endothelial cells are the most abundant non-myocyte cell type in the heart and are key players in cardiovascular physiology and pathophysiology. These cells can regulate vascular tone, angiogenesis, hemostasis, and inflammation. Accordingly, endothelial dysfunction plays a fundamental role in cardiovascular diseases, which may ultimately lead to myocardial infarction. The endothelium is of paramount importance to protect the myocardium from ischemia/reperfusion injury via conditioning strategies or cardioprotective drugs. This review will provide updated information on the most promising therapeutic agents and protective approaches targeting endothelial cells in the context of myocardial infarction.

Inhibition of adenosine kinase attenuates myocardial ischaemia/reperfusion injury.

Increased adenosine helps limit infarct size in ischaemia/reperfusion‐injured hearts. In cardiomyocytes, 90% of adenosine is catalysed by adenosine kinase (ADK) and ADK inhibition leads to higher concentrations of both intracellular adenosine and extracellular adenosine. However, the role of ADK inhibition in myocardial ischaemia/reperfusion (I/R) injury remains less obvious. We explored the role of ADK inhibition in myocardial I/R injury using mouse left anterior ligation model. To inhibit ADK, the inhibitor ABT‐702 was intraperitoneally injected or AAV9 (adeno‐associated virus)—ADK—shRNA was introduced via tail vein injection. H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to elucidate the underlying mechanisms. ADK was transiently increased after myocardial I/R injury. Pharmacological or genetic ADK inhibition reduced infarct size, improved cardiac function and prevented cell apoptosis and necroptosis in I/R‐injured mouse hearts. In vitro, ADK inhibition also prevented cell apoptosis and cell necroptosis in H/R‐treated H9c2 cells. Cleaved caspase‐9, cleaved caspase‐8, cleaved caspase‐3, MLKL and the phosphorylation of MLKL and CaMKII were decreased by ADK inhibition in reperfusion‐injured cardiomyocytes. X‐linked inhibitor of apoptosis protein (XIAP), which is phosphorylated and stabilized via the adenosine receptors A2B and A1/Akt pathways, should play a central role in the effects of ADK inhibition on cell apoptosis and necroptosis. These data suggest that ADK plays an important role in myocardial I/R injury by regulating cell apoptosis and necroptosis.

Remote liver ischemic preconditioning attenuates myocardial ischemia/reperfusion injury in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) exhibits a higher sensitivity to myocardial ischemia/reperfusion (I/R) injury and may compromise the effectiveness of cardioprotective interventions, including ischemic preconditioning. We previously found that liver ischemic preconditioning (RLIPC) could limit infarct size post I/R in non-diabetic rat hearts and further exerted anti-arrhythmic effects in diabetic or non-diabetic rats after myocardial I/R, however, little is known regarding the effect of RLIPC on infarct-sparing in diabetic hearts. In this study, we evaluated the protective effects of RLIPC on I/R injury in streptozotocin-induced type 1 diabetic rats. Type 1 diabetes mellitus was induced by one-time intraperitoneal injection of streptozotocin in Sprague–Dawley rats. Rats were exposed to 45 min of left anterior descend in (LAD) coronary artery occlusion, followed by 3 h of reperfusion. For liver ischemic preconditioning, four cycles of 5 min of liver I/R stimuli were performed before LAD occlusion. The cardioprotective effect of RLIPC was determined in diabetic rats. Compared to non-RLIPC treated DM rats, RLIPC treatment significantly reduced infarct size and cardiac tissue damage, inhibited apoptosis in diabetic hearts post I/R. RLIPC also improved cardiac functions including LVESP, LVEDP, dp/dtmax, and − dp/dtmax. In addition, RLIPC preserved cardiac morphology by reducing the pathological score post I/R in diabetic hearts. Finally, Westernblotting showed that RLIPC stimulated phosphorylation of ventricular GSK-3β and STAT-5, which are key components of RISK and SAFE signaling pathways. Our study showed that liver ischemic preconditioning retains strong cardioprotective properties in diabetic hearts against myocardial I/R injury via GSK-3β/STAT5 signaling pathway.

Protective Effect of Nicorandil on Cardiac Microvascular Injury: Role of Mitochondrial Integrity.

A major shortcoming of postischemic therapy for myocardial infarction is the no-reflow phenomenon due to impaired cardiac microvascular function including microcirculatory barrier function, loss of endothelial activity, local inflammatory cell accumulation, and increased oxidative stress. Consequently, inadequate reperfusion of the microcirculation causes secondary ischemia, aggravating the myocardial reperfusion injury. ATP-sensitive potassium ion (KATP) channels regulate the coronary blood flow and protect cardiomyocytes from ischemia-reperfusion injury. Studies in animal models of myocardial ischemia-reperfusion have illustrated that the opening of mitochondrial KATP (mito-KATP) channels alleviates endothelial dysfunction and reduces myocardial necrosis. By contrast, blocking mito-KATP channels aggravates microvascular necrosis and no-reflow phenomenon following ischemia-reperfusion injury. Nicorandil, as an antianginal drug, has been used for ischemic preconditioning (IPC) due to its mito-KATP channel-opening effect, thereby limiting infarct size and subsequent severe ischemic insult. In this review, we analyze the protective actions of nicorandil against microcirculation reperfusion injury with a focus on improving mitochondrial integrity. In addition, we discuss the function of mitochondria in the pathogenesis of myocardial ischemia.

Abstract 13306: Impella Combined With Extracorporeal Membrane Oxygenation Synergistically Unloads the Left Ventricle and Reduces Infarct Size in a Model of Myocardial Infarction With Cardiogenic Shock

Introduction: Extracorporeal membrane oxygenation (ECMO) supports hemodynamics in cardiogenic shock (CS) at the expense of left ventricular (LV) overload. LV assist device (LVAD) also supports hemodynamics, whereas LVAD unloads LV. Therefore, the combination of ECMO and LVAD would augment hemodynamic support and unload LV. We hypothesized that the combination therapy in acute myocardial infarct (AMI) in CS could synergistically improve hemodynamics and unload LV, which, in turn, reduces infarct size. Methods: In protocol 1, we ligated coronary arteries and created AMI with CS in 5 mongrel dogs (15.1±0.3 kg). We transvascularly introduced Impella CP into LV. We kept the ECMO flow constant at 1.8L/min. We compared hemodynamics and the LV pressure-volume area (PVA, an index of LV oxygen consumption) under 3 conditions; Control, ECMO, and ECMO+Impella (ECPELLA) in each dog. In protocol 2 (n=15), we ligated coronary arteries for 180 min and then reperfused. We activated Impella CP and/or ECMO from 60 min after the coronary ligation to the end of the experiment. We allocated dogs into 3 groups, no support (Control), ECMO, and ECPELLA and compared infarct size at 180 min after reperfusion among 3 groups. Results: In protocol 1, both ECMO and ECPELLA increased arterial pressure compared to Control (Control: 63±9, ECMO: 88±10 and ECPELLA: 97±18 mmHg, p &lt; 0.05), and resolved the CS status. ECPELLA strikingly reduced PVA by 83% relative to Control (1500±326, 2038±357 and 258±182 mmHg*ml, p&lt;0.001). In protocol 2, ECPELLA markedly reduced the infarct size (15±8%) compared to Control (53±7%, p&lt;0.05) and ECMO (39±10%, p&lt;0.05). Conclusions: ECPELLA before reperfusion markedly improved hemodynamics, reduced PVA, and limited infarct size in a dog model of MI with CS. ECPELLA could prevent ECMO-induced LV overload and synergistically exert powerful anti-infarct effects in AMI with CS.

Administration of a soluble ADPase, AZD3366, on top of ticagrelor confers additional cardioprotective benefits to that of ticagrelor alone

Abstract Background Preclinical and pilot human studies suggest platelet-independent cardioprotective effects of ticagrelor most likely due to its ability to block cellular uptake of adenosine. Adenosine is a potent endogenous protective molecule, concentrations of which locally rise as a response to ischemia because of the breakdown of extracellular ATP by an endothelial ADPase (apyrase, CD39) to AMP that is subsequently converted to adenosine by CD73. Purpose In the present study we used cardiac magnetic resonance (CMR) imaging in a pig model of myocardial infarction (MI) to examine whether administration of a recombinant soluble form of ADPase, AZD3366 (APT102), confers additional benefits to that of ticagrelor alone in terms of reduced infarct size and improved heart function. Methods Pigs (n=20) were administered an oral loading dose of ticagrelor (180mg) and 2h later subjected to MI induction (1.5h closed-chest LAD coronary balloon occlusion). Prior to reperfusion, pigs were randomized to intravenously receive 1) vehicle (n=5); 2) 1mg/kg AZD3366 (n=5); or 3) 3mg/kg AZD3366 (n=5). After reperfusion all pigs were administered ticagrelor (90mg/bid) for 42 days. A non-treated control-MI group (n=5) was run for comparative purposes. Serial-CMR imaging was performed at baseline and 3 and 42 days post-MI for global and regional structural and functional assessments. Light transmittance aggregometry (LTA; challenged by 5, 10 and 20μM ADP) and ear bleeding time were monitored throughout the study. Results Ticagrelor significantly reduced edema formation (29.8±1.9 vs. 13.1±0.9%LV) and limited infarct size (17.7±1.5 vs. 8.2±1.2%LV) at 3 days post-MI as compared to control-MI pigs (p&amp;lt;0.05), an effect that persisted up to 42 days. Infusion of 1mg/kg AZD3366 showed a clear signal towards further prevention of myocardial damage that reached significance at doses of 3mg/kg (additional reduction of 35% and 52% in edema and infarct size, respectively, as compared to pigs treated with ticagrelor alone; p&amp;lt;0.05). Left ventricular ejection fraction was higher in all ticagrelor-treated pigs at 3 and 42 days post-MI vs. control (p&amp;lt;0.05). Yet, regional analysis of the jeopardized myocardium revealed that pigs administered 3mg/kg AZD3366 on top of ticagrelor presented minimal dysfunctional segmental contraction as compared to the mild hypokinetic and akinetic disturbances observed in ticagrelor-alone and control-MI pigs (χ2 p&amp;lt;0.05 vs. all). Ticagrelor inhibited ADP-induced platelet aggregation by 30% and addition of AZD3366 acutely abolished (90% inhibition) LTA at all tested ADP doses, an effect remaining significant up to 3 days post-infusion. Ear bleeding time was not affected by AZD3366. Conclusion Infusion of a soluble recombinant ADPase (AZD3366) on top of ticagrelor leads to a greater cardioprotection as compared to ticagrelor alone. Co-administration of both drugs in AMI patients undergoing revascularization deserves to be investigated. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Ministerio de Ciencia, Innovaciόn y Universidades / Instituto de Salud Carlos III

Cardioprotective strategy in ST-elevation acute myocardial infarction patients after reperfusion with percutaneous coronary intervention

Abstract Objectives Reperfusion may cause no-reflow phenomenon. Both microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH) have been recognized as poor prognostic factors in myocardial infarction (MI) patients. The aim of the study was to evaluate hypothesis whether cardioprotective strategy prevent IMH in MI patients after primary percutaneous coronary intervention (PCI). Methods This multicenter open-label randomized clinical trial enrolled 143 patients with first acute anterior ST-elevation MI (STEMI) reperfused within 6 h after symptoms onset. Cardiac magnetic resonance (CMR) was performed to assess left ventricular (LV) function and microvascular injury in 23 patients within the first week (3.5±1.2 days) after STEMI. Nine patients were randomized into soluble intravenous form of quercetin (Q) group and 14 - to the control group. Q infusions were started before PCI and used during the next 5 days. MVO was visualized using early gadolinium enhancement (EGE) and IMH was detected by using T2-WI. Results The study groups did not differ in terms of demographic characteristics, time to admission and main clinical data. Initially, the number of LV myocardial segments with edema was similar - 7.8±1.7 in patients of Q subgroup versus 6.8±1.8 in patients of the control subgroup (p=0.245). However, patients of the Q subgroup tended to have greater number of segments with gadolinium accumulation and higher value of the transmural index (7.7±1.2 compared to 6.2±1.5; p&amp;lt;0.05) according to the late gadolinium enhancement (Area at Risk, gray zone of AMI). According to gadolinium enhancement MVO was detected in more than 90% patients of both groups, but IMH rate was higher in the control group (53.3 vs 11.1%; p=0.03). Additionally, Q limited final infarct size assessed by CK-MB AUC 18% compare to control group (p&amp;lt;0.021). Conclusion Detection of MVO and IMH by CMR can accurately demonstrate the severity of myocardial injury. Intravenous Q can decrease the rate of IMH additionally to infarct size limitation. Further investigations are needed to confirm our results and to determine whether prevention of IMH can impact on better prognosis. Funding Acknowledgement Type of funding source: None

Rituximab in patients with acute ST-elevation myocardial infarction (RITA-MI)

Abstract Background In pre-clinical models of acute myocardial infarction (MI), mature B cells selectively mobilise inflammatory monocytes into the heart, leading to increased infarct size and deterioration of myocardial function. Anti-CD20 antibody-mediated depletion of B cells limited infarct size and improved cardiac function. Rituximab is a monoclonal antibody targeted against human B cells and has been used in the treatment of autoimmune diseases and cancers. However, its use in cardiovascular disease is untested and is currently contraindicated. Purpose We assessed the safety, feasibility and pharmacodynamic effect of rituximab given acutely to patients with ST-elevation MI (STEMI). Method RITA-MI was a prospective, open-label, dose-escalation, single-arm, phase 1/2a clinical trial, which tested rituximab administered as a single intravenous dose in patients with STEMI within 48 hours of symptom onset. Four escalating doses (200, 500, 700 and 1000mg) were used with 6 patients in each group. Follow-up was performed during initial inpatient stay; on days 6 and 14; and at 3 and 6 months. The primary endpoint was safety, whilst secondary endpoints were changes in B cells and their subsets, immune cell subsets, and cardiac and inflammatory biomarkers. [NCT:03072199] Results Overall, rituximab was well tolerated across all doses with the most common adverse event being gastrointestinal disturbance. This was due to the concomitant oral secondary prevention medication started after a STEMI. Five severe adverse events were reported, none of which were assessed as being related. Rituximab caused a mean 96.3% (95% CI 93.8–98.8%) depletion of B cell within 30 mins of the infusion starting across all dose groups. At 6 hours a rebound in B cells was seen in the 200, 500 and 700mg doses, likely related to the emigration of B cells from secondary lymphoid tissues. Maximal B cell depletion was seen at day 6, which was lower than baseline for all doses (p&amp;lt;0.001) (figure 1). B cell repopulation at 6months was dose-dependent. In addition, there was modulation of returning B cell subsets characterised by increased transitional B cells (figure 1C). Immunoglobulin (IgG, IgM and IgA) levels were not affected during follow-up. Rituximab also caused an acute and transient decrease in lymphocytes (both CD4+ and CD8+ T cells) and monocytes, whilst transiently increasing neutrophils at the 6-hour timepoint. Cardiac biomarkers showed a decrease in CRP and BNP. Clinical echocardiogram showed an increase in ejection fraction at follow up (mean increase in EF of 7.8% (95% CI 3.11–12.6)). Conclusion Rituximab appears safe and feasible when given in acute STEMIs. We have shown for the first time that depletion of B cells within 30mins of starting rituximab which demonstrates the biological plausibility of our treatment paradigm. Additional new insight into the mechanism of action of rituximab was found. This has led directly to the setting up of a phase 2b trial. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): European Union Research Council

First Human Use of RUC-4: A Nonactivating Second-Generation Small-Molecule Platelet Glycoprotein IIb/IIIa (Integrin αIIbβ3) Inhibitor Designed for Subcutaneous Point-of-Care Treatment of ST-Segment-Elevation Myocardial Infarction.

BackgroundDespite reductions in door‐to‐balloon times for primary coronary intervention, mortality from ST‐segment–elevation myocardial infarction has plateaued. Early pre–primary coronary intervention treatment of ST‐segment–elevation myocardial infarction with glycoprotein IIb/IIIa inhibitors improves pre–primary coronary intervention coronary flow, limits infarct size, and improves survival. We report the first human use of a novel glycoprotein IIb/IIIa inhibitor designed for subcutaneous first point‐of‐care ST‐segment–elevation myocardial infarction treatment.Methods and ResultsHealthy volunteers and patients with stable coronary artery disease receiving aspirin received escalating doses of RUC‐4 or placebo in a sentinel‐dose, randomized, blinded fashion. Inhibition of platelet aggregation (IPA) to ADP (20 μmol/L), RUC‐4 blood levels, laboratory evaluations, and clinical assessments were made through 24 hours and at 7 days. Doses were increased until reaching the biologically effective dose (the dose producing ≥80% IPA within 15 minutes, with return toward baseline within 4 hours). In healthy volunteers, 15 minutes after subcutaneous injection, mean±SD IPA was 6.9%+7.1% after placebo and 71.8%±15.0% at 0.05 mg/kg (n=6) and 84.7%±16.7% at 0.075 mg/kg (n=6) after RUC‐4. IPA diminished over 90 to 120 minutes. In patients with coronary artery disease, 15 minutes after subcutaneous injection of placebo or 0.04 mg/kg (n=2), 0.05 mg/kg (n=6), and 0.075 mg/kg (n=18) of RUC‐4, IPA was 14.6%±11.7%, 53.6%±17.0%, 76.9%±10.6%, and 88.9%±12.7%, respectively. RUC‐4 blood levels correlated with IPA. Aspirin did not affect IPA or RUC‐4 blood levels. Platelet counts were stable and no serious adverse events, bleeding, or injection site reactions were observed.ConclusionsRUC‐4 provides rapid, high‐grade, limited‐duration platelet inhibition following subcutaneous administration that appears to be safe and well tolerated.RegistrationURL: https://www.clini​caltr​ials.gov; Unique identifier: NTC03844191.

The role of aldosterone inhibitors in cardiac ischemia-reperfusion injury.

Myocardial ischaemia-reperfusion (I/R) injury is a well-known term for exacerbation of cellular destruction and dysfunction after the restoration of blood flow to a previously ischaemic heart. A vast number of studies that have demonstrated that the role of mineralocorticoids in cardiovascular diseases is based on the use of pharmacological mineralocorticoid receptor (MR) antagonists. This review paper aimed to summarize current knowledge on the effects of MR antagonists on myocardial I/R injury as well as postinfarction remodeling. Animal models, predominantly the Langendorff technique and left anterior descending coronary artery occlusion, have confirmed the potency of MR antagonists as preconditioning and postconditioning agents in limiting infarct size and postinfarction remodeling. Several preclinical studies in rodents have established and proved possible mechanisms of cardioprotection by MR antagonists, such as reduction of oxidative stress, reduction of inflammation, and apoptosis, therefore limiting the infarct zone. However, the results of some clinical trials are inconsistent, since they reported no benefit of MR antagonists in acute myocardial infarction. Due to this, further studies and the results of ongoing clinical trials regarding MR antagonist administration in patients with acute myocardial infarction are being awaited with great interest.

Nox4 regulates InsP3 receptor‐dependent Ca2+ release into mitochondria to promote cell survival

Cells subjected to environmental stresses undergo regulated cell death (RCD) when homeostatic programs fail to maintain viability. A major mechanism of RCD is the excessive calcium loading of mitochondria and consequent triggering of the mitochondrial permeability transition (mPT), which is especially important in post‐mitotic cells such as cardiomyocytes and neurons. Here, we show that stress‐induced upregulation of the ROS‐generating protein Nox4 at the ER‐mitochondria contact sites (MAMs) is a pro‐survival mechanism that inhibits calcium transfer through InsP3 receptors (InsP3R). Nox4 mediates redox signaling at the MAM of stressed cells to augment Akt‐dependent phosphorylation of InsP3R, thereby inhibiting calcium flux and mPT‐dependent necrosis. In hearts subjected to ischemia–reperfusion, Nox4 limits infarct size through this mechanism. These results uncover a hitherto unrecognized stress pathway, whereby a ROS‐generating protein mediates pro‐survival effects through spatially confined signaling at the MAM to regulate ER to mitochondria calcium flux and triggering of the mPT.

Potential role of EphrinA2 receptors in postconditioning induced cardioprotection in rats

EphA2 receptor has emerged as a novel cardioprotective target against myocardial infarction by preserving cardiac function, limiting infarct size and inflammation and enhancing cell survival via elevating phosphorylated Akt protein levels. However, the role of Eph receptors in postconditioning remains to be elucidated. Thus, the present study was designed to explore the role of EphA2 receptors in cardioprotective mechanism of postconditioning by employing Doxazosin as EphA2 receptor agonist, Lithocholic acid as antagonist and Wortmannin as specific phosphoinositide 3-kinase (PI3K) inhibitor.In Langendorff perfused isolated rat hearts, exposure of ischemia for 30 min succeeded by reperfusion for 2 h produced cardiac damage as determined by increase in size of infarct, LVDP, liberation of LDH and CK in effluent from coronary arteries. The reperfused hearts were homogenized and tissue concentrations of TBARs, reduced GSH and Catalase were determined.A marked rise in infarct size, liberation of LDH and CK in effluent and TBARs in myocardial tissue was observed in ischemic and reperfused hearts. Ischemic postconditioning comprising of 6 alternate episodes of 10 s ischemia and 10 s reperfusion and pharmacological post-conditioning by Doxazosin infusion for 5 min Before reperfusion confers significant protection against myocardial injury as manifested by remarkably decreased infarct size, levels of LDH, CK and tissue TBARs along with increase in GSH and Catalase activity. Pre-treatment of EphA2 antagonist, Lithocholic acid and PI3K inhibitor, Wortmannin attenuated the cardioprotective effect of postconditioning. Our results suggest that EphA2 receptors may be involved in postconditioning mediated cardioprotection probably through PI3K/Akt pathway.