The RIPOST-MI study, assessing remote ischemic perconditioning alone or in combination with local ischemic postconditioning in ST-segment elevation myocardial infarction

Myocardial protection in cardiac surgery: a comprehensive review of current therapies and future cardioprotective strategies

Cardiac surgery with cardiopulmonary bypass results in global myocardial ischemia-reperfusion injury, leading to significant postoperative morbidity and mortality. Although cardioplegia is the cornerstone of intraoperative cardioprotection, a number of additional strategies have been identified. The concept of preconditioning and postconditioning, despite its limited direct clinical application, provided an essential contribution to the understanding of myocardial injury and organ protection. Therefore, physicians can use different tools to limit perioperative myocardial injury. These include the choice of anesthetic agents, remote ischemic preconditioning, tight glycemic control, optimization of respiratory parameters during the aortic unclamping phase to limit reperfusion injury, appropriate choice of monitoring to optimize hemodynamic parameters and limit perioperative use of catecholamines, and early reintroduction of cardioprotective agents in the postoperative period. Appropriate management before, during, and after cardiopulmonary bypass will help to decrease myocardial damage. This review aimed to highlight the current advancements in cardioprotection and their potential applications during cardiac surgery.

Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

Remote ischemic conditioning for stroke: A critical systematic review

Remote ischemic conditioning (RIC) is the application of brief periods of ischemia to an organ or tissue with the aim of inducing protection from ischemia in a distant organ. It was first developed as a cardioprotective strategy but has been increasingly investigated as a neuroprotective intervention. The mechanisms by which RIC achieves neuroprotection are incompletely understood. Preclinical studies focus on the hypothesis that RIC can protect the brain from ischemia reperfusion (IR) injury following the restoration of blood flow after occlusion of a large cerebral artery. However, increasingly, a role of chronic RIC (CRIC) is being investigated as a means of promoting recovery following an ischemic insult to the brain. The recent publication of two large, randomized control trials has provided promise that RIC could improve functional outcomes after acute ischemic stroke, and that there may be a role for CRIC in the prevention of recurrent stroke. Although less developed, there is also proof-of-concept to suggest that RIC may be used to reduce vasospasm after subarachnoid hemorrhage or improve cognitive outcomes in vascular dementia. As a cheap, well-tolerated and almost universally applicable intervention, the motivation for investigating possible benefit of RIC in patients with cerebrovascular disease is great. In this review, we shall review the current evidence for RIC as applied to cerebrovascular disease.

Reperfusion Injury: How Can We Reduce It by Pre-, Per-, and Postconditioning

While early coronary reperfusion via primary percutaneous coronary intervention (pPCI) is established as the most efficacious therapy for minimizing infarct size (IS) in acute ST-elevation myocardial infarction (STEMI), the restoration of blood flow also introduces myocardial ischemia-reperfusion injury (IRI), leading to cardiomyocyte death. Among diverse methods, ischemic conditioning (IC), achieved through repetitive cycles of ischemia and reperfusion, has emerged as the most promising method to mitigate IRI. IC can be performed by applying the protective stimulus directly to the affected myocardium or indirectly to non-affected tissue, which is known as remote ischemic conditioning (RIC). In clinical practice, RIC is often applied by serial inflations and deflations of a blood pressure cuff on a limb. Despite encouraging preclinical studies, as well as clinical studies demonstrating reductions in enzymatic IS and myocardial injury on imaging, the observed impact on clinical outcome has been disappointing so far. Nevertheless, previous studies indicate a potential benefit of IC in high-risk STEMI patients. Additional research is needed to evaluate the impact of IC in such high-risk cohorts. The objective of this review is to summarize the pathophysiological background and preclinical and clinical data of IRI reduction by IC.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

The Signaling Mechanism of Remote Postconditioning of the Heart: Prospects of the Use of Remote Postconditioning for the Treatment of Acute Myocardial Infarction

Acute myocardial infarction (AMI) remains the leading cause of mortality in the world, highlighting an urgent need for the development of novel, more effective approaches for the treatment of AMI. Remote postconditioning (RPost) of the heart could be a useful approach. It was demonstrated that RPost triggers infarct size reduction, improves contractile function of the heart in reperfusion, mitigates apoptosis, and stimulates autophagy in animals with coronary artery occlusion and reperfusion. Endogenous opioid peptides and adenosine could be involved in RPost. It was found that kinases and NO-synthase participate in RPost. KATP channels, MPT pore, and STAT3 could be hypothetical end-effectors of RPost. Metabolic syndrome and old age abolish the cardioprotective effect of RPost in rats. The data on the efficacy of RPost in clinical practice are inconsistent. These data are discussed in the review.

Interaction of Cardiovascular Nonmodifiable Risk Factors, Comorbidities and Comedications With Ischemia/Reperfusion Injury and Cardioprotection by Pharmacological Treatments and Ischemic Conditioning

Preconditioning, postconditioning, and remote conditioning of the myocardium enhance the ability of the heart to withstand a prolonged ischemia/reperfusion insult and the potential to provide novel therapeutic paradigms for cardioprotection. While many signaling pathways leading to endogenous cardioprotection have been elucidated in experimental studies over the past 30 years, no cardioprotective drug is on the market yet for that indication. One likely major reason for this failure to translate cardioprotection into patient benefit is the lack of rigorous and systematic preclinical evaluation of promising cardioprotective therapies prior to their clinical evaluation, since ischemic heart disease in humans is a complex disorder caused by or associated with cardiovascular risk factors and comorbidities. These risk factors and comorbidities induce fundamental alterations in cellular signaling cascades that affect the development of ischemia/reperfusion injury and responses to cardioprotective interventions. Moreover, some of the medications used to treat these comorbidities may impact on cardioprotection by again modifying cellular signaling pathways. The aim of this article is to review the recent evidence that cardiovascular risk factors as well as comorbidities and their medications may modify the response to cardioprotective interventions. We emphasize the critical need for taking into account the presence of cardiovascular risk factors as well as comorbidities and their concomitant medications when designing preclinical studies for the identification and validation of cardioprotective drug targets and clinical studies. This will hopefully maximize the success rate of developing rational approaches to effective cardioprotective therapies for the majority of patients with multiple comorbidities. SIGNIFICANCE STATEMENT: Ischemic heart disease is a major cause of mortality; however, there are still no cardioprotective drugs on the market. Most studies on cardioprotection have been undertaken in animal models of ischemia/reperfusion in the absence of comorbidities; however, ischemic heart disease develops with other systemic disorders (e.g., hypertension, hyperlipidemia, diabetes, atherosclerosis). Here we focus on the preclinical and clinical evidence showing how these comorbidities and their routine medications affect ischemia/reperfusion injury and interfere with cardioprotective strategies.

Can Clinical and Functional Outcomes Be Improved with an Intelligent "Internet Plus"-Based Full Disease Cycle Remote Ischemic Conditioning Program in Acute ST-elevation Myocardial Infarction Patients Undergoing Percutaneous Coronary Intervention? Rationale and Design of the i-RIC Trial

BACKGROUND

Acute ST-elevation myocardial infarction (STEMI) is associated with a high incidence of complications as well as a considerable hospitalization rate and economic burden. Preliminary evidence suggests that remote ischemic conditioning (RIC) is a promising non-invasive intervention that may effectively and safely reduce myocardial infarct size, subsequent cardiac events and complications, and mortality. However, RIC's cardio-protective effect remains under debate, especially for single timepoint RIC programs. Adequately powered large-scale randomized controlled trials investigating clinical outcomes are thus needed to clarify the role of full disease cycle RIC programs.

METHODS

The intelligent "Internet Plus"-based full disease cycle remote ischemic conditioning (i-RIC) trial is a pragmatic, multicenter, randomized controlled, parallel group, clinical trial. The term, intelligent "Internet Plus"-based full disease cycle, refers to smart devices aided automatic and real-time monitoring of remote ischemic pre-, per- or post-conditioning intervention for patients with STEMI undergoing percutaneous coronary intervention (PCI). Based on this perspective, 4700 STEMI patients from five hospitals in China will be randomized to a control and an intervention group. The control group will receive PCI and usual care, including pharmacotherapy, before and after PCI. The intervention group will receive pre-, per-, and post-operative RIC combined with long-term i-RIC over a one-month period in addition. A smartphone application, an automated cuff inflation/deflation device and "Internet Plus"-based administration will be used in the long-term phase. The primary outcome is the combined cardiac death or hospitalization for heart failure rate. Secondary outcomes include clinical and functional outcomes: major adverse cardiac and cerebrovascular events rate, all-cause mortality, myocardial reinfarction rate, readmission rate for heart failure and ischemic stroke rate, unplanned revascularization rate, plasma concentration of myocardial infarction-related key biomarkers, infarct size, cardiac function, cardiopulmonary endurance, health-related quality of life, total hospital length of stay, total medical cost, and compliance with treatment regime.

DISCUSSION

The i-RIC trial is designed to test the hypothesis that clinical and functional outcomes can be improved with the i-RIC program in STEMI patients undergoing PCI. The concept of RIC is expected to be enhanced with this intelligent "Internet Plus"-based program focusing on the full disease cycle. If the i-RIC program results in superior improvement in primary and secondary outcomes, it will offer an innovative treatment option for STEMI patients and form the basis of future recommendations.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry ( http://www.chictr.org.cn ): ChiCTR2000031550, 04 April 2020.

Effects of late, repetitive remote ischaemic conditioning on myocardial strain in patients with acute myocardial infarction

Late, repetitive or chronic remote ischaemic conditioning (CRIC) is a potential cardioprotective strategy against adverse remodelling following ST-segment elevation myocardial infarction (STEMI). In the randomised Daily Remote Ischaemic Conditioning Following Acute Myocardial Infarction (DREAM) trial, CRIC following primary percutaneous coronary intervention (P-PCI) did not improve global left ventricular (LV) systolic function. A post-hoc analysis was performed to determine whether CRIC improved regional strain. All 73 patients completing the original trial were studied (38 receiving 4 weeks' daily CRIC, 35 controls receiving sham conditioning). Patients underwent cardiovascular magnetic resonance at baseline (5-7 days post-STEMI) and after 4 months, with assessment of LV systolic function, infarct size and strain (longitudinal/circumferential, in infarct-related and remote territories). At both timepoints, there were no significant between-group differences in global indices (LV ejection fraction, infarct size, longitudinal/circumferential strain). However, regional analysis revealed a significant improvement in longitudinal strain in the infarcted segments of the CRIC group (from - 16.2 ± 5.2 at baseline to - 18.7 ± 6.3 at follow up, p = 0.0006) but not in corresponding segments of the control group (from - 15.5 ± 4.0 to - 15.2 ± 4.7, p = 0.81; for change: - 2.5 ± 3.6 versus + 0.3 ± 5.6, respectively, p = 0.027). In remote territories, there was a lower increment in subendocardial circumferential strain in the CRIC group than in controls (- 1.2 ± 4.4 versus - 2.5 ± 4.0, p = 0.038). In summary, CRIC following P-PCI for STEMI is associated with improved longitudinal strain in infarct-related segments, and an attenuated increase in circumferential strain in remote segments. Further work is needed to establish whether these changes may translate into a reduced incidence of adverse remodelling and clinical events. Clinical Trial Registration: http://clinicaltrials.gov/show/NCT01664611 .

Remote Ischemic Conditioning in Ischemic Stroke and Myocardial Infarction: Similarities and Differences

Acute myocardial infarction and ischemic stroke are leading causes of morbidity and mortality worldwide. Although reperfusion therapies have greatly improved the outcomes of patients with these conditions, many patients die or are severely disabled despite complete reperfusion. It is therefore important to identify interventions that can prevent progression to ischemic necrosis and limit ischemia-reperfusion injury. A possible strategy is ischemic conditioning, which consists of inducing ischemia – either in the ischemic organ or in another body site [i.e., remote ischemic conditioning (RIC), e.g., by inflating a cuff around the patient's arm or leg]. The effects of ischemic conditioning have been studied, alone or in combination with revascularization techniques. Based on the timing (before, during, or after ischemia), RIC is classified as pre-, per-/peri-, or post-conditioning, respectively. In this review, we first highlight some pathophysiological and clinical similarities and differences between cardiac and cerebral ischemia. We report evidence that RIC reduces circulating biomarkers of myocardial necrosis, infarct size, and edema, although this effect appears not to translate into a better prognosis. We then review cutting-edge applications of RIC for the treatment of ischemic stroke. We also highlight that, although RIC is a safe procedure that can easily be implemented in hospital and pre-hospital settings, its efficacy in patients with ischemic stroke remains to be proven. We then discuss possible methodological issues of previous studies. We finish by highlighting some perspectives for future research, aimed at increasing the efficacy of ischemic conditioning for improving tissue protection and clinical outcomes, and stratifying myocardial infarction and brain ischemia patients to enhance treatment feasibility.

Remote but not Distant: a Review on Experimental Models and Clinical Trials in Remote Ischemic Conditioning as Potential Therapy in Ischemic Stroke

Stroke is one of the main causes of neurological disability worldwide and the second cause of death in people over 65 years old, resulting in great economic and social burden. Ischemic stroke accounts for 85% of total cases, and the approved therapies are based on re-establishment of blood flow, and do not directly target brain parenchyma. Thus, novel therapies are urgently needed. In this review, limb remote ischemic conditioning (RIC) is revised and discussed as a potential therapy against ischemic stroke. The review targets both (i) fundamental research based on experimental models and (ii) clinical research based on clinical trials and human interventional studies with healthy volunteers. Moreover, it also presents two approaches concerning RIC mechanisms in stroke: (i) description of the underlying cerebral cellular and molecular mechanisms triggered by limb RIC that promote neuroprotection against stroke induced damage and (ii) the identification of signaling factors involved in inter-organ communication following RIC procedure. Limb to brain remote signaling can occur via circulating biochemical factors, immune cells, and/or stimulation of autonomic nervous system. In this review, these three hypotheses are explored in both humans and experimental models. Finally, the challenges involved in translating experimentally generated scientific knowledge to a clinical setting are also discussed.

Reducing Cardiac Injury during ST-Elevation Myocardial Infarction: A Reasoned Approach to a Multitarget Therapeutic Strategy

The significant reduction in ‘ischemic time’ through capillary diffusion of primary percutaneous intervention (pPCI) has rendered myocardial-ischemia reperfusion injury (MIRI) prevention a major issue in order to improve the prognosis of ST elevation myocardial infarction (STEMI) patients. In fact, while the ischemic damage increases with the severity and the duration of blood flow reduction, reperfusion injury reaches its maximum with a moderate amount of ischemic injury. MIRI leads to the development of post-STEMI left ventricular remodeling (post-STEMI LVR), thereby increasing the risk of arrhythmias and heart failure. Single pharmacological and mechanical interventions have shown some benefits, but have not satisfactorily reduced mortality. Therefore, a multitarget therapeutic strategy is needed, but no univocal indications have come from the clinical trials performed so far. On the basis of the results of the consistent clinical studies analyzed in this review, we try to design a randomized clinical trial aimed at evaluating the effects of a reasoned multitarget therapeutic strategy on the prevention of post-STEMI LVR. In fact, we believe that the correct timing of pharmacological and mechanical intervention application, according to their specific ability to interfere with survival pathways, may significantly reduce the incidence of post-STEMI LVR and thus improve patient prognosis.

Remote Ischemic Conditioning in Emergency Medicine-Clinical Frontiers and Research Opportunities

Time-critical acute ischemic conditions such as ST-elevation myocardial infarction and acute ischemic stroke are staples in Emergency Medicine practice. While timely reperfusion therapy is a priority, the resultant acute ischemia/reperfusion injury contributes to significant mortality and morbidity. Among therapeutics targeting ischemia/reperfusion injury (IRI), remote ischemic conditioning (RIC) has emerged as the most promising.RIC, which consists of repetitive inflation and deflation of a pneumatic cuff on a limb, was first demonstrated to have protective effect on IRI through various neural and humoral mechanisms. Its attractiveness stems from its simplicity, low-cost, safety, and efficacy, while at the same time it does not impede reperfusion treatment. There is now good evidence for RIC as an effective adjunct to reperfusion in ST-elevation myocardial infarction patients for improving clinical outcomes. For other applications such as acute ischemic stroke, subarachnoid hemorrhage, traumatic brain injury, cardiac arrest, and spinal injury, there is varying level of evidence.This review aims to describe the RIC phenomenon, briefly recount its historical development, and appraise the experimental and clinical evidence for RIC in selected emergency conditions. Finally, it describes the practical issues with RIC clinical application and research in Emergency Medicine.

Effect of COMBinAtion therapy with remote ischemic conditioning and exenatide on the Myocardial Infarct size: a two-by-two factorial randomized trial (COMBAT-MI)

Remote ischemic conditioning (RIC) and the GLP-1 analog exenatide activate different cardioprotective pathways and may have additive effects on infarct size (IS). Here, we aimed to assess the efficacy of RIC as compared with sham procedure, and of exenatide, as compared with placebo, and the interaction between both, to reduce IS in humans. We designed a two-by-two factorial, randomized controlled, blinded, multicenter, clinical trial. Patients with ST-segment elevation myocardial infarction receiving primary percutaneous coronary intervention (PPCI) within 6 h of symptoms were randomized to RIC or sham procedure and exenatide or matching placebo. The primary outcome was IS measured by late gadolinium enhancement in cardiac magnetic resonance performed 3-7 days after PPCI. The secondary outcomes were myocardial salvage index, transmurality index, left ventricular ejection fraction and relative microvascular obstruction volume. A total of 378 patients were randomly allocated, and after applying exclusion criteria, 222 patients were available for analysis. There were no significant interactions between the two randomization factors on the primary or secondary outcomes. IS was similar between groups for the RIC (24 ± 11.8% in the RIC group vs 23.7 ± 10.9% in the sham group, P = 0.827) and the exenatide hypotheses (25.1 ± 11.5% in the exenatide group vs 22.5 ± 10.9% in the placebo group, P = 0.092). There were no effects with either RIC or exenatide on the secondary outcomes. Unexpected adverse events or side effects of RIC and exenatide were not observed. In conclusion, neither RIC nor exenatide, or its combination, were able to reduce IS in STEMI patients when administered as an adjunct to PPCI.

Perioperative Cardioprotection: Clinical Implications

Perioperative cardioprotection aims to minimize the consequences of myocardial ischemia-reperfusion injury. In isolated tissue and animal experiments, several treatments have been identified providing cardioprotection. Some of these strategies have been confirmed in clinical proof-of-concept studies. However, the final translation of cardioprotective strategies to really improve clinical outcome has been disappointing: large randomized controlled clinical trials mostly revealed inconclusive, neutral, or negative results. This review provides an overview of the currently available evidence regarding clinical implications of perioperative cardioprotective therapies from an anesthesiological perspective, highlighting nonpharmacological as well as pharmacological strategies. We discuss reasons why translation of promising experimental results into clinical practice and outcome improvement is hampered by potential confounders and suggest future perspectives to overcome these limitations.

Co-morbidities and co-medications as confounders of cardioprotection-Does it matter in the clinical setting?

The translation of cardioprotection from robust experimental evidence to beneficial clinical outcome for patients suffering acute myocardial infarction or undergoing cardiovascular surgery has been largely disappointing. The present review attempts to critically analyse the evidence for confounders of cardioprotection in patients with acute myocardial infarction and in patients undergoing cardiovascular surgery. One reason that has been proposed to be responsible for such lack of translation is the confounding of cardioprotection by co-morbidities and co-medications. Whereas there is solid experimental evidence for such confounding of cardioprotection by single co-morbidities and co-medications, the clinical evidence from retrospective analyses of the limited number of clinical data is less robust. The best evidence for interference of co-medications is that for platelet inhibitors to recruit cardioprotection per se and thus limit the potential for further protection from myocardial infarction and for propofol anaesthesia to negate the protection from remote ischaemic conditioning in cardiovascular surgery. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

Comparison of infarction size, complete ST-segment resolution incidence, mortality and re-infarction and target vessel revascularization between remote ischemic conditioning and ischemic postconditioning in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

Introduction

Due to higher morbidity and mortality, ST-segment elevation myocardial infarction (STEMI) causes many public health problems.

Aim

To observe effects of remote ischemic conditioning (RIC) and ischemic postconditioning (IPC) on patients diagnosed as STEMI undergoing primary percutaneous coronary intervention (pPCI).

Material and methods

This meta-analysis was conducted using indirect comparison by conducting a network meta-analysis (NMA). We conducted searches by utilizing PubMed and the other databases to identify randomized controlled trials (RCTs) that described IPC or RIC treated patients diagnosed with STEMI during processes of pPCI. Enzymatic infarct size and infarction size were evaluated and cardiac events were assessed during the follow-up.

Results

Pooled results showed that lower enzymatic infarction size was associated with the RIC group compared to the IPC group (IPC vs. RIC: standardized mean difference (SMD) = 1.126; 95% confidence interval (CI): 0.756–1.677). Compared with IPC, RIC significantly reduced infarction size, which was assessed using cardiac magnetic resonance (CMR) (SMD = 1.113; 95% CI: 0.674–1.837). We noted a potential toward greater complete ST-segment resolution in RIC patients compared with IPC patients (odds ratio (OR) = 0.821; 95% CI: 0.166–4.051). No significant difference existed in all-cause mortality (OR = 2.211; 95% CI: 0.845–5.784), Target vessel revascularization (TVR) (OR = 0.045; 95% CI: 0.001–.662) or re-infarction (OR = 1.763; 95% CI: 0.741–4.193).

Conclusions

This meta-analysis suggested RIC was correlated with significantly smaller infarction size compared to IPC. No significant superiority between RIC and IPC has been observed in this study on cSTR incidence, mortality and re-infarction or TVR.

Kinetic modelling of myocardial necrosis biomarkers offers an easier, reliable and more acceptable assessment of infarct size

Infarct size is a major prognostic factor in ST-segment elevation myocardial infarction (STEMI). It is often assessed using repeated blood sampling and the estimation of biomarker area under the concentration versus time curve (AUC) in translational research. We aimed at developing limited sampling strategies (LSS) to accurately estimate biomarker AUC using only a limited number of blood samples in STEMI patients. This retrospective study was carried out on pooled data from five clinical trials of STEMI patients (TIMI blood flow 0/1) studies where repeated blood samples were collected within 72 h after admission to assess creatine kinase (CK), cardiac troponin I (cTnI) and muscle-brain CK (CK-MB). Biomarker kinetics was assessed using previously described biomarker kinetic models. A number of LSS models including combinations of 1 to 3 samples were developed to identify sampling times leading to the best estimation of AUC. Patients were randomly assigned to either learning (2/3) or validation (1/3) subsets. Descriptive and predictive performances of LSS models were compared using learning and validation subsets, respectively. An external validation cohort was used to validate the model and its applicability to different cTnI assays, including high-sensitive (hs) cTnI. 132 patients had full CK and cTnI dataset, 49 patients had CK-MB. For each biomarker, 180 LSS models were tested. Best LSS models were obtained for the following sampling times: T4-16 for CK, T8-T20 for cTnI and T8-T16 for CK-MB for 2-sample LSS; and T4-T16-T24 for CK, T4-T12-T20 for cTnI and T8-T16-T20 for CK-MB for 3-sample LSS. External validation was achieved on 103 anterior STEMI patients (TIMI flow 0/1), and the cTnI model applicability to recommended hs cTnI confirmed. Biomarker kinetics can be assessed with a limited number of samples using kinetic modelling. This opens the way for substantial simplification of future cardioprotection studies, more acceptable for the patients.

Myocardial ischaemia-reperfusion injury and cardioprotection in perspective

Despite the increasing use and success of interventional coronary reperfusion strategies, morbidity and mortality from acute myocardial infarction are still substantial. Myocardial infarct size is a major determinant of prognosis in these patients. Therefore, cardioprotective strategies aim to reduce infarct size. However, a perplexing gap exists between the many preclinical studies reporting infarct size reduction with mechanical and pharmacological interventions and the poor translation into better clinical outcomes in patients. This Review revisits the pathophysiology of myocardial ischaemia-reperfusion injury, including the role of autophagy and forms of cell death such as necrosis, apoptosis, necroptosis and pyroptosis. Other cellular compartments in addition to cardiomyocytes are addressed, notably the coronary microcirculation. Preclinical and clinical research developments in mechanical and pharmacological approaches to induce cardioprotection, and their signal transduction pathways, are discussed. Additive cardioprotective interventions are advocated. For clinical translation into treatments for patients with acute myocardial infarction, who typically are of advanced age, have comorbidities and are receiving several medications, not only infarct size reduction but also attenuation of coronary microvascular obstruction, as well as longer-term targets including infarct repair and reverse remodelling, must be considered to improve patient outcomes. Future clinical trials must focus on patients who really need adjunct cardioprotection, that is, those with severe haemodynamic alterations.

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.

[Impact of endothelial dysfunction on the course of acute ST-elevation myocardial infarction and its correction by remote ischemic preconditioning]

Aim of the study - to assess the effect of remote ischemic preconditioning (RIPC) on the incidence of endothelial dysfunction (ED) and its impact on hospital prognosis in patients with ST segment elevation acute myocardial infarction (STEMI).

MATERIALS AND METHODS

We conducted a single - centre, open - label prospective study that included 173 patients with STEMI who underwent primary percutaneous coronary intervention within the first 24 hours of the symptoms onset. Before the PCI, patients were randomized into two groups. In the first group (n=86) during the preparation for PCI, we performed RIPC procedure by inflation of the cuff of the tonometer to 200 mm Hg and its further deflation on patient's shoulder, thus creating short cycles of controlled ischemia/reperfusion in hand (4 cycles of ischemia/reperfusion for 5/5 minutes respectively). In the second, control group (n=87), the standard primary PCI was performed without the previous RIPC. Evaluation of the endothelial function was performed on the 2-7th day after admission using the endothelium - dependent flow - mediated dilatation test (FMD) of the brachial artery. Primary endpoints in this study included the presence of ED, in - hospital mortality, life - threatening arrhythmias (ventricular fibrillation/ventricular tachycardia after first 24 hours upon admission), stent thrombosis, clinical signs of heart failure, and a combined endpoint consisting of all the listed above.

RESULTS

The median values for FMD-test did not differ significantly between the study groups upon admission. Assessment of the FMD of the brachial artery on the 2-7th day after PCI showed that among the patients who underwent RIPC there was a significantly lower percentage of patients with ED than in the patients with STEMI who did not undergo RIPC before PCI (43.1% vs. 75.8% respectively, p=0.0001). We found a significant reduction in the incidence of heart failure and of combined endpoint in the group of patients without ED compared with patients with ED: 0% vs. 9.3% (n=7; p=0.023) and 3.8% (n=2) vs. 16% (n=12; p=0.032) respectively. When assessing the effect of RIPC on hospital prognosis, we also found a significant decrease in the incidence of heart failure and a trend towards a decrease in the combined endpoint in the group of patients who underwent RIPC compared to the control group: 1.5% (n=1) vs. 9.7% (n=6; p=0.045) and 6.2% (n=4) vs. 16.1% (n=10; p=0.073) respectively.

CONCLUSION

Performance of RIPC before the primary PCI significantly reduces the incidence of ED in patients with STEMI on the 2-7th day of the disease onset. The presence of ED in patients with STEMI is associated with a significant increase in the incidence of heart failure and of the combined endpoint during in - hospital period. RIPC significantly reduces the incidence of heart failure in patients with STEMI during in - hospital period.

Field Implementation of Remote Ischemic Conditioning in ST-Segment-Elevation Myocardial Infarction: The FIRST Study

BACKGROUND

Remote ischemic conditioning (RIC) is a noninvasive therapeutic strategy that uses brief cycles of blood pressure cuff inflation and deflation to protect the myocardium against ischemia-reperfusion injury. We sought to compare major adverse cardiovascular events (MACE) for patients who received RIC before PCI for ST-segment-elevation myocardial infarction (STEMI) compared with standard care.

METHODS

We conducted a pre- and postimplementation study. In the preimplementation phase, STEMI patients were taken directly to the PCI lab. After implementation, STEMI patients received 4 cycles of RIC by paramedics or emergency department staff before PCI. The primary outcome was MACE at 90 days. Secondary outcomes included MACE at 30, 60, and 180 days. Inverse probability of treatment weighting using propensity scores estimated causal effects independent from baseline covariables.

RESULTS

A total of 1667 (866 preimplementation, 801 postimplementation) patients were included. In the preimplementation phase, 13.4% had MACE at 90 days compared with 11.8% in the postimplementation phase (odds ratio [OR] 0.86, 95% CI 0.62-1.21). There were no significant differences in MACE at 30, 60, and 180 days. Patients presenting with cardiogenic shock or cardiac arrest before PCI were less likely to have MACE at 90 days (42.7% pre vs 27.8% post) if they received RIC before PCI (OR 0.52, 95% CI 0.27-0.98).

CONCLUSIONS

A strategy of RIC before PCI for STEMI did not reduce 90-day MACE. Future research should explore the impact of RIC before PCI for longer-term clinical outcomes and for patients presenting with cardiogenic shock or cardiac arrest.

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial

BACKGROUND

Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months.

METHODS

We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed.

FINDINGS

Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed.

INTERPRETATION

Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI.

FUNDING

British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden.

Autonomic nervous system response to remote ischemic conditioning: heart rate variability assessment

Background

Remote ischemic conditioning (RIC) is a procedure applied in a limb for triggering endogenous protective pathways in distant organs, namely brain or heart. The underlying mechanisms of RIC are still not fully understood, and it is hypothesized they are mediated either by humoral factors, immune cells and/or the autonomic nervous system. Herein, heart rate variability (HRV) was used to evaluate the electrophysiological processes occurring in the heart during RIC and, in turn to assess the role of autonomic nervous system.

Methods

Healthy subjects were submitted to RIC protocol and electrocardiography (ECG) was used to evaluate HRV, by assessing the variability of time intervals between two consecutive heart beats. This is a pilot study based on the analysis of 18 ECG from healthy subjects submitted to RIC. HRV was characterized in three domains (time, frequency and non-linear features) that can be correlated with the autonomic nervous system function.

Results

RIC procedure increased significantly the non-linear parameter SD2, which is associated with long term HRV. This effect was observed in all subjects and in the senior (> 60 years-old) subset analysis. SD2 increase suggests an activation of both parasympathetic and sympathetic nervous system, namely via fast vagal response (parasympathetic) and the slow sympathetic response to the baroreceptors stimulation.

Conclusions

RIC procedure modulates both parasympathetic and sympathetic autonomic nervous system. Furthermore, this modulation is more pronounced in the senior subset of subjects. Therefore, the autonomic nervous system regulation could be one of the mechanisms for RIC therapeutic effectiveness.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1181-5) contains supplementary material, which is available to authorized users.

HIF-1α Preconditioning Potentiates Antioxidant Activity in Ischemic Injury: The Role of Sequential Administration of Dihydrotanshinone I and Protocatechuic Aldehyde in Cardioprotection

Aims: The management of myocardial ischemia has been challenged by reperfusion injury. Reactive oxygen species (ROS) production is the critical cause of reperfusion injury, but antioxidant treatment failed to gain satisfactory effects. We hypothesized that improvement of redox homeostasis by preconditioning regulation should potentiate the ability of antioxidants to protect the heart from reperfusion injury. Results: By phenotype-based screening, we identified that dihydrotanshinone I (DT) and protocatechuic aldehyde (PCA) potently protected cardiomyocytes through preconditioning regulation and antioxidant activity, respectively. DT induced transient ROS generation via reversible inhibition of mitochondrial respiratory complex I and thereby stabilizing HIF-1α, while PCA elevated the levels of reduced glutathione (GSH) by providing reducing equivalents to scavenge ROS. HIF-1α, stabilized by DT, transcriptionally upregulated Nrf2 and thereby activated antioxidant enzymes, potentiating PCA to protect cardiomyocytes from reperfusion injury by strengthening intrinsic ROS scavenging capacity. In rat ischemia/reperfusion (I/R) model, sequential administration of DT and PCA, but not in reverse, additively protected the heart from I/R injury, manifested by reduced infarct size and improved cardiac function. These results were further supported by sequential administration of metformin and vitamin E in the rat and porcine I/R models. Innovation and Conclusion: Our work demonstrates that preconditioning regulation of redox state is essential for antioxidants to protect the heart from I/R injury, providing a new direction for the treatment of myocardial injury.

Influence of Cardiovascular Risk Factors, Comorbidities, Medication Use and Procedural Variables on Remote Ischemic Conditioning Efficacy in Patients with ST-Segment Elevation Myocardial Infarction

Remote ischemic conditioning (RIC) confers cardioprotection in patients with ST-segment elevation myocardial infarction (STEMI). Despite intense research, the translation of RIC into clinical practice remains a challenge. This may, at least partly, be due to confounding factors that may modify the efficacy of RIC. The present review focuses on cardiovascular risk factors, comorbidities, medication use and procedural variables which may modify the efficacy of RIC in patients with STEMI. Findings of such efficacy modifiers are based on subgroup and post-hoc analyses and thus hold risk of type I and II errors. Although findings from studies evaluating influencing factors are often ambiguous, some but not all studies suggest that smoking, non-statin use, infarct location, area-at-risk of infarction, pre-procedural Thrombolysis in Myocardial Infarction (TIMI) flow, ischemia duration and coronary collateral blood flow to the infarct-related artery may influence on the cardioprotective efficacy of RIC. Results from the on-going CONDI2/ERIC-PPCI trial will determine any clinical implications of RIC in the treatment of patients with STEMI and predefined subgroup analyses will give further insight into influencing factors on the efficacy of RIC.

Trigger, Signaling Mechanism and End Effector of Cardioprotective Effect of Remote Postconditioning of Heart

The hypothetical trigger of remote postconditioning (RPost) of the heart is the high-molecular weight hydrophobic peptide(s). Nitric oxide and adenosine serve as intermediaries between the peptide and intracellular structures. The role of the autonomic nervous system in RPost requires further study. In signaling mechanism RPost, kinases are involved: protein kinase C, PI3, Akt, JAK. The hypothetical end effector of RPost is aldehyde dehydrogenase-2, the transcription factors STAT, Nrf2, and also the BKCa channel.

Remote ischemic conditioning during primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction: a systematic review and meta-analysis

Objective

This systematic review was designed to evaluate the efficacy of remote ischemic conditioning (RIC) with primary percutaneous coronary intervention (PCI) versus primary PCI alone for ST-segment elevation myocardial infarction (STEMI).

Search strategy

Computerized search for trials from PubMed, EMBASE, CENTRAL and Cochrane Database of Systematic Reviews databases.

Selection criteria

Trials investigating RIC plus primary PCI (group A) versus primary PCI alone (group B).

Outcome measures

Myocardial enzyme levels; left ventricular ejection fraction (LVEF); major adverse cardiac and cerebrovascular events (MACCEs); TIMI flow grade III; myocardial salvage index or infarct size per patients.

Results

In all, 14 studies involving 3165 subjects were included. There was a significant association of myocardial edema levels, myocardial salvage index and incidence of MACCEs in group A compared with group B (myocardial edema levels: SMD = − 0.36, 95% CI (− 0.59, − 0.13); myocardial salvage index: MD = 0.06, 95% CI (0.02, 0.10); MACCE: OR = 0.70, 95% CI (0.57, 0.85)). With regard to infarct size, TIMI flow grade III and LVEF, group A appeared to be equivalent with group B (infarct size: MD = − 1.67, 95% CI (− 3.46, 0.11); TIMI flow grade III: OR = 1.04, 95% CI (0.71, 1.52); LVEF: MD = 0.74, 95% CI (− 0.80, 2.28)).

Conclusion

RIC was associated with lower myocardial edema levels, myocardial salvage index and incidence of MACCE, while non-significant beneficial effect on infarct size, TIMI flow grade III or LVEF. These findings suggest that RIC is a promising adjunctive treatment to PCI for the prevention of reperfusion injury in STEMI patients.

Multitarget Strategies to Reduce Myocardial Ischemia/Reperfusion Injury: JACC Review Topic of the Week

Many treatments have been identified that confer robust cardioprotection in experimental animal models of acute ischemia and reperfusion injury. However, translation of these cardioprotective therapies into the clinical setting of acute myocardial infarction (AMI) for patient benefit has been disappointing. One important reason might be that AMI is multifactorial, causing cardiomyocyte death via multiple mechanisms, as well as affecting other cell types, including platelets, fibroblasts, endothelial and smooth muscle cells, and immune cells. Many cardioprotective strategies act through common end-effectors and may be suboptimal in patients with comorbidities. In this regard, emerging data suggest that optimal cardioprotection may require the combination of additive or synergistic multitarget therapies. This review will present an overview of the state of cardioprotection today and provide a roadmap for how we might progress towards successful clinical use of cardioprotective therapies following AMI, focusing on the rational combination of judiciously selected, multitarget therapies. This paper emerged as part of the discussions of the European Union (EU)-CARDIOPROTECTION Cooperation in Science and Technology (COST) Action, CA16225.

Impact of combined ischemic preconditioning and remote ischemic perconditioning on ischemia-reperfusion injury after liver transplantation

Ischemic preconditioning (IPC) and remote ischemic perconditioning (RIPer) confer protective effects against liver ischemia-reperfusion injury (IRI), but data about RIPer applying in liver transplantation is lacking. The study aimed to evaluate whether the combination of IPC and RIPer provides reinforced protective effects. C57BL/6 mice (160 pairs) were allocated into four groups: control, subjected to liver transplantation only; IPC, donor hilar was clamped for 10 min followed by 15 min of reperfusion; RIPer, three cycles of occlusion (5 min) and opening (5 min) of femoral vascular bundle were performed before reperfusion; IPC + RIPer, donors and recipients were subjected to IPC and RIPer respectively. Liver tissues were obtained for histological evaluation, TUNEL staining, malondialdehyde assays, GSH-Px assays, and NF-κB p65 protein and Bcl-2/Bax mRNA analyses. Blood samples were used to evaluate ALT, AST, TNF-α, NOx levels and flow cytometry. We found that protective efficacy of RIPer is less than IPC in terms of ALT, TNF-α, GSH-Px and NOx at 2 h postoperation, but almost equivalent at 24 h and 72 h postoperation. Except for Suzuki scores, ALT, Bcl-2/Bax mRNA ratio, other indices showed that combined treatment brought enhanced attenuation in IRI, compared with single treatment, through additive effects on antioxidation, anti-apoptosis, modulation of microcirculation disturbance, and inhibition of innate immune response. This study suggested a combined strategy that could enhance protection against IRI in clinical liver transplantation, otherwise, provided a hint that RIPer's mechanism might be partly or totally different from IPC in humoral pathway.

Cardioprotection during ischemia by coronary collateral growth

Ischemic heart diseases (IHD) cause millions of deaths around the world annually. While surgical and pharmacological interventions are commonly used to treat patients with IHD, their efficacy varies from patient to patient and is limited by the severity of the disease. One promising, at least theoretically, approach for treating IHD is induction of coronary collateral growth (CCG). Coronary collaterals are arteriole-to-arteriole anastomoses that can undergo expansion and remodeling in the setting of coronary disease when the disease elicits myocardial ischemia and creates a pressure difference across the collateral vessel that creates unidirectional flow. Well-developed collaterals can restore blood flow in the ischemic area of the myocardium and protect the myocardium at risk. Moreover, such collaterals are correlated to reduced mortality and infarct size and better cardiac function during occlusion of coronary arteries. Therefore, understanding the process of CCG is highly important as a potentially viable treatment of IHD. While there are several excellent review articles on this topic, this review will provide a unified overview of the various aspects related to CCG as well as an update of the advancements in the field. We also call for more detailed studies with an interdisciplinary approach to advance our knowledge of CCG. In this review, we will describe growth of coronary collaterals, the various factors that contribute to CCG, animal models used to study CCG, and the cardioprotective effects of coronary collaterals during ischemia. We will also discuss the impairment of CCG in metabolic syndrome and the therapeutic potentials of CCG in IHD.

Remote ischemic conditioning protects against endothelial ischemia-reperfusion injury via a glucagon-like peptide-1 receptor-mediated mechanism in humans

BACKGROUND

Remote ischemic conditioning (RIC), i.e. short cycles of ischemia and reperfusion in remote tissue, is a novel approach to protect against myocardial ischemia-reperfusion injury in ST-elevation myocardial infarction. The nature of the factors transmitting the protective effect of RIC remains unknown, and both neuronal and hormonal mechanisms appear to be involved. A recent study indicated involvement of glucagon-like peptide-1 (GLP-1) regulated by the vagal nerve in RIC in rats. In the present study we aimed to investigate whether the protective effect of RIC is mediated by a GLP-1 receptor-dependent mechanism in humans.

METHODS

Endothelial function was determined from flow-mediated dilatation (FMD) of the brachial artery before and after 20 min of forearm ischemia and 20 min of reperfusion in twelve healthy subjects on three occasions: (A) ischemia-reperfusion without intervention, (B) ischemia-reperfusion + RIC and (C) iv administration of the GLP-1 receptor antagonist exendin(9-39) + ischemia-reperfusion + RIC.

RESULTS

Ischemia-reperfusion reduced FMD from 4.7 ± 0.8% at baseline to 1.5 ± 0.4% (p < 0.01). RIC protected from the impairment in FMD induced by ischemia-reperfusion (4.6 ± 1.1% at baseline vs. 5.0 ± 1.1% following ischemia-reperfusion). Exendin(9-39) abolished the protection induced by RIC (FMD 4.9 ± 0.9% at baseline vs. 1.4 ± 1.3% following ischemia-reperfusion; p < 0.01) but did not affect basal FMD. Plasma GLP-1 levels did not change significantly between examinations.

CONCLUSION

The present study is the first to suggest that RIC protects against endothelial ischemia-reperfusion injury via a GLP-1 receptor-mediated mechanism in humans.

Effect of comprehensive remote ischemic conditioning in anterior ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention: Design and rationale of the CORIC-MI randomized trial

Remote ischemic conditioning (RIC) applied during or after ST-segment elevation myocardial infarction (STEMI) is currently the most promising adjuvant therapy to reduce reperfusion injury. Recent animal studies showed that RIC may help the myocardium recover if applied daily during the month after STEMI. The Comprehensive Remote Ischemic Conditioning in Myocardial Infarction (CORIC-MI) trial is a single-center randomized controlled study in which 200 patients undergoing primary percutaneous coronary intervention (PPCI) for anterior STEMI will be randomized in a 1:1 ratio into comprehensive RIC (CORIC) or no intervention (control) groups. CORIC consists of per-RIC (5 cycles of 5-minute ischemia and 5-minute reperfusion of the lower limb immediately after randomization and before reperfusion), post-RIC (5 cycles of 5-minute ischemia and 5-minute reperfusion of the lower limb immediately post-PPCI), and delayed RIC (5 cycles of 5-minute ischemia and 5-minute reperfusion of the lower limb once daily on 2-28 days). Primary endpoint is left ventricular ejection fraction assessed by cardiac magnetic resonance imaging at 30 days. Major secondary endpoints include infarct size and left ventricular volume assessed by cardiac magnetic resonance imaging at 30 days, left ventricular ejection fraction assessed by echocardiography, and major adverse cardiovascular events up to 12 months. This report presents the baseline characteristics of 93 patients (CORIC group, n = 49; control group, n = 44) enrolled into the study as of March 31, 2018. The CORIC-MI trial aims to test the hypothesis that CORIC will improve cardiac function and remodeling in patients with anterior STEMI undergoing PPCI.

Remote ischaemic conditioning for myocardial infarction or elective PCI: systematic review and meta-analyses of randomised trials

BACKGROUND

The efficacy of remote ischaemic conditioning in clinical trials of ST-segment elevation myocardial infarction (STEMI) or elective percutaneous coronary intervention is controversial. We aimed to systematically review and meta-analyse whether remote ischaemic conditioning reduces myocardial damage in those patients.

METHODS

We searched PubMed, Embase and Web of Science from inception until December 2017 for randomised clinical trials evaluating remote ischaemic conditioning versus a control group. Two independent reviewers extracted data of 23 trials (2118 patients with STEMI; 2048 patients undergoing elective percutaneous coronary intervention) which were meta-analysed using random-effects models.

RESULTS

Remote ischaemic conditioning reduced infarct size in STEMI patients when assessed by imaging (mean difference of infarct size as percentage of left ventricle -2.43, 95% confidence interval (CI) -4.37 to -0.48; P=0.01; I²=44%; n=925) or biomarkers related to myocardial injury (peak values of cardiac biomarker release reported as standardised mean difference -0.19, 95% CI -0.37 to -0.02; P=0.03; I²=58%; n=1483) and increased myocardial salvage index (mean difference 0.07, 95% CI 0.01 to 0.13; P=0.02; I²=49%; n= 636). Left ventricular ejection fraction was increased when assessed during the first days after STEMI (mean difference 1.53, 95% CI 0.23 to 2.83; P=0.02; I²=28%; n=1192). Remote ischaemic conditioning had no influence on biomarker values after elective percutaneous coronary intervention (standardised mean difference 0.06, 95% CI -0.17 to 0.30; P=0.59).

CONCLUSIONS

Despite a statistically significant reduction of myocardial damage in STEMI patients, the magnitude of the reduction was small and a significant impact on clinical events is unlikely. With respect to elective percutaneous coronary intervention, remote ischaemic conditioning had no influence on myocardial injury and its use is not supported by our analysis.

Neural mechanisms in remote ischaemic conditioning in the heart and brain: mechanistic and translational aspects

Remote ischaemic conditioning (RIC) is a promising method of cardioprotection, with numerous clinical studies having demonstrated its ability to reduce myocardial infarct size and improve prognosis. On the other hand, there are several clinical trials, in particular those conducted in the setting of elective cardiac surgery, that have failed to show any benefit of RIC. These contradictory data indicate that there is insufficient understanding of the mechanisms underlying RIC. RIC is now known to signal indiscriminately, protecting not only the heart, but also other organs. In particular, experimental studies have demonstrated that it is able to reduce infarct size in an acute ischaemic stroke model. However, the mechanisms underlying RIC-induced neuroprotection are even less well understood than for cardioprotection. The existence of bidirectional feedback interactions between the heart and the brain suggests that the mechanisms of RIC-induced neuroprotection and cardioprotection should be studied as a whole. This review, therefore, addresses the topic of the neural component of the RIC mechanism.

Clinical translation of myocardial conditioning

Rapid admission and acute interventional treatment combined with modern antithrombotic pharmacologic therapy have improved outcomes in patients with ST elevation myocardial infarction. The next major target to further advance outcomes needs to address ischemia-reperfusion injury, which may contribute significantly to the final infarct size and hence mortality and postinfarction heart failure. Mechanical conditioning strategies including local and remote ischemic pre-, per-, and postconditioning have demonstrated consistent cardioprotective capacities in experimental models of acute ischemia-reperfusion injury. Their translation to the clinical scenario has been challenging. At present, the most promising mechanical protection strategy of the heart seems to be remote ischemic conditioning, which increases myocardial salvage beyond acute reperfusion therapy. An additional aspect that has gained recent focus is the potential of extended conditioning strategies to improve physical rehabilitation not only after an acute ischemia-reperfusion event such as acute myocardial infarction and cardiac surgery but also in patients with heart failure. Experimental and preliminary clinical evidence suggests that remote ischemic conditioning may modify cardiac remodeling and additionally enhance skeletal muscle strength therapy to prevent muscle waste, known as an inherent component of a postoperative period and in heart failure. Blood flow restriction exercise and enhanced external counterpulsation may represent cardioprotective corollaries. Combined with exercise, remote ischemic conditioning or, alternatively, blood flow restriction exercise may be of aid in optimizing physical rehabilitation in populations that are not able to perform exercise practice at intensity levels required to promote optimal outcomes.

Novel targets and future strategies for acute cardioprotection: Position Paper of the European Society of Cardiology Working Group on Cellular Biology of the Heart

Ischaemic heart disease and the heart failure that often results, remain the leading causes of death and disability in Europe and worldwide. As such, in order to prevent heart failure and improve clinical outcomes in patients presenting with an acute ST-segment elevation myocardial infarction and patients undergoing coronary artery bypass graft surgery, novel therapies are required to protect the heart against the detrimental effects of acute ischaemia/reperfusion injury (IRI). During the last three decades, a wide variety of ischaemic conditioning strategies and pharmacological treatments have been tested in the clinic-however, their translation from experimental to clinical studies for improving patient outcomes has been both challenging and disappointing. Therefore, in this Position Paper of the European Society of Cardiology Working Group on Cellular Biology of the Heart, we critically analyse the current state of ischaemic conditioning in both the experimental and clinical settings, provide recommendations for improving its translation into the clinical setting, and highlight novel therapeutic targets and new treatment strategies for reducing acute myocardial IRI.

The pathophysiology of acute myocardial infarction and strategies of protection beyond reperfusion: a continual challenge

The incidence of ST segment elevation myocardial infarction (STEMI) has decreased over the last two decades in developed countries, but mortality from STEMI despite widespread access to reperfusion therapy is still substantial as is the development of heart failure, particularly among an expanding older population. In developing countries, the incidence of STEMI is increasing and interventional reperfusion is often not available. We here review the pathophysiology of acute myocardial infarction and reperfusion, notably the temporal and spatial evolution of ischaemic and reperfusion injury, the different modes of cell death, and the resulting coronary microvascular dysfunction. We then go on to briefly characterize the cardioprotective phenomena of ischaemic preconditioning, ischaemic postconditioning, and remote ischaemic conditioning and their underlying signal transduction pathways. We discuss in detail the attempts to translate conditioning strategies and drug therapy into the clinical setting. Most attempts have failed so far to reduce infarct size and improve clinical outcomes in STEMI patients, and we discuss potential reasons for such failure. Currently, it appears that remote ischaemic conditioning and a few drugs (atrial natriuretic peptide, exenatide, metoprolol, and esmolol) reduce infarct size, but studies with clinical outcome as primary endpoint are still underway.

Reflection of Cardioprotection by Remote Ischemic Perconditioning in Attenuated ST-Segment Elevation During Ongoing Coronary Occlusion in Pigs: Evidence for Cardioprotection From Ischemic Injury

RATIONALE

Reduction of infarct size by remote ischemic perconditioning (perRIC) is evident only after several hours reperfusion.

OBJECTIVE

To develop a potential real-time estimate of cardioprotection by perRIC, we have analyzed the time course of ST-segment elevation.

METHODS AND RESULTS

Anesthetized open-chest pigs were subjected to 60-minute coronary occlusion and 180-minute reperfusion (placebo; n=19). PerRIC (n=18; 4×5 min/5 min hindlimb occlusion/reperfusion) was induced 20 minutes after coronary occlusion. Regional myocardial blood flow was measured with microspheres, areas of no-reflow with thioflavin-S, area at risk with blue dye, and infarct size with triphenyl tetrazolium chloride staining. Phosphorylation of protein kinase B α/β/γ, extracellular signal-regulated kinase 1/2, and signal transducer and activator of transcription 3 was determined by Western blot. ST-segment elevation was analyzed in a V2-like ECG-lead at baseline, 5- and 55-minute coronary occlusion, and 10-, 30-, 60-, and 120-minute reperfusion. Transmural blood flow at 5-minute coronary occlusion was not different between perRIC (0.029±0.015 mL/min per gram; mean±SD) and placebo (0.024±0.018 mL/min per gram) as was area at risk (perRIC: 24±6% of the left ventricle; placebo: 21±4%). Areas of no-reflow tended to be smaller with perRIC (9±12% of area at risk versus 15±14% with placebo; P=0.13). Infarct size with perRIC was 23±12% of area at risk versus 40±11% with placebo (P<0.001). PerRIC increased phosphorylation of signal transducer and activator of transcription 3 at 120-minute reperfusion by 196±142% versus 109±120% with placebo (P=0.047). The time courses of ST-segment elevation in perRIC and placebo protocols, respectively, were different (P=0.017). With similar ST-segment elevation at 5-minute coronary occlusion (perRIC 282±34 µV; placebo 259±28 µV), partial recovery of ST-segment elevation between 5- and 55-minute coronary occlusion was more pronounced with perRIC than placebo (by 111±84 versus 15±94 µV; P=0.028).

CONCLUSION

Infarct size reduction by perRIC is reflected in the ST-segment elevation during coronary occlusion in pigs, supporting the notion of protection from ischemic injury.

Rationale and Study Design for a Single-Arm Phase IIa Study Investigating Feasibility of Preventing Ischemic Cerebrovascular Events in High-Risk Patients with Acute Non-disabling Ischemic Cerebrovascular Events Using Remote Ischemic Conditioning

Background:

Acute minor ischemic stroke (AMIS) or transient ischemic attack (TIA) is a common cerebrovascular event with a considerable high recurrence. Prior research demonstrated the effectiveness of regular long-term remote ischemic conditioning (RIC) in secondary stroke prevention in patients with intracranial stenosis. We hypothesized that RIC can serve as an effective adjunctive therapy to pharmacotherapy in preventing ischemic events in patients with AMIS/TIA. This study aimed to investigate the feasibility, safety, and preliminary efficacy of daily RIC in inhibiting cerebrovascular/cardiovascular events after AMIS/TIA.

Methods:

This is a single-arm, open-label, multicenter Phase IIa futility study with a sample size of 165. Patients with AMIS/TIA receive RIC as an additional therapy to secondary stroke prevention regimen. RIC consists of five cycles of 5-min inflation (200 mmHg) and 5-min deflation of cuffs on bilateral upper limbs twice a day for 90 days. The antiplatelet strategy is based on individual physician's best practice: aspirin alone, clopidogrel alone, or combination of aspirin and clopidogrel. We will assess the recurrence rate of ischemic stroke/TIA within 3 months as the primary outcomes.

Conclusions:

The data gathered from the study will be used to determine whether a further large-scale, multicenter randomized controlled Phase II trial is warranted in patients with AMIS/TIA.

Trial Registration:

ClinicalTrials.gov, NCT03004820; https://www.clinicaltrials.gov/ct2/show/NCT03004820.

Remote ischemic conditioning improves myocardial parameters and clinical outcomes during primary percutaneous coronary intervention: a meta-analysis of randomized controlled trials

We conducted a systematic review and meta-analysis to evaluate the effects of remote ischemic conditioning on myocardial parameters and clinical outcomes in ST segment elevation acute myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention. Ten eligible randomized controlled trials with 1006 STEMI patients were identified. Compared with controls, remote ischemic conditioning reduced the myocardial enzyme levels (standardized mean difference =-0.86; 95% CI: -1.44 to -0.28; P = 0.004; I2 = 94.5%), and increased the incidence of complete ST-segment resolution [odds ratio (OR) = 1.74; 95% CI: 1.09 to 2.77; P = 0.02; I2 = 47.9%]. Remote ischemic conditioning patients had a lower risk of all-cause mortality (OR = 0.27; 95% CI: 0.12 to 0.62; P = 0.002; I2 = 0.0%) and lower major adverse cardiovascular and cerebrovascular events rate (OR=0.45; 95% CI: 0.27 to 0.75; P = 0.002; I2 = 0.0%). Meta-analysis suggested that remote ischemic conditioning conferred cardioprotection by reducing myocardial enzymes and increasing the incidence of complete ST-segment resolution in patients after STEMI. As a result, clinical outcomes were improved in terms of mortality and incidence of major adverse cardiovascular and cerebrovascular events.

Meta-analysis of the effects of ischemic postconditioning on structural pathology in ST-segment elevation acute myocardial infarction

In this meta-analysis, we assessed cardiac magnetic resonance imaging data to determine the effects of local and remote ischemic postconditioning (LPoC and RPoC, respectively) on structural pathology in ST-segmentel elevation acute myocardial infarction (STEMI). We searched the Pubmed, Embase and Cochrane Library databases up to May 2017 and included 12 randomized controlled trials (10 LPoC and 2 RPoC)containing 1069 study subjects with thrombolysis in myocardial infarction flow grade 0~1. Weighed mean difference (WMD), standardized mean difference (SMD), and odds ratio (OR) were used for the pooled analysis. Random-effect model was used for the potential clinical inconsistency. LPoC and RPoC increased the myocardial salvage index (n = 5; weighted mean difference (WMD) = 5.52; P = 0.005; I2 = 76.0%), and decreased myocardial edema (n = 7; WMD = -3.35; P = 0.0009; I2 = 18.0%). However, LPoC and RPoC did not reduce the final infarct size (n = 10; WMD = -1.01; P > 0.05; I2 = 68.0%), left ventricular volume (n = 10; standardized mean difference = 0.23; P > 0.05; I2 = 93.0%), the incidence of microvascular obstruction (n = 6; OR = 0.99; P > 0.05; I2 = 0.0%) or the extent of microvascular obstruction (n = 3; WMD = -0.09; P > 0.05; I2 = 6.0%). This meta-analysis shows that LPoC and/or RPoC improves myocardial salvage and decreases myocardial edema in STEMI patients without affecting final infarct size, left ventricular volume or microvascular obstruction.

Remote Ischemic Postconditioning Protects against Myocardial Ischemia-Reperfusion Injury by Inhibition of the RAGE-HMGB1 Pathway

Background

The aim of the present study was to observe the effect of RAGE-HMGB1 signal pathway on remote ischemic postconditioning in mice with myocardial ischemia reperfusion injury.

Methods

Mice model of MIRI was established and randomly divided into three groups: control group, ischemia reperfusion group, and remote ischemic postconditioning group. Infarction size was detected by Evans blue and TTC staining. Cardiac function was detected by echocardiography measurement. The protein levels of RAGE, HMGB1, P-AKT, and ERK1/2 were detected by Western blot 120 min following reperfusion.

Results

RIPostC could decrease the infarct size and increase LVEF and FS compared with I/R group. Two hours after myocardial ischemia reperfusion, the levels of RAGE and HMGB1 were significantly decreased in RIPostC group compared with those in I/R group. The level of p-AKT was significantly higher in the RIPostC group than in the I/R group. LY294002 significantly attenuated RIPostC-increased levels of Akt phosphorylation.

Conclusion

RIPostC may inhibit the expression of RAGE and HMGB1 and activate PI3K/Akt signaling pathway to extenuate ischemic reperfusion injury in mice. It could further suppress the oxidative stress, have antiapoptosis effect, and reduce inflammatory reaction, but this effect has certain timeliness.

A systematic review and meta-analysis evaluating ischemic conditioning during percutaneous coronary intervention

AIM

A systematic review and meta-analysis, evaluating ischemic conditioning during percutaneous coronary intervention (PCI).

METHODS & RESULTS

A database search of randomized trials of ischemic conditioning in PCI created three subgroups for meta-analysis: mortality in elective PCI with remote ischemic preconditioning (RIPreC; subgroup 1a, n = 3) - no outcome difference between RIPreC and control (odds ratio: 0.34; 95% CI: 0.08-1.56), myocardial salvage index in ST-elevation myocardial infarction (STEMI) with RIPreC (subgroup 1b, n = 2) - favored RIPreC (mean difference: 0.13; 95% CI: 0.07-0.19), and infarct size in STEMI with local ischemic postconditioning (LIPostC) (subgroup 4b, n = 12) - favored LIPostC (mean difference: -4.13 g.m^-2; 95% CI: -7.36 to -0.90 g.m^-2).

CONCLUSION

RIPreC and LIPostC improve myocardial salvage index and myocardial infarct size respectively in PCI for STEMI. No mortality benefit detected with RIPreC in elective PCI.

Effect of Remote Ischemic Preconditioning on Perioperative Cardiac Events in Patients Undergoing Elective Percutaneous Coronary Intervention: A Meta-Analysis of 16 Randomized Trials

Background

The main objective of this meta-analysis was to investigate whether remote ischemic preconditioning (RIPC) reduces cardiac and renal events in patients undergoing elective cardiovascular interventions.

Methods and Results

We systematically searched articles published from 2006 to 2016 in PubMed, EMBASE, Web of Science, Cochrane Library, and Google Scholar. Odds ratios (ORs) with 95% confidence intervals (CIs) were used as the effect index for dichotomous variables. The standardized mean differences (SMDs) with 95% CIs were calculated as the pooled continuous effect. Sixteen RCTs of 2435 patients undergoing elective PCI were selected. Compared with control group, RIPC could significantly reduce the incidence of perioperative myocardial infarction (OR = 0.64; 95% CI: 0.48–0.86; P = 0.003) and acute kidney injury (OR = 0.56; 95% CI: 0.322–0.99; P = 0.049). Metaregression analysis showed that the reduction of PMI by RIPC was enhanced for CAD patients with multivessel disease (coef.: −0.05 [−0.09; −0.01], P = 0.022). There were no differences in the changes of cTnI (P = 0.934) and CRP (P = 0.075) in two groups.

Conclusion

Our meta-analysis of RCTs demonstrated that RIPC can provide cardiac and renal protection for patients undergoing elective PCI, while no beneficial effect on reducing the levels of cTnI and CRP after PCI was reported.

Revisiting myocardial necrosis biomarkers: assessment of the effect of conditioning therapies on infarct size by kinetic modelling

Infarct size is a major predictor of subsequent cardiovascular events following ST-segment elevation myocardial infarction (STEMI) and is frequently used in clinical trials focused on cardioprotection. Approximately assessed through serial blood sampling, it can be accurately measured by imaging techniques, e.g. cardiac magnetic resonance imaging, which is the actual gold standard for infarct size determination but with limited availability in daily practice. We developed a mathematical biomarker kinetic model based on pharmacokinetic compartment models to easily and accurately estimate infarct size using individual data from five clinical trials evaluating the impact of conditioning therapies in STEMI between 2005 and 2013. Serial blood sampling was available in all studies with data regarding creatine kinase (CK), CK specific of cardiomyocytes (CK-MB) and cardiac troponin I. Our model allowed an accurate estimation of biomarker release as a surrogate marker of infarct size and a powerful assessment of conditioning treatments. This biomarker kinetic modelling approach identified CK-MB as the most accurate biomarker in determining infarct size and supports the development of limited sampling strategies that estimate total biomarker amount released with a lower number of samples. It will certainly be a useful add-on to future studies in the field of STEMI and cardioprotection.