Cardioprotective effect of remote ischemic preconditioning with postconditioning on donor hearts in patients undergoing heart transplantation: a single-center, double-blind, randomized controlled trial.

BACKGROUND: The cardioprotective effect of remote ischemic preconditioning (RIPC) in cardiovascular surgery is controversial. This study investigated whether RIPC combined with remote ischemic postconditioning (RIPostC) reduces myocardial injury to donor hearts in patients undergoing heart transplantation. METHODS: One hundred and twenty patients scheduled for orthotopic heart transplantation were enrolled and randomly assigned to an RIPC+RIPostC group (n = 60) or a control (n = 60) group. In the RIPC+RIPostC group, after anesthesia induction, four cycles of 5-min of ischemia and 5-min of reperfusion were applied to the right upper limb by a cuff inflated to 200 mmHg (RIPC) and 20 min after aortic declamping (RIPostC). Serum cardiac troponin I (cTnI) levels were determined preoperatively and at 3, 6, 12, and 24 h after aortic declamping. Postoperative clinical outcomes were recorded. The primary endpoint was a comparison of serum cTnI levels at 6 h after aortic declamping. RESULTS: Compared with the preoperative baseline, in both groups, serum cTnI levels peaked at 6 h after aortic declamping. Compared with the control group, RIPC+RIPostC significantly reduced serum cTnI levels at 6 h after aortic declamping (38.87 ± 31.81 vs 69.30 ± 34.13 ng/ml, P = 0.02). There were no significant differences in in-hospital morbidity and mortality between the two groups. CONCLUSION: In patients undergoing orthotopic heart transplantation, RIPC combined with RIPostC reduced myocardial injury at 6 h after aortic declamping, while we found no evidence of this function provided by RIPC+RIPostC could improve clinical outcomes. TRIAL REGISTRATION: Trial Registration Number: chictr.org.cn . no. ChiCTR-INR-16010234 (prospectively registered). The initial registration date was 9/1/2017.

Time to Give Up on Cardioprotection? A Critical Appraisal of Clinical Studies on Ischemic Pre-, Post-, and Remote Conditioning.

The mortality from acute myocardial infarction (AMI) remains significant, and the prevalence of post-myocardial infarction heart failure is increasing. Therefore, cardioprotection beyond timely reperfusion is needed. Conditioning procedures are the most powerful cardioprotective interventions in animal experiments. However, ischemic preconditioning cannot be used to reduce infarct size in patients with AMI because its occurrence is not predictable; several studies in patients undergoing surgical coronary revascularization report reduced release of creatine kinase and troponin. Ischemic postconditioning reduces infarct size in most, but not all, studies in patients undergoing interventional reperfusion of AMI, but may require direct stenting and exclusion of patients with >6 hours of symptom onset to protect. Remote ischemic conditioning reduces infarct size in patients undergoing interventional reperfusion of AMI, elective percutaneous or surgical coronary revascularization, and other cardiovascular surgery in many, but not in all, studies. Adequate dose-finding phase II studies do not exist. There are only 2 phase III trials, both on remote ischemic conditioning in patients undergoing cardiovascular surgery, both with neutral results in terms of infarct size and clinical outcome, but also both with major problems in trial design. We discuss the difficulties in translation of cardioprotection from animal experiments and proof-of-concept trials to clinical practice. Given that most studies on ischemic postconditioning and all studies on remote ischemic preconditioning in patients with AMI reported reduced infarct size, it would be premature to give up on cardioprotection.

Time-course Study on Left Ventricular Function in a Rabbit Model of Ischemia-reperfusion Injury With Morphine Preconditioning.

AIMS: To analyze the left ventricular longitudinal function in a rabbit model of myocardial ischemia reperfusion with morphine preconditioning through strain rate imaging and to evaluate the effect of morphine preconditioning. METHODS: A myocardial ischemia-reperfusion model was induced by occlusion and recanalization of the coronary artery in 40 male New Zealand white rabbits, which were divided into a sham group, morphine group, and vehicle control group. Routine echocardiography data were recorded 1 day before and within 28 days after the operation. Dynamic images were also collected and analyzed off-line using Doppler tissue imaging software. RESULTS: On the first day after the operation, the global and regional systolic functions of the left ventricle in the morphine and vehicle control groups were lower than those in the sham group. After ischemia reperfusion, some of the values of the above-mentioned parameters decreased over time, which was more obvious in the vehicle control group at each examined time point. CONCLUSIONS: The current study revealed that detection of changes in regional myocardial function after myocardial ischemia reperfusion by strain rate imaging is objective and accurate. In addition, our results indicated that morphine preconditioning significantly attenuates myocardial ischemia-reperfusion injury in rabbits.

9th Hatter Biannual Meeting: position document on ischaemia/reperfusion injury, conditioning and the ten commandments of cardioprotection.

In the 30 years since the original description of ischaemic preconditioning, understanding of the pathophysiology of ischaemia/reperfusion injury and concepts of cardioprotection have been revolutionised. In the same period of time, management of patients with coronary artery disease has also been transformed: coronary artery and valve surgery are now deemed routine with generally excellent outcomes, and the management of acute coronary syndromes has seen decade on decade reductions in cardiovascular mortality. Nonetheless, despite these improvements, cardiovascular disease and ischaemic heart disease in particular, remain the leading cause of death and a significant cause of long-term morbidity (with a concomitant increase in the incidence of heart failure) worldwide. The need for effective cardioprotective strategies has never been so pressing. However, despite unequivocal evidence of the existence of ischaemia/reperfusion in animal models providing a robust rationale for study in man, recent phase 3 clinical trials studying a variety of cardioprotective strategies in cardiac surgery and acute ST-elevation myocardial infarction have provided mixed results. The investigators meeting at the Hatter Cardiovascular Institute workshop describe the challenge of translating strong pre-clinical data into effective clinical intervention strategies in patients in whom effective medical therapy is already altering the pathophysiology of ischaemia/reperfusion injury-and lay out a clearly defined framework for future basic and clinical research to improve the chances of successful translation of strong pre-clinical interventions in man.

Myocardial conditioning: opportunities for clinical translation.

Myocardial conditioning is an endogenous cardioprotective phenomenon that profoundly limits infarct size in experimental models. The current challenge is to translate this paradigm from the laboratory to the clinic. Accordingly, our goal in this review is to provide a critical summary of the progress toward, opportunities for, and caveats to, the successful clinical translation of postconditioning and remote conditioning, the 2 conditioning strategies considered to have the broadest applicability for real-world patient care. In the majority of phase II studies published to date, postconditioning evoked a ≈35% reduction of infarct size in ST-segment-elevation myocardial infarction patients. Essential criteria for the successful implementation of postconditioning include the appropriate choice of patients (ie, those with large risk regions and negligible collateral flow), timely application of the postconditioning stimulus (immediately on reperfusion), together with proper choice of end points (infarct size, with concomitant assessment of risk region). Remote conditioning has been applied in planned ischemic events (including cardiac surgery and elective percutaneous coronary intervention) and in ST-segment-elevation myocardial infarction patients during hospital transport. Controversies with regard to efficacy have emerged, particularly among surgical trials. These disparate outcomes in all likelihood reflect the remarkable heterogeneity within and among studies, together with a deficit in our understanding of the impact of these variations on the infarct-sparing effect of remote conditioning. Ongoing phase III trials will provide critical insight into the future role of postconditioning and remote conditioning as clinically relevant cardioprotective strategies.

The Year in Cardiology 2013: coronary intervention.

The year 2013 was rich of new developments in cardiology, and percutaneous coronary intervention (PCI) in particular. This overview article will focus on contributions in the following areas: training for PCI, appropriateness and indications; access site selection, risk scores, peri-procedural myocardial infarction; trial results and long-term follow-up; PCI for specific patient and lesion subsets, including acute coronary syndrome and ST-segment myocardial infarction; prevention of ischemic and reperfusion injury; stent thrombosis and new coronary stents and scaffolds.

Remote ischemic preconditioning does not affect the incidence of acute kidney injury after elective abdominal aortic aneurysm repair.

OBJECTIVE: Open abdominal aortic aneurysm (AAA) repair is associated with a high risk of renal injury with few known strategies demonstrating a reduction in this risk. Remote ischemic preconditioning (RIPC) has been identified as having the potential to minimize organ injury following major vascular surgery. This trial investigated the potential for RIPC to attenuate renal and myocardial injury in patients undergoing elective open AAA repair. DESIGN: Prospective, randomized double-blinded control trial. SETTING: Tertiary referral hospital. PARTICIPANTS: Sixty-two patients undergoing elective open AAA repair. INTERVENTION: RIPC was achieved via three 5-minute cycles of upper limb ischemia using a blood pressure cuff or control (sham cuff). MEASUREMENTS: Primary outcome was the occurrence of renal injury, as measured by an increase in creatinine during the first 4 postoperative days. Secondary outcomes included urinary neutrophil-gelatinase-associated lipocalin (NGAL), occurrence of acute kidney injury (AKI), occurrence of myocardial injury as defined by troponin rise, incidence of postoperative complications, and mortality. There was no difference in postoperative creatinine levels, NGAL levels, or the occurrence of AKI between the groups at any postoperative time point. Similarly, there was no difference in the occurrence of myocardial injury or mortality. Of note, 6 patients in the RIPC group, while no patient in the control group, experienced postoperative complications that required repeat surgical laparotomy, potentially masking any renoprotective effects of RIPC. CONCLUSION: RIPC did not reduce the risk of postoperative renal failure or myocardial injury in patients undergoing open AAA repair. The authors' results do not support the introduction of this technique to routine clinical practice.

[Cardioprotective effect of remote postconditioning: mechanisms and possibility of clinical application].

Experimental data indicate that postconditioning at distance is an effective method of cardiac protection against reperfusion injury. Remote postconditioning prevents reperfusion necrosis and apoptosis of cardiomyocytes, decreases probability of postinfarction remodeling of the heart. Cardioprotective effect of remote postconditioning is depended on release from tissues after transient ischemia of humoral factor(s) increasing cardiac tolerance to long-term ischemia-reperfusion. Clinical studies show that postconditioning at distance is an effective method of prevention of reperfusion injury of the heart during coronary artery bypass surgery.

Role of microRNAs in cardiac preconditioning.

Preconditioning (PC) of the heart by sublethal ischemia, mild heat shock, or hypoxia has evolved as a powerful experimental tool to discover novel signaling mechanisms in cardioprotection. The ultimate goal is to determine novel therapeutic targets for potential application in humans to protect the heart against ischemia-related injuries. In recent years, there has been a tremendous interest in understanding the role of small noncoding RNAs, microRNAs (miRs), in cardiovascular diseases. miRs have been recognized as regulators of gene expression by destabilization and translational inhibition of target messenger RNAs. Studies have shown that several miRs, including miR-1, miR-133, miR-21, miR-126, miR-320, miR-92a, and miR-199a, are regulated after preconditioning and play an active role in protecting the heart against ischemia/reperfusion injury. These miRs also drive the synthesis of important cardioprotective proteins including heat shock protein (HSP)-70, endothelial nitric oxide synthase, inducible nitric oxide synthase, HSP-20, Sirt1, and hypoxia-inducible factor 1a. We believe that identification and targeted delivery of miR(s) in the heart could have an immense therapeutic potential in reducing myocardial infarction in patients suffering from heart disease.

Making the heart resistant to infarction: how can we further decrease infarct size?

Acute myocardial infarction (AMI) following coronary artery occlusion is a common cause of mortality and morbidity world-wide. Patients currently receive reperfusion therapy as the only anti-infarct intervention. A number of agents have been evaluated to further improve myocardial salvage, but until recently, none has demonstrated clear efficacy in clinical trials. A new target of cardioprotection, the Reperfusion Injury Salvage Kinase (RISK) pathway, has been proposed. These kinases are involved in mediating the cardioprotection of myocardial preconditioning and postconditioning induced by short non-lethal cycles of ischemia/reperfusion performed before (preconditioning) or just after (postconditioning) a lethal ischemic insult. Many pharmacological interventions are now available that protect the heart by activating the RISK pathway at the time of reperfusion. The present review will examine the efficacy of several strategies that have been proposed to protect the acutely ischemic myocardium including (1) those intended to directly alter adverse reperfusion events (e.g., calcium overload and free radical attack), (2) those based on activation of the RISK pathway including postconditioning, and (3) myocardial cooling.

The EUROpean and Chinese cardiac and renal Remote Ischemic Preconditioning Study (EURO-CRIPS CardioGroup I): A randomized controlled trial.

BACKGROUND: The potential protective effects of remote ischemic preconditioning (RIPC) on contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) remain to be defined. METHODS AND RESULTS: A double blind, randomized, placebo controlled multicenter study was performed. Patients younger than 85years old, with a renal clearance of 30-60ml/min/1.73m2, who were candidates for PCI for all clinical indications except for primary PCI, were allocated 1:1 to RIPC or to standard therapy. The primary endpoint was incidence of CIN. The secondary endpoint was incidence of peri-procedural myocardial infarction (PMI). From February 2013 to April 2014, 3108 patients who were scheduled for coronary angiography were screened for the study. 442 fulfilled the inclusion criteria and 223 received PCI. These patients were randomized to sham RIPC (n=107) or treatment group (n=116). The only pre-specified subgroup of diabetic patients included 85 (38%) cases. RIPC significantly reduced CIN incidence in the overall population (12.1% vs. 26.1%, p=0.01, with a NNT=9) and in non-diabetic patients (9.2% vs. 25.0%, p=0.02), but showed no benefit in diabetics (16.7% vs. 28.2%, p=0.21). A trend for lower PMI was seen in the intervention arm (creatine kinase - muscle brain >5 URL; 8.4% vs. 16.4%, p=0.07; troponin T >5 URL; 27% vs. 38%, p=0.21). CONCLUSIONS: Remote ischemic preconditioning significantly reduces the incidence of acute kidney injury in non-diabetic patients undergoing PCI. Larger sample size is presumably needed to assess the effect of RIPC for patients with diabetes mellitus. Clinical Trial number:NCT02195726https://www.clinicaltrial.gov/.

Cardioprotective signalling: Past, present and future.

A few decades ago, cardiac muscle was discovered to possess signalling pathways that, when activated, protect the myocardium against the damage induced by ischaemia-reperfusion. The ability of cardiac muscle to protect itself against injury has been termed 'cardioprotection'. Many compounds and procedures can trigger cardioprotection including conditionings (exposure to brief episodes of ischaemia-reperfusion to protect against sustained ischaemia-reperfusion), hypoxia, adenosine, acetylcholine, adrenomedullin, angiotensin, bradykinin, catecholamines, endothelin, estrogens, phenylephrine, opioids, testosterone, and many more. These triggers activate many intracellular signalling factors including protein kinases, different enzymes, transcription factors and defined signalling pathways to target structures in mitochondria, sarcoplasmic reticulum, nucleus and sarcolemma to mediate cardioprotection. Although a lot of information about cardioprotection has been acquired, there are still two major outstanding issues to be addressed in the future 1) better understanding of spatio-temporal relationships between signalling elements, and; 2) devising therapeutic strategies against myocardial diseases based on cardioprotective signalling. Further research is required to paint integral picture of cardioprotective signalling and more clinical studies are required to properly test clinical efficacy and safety of potential cardioprotective strategies. Therapies against cardiac diseases based on cardioprotective strategies would be a perfect adjunct to current therapeutic strategies based on restitution of coronary blood flow and regulation of myocardial metabolic demands.

Impact of remote ischaemic preconditioning on major clinical outcomes in patients undergoing cardiovascular surgery: A meta-analysis with trial sequential analysis of 32 randomised controlled trials.

BACKGROUND: The impact of remote ischaemic preconditioning (RIPC) on major clinical outcomes in patients undergoing cardiovascular surgery remains controversial. We systematically reviewed the available evidence to evaluate the potential benefits of RIPC in such patients. METHODS: PubMed, Embase, and Cochrane Library databases were searched for relevant randomised controlled trials (RCTs) conducted between January 2006 and March 2016. The pooled population of patients who underwent cardiovascular surgery was divided into the RIPC and control groups. Trial sequential analysis was applied to judge data reliability. The pooled relative risks (RRs) with 95% confidence intervals (CIs) between the groups were calculated for all-cause mortality, major adverse cardiovascular and cerebral events (MACCEs), myocardial infarction (MI), and renal failure. RESULTS: RIPC was not associated with improvement in all-cause mortality (RR, 1.04; 95%CI, 0.82-1.31; I2=26%; P>0.05) or MACCE incidence (RR, 0.90; 95%CI, 0.71-1.14; I2=40%; P>0.05) after cardiovascular surgery, and both results were assessed by trial sequential analysis as sufficient and conclusive. Nevertheless, RIPC was associated with a significantly lower incidence of MI (RR, 0.87; 95%CI, 0.76-1.00; I2=13%; P≤0.05). However, after excluding a study that had a high contribution to heterogeneity, RIPC was associated with increased rates of renal failure (RR, 1.53; 95%CI, 1.12-2.10; I2=5%; P≤0.05). CONCLUSIONS: In patients undergoing cardiovascular surgery, RIPC reduced the risk for postoperative MI, but not that for MACCEs or all-cause mortality, a discrepancy likely related to the higher rate of renal failure associated with RIPC.

Renoprotection by remote ischemic conditioning during elective coronary revascularization: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Remote ischemic conditioning (RIC) has been recognized an emerging non-invasive approach for preventing acute kidney injury (AKI) in patients undergoing either elective coronary artery bypass graft (CABG) surgery or percutaneous coronary intervention (PCI). On the other hand, accumulating evidence has indicated the involving role of pre-CABG contrast usage for coronary angiography in post-surgery AKI risk. Along with the shortening time delay of CABG after coronary angiography, and the prevalent hybrid coronary revascularization (HCR), the AKI prevention by RIC has faced challenges following coronary revascuralization. METHODS: Randomized controlled trials (RCTs) were searched from Pubmed, EMBase, and Cochrane library (until May 2016). The primary outcome was postoperative AKI. The second outcomes were included the requirement for renal replacement therapy (RRT), and in-hospital or 30-day mortality. RESULTS: Twenty eligible RCTs (CABG, 3357 patients; PCI, 1501 patients) were selected. RIC significantly halved the incidence of AKI following PCI when compared with controls [n=1501; odds ratio (OR)=0.51; 95% CI, 0.32 to 0.82; P=0.006; I(2)=29.6%]. However, RIC did not affect the incidence of AKI following CABG (n=1850; OR=0.94; 95% CI, 0.73 to 1.19; P=0.586; I(2)=12.4%). The requirement for RRT and in-hospital mortality was not affected by RIC in CABG (n=2049, OR=1.04, P=0.87; n=1920, OR=0.89, P=0.7; respectively). CONCLUSIONS: Our meta-analysis suggests that RIC for preventing AKI following CABG has faced with challenges in terms of AKI, the requirement for RRT, and mortality. However, RIC shows a renoprotective benefit for PCI. Hence, our findings may infer the preserved renal effects of RIC in CABG with preconditioning before the coronary angiography, or in HCR.

Myocardial ischemia and reperfusion injury.

Myocardial ischemic injury results from severe impairment of coronary blood supply and produces a spectrum of clinical syndromes. As a result of intensive investigation over decades, a detailed understanding is now available of the complexity of the response of the myocardium to an ischemic insult. Myocardial ischemia results in a characteristic pattern of metabolic and ultrastructural changes that lead to irreversible injury. Recent studies have explored the relationship of myocardial ischemic injury to the major modes of cell death, namely, oncosis and apoptosis. The evidence indicates that apoptotic and oncotic mechanisms can proceed together in ischemic myocytes with oncotic mechanisms and morphology dominating the end stage of irreversible injury. Myocardial infarcts evolve as a wavefront of necrosis, extending from subendocardium to subepicardium over a 3- to 4-hour period. A number of processes can profoundly influence the evolution of myocardial ischemic injury. Timely reperfusion produces major effects on ischemic myocardium, including a component of reperfusion injury and a greater amount of salvage of myocardium. Preconditioning by several short bouts of coronary occlusion and reperfusion can temporarily salvage significant amounts of myocardium and extend the window of myocardial viability. Ongoing research into the mechanisms involved in reperfusion and preconditioning is yielding new insights into basic myocardial pathobiology.

Opioid-induced preconditioning: recent advances and future perspectives.

Opioids, named by Acheson for compounds with morphine-like actions despite chemically distinct structures, have received much research interest, particularly for their central nervous system (CNS) actions involved in pain management, resulting in thousands of scientific papers focusing on their effects on the CNS and other organ systems. A more recent area which may have great clinical importance concerns the role of opioids, either endogenous or exogenous compounds, in limiting the pathogenesis of ischemia-reperfusion injury in heart and brain. The role of endogenous opioids in hibernation provides tantalizing evidence for the protective potential of opioids against ischemia or hypoxia. Mammalian hibernation, a distinct energy-conserving state, is associated with depletion of energy stores, intracellular acidosis and hypoxia, similar to those which occur during ischemia. However, despite the potentially detrimental cellular state induced with hibernation, the myocardium remains resilient for many months. What accounts for the hypoxia-tolerant state is of great interest. During hibernation, circulating levels of opioid peptides are increased dramatically, and indeed, are considered a "trigger" of hibernation. Furthermore, administration of opioid antagonists can effectively reverse hibernation in mammals. Therefore, it is not surprising that activation of opioid receptors has been demonstrated to preserve cellular status following a hypoxic insult, such as ischemia-reperfusion in many model systems including the intestine [Zhang, Y., Wu, Y.X., Hao, Y.B., Dun, Y. Yang, S.P., 2001. Role of endogenous opioid peptides in protection of ischemic preconditioning in rat small intestine. Life Sci. 68, 1013-1019], skeletal muscle [Addison, P.D., Neligan, P.C., Ashrafpour, H., Khan, A., Zhong, A., Moses, M., Forrest, C.R., Pang, C.Y., 2003. Noninvasive remote ischemic preconditioning for global protection of skeletal muscle against infarction. Am. J. Physiol. Heart Circ. Physiol. 285, H1435-H1443], the CNS [Borlongan, C.V., Wang, Y., Su, T.P., 2005. Delta opioid peptide (d-ala 2, d-leu 5) enkephalin: linking hiberation and neuroprotection. Front Biosci. 9, 3392-3398] and the myocardium [Romano, M.A., Seymour, E.M., Berry, J.A., McNish, R.A., Bolling, S.F., 2004. Relative contribution of endogenous opioids to myocardial ischemic tolerance. J Surg Res. 118, 32-37; Peart, J.N., Gross, G.J., 2004a. Exogenous activation of delta- and kappa-opioid receptors affords cardioprotection in isolated murine heart. Basic Res Cardiol. 99(1), 29-37]. For the purpose of this review, we will focus primarily on the protective effects of opioids against post-reperfusion myocardial stunning and infarction.

Mechanisms by which K(ATP) channel openers produce acute and delayed cardioprotection.

Mitochondria are being increasingly studied for their critical role in cell survival. Multiple diverse signaling pathways have been shown to converge on the K+-sensitive ATP channels as the effectors of cytoprotection against necrosis and apoptosis. The role of potassium channel openers in regulation and transformation of cell membrane excitability, action potential and electrolyte transfer has been extensively studied. Cardiac mitoK(ATP) channels are the key effectors in cardioprotection during ischemic preconditioning, as yet with an undefined mechanism. They have been hypothesized to couple myocardial metabolism with membrane electrical activity and provide an excellent target for drug therapy. A number of K(ATP) channel openers have been characterized for their beneficial effects on the myocardium against ischemic injury. This review updates recent progress in understanding the physiological role of K(ATP) channels in cardiac protection induced by preconditioning and highlights relevant questions and controversies in the light of published data.

Cardioprotection by volatile anesthetics.

Preconditioning describes a very powerful endogenous mechanism by which the heart may be protected against ischemia and reperfusion injury. Transient administration of a volatile anesthetic before a prolonged ischemic episode reduces myocardial infarct size to a degree comparable to that observed during ischemic preconditioning. Many components of the signal transduction pathways responsible for cardioprotection are shared by anesthetic and ischemic preconditioning. Exposure to volatile anesthetics generates small "triggering" quantities of reactive oxygen species (ROS) by directly interacting with the mitochondrial electron transport chain or indirectly through a signaling cascade in which G-protein-coupled receptors, protein kinases, and mitochondrial ATP-sensitive potassium (K(ATP)) channels play important roles. Several clinical studies also suggest that preconditioning by volatile anesthetics exerts beneficial effects in patients undergoing cardiac surgery. This review summarizes some of the recent major developments in the understanding of cardioprotection by volatile anesthetics.