Long-term effects of ischemic postconditioning on clinical outcomes: 1-year follow-up of the POST randomized trial

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.

A Novel Reperfusion Strategy for Primary Percutaneous Coronary Intervention in Patients with Acute ST-Segment Elevation Myocardial Infarction: A Prospective Case Series

BACKGROUND

Ischemia reperfusion injury (IRI) remains a major problem in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). We have developed a novel reperfusion strategy for PCI and named it "volume-controlled reperfusion (VCR)". The aim of the current study was to assess the safety and feasibility of VCR in patients with STEMI.

METHODS

Consecutive patients admitted to Beijing Chaoyang Hospital with STEMI were prospectively enrolled. The feasibility endpoint was procedural success. The safety endpoints included death from all causes, major vascular complications, and major adverse cardiac event (MACE), i.e., a composite of cardiac death, myocardial reinfarction, target vessel revascularization (TVR), and heart failure.

RESULTS

A total of 30 patients were finally included. Procedural success was achieved in 28 (93.3%) patients. No patients died during the study and no major vascular complications or MACE occurred during hospitalization. With the exception of one patient (3.3%) who underwent TVR three months after discharge, no patient encountered death (0.0%), major vascular complications (0.0%), or and other MACEs (0.0%) during the median follow-up of 16 months.

CONCLUSION

The findings of the pilot study suggest that VCR has favorable feasibility and safety in patients with STEMI. Further larger randomized trials are required to evaluate the effectiveness of VCR in STEMI patients.

Ischemic Preconditioning and Postconditioning Protect the Heart by Preserving the Mitochondrial Network

Background

Mitochondria fuse to form elongated networks which are more tolerable to stress and injury. Ischemic pre- and postconditioning (IPC and IPost, respectively) are established cardioprotective strategies in the preclinical setting. Whether IPC and IPost modulates mitochondrial morphology is unknown. We hypothesize that the protective effects of IPC and IPost may be conferred via preservation of mitochondrial network.

Methods

IPC and IPost were applied to the H9c2 rat myoblast cells, isolated adult primary murine cardiomyocytes, and the Langendorff-isolated perfused rat hearts. The effects of IPC and IPost on cardiac cell death following ischemia-reperfusion injury (IRI), mitochondrial morphology, and gene expression of mitochondrial-shaping proteins were investigated.

Results

IPC and IPost successfully reduced cardiac cell death and myocardial infarct size. IPC and IPost maintained the mitochondrial network in both H9c2 and isolated adult primary murine cardiomyocytes. 2D-length measurement of the 3 mitochondrial subpopulations showed that IPC and IPost significantly increased the length of interfibrillar mitochondria (IFM). Gene expression of the pro-fusion protein, Mfn1, was significantly increased by IPC, while the pro-fission protein, Drp1, was significantly reduced by IPost in the H9c2 cells. In the primary cardiomyocytes, gene expression of both Mfn1 and Mfn2 were significantly upregulated by IPC and IPost, while Drp1 was significantly downregulated by IPost. In the Langendorff-isolated perfused heart, gene expression of Drp1 was significantly downregulated by both IPC and IPost.

Conclusion

IPC and IPost-mediated upregulation of pro-fusion proteins (Mfn1 and Mfn2) and downregulation of pro-fission (Drp1) promote maintenance of the interconnected mitochondrial network, ultimately conferring cardioprotection against IRI.

Controlling Reperfusion Injury With Controlled Reperfusion: Historical Perspectives and New Paradigms

Cardiac reperfusion injury is a well-established outcome following treatment of acute myocardial infarction and other types of ischemic heart conditions. Numerous cardioprotection protocols and therapies have been pursued with success in pre-clinical models. Unfortunately, there has been lack of successful large-scale clinical translation, perhaps in part due to the multiple pathways that reperfusion can contribute to cell death. The search continues for new cardioprotection protocols based on what has been learned from past results. One class of cardioprotection protocols that remain under active investigation is that of controlled reperfusion. This class consists of those approaches that modify, in a controlled manner, the content of the reperfusate or the mechanical properties of the reperfusate (e.g., pressure and flow). This review article first provides a basic overview of the primary pathways to cell death that have the potential to be addressed by various forms of controlled reperfusion, including no-reflow phenomenon, ion imbalances (particularly calcium overload), and oxidative stress. Descriptions of various controlled reperfusion approaches are described, along with summaries of both mechanistic and outcome-oriented studies at the pre-clinical and clinical phases. This review will constrain itself to approaches that modify endogenously-occurring blood components. These approaches include ischemic postconditioning, gentle reperfusion, controlled hypoxic reperfusion, controlled hyperoxic reperfusion, controlled acidotic reperfusion, and controlled ionic reperfusion. This review concludes with a discussion of the limitations of past approaches and how they point to potential directions of investigation for the future.

Ischemia From Nonculprit Stenoses Is Not Associated With Reduced Culprit Infarct Size in Patients with ST-Segment-Elevation Myocardial Infarction

BACKGROUND

In patients with ST-segment-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention, reperfusion injury accounts for a significant fraction of the final infarct size, which is directly related to patient prognosis. In animal studies, brief periods of ischemia in noninfarct-related (nonculprit) coronary arteries protect the culprit myocardium via remote ischemic preconditioning. Positive fractional flow reserve (FFR) documents functional significant coronary nonculprit stenosis, which may offer remote ischemic preconditioning of the culprit myocardium. The aim of the study was to investigate the association between functional significant, multivessel disease (MVD) and reduced culprit final infarct size or increased myocardial salvage (myocardial salvage index [MSI]) in a large contemporary cohort of STEMI patients.

METHODS

Cardiac magnetic resonance was performed in 610 patients with STEMI at day 1 and 3 months after primary percutaneous coronary intervention. Patients were stratified into 3 groups according to FFR measurements in nonculprit stenosis (if any): angiographic single vessel disease (SVD), FFR nonsignificant MVD (functional SVD), or FFR-significant, functional MVD.

RESULTS

A total of 431 (71%) patients had SVD, 35 (6%) had functional SVD, and 144 (23%) had functional MVD. There was no difference in final infarct size (mean infarct size [%left ventricular mass] SVD, 9±3%; functional SVD, 9±3%; and functional MVD, 9±3% [P=0.82]) or in MSI between groups (mean MSI [%left] SVD, 66±23%; functional SVD, 68±19%; and functional MVD, 69±19% [P=0.62]). In multivariable analyses, functional MVD was not associated with larger MSI (P=0.56) or smaller infarct size (P=0.55).

CONCLUSIONS

Functional MVD in nonculprit myocardium was not associated with reduced culprit final infarct size or increased MSI following STEMI. This is important knowledge for future studies examining a cardioprotective treatment in patients with STEMI, as a possible confounding effect of FFR-significant, functional MVD can be discarded. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01435408 (DANAMI 3-iPOST and DANAMI 3-DEFER) and NCT01960933 (DANAMI 3-PRIMULTI).

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.

NHLBI-Sponsored Randomized Trial of Postconditioning During Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction

RATIONALE

Postconditioning at the time of primary percutaneous coronary intervention (PCI) for ST-segment-elevation myocardial infarction may reduce infarct size and improve myocardial salvage. However, clinical trials have shown inconsistent benefit.

OBJECTIVE

We performed the first National Heart, Lung, and Blood Institute-sponsored trial of postconditioning in the United States using strict enrollment criteria to optimize the early benefits of postconditioning and assess its long-term effects on left ventricular (LV) function.

METHODS AND RESULTS

We randomized 122 ST-segment-elevation myocardial infarction patients to postconditioning (4, 30 seconds PTCA [percutaneous transluminal coronary angioplasty] inflations/deflations)+PCI (n=65) versus routine PCI (n=57). All subjects had an occluded major epicardial artery (thrombolysis in myocardial infarction=0) with ischemic times between 1 and 6 hours with no evidence of preinfarction angina or collateral blood flow. Cardiac magnetic resonance imaging measured at 2 days post-PCI showed no difference between the postconditioning group and control in regards to infarct size (22.5±14.5 versus 24.0±18.5 g), myocardial salvage index (30.3±15.6% versus 31.5±23.6%), or mean LV ejection fraction. Magnetic resonance imaging at 12 months showed a significant recovery of LV ejection fraction in both groups (61.0±11.4% and 61.4±9.1%; P<0.01). Subjects randomized to postconditioning experienced more favorable remodeling over 1 year (LV end-diastolic volume =157±34 to 150±38 mL) compared with the control group (157±40 to 165±45 mL; P<0.03) and reduced microvascular obstruction ( P=0.05) on baseline magnetic resonance imaging and significantly less adverse LV remodeling compared with control subjects with microvascular obstruction ( P<0.05). No significant adverse events were associated with the postconditioning protocol and all patients but one (hemorrhagic stroke) survived through 1 year of follow-up.

CONCLUSIONS

We found no early benefit of postconditioning on infarct size, myocardial salvage index, and LV function compared with routine PCI. However, postconditioning was associated with improved LV remodeling at 1 year of follow-up, especially in subjects with microvascular obstruction.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01324453.

Effects of ischaemic postconditioning on outcomes of patients with ST-segment elevation myocardial infarction who underwent primary percutaneous coronary intervention: a meta-analysis

OBJECTIVE

The aim of this meta-analysis was to evaluate the effects of ischaemic postconditioning (IPC) therapy on hard clinical endpoints in ST-segment elevation myocardial infarction (STEMI) patients who underwent primary percutaneous coronary intervention (PPCI).

DESIGN

Systematic review and meta-analysis to evaluate the effects of IPC on the outcomes of patients with STEMI.

DATA SOURCES

PubMed, Embase and the Cochrane Library were systematically searched for relevant articles published prior to May 1, 2018.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised trials comparing conventional PPCI to PPCI combined with IPC in STEMI patients were included. The primary endpoint was heart failure. Secondary endpoints were all-cause mortality and major adverse cardiac events (MACE), including cardiac death, heart failure and MI. The Cochrane Reviewer's Handbook 4.2 was used to assess the risk of bias.

DATA EXTRACTION AND SYNTHESIS

Relevant data were extracted by two independent investigators. We derived pooled risk ratios (RRs) with random effects models. Sensitivity and subgroup analyses were performed.

RESULTS

Ten studies that had enrolled 3137 patients were included. PPCI combined with IPC failed to reduce heart failure (RR: 0.88, 95% CI: 0.61 to 1.26, p=0.47; absolute risk: 3.64% in the IPC group and 4.11% in the PPCI only group), all-cause mortality (RR: 0.94, 95% CI: 0.69 to 1.27, p=0.68; absolute risk: 5.07% in the IPC group and 5.27% in the PPCI onlygroup), MACE (RR: 1.05, 95% CI: 0.83 to 1.32, p=0.69; absolute risk: 9.37% in the IPC group and 8.93% in the PPCI only group), cardiac death (RR: 1.28, 95% CI: 0.85 to 1.93, p=0.24; absolute risk: 4.28% in the IPC group and 3.25% in the PPCI only group) and MI (RR: 1.08, 95% CI: 0.38 to 3.12, p=0.88; absolute risk: 3.61% in the IPC group and 3.44% in the PPCI only group).

CONCLUSIONS

IPC combined with PPCI does not reduce heart failure, MACE and all-cause mortality compared with traditional PPCI in patients with STEMI.

TRIAL REGISTRATION NUMBER

CRD42017063959.

Transcriptional Alterations by Ischaemic Postconditioning in a Pig Infarction Model: Impact on Microvascular Protection

Although the application of cardioprotective ischaemia/reperfusion (I/R) stimuli after myocardial infarction (MI) is a promising concept for salvaging the myocardium, translation to a clinical scenario has not fulfilled expectations. We have previously shown that in pigs, ischaemic postconditioning (IPostC) reduces myocardial oedema and microvascular obstruction (MVO), without influencing myocardial infarct size. In the present study, we analyzed the mechanisms underlying the IPostC-induced microvascular protection by transcriptomic analysis, followed by pathway analysis. Closed-chest reperfused MI was induced by 90 min percutaneous balloon occlusion of the left anterior descending coronary artery, followed by balloon deflation in anaesthetised pigs. Animals were randomised to IPostC (n = 8), MI (non-conditioned, n = 8), or Control (sham-operated, n = 4) groups. After three hours or three days follow-up, myocardial tissue samples were harvested and subjected to RNA-seq analysis. Although the transcriptome analysis revealed similar expression between IPostC and MI in transcripts involved in cardioprotective pathways, we identified gene expression changes responding to IPostC at the three days follow-up. Focal adhesion signaling, downregulated genes participating in cardiomyopathy and activation of blood cells may have critical consequences for microvascular protection. Specific analyses of the gene subsets enriched in the endothelium of the infarcted area, revealed strong deregulation of transcriptional functional clusters, DNA processing, replication and repair, cell proliferation, and focal adhesion, suggesting sustentative function in the endothelial cell layer protection and integrity. The spatial and time-dependent transcriptome analysis of porcine myocardium supports a protective effect of IPostC on coronary microvasculature post-MI.

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.

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.

Adverse Effects on β-Adrenergic Receptor Coupling: Ischemic Postconditioning Failed to Preserve Long-Term Cardiac Function

BACKGROUND

Ischemic preconditioning (IPC) and ischemic postconditioning (IPoC) are currently among the most efficient strategies protecting the heart against ischemia/reperfusion injury. However, the effect of IPC and IPoC on functional recovery following ischemia/reperfusion is less clear, particularly with regard to the specific receptor-mediated signaling of the postischemic heart. The current article examines the effect of IPC or IPoC on the regulation and coupling of β-adrenergic receptors and their effects on postischemic left ventricular function.

METHODS AND RESULTS

The β-adrenergic signal transduction was analyzed in 3-month-old Wistar rats for each of the intervention strategies (Sham, ischemia/reperfusion, IPC, IPoC) immediately and 7 days after myocardial infarction. Directly after the infarction a cardioprotective potential was demonstrated for both IPC and IPoC: the infarct size was reduced, apoptosis and production of reactive oxygen species were lowered, and the myocardial tissue was preserved. Seven days after myocardial ischemia, only IPC hearts showed significant functional improvement. Along with a deterioration in fractional shortening, IPoC hearts no longer responded adequately to β-adrenergic stimulation. The stabilization of β-adrenergic receptor kinase-2 via increased phosphorylation of Mdm2 (an E3-ubiquitin ligase) was responsible for desensitization of β-adrenergic receptors and identified as a characteristic specific to IPoC hearts.

CONCLUSIONS

Immediately after myocardial infarction, rapid and transient activation of β-adrenergic receptor kinase-2 may be an appropriate means to protect the injured heart from excessive stress. In the long term, however, induction and stabilization of β-adrenergic receptor kinase-2, with the resultant loss of positive inotropic function, leads to the functional picture of heart failure.

SYNTAX Score of Infarct-Related Artery Other Than the Number of Coronary Balloon Inflations and Deflations as an Independent Predictor of Contrast-Induced Acute Kidney Injury in Patients with ST-Segment Elevation Myocardial Infarction

BACKGROUND

Although remote ischemic post-conditioning (RIPC) has been shown to prevent contrast-induced acute kidney injury (CIAKI) in patients with acute coronary syndrome, its efficacy in patients with ST-segment elevation myocardial infarction (STEMI) remains unclear. We examined the relationship among balloon inflations and deflations (BID) times, SYNTAX score of infarction-related artery (SI), periprocedural complications, and CIAKI in STEMI patients undergoing primary percutaneous coronary intervention (pPCI).

METHODS

Patients with STEMI undergoing pPCI with Mehran risk score (MRS) ≥ 5 were enrolled between February 2007 and September 2012. The study end point was the development of CIAKI.

RESULTS

Of 206 patients, the median age was 65 years [interquartile range (IQR): 55-77] with 72.8% male and Mehran risk score (MRS) 8 (IQR: 6-12). Receiver operating characteristic curve showed that BID times > 9 times or SI > 10 was the best cut-off associated with CIAKI. In univariate analysis, significant association with CIAKI existed in BID > 9 times [odds ratio (OR): 3.106, 95% confidence interval (CI): 1.284-7.513, p = 0.012] and SI > 10 (OR: 3.909, 95% CI: 1.570-9.735, p = 0.003). Other variables associated with CIAKI included creatinine, hemoglobin, angiotensin converting enzyme inhibitor or angiotensin receptor blocker use at discharge. In multivariate analysis, SI > 10 remained an independent predictor of CIAKI in different adjustment model, even on top of MRS (adjusted OR: 3.498, 95% CI: 1.086-11.268, p = 0.036).

CONCLUSIONS

Vascular complexity of infarct-related artery rather than higher BID times (> 9) was the major determinant of the development of CIAKI after pPCI in STEMI patients.

In vivo MRI and ex vivo histological assessment of the cardioprotection induced by ischemic preconditioning, postconditioning and remote conditioning in a closed-chest porcine model of reperfused acute myocardial infarction: importance of microvasculature

BACKGROUND

Cardioprotective value of ischemic post- (IPostC), remote (RIC) conditioning in acute myocardial infarction (AMI) is unclear in clinical trials. To evaluate cardioprotection, most translational animal studies and clinical trials utilize necrotic tissue referred to the area at risk (AAR) by magnetic resonance imaging (MRI). However, determination of AAR by MRI' may not be accurate, since MRI-indices of microvascular damage, i.e., myocardial edema and microvascular obstruction (MVO), may be affected by cardioprotection independently from myocardial necrosis. Therefore, we assessed the effect of IPostC, RIC conditioning and ischemic preconditioning (IPreC; positive control) on myocardial necrosis, edema and MVO in a clinically relevant, closed-chest pig model of AMI.

METHODS AND RESULTS

Acute myocardial infarction was induced by a 90-min balloon occlusion of the left anterior descending coronary artery (LAD) in domestic juvenile female pigs. IPostC (6 × 30 s ischemia/reperfusion after 90-min occlusion) and RIC (4 × 5 min hind limb ischemia/reperfusion during 90-min LAD occlusion) did not reduce myocardial necrosis as assessed by late gadolinium enhancement 3 days after reperfusion and by ex vivo triphenyltetrazolium chloride staining 3 h after reperfusion, however, the positive control, IPreC (3 × 5 min ischemia/reperfusion before 90-min LAD occlusion) did. IPostC and RIC attenuated myocardial edema as measured by cardiac T2-weighted MRI 3 days after reperfusion, however, AAR measured by Evans blue staining was not different among groups, which confirms that myocardial edema is not a measure of AAR, IPostC and IPreC but not RIC decreased MVO.

CONCLUSION

We conclude that IPostC and RIC interventions may protect the coronary microvasculature even without reducing myocardial necrosis.

Ischemic postconditioning during primary percutaneous coronary intervention

BACKGROUND

Although some studies have shown potential benefit for ischemic postconditioning (IPoC) during primary percutaneous coronary intervention (PCI) in improving surrogate markers of reperfusion and infarction size, the benefit of this approach on clinical outcomes remains unknown.

METHODS AND RESULTS

Electronic databases were searched for randomized clinical trials that compared IPoC versus conventional treatment during primary PCI. Random effects DerSimonian-Laird risk ratios (RR) were calculated for different clinical and surrogate outcomes. The main outcome of this analysis was all-cause mortality. A total of 25 trials involving 3,619 patients were included in the analysis. At a mean follow up of 14 months (95% confidence interval (CI) 8.6-19.4 months), the incidence of all-cause mortality was 4.9% [95% CI 3.8-6.0%] in the IPoC group versus 3.8% [95% CI 1.9-5.7%] in the control group (RR 0.92, 95% CI 0.68-1.24, P = 0.74). The risk of reinfarction (2.7% [95% CI 1.1-4.3%] vs. 2.3% [0.6-4.0%]; RR 1.29, 95% CI 0.62-2.68, P = 0.72), heart failure (3.6% [95% CI 2.0-5.1%] vs. 5.7% [95% CI 3.3-8.2%]; RR 0.77, 95% CI 0.58-1.06, P = 0.24), target vessel revascularization (3.2% [95% CI 1.7-4.7%] vs. 2.4% [95% CI 1.4-3.3%]; RR 1.40, 95% CI 0.90-2.20, P = 0.20), and stent thrombosis (2.4% [95% CI 1.1-3.8%] vs. 1.8% [95% CI 0.5-3.2%]); RR 1.50, 95% CI 0.60-3.70, P = 0.40) was similar in both groups.

CONCLUSIONS

IPoC does not appear to reduce the risk of clinical adverse events in patients with ST-elevation myocardial infarction undergoing primary PCI. © 2017 Wiley Periodicals, Inc.

[Skeletal muscle ischemia-reperfusion and ischemic conditioning pathophysiology-clinical applications for the vascular surgeon]

Ischemia-reperfusion, which is characterized by deficient oxygen supply and subsequent restoration of blood flow, can cause irreversible damage to tissue. The vascular surgeon is daily faced with ischemia-reperfusion situations. Indeed, arterial clamping induces ischemia, followed by reperfusion when declamping. Mechanisms underlying ischemia-reperfusion injury are complex and multifactorial. Increases in cellular calcium and reactive oxygen species, initiated during ischemia and then amplified upon reperfusion are thought to be the main mediators of reperfusion injury. Mitochondrial dysfunction also plays an important role. Extensive research has focused on increasing skeletal muscle tolerance to ischemia-reperfusion injury, especially through the use of ischemic conditioning strategies. The purpose of this review is to focus on the cellular responses associated with ischemia-reperfusion, as well as to discuss the effects of ischemic conditioning strategies. This would help the vascular surgeon in daily practice, in order to try to improve surgical outcome in the setting of ischemia-reperfusion.

Signaling Pathways in Cardiac Myocyte Apoptosis

Cardiovascular diseases, the number 1 cause of death worldwide, are frequently associated with apoptotic death of cardiac myocytes. Since cardiomyocyte apoptosis is a highly regulated process, pharmacological intervention of apoptosis pathways may represent a promising therapeutic strategy for a number of cardiovascular diseases and disorders including myocardial infarction, ischemia/reperfusion injury, chemotherapy cardiotoxicity, and end-stage heart failure. Despite rapid growth of our knowledge in apoptosis signaling pathways, a clinically applicable treatment targeting this cellular process is currently unavailable. To help identify potential innovative directions for future research, it is necessary to have a full understanding of the apoptotic pathways currently known to be functional in cardiac myocytes. Here, we summarize recent progress in the regulation of cardiomyocyte apoptosis by multiple signaling molecules and pathways, with a focus on the involvement of these pathways in the pathogenesis of heart disease. In addition, we provide an update regarding bench to bedside translation of this knowledge and discuss unanswered questions that need further investigation.

Ischaemic conditioning and targeting reperfusion injury: a 30 year voyage of discovery

To commemorate the auspicious occasion of the 30th anniversary of IPC, leading pioneers in the field of cardioprotection gathered in Barcelona in May 2016 to review and discuss the history of IPC, its evolution to IPost and RIC, myocardial reperfusion injury as a therapeutic target, and future targets and strategies for cardioprotection. This article provides an overview of the major topics discussed at this special meeting and underscores the huge importance and impact, the discovery of IPC has made in the field of cardiovascular research.