Effect of remote ischemic preconditioning on serum troponin T level following elective percutaneous coronary intervention

Ischemic limb preconditioning-induced anti-arrhythmic effect in reperfusion-induced myocardial injury: is it mediated by the RISK or SAFE pathway?

The mechanism for limb ischemic precondition (RLIPC)-induced suppression of reperfusion arrhythmia remains unknown. The purpose of this study was to examine the roles of the pro-survival reperfusion injury salvage kinase (RISK) and survivor activating factor enhancement (SAFE) pathways in this RLIPC-mediated antiarrhythmic activity. Male Sprague Dawley rats were assigned to sham-operated, control, or RLIPC groups. All rats except for the sham rats had 5 min of left main coronary artery occlusion with another 20 min of reperfusion. RLIPC was initiated by four cycles of limb ischemia (5 min) and reperfusion (5 min) on the bilateral femoral arteries. Hearts in every group were taken for protein phosphorylation analysis. RLIPC ameliorated reperfusion-induced arrhythmogenesis and reduced the incidence of sudden cardiac death during the entire 20-min reperfusion period (66.7% of control rats had SCD vs. only 16.7% of RLIPC-treated rats). RLIPC enhances ventricular ERK1/2 phosphorylation after reperfusion. RLIPC-induced antiarrhythmic action and ERK1/2 phosphorylation are abolished in the presence of the ERK1/2 inhibitor U0126. Limb ischemic preconditioning protects the heart against myocardial reperfusion injury-induced lethal arrhythmia. These beneficial effects may involve the activation of ERK1/2 in the RISK signaling pathway.

The Effects of Ischemic Preconditioning Supplementation on Endothelial Function: A Systematic Review and Meta-Analysis

Objective

Ischemic preconditioning (IPC) has gradually been promoted in clinical practice to lower the risk of cardiovascular surgery and postoperative complications. We investigated the role of IPC on vascular endothelial function and the relationship between IPC, flow-mediated dilation (FMD), and brachial artery diameter (BAD).

Methods

Systematic searches were conducted in PubMed, Medline, Cochrane Library, Embase, and Scopus databases from their inception to March 20, 2020. This research included randomized controlled trials (RCTs) with adults, and the values of FMD and BAD were considered as the primary outcomes. Ten studies comprising 292 participants were included in the meta-analysis.

Results

Regarding FMD, we observed beneficial effects of IPC on endothelial function (standardized mean difference (SMD): 1.82; 95% confidence interval (CI): 0.64, 3.01; p < 0.001; I ² = 89.9%). However, the available evidence did not indicate that IPC affected BAD (SMD: 0.08; 95% CI: -0.03, 0.18; p > 0.05; I ² = 76.5%).

Conclusions

Our meta-analysis indicated a significant effect of IPC on the endothelial function of the blood vessels, affecting FMD but not BAD.

The Future of Cardioprotection-Pointing Toward Patients at Elevated Risk as the Target Populations

Translation of the cardioprotective effect by pharmacological and mechanical conditioning therapies into improvement of clinical outcome for the patients has been disappointing. Confounding factors like comorbidity and comedications may explain some of the loss in translation. However, the substantial improvement of outcome in disease states involving ischemia-reperfusion injury, that is, planned cardiac surgery, elective percutaneous coronary intervention, and even primary percutaneous coronary intervention for ST-segment myocardial infarction (STEMI), is the most plausible explanation for the missed demonstration of a clinical benefit. Remote ischemic conditioning has demonstrated consistent cardioprotective effect in experimental and in clinical proof-of-concept studies. As an adjunctive cardioprotective treatment beyond reperfusion, remote ischemic conditioning should address target populations at risk of extensive tissue damage, including patients who experience complications, which may induce profound myocardial ischemia in relation to cardiac surgery or elective percutaneous coronary intervention. Moreover, patients with STEMI and predictable impaired clinical outcome due to delayed hospital admission, high Killip class, cardiogenic shock, and cardiac arrest remain target groups. For high-risk patients, daily remote ischemic conditioning or the corollary of blood flow-restricted exercise may be alternative cardioprotective options during postoperative and post-myocardial infarct rehabilitation.

Remote Ischemic Preconditioning Neither Improves Survival nor Reduces Myocardial or Kidney Injury in Patients Undergoing Transcatheter Aortic Valve Implantation (TAVI)

BACKGROUND

Peri-interventional myocardial injury occurs frequently during transcatheter aortic valve implantation (TAVI). We assessed the effect of remote ischemic preconditioning (RIPC) on myocardial injury, acute kidney injury (AKIN) and 6-month mortality in patients undergoing TAVI.

METHODS

We performed a prospective single-center controlled trial. Sixty-six patients treated with RIPC prior to TAVI were enrolled in the study and were matched to a control group by propensity-score. RIPC was applied to the upper extremity using a conventional tourniquet. Myocardial injury was assessed using high-sensitive troponin-T (hsTnT), and kidney injury was assessed using serum creatinine levels. Data were compared with the Wilcoxon-Rank and McNemar tests. Mortality was analysed with the log-rank test.

RESULTS

TAVI led to a significant rise of hsTnT across all patients (p < 0.001). No significant inter-group difference in maximum troponin release or areas-under-the-curve was detected. Medtronic CoreValve and Edwards Sapien valves showed similar peri-interventional troponin kinetics and patients receiving neither valve did benefit from RIPC. AKIN occurred in one RIPC patient and four non-RIPC patients (p = 0.250). No significant difference in 6-month mortality was observed. No adverse events related to RIPC were recorded.

CONCLUSION

Our data do not show a beneficial role of RIPC in TAVI patients for cardio- or renoprotection, or improved survival.

Egr-1 functions as a master switch regulator of remote ischemic preconditioning-induced cardioprotection

Despite improved treatment options myocardial infarction (MI) is still a leading cause of mortality and morbidity worldwide. Remote ischemic preconditioning (RIPC) is a mechanistic process that reduces myocardial infarction size and protects against ischemia reperfusion (I/R) injury. The zinc finger transcription factor early growth response-1 (Egr-1) is integral to the biological response to I/R, as its upregulation mediates the increased expression of inflammatory and prothrombotic processes. We aimed to determine the association and/or role of Egr-1 expression with the molecular mechanisms controlling the cardioprotective effects of RIPC. This study used H9C2 cells in vitro and a rat model of cardiac ischemia reperfusion (I/R) injury. We silenced Egr-1 with DNAzyme (ED5) in vitro and in vivo, before three cycles of RIPC consisting of alternating 5 min hypoxia and normoxia in cells or hind-limb ligation and release in the rat, followed by hypoxic challenge in vitro and I/R injury in vivo. Post-procedure, ED5 administration led to a significant increase in infarct size compared to controls (65.90 ± 2.38% vs. 41.00 ± 2.83%, p < 0.0001) following administration prior to RIPC in vivo, concurrent with decreased plasma IL-6 levels (118.30 ± 4.30 pg/ml vs. 130.50 ± 1.29 pg/ml, p < 0.05), downregulation of the cardioprotective JAK-STAT pathway, and elevated myocardial endothelial dysfunction. In vitro, ED5 administration abrogated IL-6 mRNA expression in H9C2 cells subjected to RIPC (0.95 ± 0.20 vs. 6.08 ± 1.40-fold relative to the control group, p < 0.05), resulting in increase in apoptosis (4.76 ± 0.70% vs. 2.23 ± 0.34%, p < 0.05) and loss of mitochondrial membrane potential (0.57 ± 0.11% vs. 1.0 ± 0.14%-fold relative to control, p < 0.05) in recipient cells receiving preconditioned media from the DNAzyme treated donor cells. This study suggests that Egr-1 functions as a master regulator of remote preconditioning inducing a protective effect against myocardial I/R injury through IL-6-dependent JAK-STAT signaling.

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.

Remote ischemic conditioning: a promising therapeutic intervention for multi-organ protection

Despite decades of formidable exploration, multi-organ ischemia-reperfusion injury (IRI) encountered, particularly amongst elderly patients with clinical scenarios, such as age-related arteriosclerotic vascular disease, heart surgery and organ transplantation, is still an unsettled conundrum that besets clinicians. Remote ischemic conditioning (RIC), delivered via transient, repetitive noninvasive IR interventions to distant organs or tissues, is regarded as an innovative approach against IRI. Based on the available evidence, RIC holds the potential of affording protection to multiple organs or tissues, which include not only the heart and brain, but also others that are likely susceptible to IRI, such as the kidney, lung, liver and skin. Neuronal and humoral signaling pathways appear to play requisite roles in the mechanisms of RIC-related beneficial effects, and these pathways also display inseparable interactions with each other. So far, several hurdles lying ahead of clinical translation that remain to be settled, such as establishment of biomarkers, modification of RIC regimen, and deep understanding of underlying minutiae through which RIC exerts its powerful function. As this approach has garnered an increasing interest, herein, we aim to encapsulate an overview of the basic concept and postulated protective mechanisms of RIC, highlight the main findings from proof-of-concept clinical studies in various clinical scenarios, and also to discuss potential obstacles that remain to be conquered. More well designed and comprehensive experimental work or clinical trials are warranted in future research to confirm whether RIC could be utilized as a non-invasive, inexpensive and efficient adjunct therapeutic intervention method for multi-organ protection.

Short-term remote ischemic conditioning may protect monkeys after ischemic stroke

Objective

We aimed to evaluate the safety and effectiveness of short-term remote ischemic postconditioning (RIPC) in acute stroke monkey models.

Methods

Acute stroke monkeys were allocated to four groups based on the number of limbs exposed to RIPC. RIPC was initiated by 5-min cuff inflation/deflation cycles of the target limb(s) for 5-10 bouts. Vital signs, skin integrity, brain MRI, and serum levels of cardiac enzymes (myoglobin, creatine kinase [CK], CK-muscle/brain [CK-MB]), one inflammatory marker (high-sensitivity C-reactive protein [hsCRP], and one endothelial injury marker (von Willebrand factor [vWF]) were assessed. Spetzler scores were used to assess neurological function.

Results

No significant differences in vital signs or local skin integrity were found. Short-term RIPC did not reduce infarct volume under any condition at the 24th hour after stroke. However, neurological function improved in multi-limb RIPC compared with sham and single-limb RIPC at the 30th day follow-up after stroke. Myoglobin, CK, and CK-MB levels were reduced after multi-limb RIPC, regardless of the number of bouts. Moreover, multi-limb RIPC produced a greater diminution in CK-MB levels, whereas two-limb RIPC was more effective in reducing serum CK levels at the 24th hour after stroke. hsCRP increased after 5 bouts of multi-limb RIPC before decreasing below baseline and single-limb RIPC levels. Serum vWF was decreased at later time points after RIPC in all RIPC groups.

Conclusions

Stroke monkeys in hyperacute stage may benefit from short-term RIPC; however, whether this intervention can be translated into clinical use in patients with acute ischemic stroke warrants further study.

Tobacco smoking protective effect via remote ischemic preconditioning on myocardial damage after elective percutaneous coronary intervention: Subanalysis of a randomized controlled trial

Background

Remote ischemic preconditioning (RIPC) is promising for preventing periprocedural myocardial damage (pMD) in patients undergoing percutaneous coronary intervention (PCI). However, the impact of RIPC on pMD on smokers is not well elucidated. The aim of this study was to investigate an association between tobacco smoking and RIPC on pMD in patients planning to undergo PCI.

Methods

This study used data from a multicenter randomized controlled trial involving patients with stable angina who planned to undergo elective PCI. We analyzed data for 262 patients in the control (n = 133) and upper-limb RIPC (n = 129) groups, including 166 current or former smokers. The major outcome was the pMD incidence following PCI, with pMD defined as an elevated level of highly sensitive cardiac troponin T or a creatine kinase myocardial band 12 or 24 h after PCI.

Results

The incidence of pMD was significantly lower in the upper-limb RIPC group than in the control group (28/83 patients [33.8%] vs. 43/83 patients [51.8%], respectively; p = 0.018). In a multiple logistic regression model, tobacco smoking was an independent predictor of interacting with and enhancing the effect of RIPC on reducing the incidence of pMD after PCI (regression coefficient, −0.4 [95% confidence interval, −0.74 to −0.082]; p = 0.015).

Conclusions

Tobacco smoking may have a beneficial effect on RIPC against pMD after PCI.

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.

Protective Effect of Remote Ischemic Preconditioning on Myocardial Damage After Percutaneous Coronary Intervention in Stable Angina Patients With Complex Coronary Lesions - Subanalysis of a Randomized Controlled Trial

BACKGROUND

The effect of remote ischemic preconditioning (RIPC) on periprocedural myocardial damage (pMD) in patients undergoing percutaneous coronary intervention (PCI) is controversial. The aim of this study was to investigate the effect of RIPC or intravenous nicorandil on pMD following elective PCI in a subgroup of patients with complex coronary lesions from a multicenter randomized controlled trial.Methods and Results:Patients with stable angina who underwent elective PCI were assigned to 3 groups: control, upper-limb RIPC or intravenous nicorandil. The major outcome was pMD incidence following PCI, with pMD defined as an elevated level of high-sensitivity cardiac troponin T or creatine kinase myocardial band at 12 or 24 h after PCI. A total of 171 patients with complex coronary lesions (ACC-AHA coronary classification type B2 or C) were analyzed. The incidence of pMD following PCI was significantly lower in the RIPC group than in the control group (44.4% vs. 66.1%; P=0.023). The adjusted odds ratio (95% confidence interval) for pMD in the RIPC vs. the controls was 0.41 (0.18-0.94). The incidence of pMD in the nicorandil group was not significantly reduced compared with the control groups.

CONCLUSIONS

This substudy suggested that RIPC prior to PCI prevented pMD in patients with complex coronary lesions. Further investigation in a multicenter prospective study is needed to confirm these results.

Protective effect of nicorandil on myocardial injury following percutaneous coronary intervention in older patients with stable coronary artery disease: Secondary analysis of a randomized, controlled trial (RINC)

Background

Our previous study examined an effect of remote ischemic preconditioning (RIPC) or intravenous nicorandil on reduction of periprocedural myocardial injury (pMI) following percutaneous coronary intervention (PCI) in patients with stable coronary artery disease (CAD). We further investigated the effect of RIPC or nicorandil on pMI in older patients.

Methods

Patients with stable CAD who planned to undergo PCI were assigned to a 1:1:1 ratio to control, intravenous nicorandil, or upper-limb RIPC groups. This substudy analyzed patients aged >65 years (n = 282) from the principal cohort. The primary outcome was the incidence of pMI following PCI. We defined pMI as an elevated level of high-sensitive cardiac troponin T or creatine kinase myocardial band 12 or 24 hours after PCI.

Results

We found that pMI following PCI was significantly reduced in the nicorandil group compared with the control group (37.2% vs. 53.7%, multiplicity-adjusted p = 0.046), but not in the RIPC group compared with the control group (43.0% vs. 53.7%, multiplicity-adjusted p = 0.245). The adjusted odds ratios (95% confidence interval) for pMI in the RIPC and nicorandil groups versus the control group were 0.63 (0.34 to 1.16) and 0.51 (0.27 to 0.96), respectively.

Conclusion

Intravenous nicorandil significantly reduces pMI following PCI in a subgroup of older patients with stable CAD. Phase 3 trials are required to validate our results.

Trial registration

UMIN Clinical Trials Registry UMIN000005607.

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.

Cyclical blood flow restriction resistance exercise: a potential parallel to remote ischemic preconditioning?

Remote ischemic preconditioning (RIPC) is characterized by the cyclical application of limb blood flow restriction and reperfusion and has been shown to protect vital organs during a subsequent ischemic insult. Blood flow restriction exercise (BFRE) similarly combines bouts of blood flow restriction with low-intensity exercise and thus could potentially emulate the protection demonstrated by RIPC. One concern with BFRE, however, is the potential for an augmented rise in sympathetic outflow due to greater activation of the exercise pressor reflex. Because of the use of lower workloads, however, we hypothesized that BFRE would elicit an attenuated increase in sympathetic outflow [assessed via plasma norepinephrine (NE) and mean arterial pressure (MAP)] and middle cerebral artery velocity (MCAv) when compared with conventional exercise (CE). Fifteen subjects underwent two leg press exercise interventions: 1) BFRE-220 mmHg bilateral thigh occlusion at 20% 1 rep-max (1RM), and 2) CE-65% 1RM without occlusion. Each condition consisted of 4 × 5-min cycles of exercise, with 3 × 10-reps in each cycle. Five minutes of rest and reperfusion (for BFRE) followed each cycle. MAP increased with exercise (P < 0.001) and was 4-5 mmHg higher with CE versus BFRE (P ≤ 0.09). Mean MCAv also increased with exercise (P < 0.001) and was higher with CE compared with BFRE during the first bout of exercise only (P = 0.07). Plasma NE concentration increased with CE only (P < 0.001) and was higher than BFRE throughout exercise (P ≤ 0.02). The attenuated sympathetic response, combined with similar cerebrovascular responses, suggest that cyclical BFRE could be explored as an alternative to CE in the clinical setting.

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.

Noninvasive approach to mend the broken heart: Is "remote conditioning" a promising strategy for application in humans?

Currently, there are no satisfactory interventions to protect the heart against the detrimental effects of ischemia-reperfusion injury. Although ischemic preconditioning (PC) is the most powerful form of intrinsic cardioprotection, its application in humans is limited to planned interventions, due to its short duration and technical requirements. However, many organs/tissues are capable of producing "remote" PC (RPC) when subjected to brief bouts of ischemia-reperfusion. RPC was first described in the heart where brief ischemia in one territory led to protection in other area. Later on, RPC started to be used in patients with acute myocardial infarction, albeit with ambiguous results. It is hypothesized that the connection between the signal triggered in remote organ and protection induced in the heart can be mediated by humoral and neural pathways, as well as via systemic response to short sublethal ischemia. However, although RPC has a potentially important clinical role, our understanding of the mechanistic pathways linking the local stimulus to the remote organ remains incomplete. Nevertheless, RPC appears as a cost-effective and easily performed intervention. Elucidation of protective mechanisms activated in the remote organ may have therapeutic and diagnostic implications in the management of myocardial ischemia and lead to development of pharmacological RPC mimetics.

Remote Ischemic Conditioning: The Commercial Market? CellAegis Perspective

Remote ischemic conditioning (RIC) is at a pivotal point in its evolution, both in terms of its adoption as a therapy and its viability commercially. The most usual way of inducing RIC, with a standard blood pressure cuff and a stopwatch, is time-consuming and potentially inaccurate and unsafe. Development of automated devices have facilitated large-scale randomized trials and will make clinical deployment of the technique more straightforward. Both the medical and commercial future of RIC will depend on the results of upcoming phase 3 pivotal trials.

Remote Ischemic Perconditioning to Reduce Reperfusion Injury During Acute ST-Segment-Elevation Myocardial Infarction: A Systematic Review and Meta-Analysis

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. The objective of this systematic review was to determine the impact of RIC on myocardial salvage index, infarct size, and major adverse cardiovascular events when initiated before catheterization.

Methods and Results

Electronic searches of Medline, Embase, and Cochrane Central Register of Controlled Trials were conducted and reference lists were hand searched. Randomized controlled trials comparing percutaneous coronary intervention (PCI) with and without RIC for patients with ST‐segment–elevation myocardial infarction were included. Two reviewers independently screened abstracts, assessed quality of the studies, and extracted data. Data were pooled using random‐effects models and reported as mean differences and relative risk with 95% confidence intervals. Eleven articles (9 randomized controlled trials) were included with a total of 1220 patients (RIC+PCI=643, PCI=577). Studies with no events were excluded from meta‐analysis. The myocardial salvage index was higher in the RIC+PCI group compared with the PCI group (mean difference: 0.08; 95% confidence interval, 0.02–0.14). Infarct size was reduced in the RIC+PCI group compared with the PCI group (mean difference: −2.46; 95% confidence interval, −4.66 to −0.26). Major adverse cardiovascular events were lower in the RIC+PCI group (9.5%) compared with the PCI group (17.0%; relative risk: 0.57; 95% confidence interval, 0.40–0.82).

Conclusions

RIC appears to be a promising adjunctive treatment to PCI for the prevention of reperfusion injury in patients with ST‐segment–elevation myocardial infarction; however, additional high‐quality research is required before a change in practice can be considered.

Remote preconditioning as a novel "conditioning" approach to repair the broken heart: potential mechanisms and clinical applications

Remote ischemic preconditioning (RIPC) is a novel strategy of protection against ischemia-reperfusion (IR) injury in the heart (and/or other organs) by brief episodes of non-lethal IR in a distant organ/tissue. Importantly, RIPC can be induced noninvasively by limitation of blood flow in the extremity implying the applicability of this method in clinical situations. RIPC (and its delayed phase) is a form of relatively short-term adaptation to ischemia, similar to ischemic PC, and likely they both share triggering mechanisms, whereas mediators and end-effectors may differ. It is hypothesized that communication between the signals triggered in the remote organs and protection in the target organ may be mediated through substances released from the preconditioned organ and transported via the circulation (humoral pathways), by neural pathways and/or via systemic anti-inflammatory and antiapoptotic response to short ischemic bouts. Identification of molecules involved in RIPC cascades may have therapeutic and diagnostic implications in the management of myocardial ischemia. Elucidation of the mechanisms of endogenous cardioprotection triggered in the remote organ could lead to the development of diverse pharmacological RIPC mimetics. In the present article, the authors provide a short overview of RIPC-induced protection, proposed underlying mechanisms and factors modulating RIPC as a promising cardioprotective strategy.

Remote Ischemic Conditioning in Elective PCI?

This review examines the rationale for using remote ischemic conditioning (RIC) in elective percutaneous coronary intervention (PCI) to prevent procedure-related ischemia-reperfusion injury and justifies the importance of periprocedural biomarker elevation following elective PCI as a valid target for RIC. We review the evidence for the use of RIC as a treatment in this setting and document the salutary rules that must be followed to successfully translate RIC for clinical benefit.

The impact of a single episode of remote ischemic preconditioning on myocardial injury after elective percutaneous coronary intervention

Introduction

Myocardial injury after percutaneous coronary intervention (PCI) occurs in approximately 30% of procedures, and is related to worse prognosis. Effects of remote ischemic preconditioning (RIPC) on reperfusion injury have been investigated before, yielding conflicting results.

Aim

To assess the impact of a single episode of RIPC on myocardial injury after elective PCI.

Material and methods

One hundred and four patients undergoing elective PCI, with normal baseline cardiac troponin-I (cTn-I) values, were randomized to two groups. Two patients were excluded due to data loss, and 102 patients were analyzed. Five minutes of ischemic preconditioning was delivered just before the intervention to the preconditioning group, by inflating the blood pressure cuff up to 200 mm Hg on the non-dominant arm. Postprocedural 16^th hour cTn-I, ΔcTn-I (difference between the 16^th h and baseline cTn-I values) and the prevalence of type 4a myocardial infarction were compared between the two groups.

Results

Median cTn-I values after the procedure were compared. 16^th hour cTn-I was insignificantly lower in the preconditioning arm (0.026 μg/l vs. 0.045 μg/l, p = 0.186). The incidence of cTn-I elevation 5-fold above the upper reference limit (URL) (> 0.115 μg/l) was lower in the preconditioning group, but it was also not significant (21.6% vs. 11.8%, p = 0.184).

Conclusions

A single episode of RIPC before elective PCI demonstrated less troponin elevation but failed to show a significant effect.

Remote ischemic preconditioning attenuates EGR-1 expression following myocardial ischemia reperfusion injury through activation of the JAK-STAT pathway

BACKGROUND/OBJECTIVES

Remote ischemic preconditioning (RIPC) protects the myocardium from ischemia/reperfusion (I/R) injury however the molecular pathways involved in cardioprotection are yet to be fully delineated. Transcription factor Early growth response-1 (Egr-1) is a key upstream activator in a variety of cardiovascular diseases. In this study, we elucidated the role of RIPC in modulating the regulation of Egr-1.

METHODS

This study subjected rats to transient blockade of the left anterior descending (LAD) coronary artery with or without prior RIPC of the hind-limb muscle and thereafter excised the heart 24h following surgical intervention. In vitro, rat cardiac myoblast H9c2 cells were exposed to ischemic preconditioning by subjecting them to 3cycles of alternating nitrogen-flushed hypoxia and normoxia. These preconditioned media were added to recipient H9c2 cells which were then subjected to 30min of hypoxia followed by 30min of normoxia to simulate myocardial I/R injury. Thereafter, the effects of RIPC on cell viability, apoptosis and inflammatory markers were assessed.

RESULTS

We showed reduced infarct size and suppressed Egr-1 in the heart of rats when RIPC was administered to the hind leg. In vitro, we showed that RIPC improved cell viability, reduced apoptosis and attenuated Egr-1 in recipient cells.

CONCLUSIONS

Selective inhibition of intracellular signaling pathways confirmed that RIPC increased production of intracellular nitric oxide (NO) and reactive oxygen species (ROS) via activation of the JAK-STAT pathway which then inactivated I/R-induced ERK 1/2 signaling pathways, ultimately leading to the suppression of Egr-1.

Time to Give Up on Cardioprotection?

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.

Remote Ischemic Preconditioning in the PICU: A Simple Concept With a Complex Past

OBJECTIVE

In this study, we will review the most recently proposed mechanisms for remote ischemic preconditioning and summarize the past 10 years of clinical studies, as well as potential reasons for why, despite over 20 years of research on remote ischemic preconditioning, it is not routinely used in the pediatric critical care patient. In addition, future directions for remote ischemic preconditioning research will be discussed.

DATA SOURCES

We searched the PubMed database for relevant literature.

STUDY SELECTION AND DATA EXTRACTION

In PubMed, the search terms "ischemic preconditioning" and "remote preconditioning" were used. Randomized controlled trials published from 2006 until the present time that used a blood pressure cuff to induce remote ischemic preconditioning were included. We also reviewed the reference lists of the articles found in the PubMed search and included those thought to contribute to the objectives. All studies pertaining to remote ischemic preconditioning that included pediatric patients were reviewed.

DATA SYNTHESIS AND CONCLUSIONS

Differences in study outcomes in the effect of remote ischemic preconditioning on organ protection have been reported and may have played a large role in limiting the translation of findings into routine clinical practice. Ongoing efforts to protocolize the remote ischemic preconditioning technique in large multicenter trials with clearly delineated patient risk groups, including the use of biomarkers for enrichment, may help to ultimately determine if this procedure can be safely and effectively used for critically ill children.

Remote ischaemic conditioning and remodelling following myocardial infarction: current evidence and future perspectives

Remote ischaemic conditioning (rIC) has demonstrated its effectiveness as a powerful cardioprotective tool in number of preclinical and limited clinical settings. More recently, ischaemic postconditioning given after an ischaemic event such as a myocardial infarction (MI) has shown not only to reduce infarct size but also to have beneficial effects on acute remodelling post-MI and to reduce the burden of heart failure and other detrimental outcomes. Building on this platform, repeated rIC over a number of days has the potential to augment the protective process even further. This review considers the current evidence base from which the concept of rIC in the setting of post-MI remodelling has grown. It also discusses the ongoing and planned clinical trials which are attempting to elucidate whether the protection imparted by rIC in the preclinical setting can be translated to the clinic and become a realistic weapon in the clinician’s armoury to tackle acute remodelling and heart failure post-MI.

From Protecting the Heart to Improving Athletic Performance - the Benefits of Local and Remote Ischaemic Preconditioning

Remote Ischemic Preconditioning (RIPC) is a non-invasive cardioprotective intervention that involves brief cycles of limb ischemia and reperfusion. This is typically delivered by inflating and deflating a blood pressure cuff on one or more limb(s) for several cycles, each inflation-deflation being 3-5 min in duration. RIPC has shown potential for protecting the heart and other organs from injury due to lethal ischemia and reperfusion injury, in a variety of clinical settings. The mechanisms underlying RIPC are under intense investigation but are just beginning to be deciphered. Emerging evidence suggests that RIPC has the potential to improve exercise performance, via both local and remote mechanisms. This review discusses the clinical studies that have investigated the role of RIPC in cardioprotection as well as those studying its applicability in improving athletic performance, while examining the potential mechanisms involved.

Cardioprotection by remote ischemic conditioning: Mechanisms and clinical evidences

In remote ischemic conditioning (RIC), several cycles of ischemia and reperfusion render distant organ and tissues more resistant to the ischemia-reperfusion injury. The intermittent ischemia can be applied before the ischemic insult in the target site (remote ischemic preconditioning), during the ischemic insult (remote ischemic perconditioning) or at the onset of reperfusion (remote ischemic postconditioning). The mechanisms of RIC have not been completely defined yet; however, these mechanisms must be represented by the release of humoral mediators and/or the activation of a neural reflex. RIC has been discovered in the heart, and has been arising great enthusiasm in the cardiovascular field. Its efficacy has been evaluated in many clinical trials, which provided controversial results. Our incomplete comprehension of the mechanisms underlying the RIC could be impairing the design of clinical trials and the interpretation of their results. In the present review we summarize current knowledge about RIC pathophysiology and the data about its cardioprotective efficacy.

Remote Ischemic Preconditioning May Attenuate Renal Ischemia-Reperfusion Injury in a Porcine Model of Supraceliac Aortic Cross-Clamping

AIM

The effect of remote ischemic preconditioning (RIPC) in decreasing renal ischemia-reperfusion injury (IRI) during a suprarenal aortic cross-clamping was examined in a swine model.

MATERIALS AND METHODS

Four groups of pigs were examined: (a) ischemia-reperfusion (IR) group, renal IRI produced by 30 min of supraceliac aortic cross-clamping; (b) RIPC I group, the same renal IRI following RIPC by brief occlusion of the infrarenal aorta (15 min ischemia and 15 min reperfusion); (c) RIPC II group, the same renal IRI following RIPC by brief occlusion of the infrarenal aorta (3 cycles of 5 min ischemia and 5 min reperfusion); (d) sham group. Renal function was assessed before and after IRI by examining creatinine, neutrophil gelatinase-associated lipocalin (NGAL), TNF-α, malondialdehyde (MDA), cystatin C and C-reactive protein (CRP) from renal vein blood samples at specific time intervals.

RESULTS

Both RIPC groups presented significantly less impaired results compared to the IR group when considering MDA, cystatin C, CRP and creatinine. Between the two RIPC groups, RIPC II presented a better response with regard to CRP, NGAL, TNF-α, MDA and cystatin C.

CONCLUSIONS

Remote IR protocols and mainly repetitive short periods of cycles of IR ameliorate the biochemical kidney effects of IRI in a model of suprarenal aortic aneurysm repair.

Interaction of risk factors, comorbidities, and comedications with ischemia/reperfusion injury and cardioprotection by preconditioning, postconditioning, and remote conditioning

Pre-, post-, and remote conditioning of the myocardium are well described adaptive responses that markedly enhance the ability of the heart to withstand a prolonged ischemia/reperfusion insult and provide therapeutic paradigms for cardioprotection. Nevertheless, more than 25 years after the discovery of ischemic preconditioning, we still do not have established cardioprotective drugs on the market. Most experimental studies on cardioprotection are still undertaken in animal models, in which ischemia/reperfusion is imposed in the absence of cardiovascular risk factors. However, ischemic heart disease in humans is a complex disorder caused by, or associated with, cardiovascular risk factors and comorbidities, including hypertension, hyperlipidemia, diabetes, insulin resistance, heart failure, altered coronary circulation, and aging. These risk factors induce fundamental alterations in cellular signaling cascades that affect the development of ischemia/reperfusion injury per se and responses to cardioprotective interventions. Moreover, some of the medications used to treat these risk factors, including statins, nitrates, and antidiabetic drugs, may impact cardioprotection by modifying cellular signaling. The aim of this article is to review the recent evidence that cardiovascular risk factors and their medication may modify the response to cardioprotective interventions. We emphasize the critical need to take into account the presence of cardiovascular risk factors and 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 risk factors.

Remote ischemic conditioning

In remote ischemic conditioning (RIC), brief, reversible episodes of ischemia with reperfusion in one vascular bed, tissue, or organ confer a global protective phenotype and render remote tissues and organs resistant to ischemia/reperfusion injury. The peripheral stimulus can be chemical, mechanical, or electrical and involves activation of peripheral sensory nerves. The signal transfer to the heart or other organs is through neuronal and humoral communications. Protection can be transferred, even across species, with plasma-derived dialysate and involves nitric oxide, stromal derived factor-1α, microribonucleic acid-144, but also other, not yet identified factors. Intracardiac signal transduction involves: adenosine, bradykinin, cytokines, and chemokines, which activate specific receptors; intracellular kinases; and mitochondrial function. RIC by repeated brief inflation/deflation of a blood pressure cuff protects against endothelial dysfunction and myocardial injury in percutaneous coronary interventions, coronary artery bypass grafting, and reperfused acute myocardial infarction. RIC is safe and effective, noninvasive, easily feasible, and inexpensive.

Remote ischemic preconditioning reduces perioperative cardiac and renal events in patients undergoing elective coronary intervention: a meta-analysis of 11 randomized trials

Background

Results from randomized controlled trials (RCT) concerning cardiac and renal effect of remote ischemic preconditioning(RIPC) in patients with stable coronary artery disease(CAD) are inconsistent. The aim of this study was to explore whether RIPC reduce cardiac and renal events after elective percutaneous coronary intervention (PCI).

Methods and Results

RCTs with data on cardiac or renal effect of RIPC in PCI were searched from Pubmed, EMBase, and Cochrane library (up to July 2014). Meta-regression and subgroup analysis were performed to identify the potential sources of significant heterogeneity(I²≥40%). Eleven RCTs enrolling a total of 1713 study subjects with stable CAD were selected. Compared with controls, RIPC significantly reduced perioperative incidence of myocardial infarction (MI) [odds ratio(OR)  = 0.68; 95% CI, 0.51 to 0.91; P = 0.01; I² = 41.0%] and contrast-induced acute kidney injury(AKI) (OR = 0.61; 95% CI, 0.38 to 0.98; P = 0.04; I² = 39.0%). Meta-regression and subgroup analyses confirmed that the major source of heterogeneity for the incidence of MI was male proportion (coefficient  = −0.049; P = 0.047; adjusted R² = 0.988; P = 0.02 for subgroup difference).

Conclusions

The present meta-analysis of RCTs suggests that RIPC may offer cardiorenal protection by reducing the incidence of MI and AKI in patients undergoing elective PCI. Moreover, this effect on MI is more pronounced in male subjects. Future high-quality, large-scale clinical trials should focus on the long-term clinical effect of RIPC.

Ischemic preconditioning-an unfulfilled promise

Myocardial reperfusion injury has been identified as a key determinant of myocardial infarct size in patients undergoing percutaneous or surgical interventions. Although the molecular mechanisms underpinning reperfusion injury have been elucidated, attempts at translating this understanding into clinical benefit for patients undergoing cardiac interventions have produced mixed results. Ischemic conditioning has been applied before, during, or after an ischemic insult to the myocardium and has taken the form of local induction of ischemia or ischemia of distant tissues. Clinical studies have confirmed the safety of differing conditioning techniques, but the benefit of such techniques in reducing hard clinical event rates has produced mixed results. The aim of this article is to review the role of ischemic conditioning in patients undergoing percutaneous and surgical coronary revascularization.

Remote Ischemic Preconditioning of the Heart: Protective Responses in Functional and Biophysical Properties of Cardiac Mitochondria

Remote ischemic preconditioning (RIP)-induced protection of myocardial energetics was well documented on the level of tissue, but data concerning the involvement of mitochondria were missing. We aimed at the identification of changes in membrane properties and respiratory functions induced in rat heart mitochondria by RIP. Experiments were performed on 46 male Wistar rats divided into control and RIP-treated groups of 21 animals each. Blood flow in the occluded area was recorded by MRI angiography in four animals. RIP protocol comprised of three successive 5-min occlusions each followed by 5-min reperfusions of descending branches of the right hind limb femoral artery. The efficacy of RIP was evaluated as the extent of RIP-induced protection against damage to the functions of mitochondria isolated by differential centrifugation after 30-min global ischemia followed by 40-min reperfusion of the hearts in Langendorff mode. Assessments: mitochondrial membrane fluidity with a fluorescent probe DPH, CoQ9 and CoQ10 with HPLC, mitochondrial respiration with the Oxygraph-2k (Oroboros). Results revealed that RIP was affecting the mitochondria. The immediate protection conferred by RIP involves beneficial and prognostically significant effects: a total elimination of ischemia/reperfusion-induced depression of mitochondrial membrane fluidity and a trend for better preservation of mitochondrial state 3 respiration.

Remote ischaemic conditioning in percutaneous coronary intervention: a meta-analysis of randomised trials

Introduction

It remains uncertain whether remote ischaemic conditioning (RIC) using cycles of limb ischaemia-reperfusion as a conditioning stimulus benefits patients undergoing percutaneous coronary intervention (PCI).

Aim

We performed a meta-analysis toassessthe effect of RIC in PCI.

Material and methods

The PubMed, EMBASE, Web of Science, and CENTRAL databases were searched for randomised controlled trials (RCTs) comparing RIC with controls. The treatment effects were measured as a pooled odds ratio (OR), standardised mean difference (SMD), and corresponding 95% confidence intervals (95% CIs) using random-effects models.

Results

Fourteen RCTs, including 2,301 patients, were analysed. Compared to the controls, RIC significantly reduced the cardiac enzyme levels (SMD = –0.21; 95% CI: –0.39 to –0.04; p = 0.015; heterogeneity test, I² = 75%), and incidence of PCI-related myocardial infarction (OR = 0.70; 95% CI, 0.51–0.98; p = 0.037). There was a trend toward an improvement in the complete ST-segment resolution rate with RIC (OR = 1.83; 95% CI: 0.99–3.40; p = 0.054). No significant difference could be detected between the two groups regarding the risk for acute kidney injury after PCI. Univariate meta-regression analysis suggested that the major source of significant heterogeneity was the PCI type (primary or non-emergent) for the myocardial enzyme levels (adjusted R² = 0.44). Subsequent subgroup analysis confirmed the results.

Conclusions

The present meta-analysis showed that RIC could confer cardioprotection for patients undergoing coronary stent implantation. Moreover, the decrease in the myocardial enzyme levels was more pronounced in the patients treated with primary PCI.

Cardiac remote ischaemic preconditioning reduces periprocedural myocardial infarction for patients undergoing percutaneous coronary interventions: a meta-analysis of randomised clinical trials

AIMS

To establish the cardioprotective effect of remote ischaemic preconditioning (RIPC) in patients undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Pubmed (MEDLINE), Cochrane and Embase were systematically searched for randomised controlled trials of RIPC in patients undergoing PCI. Periprocedural myocardial infarction (PMI) was the primary endpoint (defined as troponin elevation >3 times upper reference limit) and C-reactive protein (CRP) was a secondary endpoint. Five studies with 731 patients were included. The median age of the patients was 62 (59-68) years old, 25% were female (23-33), 29% (25-33) had diabetes mellitus, and 26.5% (19-31) presented with multivessel disease. RIPC significantly reduced the incidence of PMI (odds ratio: 0.58 [0.36, 0.93]; I2 43%), with a greater benefit when performed using the lower limb (0.21 [0.07-0.66]) compared to the upper limb (0.67 [0.46-0.99]). This reduction was enhanced for patients with multivessel disease (beta -0.05 [-0.09;-0.01], p=0.01) and with type C lesion (beta -0.014 [-0.04;-0.010], p=0.01) and did not vary according to age, female gender, diabetes mellitus, use of beta-blockers and of angiotensin converting enzyme inhibitors. Absolute risk difference was -0.10 [-0.19, -0.02], with a number needed to treat of 10 [6-50] patients to avoid one event. CRP -0.69 [-1.69, 0.31] was not significantly reduced by RIPC.

CONCLUSIONS

RIPC reduced the incidence of PMI following PCI, especially when performed in the lower limb and for patients with multivessel disease and complex lesions.

Remote ischemic preconditioning and endothelial function in patients with acute myocardial infarction and primary PCI

BACKGROUND

Remote ischemic preconditioning by transient limb ischemia reduces myocardial ischemia-reperfusion injury in patients undergoing percutaneous coronary intervention. The aim of the study we report here was to assess the effect of remote ischemic preconditioning on endothelial function in patients with acute myocardial infarction who underwent primary percutaneous coronary intervention.

METHODS

Forty-eight patients with acute myocardial infarction were enrolled. All participants were randomly divided into 2 groups. In Group I (n = 23), remote ischemic preconditioning was performed before primary percutaneous coronary intervention (intermittent arm ischemia-reperfusion through 4 cycles of 5-minute inflation and 5-minute deflation of a blood-pressure cuff to 200 mm Hg). In Group II (n = 25), standard percutaneous coronary intervention without preconditioning was performed. We assessed endothelial function using the flow-mediated dilation test on baseline, then within 1-3 hours after percutaneous coronary intervention, and again on days 2 and 7 after percutaneous coronary intervention.

RESULTS

The brachial artery flow-mediated dilation results were significantly higher on the first day after primary percutaneous coronary intervention in the preconditioning group (Group I) than in the control group (Group II) (12.1% vs 0.0%, P = .03, and 11.1% vs 6.3%, P = .016, respectively), and this difference remained on the seventh day (12.3% vs 7.4%, P = .0005, respectively).

CONCLUSION

We demonstrated for the first time that remote ischemic preconditioning before primary percutaneous coronary intervention significantly improves endothelial function in patients with acute myocardial infarction, and this effect remains constant for at least a week. We suppose that the improvement of endothelial function may be one of the possible explanations of the effect of remote ischemic preconditioning.

Effect of one-cycle remote ischemic preconditioning to reduce myocardial injury during percutaneous coronary intervention

Up to 1/3 of percutaneous coronary interventions (PCIs) are complicated by troponin release. Remote ischemic preconditioning (IPC) confers effective cardioprotection; however, a 30-minute remote IPC protocol may be difficult to implement during ad hoc PCI. This study was performed to assess the ability of a brief remote IPC protocol to attenuate cardiac troponin I (cTnI) release after ad hoc PCI. Ninety-four patients undergoing ad hoc PCI for stable coronary artery disease, with undetectable preprocedural cTnI, were recruited and randomized to receive remote IPC (induced by one 5-minute inflation of a blood pressure cuff to 200 mm Hg around the upper arm) or control after the decision for PCI was made. The primary outcome was the difference between cTnI levels 24 hours after PCI and cTnI levels before coronary angiography (ΔcTnI). ΔcTnI in the remote IPC group was significantly lower compared with the control group (0.04 ng/ml [interquartile range 0.01 to 0.14] vs 0.19 ng/ml [interquartile range 0.18 to 0.59], p <0.001). The incidence of PCI-related myocardial infarction (MI) was greater in the control group (42.6% vs 19.1%, p = 0.014). In multivariate analysis, remote IPC was independently associated with ΔcTnI and PCI-related MI. In conclusion, our results suggest that even 1 cycle of remote IPC immediately before ad hoc PCI attenuates periprocedural cTnI release and reduces the incidence of type 4a MI.

Cardiac phosphoproteomics during remote ischemic preconditioning: a role for the sarcomeric Z-disk proteins

Remote ischemic preconditioning (RIPC) induced by brief ischemia/reperfusion cycles of remote organ (e.g., limb) is cardioprotective. The myocardial cellular changes during RIPC responsible for this phenomenon are not currently known. The aim of this work was to identify the activation by phosphorylation of cardiac proteins following RIPC. To achieve our aim we used isobaric tandem mass tagging (TMT) and reverse phase nanoliquid chromatography tandem spectrometry using a Linear Trap Quadropole (LTQ) Orbitrap Velos mass spectrometer. Male C57/Bl6 mice were anesthetized by an intraperitoneal injection of Tribromoethanol. A cuff was placed around the hind limb and inflated at 200 mmHg to prevent blood flow as confirmed by Laser Doppler Flowmetry. RIPC was induced by 4 cycles of 5 min of limb ischemia followed by 5 min of reperfusion. Hearts were extracted for phosphoproteomics. We identified approximately 30 phosphoproteins that were differentially expressed in response to RIPC protocol. The levels of several phosphoproteins in the Z-disk of the sarcomere including phospho-myozenin-2 were significantly higher than control. This study describes and validates a novel approach to monitor the changes in the cardiac phosphoproteome following the cardioprotective intervention of RIPC and prior to index ischemia. The increased level of phosphorylated sarcomeric proteins suggests they may have a role in cardiac signaling during RIPC.