A randomised trial of selective intracoronary hypothermia during primary PCI

BACKGROUND

While experimental data suggest that selective intracoronary hypothermia decreases infarct size, studies in patients with ST-elevation myocardial infarction (STEMI) are lacking.

AIMS

We investigated the efficacy of selective intracoronary hypothermia during primary percutaneous coronary intervention (PCI) to decrease infarct size in patients with STEMI.

METHODS

In this multicentre randomised controlled trial, 200 patients with large anterior wall STEMI were randomised 1:1 to selective intracoronary hypothermia during primary PCI or primary PCI alone. Using an over-the-wire balloon catheter for infusion of cold saline and a pressure-temperature wire to monitor the intracoronary temperature, the anterior myocardium distal to the occlusion was selectively cooled to 30-33°C for 7-10 minutes before reperfusion (occlusion phase), immediately followed by 10 minutes of cooling after reperfusion (reperfusion phase). The primary endpoint was infarct size as a percentage of left ventricular mass on cardiovascular magnetic resonance imaging after 3 months.

RESULTS

Selective intracoronary hypothermia was performed in 94/100 patients randomised to cooling. Distal coronary temperature decreased by 6°C within 43 seconds (interquartile range [IQR] 18-113). The median duration of the occlusion phase and reperfusion phase were 8.2 minutes (IQR 7.2-9.0) and 9.1 minutes (IQR 8.2-10.0), respectively. The infarct size at 3 months was 23.1±12.5% in the selective intracoronary hypothermia group and 21.6±12.2% in the primary PCI alone group (p=0.43). The left ventricular ejection fraction at 3 months in each group were 49.1±10.2% and 50.1±10.4%, respectively (p=0.53).

CONCLUSIONS

Selective intracoronary hypothermia during primary PCI in patients with anterior wall STEMI was feasible and safe but did not decrease infarct size compared with standard primary PCI. (ClinicalTrials.gov: NCT03447834).

Early unfractionated heparin treatment in patients with STEMI - trial design and rationale

The early unfractionated heparin (UFH) treatment in patients with ST-elevation myocardial infarction (STEMI) is a single-center, open-label, randomized controlled trial. The study population are patients with STEMI that undergo primary percutaneous coronary intervention (PPCI). The trial was designed to investigate whether early administration of unfractionated heparin immediately after diagnosis of STEMI is beneficial in terms of patency of infarct-related coronary artery (IRA) when compared to established UFH administration at the time of coronary intervention. The patients will be randomized in 1:1 fashion in one of the two groups. The primary efficacy endpoint of the study is Thrombolysis in myocardial infarction (TIMI) flow grades 2 and 3 on diagnostic coronary angiography. Secondary outcome measures are: TIMI flow after PPCI, progression to cardiogenic shock, 30-day mortality, ST-segment resolution, highest Troponin I and Troponin I values at 24 hours. The safety outcome is bleeding complications. The study of early heparin administration in patients with STEMI will address whether pretreatment with UFH can increase the rate of spontaneous reperfusion of infarct-related coronary artery.

Coronary microvascular obstruction and dysfunction in patients with acute myocardial infarction

Despite prompt epicardial recanalization in patients presenting with ST-segment elevation myocardial infarction (STEMI), coronary microvascular obstruction and dysfunction (CMVO) is still fairly common and is associated with poor prognosis. Various pharmacological and mechanical strategies to treat CMVO have been proposed, but the positive results reported in preclinical and small proof-of-concept studies have not translated into benefits in large clinical trials conducted in the modern treatment setting of patients with STEMI. Therefore, the optimal management of these patients remains a topic of debate. In this Review, we appraise the pathophysiological mechanisms of CMVO, explore the evidence and provide future perspectives on strategies to be implemented to reduce the incidence of CMVO and improve prognosis in patients with STEMI.

A novel intracoronary hypothermia device reduces myocardial reperfusion injury in pigs

BACKGROUND

Hypothermia therapy has been suggested to attenuate myocardial necrosis; however, the clinical implementation as a valid therapeutic strategy has failed, and new approaches are needed to translate into clinical applications. This study aimed to assess the feasibility, safety, and efficacy of a novel selective intracoronary hypothermia (SICH) device in mitigating myocardial reperfusion injury.

METHODS

This study comprised two phases. The first phase of the SICH was performed in a normal porcine model for 30 minutes ( n = 5) to evaluate its feasibility. The second phase was conducted in a porcine myocardial infarction (MI) model of myocardial ischemia/reperfusion was performed by balloon occlusion of the left anterior descending coronary artery for 60 minutes and maintained for 42 days. Pigs in the hypothermia group ( n = 8) received hypothermia intervention onset reperfusion for 30 minutes and controls ( n = 8) received no intervention. All animals were followed for 42 days. Cardiac magnetic resonance analysis (5 and 42 days post-MI) and a series of biomarkers/histological studies were performed.

RESULTS

The average time to lower temperatures to a steady state was 4.8 ± 0.8 s. SICH had no impact on blood pressure or heart rate and was safely performed without complications by using a 3.9 F catheter. Interleukin-6 (IL-6), tumor necrosis factor-α, C-reactive protein (CRP), and brain natriuretic peptide (BNP) were lower at 60 min post perfusion in pigs that underwent SICH as compared with the control group. On day 5 post MI/R, edema, intramyocardial hemorrhage, and microvascular obstruction were reduced in the hypothermia group. On day 42 post MI/R, the infarct size, IL-6, CRP, BNP, and matrix metalloproteinase-9 were reduced, and the ejection fraction was improved in pigs that underwent SICH.

CONCLUSIONS

The SICH device safely and effectively reduced the infarct size and improved heart function in a pig model of MI/R. These beneficial effects indicate the clinical potential of SICH for treatment of myocardial reperfusion injury.

Cardioprotective Strategies After Ischemia-Reperfusion Injury

Acute myocardial infarction (AMI) is associated with high morbidity and mortality worldwide. Although early reperfusion is the most effective strategy to salvage ischemic myocardium, reperfusion injury can develop with the restoration of blood flow. Therefore, it is important to identify protection mechanisms and strategies for the heart after myocardial infarction. Recent studies have shown that multiple intracellular molecules and signaling pathways are involved in cardioprotection. Meanwhile, device-based cardioprotective modalities such as cardiac left ventricular unloading, hypothermia, coronary sinus intervention, supersaturated oxygen (SSO2), and remote ischemic conditioning (RIC) have become important areas of research. Herein, we review the molecular mechanisms of cardioprotection and cardioprotective modalities after ischemia-reperfusion injury (IRI) to identify potential approaches to reduce mortality and improve prognosis in patients with AMI.

Recent advances in the diagnosis and management of acute myocardial infarction

With the discovery of new biomarkers for the early detection of acute myocardial infarction (AMI), advancements in valid medication, and percutaneous coronary intervention (PCI), the overall prognosis of AMI has improved remarkably. Nevertheless, challenges remain which require more difficult work to overcome. Novel diagnostic and therapeutic techniques include new AMI biomarkers, hypothermia therapy, supersaturated oxygen (SSO 2 ) therapy, targeted anti-inflammatory therapy, targeted angiogenesis therapy, and stem cell therapy. With these novel methods, we believe that the infarction size after AMI will decrease, and myocardial injury-associated ventricular remodeling may be avoided. This review focuses on novel advances in the diagnosis and management of AMI.

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

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

Efficacy and Safety of Therapeutic Hypothermia as an Adjuvant Therapy for Percutaneous Coronary Intervention in Acute Myocardial Infarction: A Systematic Review and Meta-Analysis

The study aims to compare the use of hypothermia in patients with myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI) with control. We systematically searched four electronic databases until March 2022. The inclusion criteria were any study design that compared hypothermia in patients with MI undergoing PCI with control. The risk of bias assessment of the included randomized controlled trials was conducted through Cochrane Tool, while the quality of the included cohort studies was assessed by the NIH tool. The meta-analysis was performed on RevMan. A total of 19 studies were entered. Regarding the mortality, there were nonsignificant differences between hypothermia and control (odds ratio [OR] = 1.06, 95% confidence interval [CI] 0.75 to 1.50, p = 0.73). There was also no significant difference between the control and hypothermia in recurrent MI (OR = 1.21, 95% CI 0.64 to 2.30, p = 0.56). On the other hand, the analysis showed a significant favor for hypothermia over the control infarct size (mean difference = -1.76, 95% CI -3.04 to -0.47, p = 0.007), but a significant favor for the control over hypothermia in the overall bleeding complications (OR = 1.88, 95% CI 1.11 to 3.18, p = 0.02). Compared with the control, hypothermia reduced the infarct size of the heart, but this finding was not consistent across studies. However, the control had lower rates of bleeding problems. The other outcomes, such as death and the incidence of recurrent MI, were similar between the two groups.

Hypothermia as an Adjunctive Therapy to Percutaneous Intervention in ST-Elevation Myocardial Infarction: A Systematic Review and Meta-Analysis of Randomized Control Trials

INTRODUCTION

In the setting of acute ST-elevation myocardial infarction (STEMI), several randomized control trials (RCTs) suggested a potential benefit with the use of therapeutic hypothermia (TH). However, results from previous studies are contradictory.

METHOD

We performed a comprehensive literature search for studies that evaluated the efficacy and safety of adjunctive TH compared to the standard percutaneous coronary intervention (PCI) in awake patients with STEMI. The primary outcomes were the infarct size (IS) and microvascular obstruction (MVO) assessed by cardiac imaging at the end of follow-up. The secondary outcomes were major adverse cardiovascular events (MACE), procedure-related complications, and door-to-balloon time. Relative risk (RR) or the mean difference (MD) and corresponding 95 % confidence intervals (CIs) were calculated using the random-effects model.

RESULTS

A total of 10 RCTs, including 706 patients were included. As compared to standard PCI, TH was not associated with a statistically significant improvement in the IS (MD: -0.87 %, 95%CI: -2.97, 1.23; P = 0.42) or in the MVO (MD: 0.11 %, 95%CI: -0.06, 0.27; P = 0.21). MACE and its components were comparable between the two groups. However, the TH approach was associated with an increased risk of infection and prolonged door-to-balloon time. Furthermore, there was a trend in the TH group toward an increased incidence of stent thrombosis and paroxysmal atrial fibrillation.

CONCLUSIONS

According to our meta-analysis of published RCTs, TH is not beneficial in awake patients with STEMI and has a marginal safety profile with potential for care delays. Larger-scale RCTs are needed to further clarify our results.

Hypothermia and its role in patients with ST-segment-elevation myocardial infarction and cardiac arrest

Background

Patients suffering cardiac arrest resulting from ST-segment-elevation myocardial infarction (STEMI) are at very high risk of death. In addition to reperfusion strategies, therapeutic hypothermia is recommended for cardiac arrest patients who remain unconscious after resuscitation. However, data analysis of the impact of therapeutic hypothermia on survival showed inconsistent results. We aimed to investigate the benefits of therapeutic hypothermia in STEMI patients after cardiopulmonary resuscitation (CPR).

Methods

Patients with STEMI who received CPR were identified after nationwide German inpatient data (2005–2019) were screened. These patients were stratified for therapeutic hypothermia. The impact of hypothermia on mortality and adverse in-hospital outcomes was analyzed.

Results

Overall, 133,070 inpatients with STEMI and CPR (53.3% aged ≥70 years; 34% females) were recorded in Germany between 2005 and 2019, of which 12.3% (16,386 patients) underwent therapeutic hypothermia. Females (23.8 vs. 35.4%, p < 0.001) and patients aged ≥70 years (34.9 vs. 55.9%, p < 0.001) were less frequently treated with therapeutic hypothermia. The in-hospital case fatality rate was lower for STEMI with CPR and subsequent therapeutic hypothermia than for treatment without therapeutic hypothermia (53.5 vs. 66.7%, p < 0.001). Therapeutic hypothermia was independently associated with a reduced in-hospital case fatality rate {OR 0.83 [95% confidence interval (CI) 0.80–0.86], p < 0.001}. In addition, therapeutic hypothermia was associated with an increased risk for stroke (OR 1.37 [95% CI 1.25–1.49], p < 0.001), pneumonia (OR 1.75 [95% CI 1.68–1.82], p < 0.001), and acute kidney injury (OR 2.21 [95% CI 2.07–2.35], p < 0.001).

Conclusion

Therapeutic hypothermia is associated with a survival benefit for STEMI patients after cardiac arrest.

Timing and predictors of definite stent thrombosis in comatose survivors of out-of-hospital cardiac arrest undergoing percutaneous coronary intervention and therapeutic hypothermia (ST-OHCA study)

BACKGROUND

Incidence of stent thrombosis (ST) in comatose survivors of out-of-hospital cardiac arrest (OHCA) undergoing immediate percutaneous coronary intervention (PCI) and therapeutic hypothermia (TH) varies considerably, from 2.7% to 31.2%, in retrospective studies.

AIMS

We aimed to investigate occurrence, timing and predictors of definite ST.

METHODS

We prospectively investigated consecutive comatose survivors of OHCA with presumed cardiac aetiology undergoing immediate PCI with drug-eluting stents (DES) and TH targeted at 32-34°C admitted between August 2016 and July 2021. Repeat coronary angiography (CAG) was performed if ST was suspected and systematically between day 8-12 in the absence of clinical signs. All deceased patients underwent autopsy and histopathological analysis.  Results: Among 362 comatose survivors of OHCA, immediate PCI with stenting was performed in 169 patients (47%). Since 18 patients did not complete follow-up, 151 patients were ultimately enrolled in ST analysis. Definite ST was confirmed in 29 patients (19.2%; 95% confidence interval [CI]: 12.9%-25.6%) either by CAG (n=18) or autopsy (n=11). ST occurred within 3 days in 62% and presented with at least one clinical sign in 79%. Survival with good neurological recovery was observed in 17% of patients with ST and in 60% of patients without ST (p<0.001). Independent predictors of ST were longer prehospital resuscitation, lower arterial pH and increased creatinine on admission.

CONCLUSIONS

The incidence of definite ST in comatose survivors of OHCA undergoing immediate PCI and TH targeted at 32-34°C is substantial (19.2%) and significantly higher than in other PCI subsets despite systematic use of contemporary DES and anticoagulation/antiplatelet treatment.

Novel therapeutic strategies to reduce reperfusion injury after acute myocardial infarction

For almost 30 years, urgent revascularization termed primary percutaneous coronary intervention (pPCI) has been a cornerstone of modern care for acute myocardial infarction (AMI). It lowers mortality and improved cardiovascular outcome compared to conservative therapy including thrombolysis. Reperfusion injury, which occurs after successful re-opening of the formerly occluded coronary artery, had been exploited as a potential therapeutic target. When revascularisation became faster and pPCI was successfully performed within 60-90 minutes of symptom onset, the interest in a potential additive effect of targeting reperfusion injury vanished. More recently, several meta-analyses indicated that limiting reperfusion injury prevents microvascular obstruction and reduces final infarct size, thereby lowering the probability of heart failure events and improving quality of life in AMI survivors. Here, we describe the current strategies to limit reperfusion injury and to improve post-AMI outcomes such as systemic or intracoronary hypothermia, left-ventricular unloading, intracoronary infusion of super-saturated oxygen, intermittent coronary sinus occlusion, and C-reactive protein apharesis.

Therapeutic hypothermia for acute myocardial infarction: a narrative review of evidence from animal and clinical studies

Myocardial infarction (MI) is the leading cause of death from coronary heart disease and requires immediate reperfusion therapy with thrombolysis, primary percutaneous coronary intervention, or coronary artery bypass grafting. However, myocardial reperfusion therapy is often accompanied by cardiac ischemia/reperfusion (I/R) injury, which leads to myocardial injury with detrimental consequences. The causes of I/R injury are unclear, but are multifactorial, including free radicals, reactive oxygen species, calcium overload, mitochondria dysfunction, inflammation, and neutrophil-mediated vascular injury. Mild hypothermia has been introduced as one of the potential inhibitors of myocardial I/R injury. Although animal studies have demonstrated that mild hypothermia significantly reduces or delays I/R myocardium damage, human trials have not shown clinical benefits in acute MI (AMI). In addition, the practice of hypothermia treatment is increasing in various fields such as surgical anesthesia and intensive care units. Adequate sedation for anesthetic procedures and protection from body shivering has become essential during therapeutic hypothermia. Therefore, anesthesiologists should be aware of the effects of therapeutic hypothermia on the metabolism of anesthetic drugs. In this paper, we review the existing data on the use of therapeutic hypothermia for AMI in animal models and human clinical trials to better understand the discrepancy between perceived benefits in preclinical animal models and the absence thereof in clinical trials thus far.

Intracoronary Application of Super-Saturated Oxygen to Reduce Infarct Size Following Myocardial Infarction

Optimal medical therapy for secondary prevention following acute myocardial infarction reduces non-fatal ischaemic events. Intensive antithrombotic or lipid-lowering approaches have failed to significantly lower mortality. In the past, reduction of infarct size in patients undergoing primary percutaneous revascularisation for acute myocardial infarction had been considered as a surrogate outcome marker. However, infarct size measured by magnetic resonance imaging or SPECT is strongly associated with all-cause mortality and hospitalization for heart failure within the first year after an acute myocardial infarction. Intracoronary administration of super-saturated oxygen (SSO₂) immediately after revascularisation is an approach that can be used to reduce infarct size and, therefore, improve cardiovascular outcome in patients with acute myocardial infarction. In this article, we describe the modulation of pathophysiology by SSO₂, review the existing trial data and present our first impressions with the technique in real clinical practice.

Hypothermia for Cardioprotection in Patients with St-Elevation Myocardial Infarction: Do Not Give It the Cold Shoulder Yet!

The timely revascularization of an occluded coronary artery is the cornerstone of treatment in patients with ST-elevation myocardial infarction (STEMI). As essential as this treatment is, it can also cause additional damage to cardiomyocytes that were still viable before reperfusion, increasing infarct size. This has been termed “myocardial reperfusion injury”. To date, there is still no effective treatment for myocardial reperfusion injury in patients with STEMI. While numerous attempts have been made to overcome this hurdle with various experimental therapies, the common denominator of these therapies is that, although they often work in the preclinical setting, they fail to demonstrate the same results in human trials. Hypothermia is an example of such a therapy. Although promising results were derived from experimental studies, multiple randomized controlled trials failed to do the same. This review includes a discussion of hypothermia as a potential treatment for myocardial reperfusion injury, including lessons learned from previous (negative) trials, advanced techniques and materials in current hypothermic treatment, and the possible future of hypothermia for cardioprotection in patients with STEMI.

Feasibility of early waking cardiac arrest patients whilst receiving therapeutic hypothermia: The therapeutic hypothermia and early waking (THAW) trial

AIM

To determine the safety and feasibility of an early (12 h) waking and extubation protocol for out-of-hospital cardiac arrest (OHCA) patients receiving targeted temperature management (TTM).

METHODS

This was a single-centre, prospective, non-randomised, observational, safety and feasibility pilot study which included successfully resuscitated OHCA patients, of presumed cardiac cause. Inclusion criteria were: OHCA patients aged over 18 years with a return of spontaneous circulation, who were going to receive TTM33 (TTM at 33 °C for 24 h and prevention of hyperthermia for 72 h) as part of their post cardiac arrest care. Clinical stability was measured against physiological and neurological parameters as well as clinical assessment.

RESULTS

50 consecutive patients were included (median age 65.5 years, 82% male) in the study. Four (8%) patients died within the first twelve hours and were excluded from the final cohort (n = 46). Twenty-three patients (46%) were considered clinically stable and suitable for early waking based on the intention to treat analysis; 12 patients were extubated early based on a variety of clinical factors (21.4 ± 8.6 h) whilst continuing to receive TTM33 with a mean core temperature of 34.2 °C when extubated. Of these, five patients were discharged from the intensive care unit (ICU) <48 h after admission with a mean ICU length of stay 1.8 ± 0.4 days. Twenty-eight patients (56%) were discharged from the ICU with a modified Rankin Score of 0-2. The overall intra-hospital mortality was 50% (n = 25).

CONCLUSIONS

It is safe and feasible to wake selected comatose OHCA patients at 12 h, allowing for earlier positive neuro-prognostication and reduced ICU stay.

Copeptin Levels Are Independent from Mild Therapeutic Hypothermia but Do Not Predict Infarct Size in Patients Presenting with ST-Segment Elevation Myocardial Infarction

Background: Mild therapeutic hypothermia (MTH) is a treatment adjunct in ST-segment elevation myocardial infarction (STEMI) that deserves investigation. Copeptin―a surrogate marker for vasopressin―is an early biomarker in STEMI. Data from cardiac arrest patients suggest a reduction of copeptin levels through MTH; however, copeptin levels have not been investigated in MTH during STEMI. Methods: We analyzed patients treated with MTH during STEMI in a sub-study of the STATIM trial (Testori, Heart 2019). Patients were randomized to normothermia or MTH with out-of-hospital initiation. Seven copeptin samples were collected from each patient. Primary endpoint was the difference in copeptin levels between the groups. As secondary endpoints, we defined differences in the kinetics between the sampling timepoints and the correlation between copeptin and the infarct size in relation to left ventricular myocardium. Results: We included 99 patients (MTH n = 47, control n = 52) in our intention to treat analysis. No differences in copeptin values at first medical contact between the MTH and normothermia groups were found. MTH showed no effect on copeptin levels, neither during cooling phase nor through the course. Copeptin peaked at first medical contact and hospital admission in both groups. No differences in kinetics between the timepoints were found. Copeptin showed no correlation with infarct size, neither at first medical contact nor hospital admission. Conclusions: Copeptin levels were not influenced by MTH in STEMI, suggesting the use of this biomarker also during temperature management. Furthermore, copeptin levels were not usable as a surrogate marker for infarct size at any timepoint.

Beneficial Electrophysiological Effects of Rotigaptide Are Unable to Suppress Therapeutic Hypothermia-Provoked Ventricular Fibrillation in Failing Rabbit Hearts With Acute Ischemia-Reperfusion Injury

Aims: Whether therapeutic hypothermia (TH) is proarrhythmic in preexisting failing hearts with acute ischemia–reperfusion (IR) injury is unknown. Additionally, the effectiveness of rotigaptide on improving conduction slowing in hearts with IR injury is ambiguous. We investigated the electrophysiological effects of TH and rotigaptide in failing rabbit hearts with acute IR injury and determined the underlying molecular mechanisms.

Methods and Results: Heart failure was induced by right ventricular pacing (320 beats/min, 4 weeks). Rabbits with pacing-induced heart failure were randomly divided into TH (n = 14) and non-TH (n = 7) groups. The IR rabbit model was created by ligating the coronary artery for 60 min, followed by reperfusion for 15 min in vivo. Then, the hearts were excised quickly and Langendorff-perfused for simultaneous voltage and intracellular Ca²⁺ (Ca_i) optical mapping. Electrophysiological studies were conducted, and vulnerability to ventricular fibrillation (VF) was evaluated using pacing protocols. TH (33°C) was instituted after baseline studies, and electrophysiological studies were repeated. Rotigaptide (300 nM) was infused for 20 min, and electrophysiological studies were repeated under TH. Cardiac tissues were sampled for Western blotting. TH increased the dispersion and beat-to-beat variability of action potential duration (APD), aggravated conduction slowing, and prolonged Ca_i decay to facilitate spatially discordant alternans (SDA) and VF induction. Rotigaptide reduced the dispersion and beat-to-beat variability of APD and improved slowed conduction to defer the onset of arrhythmogenic SDA by dynamic pacing and elevate the pacing threshold of VF during TH. However, the effect of rotigaptide on TH-enhanced VF inducibility was statistically insignificant. TH attenuated IR-induced dysregulation of protein expression, but its functional role remained uncertain.

Conclusion: Therapeutic hypothermia is proarrhythmic in failing hearts with acute IR injury. Rotigaptide improves TH-induced APD dispersion and beat-to-beat variability and conduction disturbance to defer the onset of arrhythmogenic SDA and elevate the VF threshold by dynamic pacing, but these beneficial electrophysiological effects are unable to suppress TH-enhanced VF inducibility significantly.

A multicentre, prospective, randomised controlled trial to assess the safety and effectiveness of cooling as an adjunctive therapy to percutaneous intervention in patients with acute myocardial infarction: the COOL AMI EU Pivotal Trial

BACKGROUND

Despite primary PCI (PPCI), ST-elevation myocardial infarction (STEMI) can still result in large infarct size (IS). New technology with rapid intravascular cooling showed positive signals for reduction in IS in anterior STEMI.

AIMS

We investigated the effectiveness and safety of rapid systemic intravascular hypothermia as an adjunct to PPCI in conscious patients, with anterior STEMI, without cardiac arrest.

METHODS

Hypothermia was induced using the ZOLL® Proteus™ intravascular cooling system. After randomisation of 111 patients, 58 to hypothermia and 53 to control groups, the study was prematurely discontinued by the sponsor due to inconsistent patient logistics between the groups resulting in significantly longer total ischaemic delay in the hypothermia group (232 vs 188 minutes; p<0.001).

RESULTS

There were no differences in angiographic features and PPCI result between the groups. Intravascular temperature at wire crossing was 33.3+0.9°C. Infarct size/left ventricular (IS/LV) mass by cardiac magnetic resonance (CMR) at day 4-6 was 21.3% in the hypothermia group and 20.0% in the control group (p=0.540). Major adverse cardiac events at 30 days increased non-significantly in the hypothermia group (8.6% vs 1.9%; p=0.117) while cardiogenic shock (10.3% vs 0%; p=0.028) and paroxysmal atrial fibrillation (43.1% vs 3.8%; p<0.001) were significantly more frequent in the hypothermia group.

CONCLUSIONS

The ZOLL Proteus intravascular cooling system reduced temperature to 33.3°C before PPCI in patients with anterior STEMI. Due to inconsistent patient logistics between the groups, this hypothermia protocol resulted in a longer ischaemic delay, did not reduce IS/LV mass and was associated with increased adverse events.

Cardiac MRI to Visualize Myocardial Damage after ST-Segment Elevation Myocardial Infarction: A Review of Its Histologic Validation

Cardiac MRI is a noninvasive diagnostic tool using nonionizing radiation that is widely used in patients with ST-segment elevation myocardial infarction (STEMI). Cardiac MRI depicts different prognosticating components of myocardial damage such as edema, intramyocardial hemorrhage (IMH), microvascular obstruction (MVO), and fibrosis. But how do cardiac MRI findings correlate to histologic findings? Shortly after STEMI, T2-weighted imaging and T2* mapping cardiac MRI depict, respectively, edema and IMH. The acute infarct size can be determined with late gadolinium enhancement (LGE) cardiac MRI. T2-weighted MRI should not be used for area-at-risk delineation because T2 values change dynamically over the first few days after STEMI and the severity of T2 abnormalities can be modulated with treatment. Furthermore, LGE cardiac MRI is the most accurate method to visualize MVO, which is characterized by hemorrhage, microvascular injury, and necrosis in histologic samples. In the chronic setting post-STEMI, LGE cardiac MRI is best used to detect replacement fibrosis (ie, final infarct size after injury healing). Finally, native T1 mapping has recently emerged as a contrast material-free method to measure infarct size that, however, remains inferior to LGE cardiac MRI. Especially LGE cardiac MRI-defined infarct size and the presence and extent of MVO may be used to monitor the effect of new therapeutic interventions in the treatment of reperfusion injury and infarct size reduction. © RSNA, 2021 Online supplemental material is available for this article.

Mild Hypothermia Therapy Lowers the Inflammatory Level and Apoptosis Rate of Myocardial Cells of Rats with Myocardial Ischemia-Reperfusion Injury via the NLRP3 Inflammasome Pathway

Objective

To explore the protective effects and mechanism of mild hypothermia treatment in the treatment of myocardial ischemia-reperfusion injury. Material and Methods. A total of 20 Sprague-Dawley (SD) rats were assigned to 4 groups: the blank control group, sham operation group, ischemia reperfusion group, and mild hypothermia therapy group (each n = 5). Some indexes were detected. In addition, myocardial cell models of oxygen-glucose deprivation/reoxygenation injury (OGD) were established. The expression of mRNA IL-6 and TNF-α and the key enzyme levels of apoptosis (cleaved-Caspase-3) and the NLRP3 inflammasome/p53 signaling pathway in the models were determined.

Results

The expression of serum IL-6 and TNF-α in the mild hypothermia therapy group was significantly lower than that in the ischemia reperfusion group. The mild hypothermia therapy group also showed a significantly lower TUNEL cell count and NLRP3 and p53 phosphorylation levels than the ischemia reperfusion group (all p < 0.05). The in vitro mild hypothermia + OGD group also showed significantly lower mRNA expression of IL-6 and TNF-α and levels of cleaved Caspase-3, NLRP3, and phosphorylated p53 protein than the OGD group (all p < 0.05).

Conclusion

In conclusion, mild hypothermia therapy can inhibit the apoptosis and myocardial inflammation of cells induced by MI/R injury in rats and inhibiting the activity of the NLRP3 inflammasome pathway and p53 signaling pathway may be the mechanism.

Hypothermia for Reduction of Myocardial Reperfusion Injury in Acute Myocardial Infarction: Closing the Translational Gap

Myocardial reperfusion injury-triggered by an inevitable inflammatory response after reperfusion-may undo a considerable part of the myocardial salvage achieved through timely percutaneous coronary intervention in patients with acute myocardial infarction. Because infarct size is strongly correlated to mortality and risk of heart failure, the importance of endeavors for cardioprotective therapies to attenuate myocardial reperfusion injury and decrease infarct size remains undisputed. Myocardial reperfusion injury is the result of several complex nonlinear phenomena, and for a therapy to be effective, it should act on multiple targets involved in this injury. In this regard, hypothermia remains a promising treatment despite a number of negative randomized controlled trials in humans with acute myocardial infarction so far. To turn the tide for hypothermia in patients with acute myocardial infarction, sophisticated solutions for important limitations of systemic hypothermia should continue to be developed. In this review, we provide a comprehensive overview of the pathophysiology and clinical expression of myocardial reperfusion injury and discuss the current status and possible future of hypothermia for cardioprotection in patients with acute myocardial infarction.

Mild Therapeutic Hypothermia Alters Hemostasis in ST Elevation Myocardial Infarction Patients

Background and Rationale: Mild therapeutic hypothermia (MTH) is a concept to reduce infarct size and improve outcome after ST-segment elevation myocardial infarction (STEMI). In the STATIM trial, we investigated MTH as an additional therapy for STEMI patients. In the intention-to-treat set, 101 patients were included. No difference in primary and secondary endpoints measured by cardiac magnetic resonance imaging was found. Platelet activation and plasmatic coagulation are key in the pathophysiology of STEMI. In the present study, we investigated the effect of MTH on primary and secondary hemostasis in STEMI patients.

Methods and Results: Platelet function and morphology were assessed by routine blood count, aggregometry testing, and flow cytometry. Soluble platelet markers were determined by enzyme-linked immunosorbent assay (ELISA) testing. Plasmatic coagulation was measured throughout the study. Platelet count remained unchanged, irrespective of treatment, whereas platelet size decreased in both patient groups. Platelet aggregometry indicated increased platelet reactivity in the MTH group. Furthermore, higher adenosine diphosphate (ADP) plasma levels were found in MTH patients. Expression of glycoprotein IIb/IIIa was increased on platelets of STEMI patients treated with MTH. Lower patient temperatures correlated with longer clotting times and resulted in reduced pH. Lower pH values were positively correlated with longer clotting times.

Conclusion: Present data indicate longer clotting times and higher platelet reactivity in STEMI patients treated with MTH. These changes did not correspond to clinical bleeding events or larger infarct size.

Effect of therapeutic hypothermia on renal and myocardial function in asphyxiated (near) term neonates: A systematic review and meta-analysis

Background

Therapeutic hypothermia (TH) is a well-established neuroprotective therapy applied in (near) term asphyxiated infants. However, little is known regarding the effects of TH on renal and/or myocardial function.

Objectives

To describe the short- and long-term effects of TH on renal and myocardial function in asphyxiated (near) term neonates.

Methods

An electronic search strategy incorporating MeSH terms and keywords was performed in October 2019 and updated in June 2020 using PubMed and Cochrane databases. Inclusion criteria consisted of a RCT or observational cohort design, intervention with TH in a setting of perinatal asphyxia and available long-term results on renal and myocardial function. We performed a meta-analysis and heterogeneity and sensitivity analyses using a random effects model. Subgroup analysis was performed on the method of cooling.

Results

Of the 107 studies identified on renal function, 9 were included. None of the studies investigated the effects of TH on long-term renal function after perinatal asphyxia. The nine included studies described the effect of TH on the incidence of acute kidney injury (AKI) after perinatal asphyxia. Meta-analysis showed a significant difference between the incidence of AKI in neonates treated with TH compared to the control group (RR = 0.81; 95% CI 0.67–0.98; p = 0.03). No studies were found investigating the long-term effects of TH on myocardial function after neonatal asphyxia. Possible short-term beneficial effects were presented in 4 out of 5 identified studies, as observed by significant reductions in cardiac biomarkers and less findings of myocardial dysfunction on ECG and cardiac ultrasound.

Conclusions

TH in asphyxiated neonates reduces the incidence of AKI, an important risk factor for chronic kidney damage, and thus is potentially renoprotective. No studies were found on the long-term effects of TH on myocardial function. Short-term outcome studies suggest a cardioprotective effect.

Effects of Therapeutic Hypothermia on Normal and Ischemic Heart

Therapeutic hypothermia has been used for treating brain injury after out-of-hospital cardiac arrest. Its potential benefit on minimizing myocardial ischemic injury has been explored, but clinical evidence has yet to confirm positive results in preclinical studies. Importantly, therapeutic hypothermia for myocardial infarction is unique in that it can be initiated prior to reperfusion, in contrast to its application for brain injury in resuscitated cardiac arrest patients. Recent advance in cooling technology allows more rapid cooling of the heart than ever and new clinical trials are designed to examine the efficacy of rapid therapeutic hypothermia for myocardial infarction. In this review, we summarize current knowledge regarding the effect of hypothermia on normal and ischemic hearts and discuss issues to be solved in order to realize its clinical application for treating acute myocardial infarction.

Cardioprotective effect of combination therapy by mild hypothermia and local or remote ischemic preconditioning in isolated rat hearts

A multitargeted strategy to treat the consequences of ischemia and reperfusion (IR) injury in acute myocardial infarction may add cardioprotection beyond reperfusion therapy alone. We investigated the cardioprotective effect of mild hypothermia combined with local ischemic preconditioning (IPC) or remote ischemic conditioning (RIC) on IR injury in isolated rat hearts. Moreover, we aimed to define the optimum timing of initiating hypothermia and evaluate underlying cardioprotective mechanisms. Compared to infarct size in normothermic controls (56 ± 4%), mild hypothermia during the entire or final 20 min of the ischemic period reduced infarct size (34 ± 2%, p < 0.01; 35 ± 5%, p < 0.01, respectively), while no reduction was seen when hypothermia was initiated at reperfusion (51 ± 4%, p = 0.90). In all groups with effect of mild hypothermia, IPC further reduced infarct size. In contrast, we found no additive effect on infarct size between hypothermic controls (20 ± 3%) and the combination of mild hypothermia and RIC (33 ± 4%, p = 0.09). Differences in temporal lactate dehydrogenase release patterns suggested an anti-ischemic effect by mild hypothermia, while IPC and RIC preferentially targeted reperfusion injury. In conclusion, additive underlying mechanisms seem to provide an additive effect of mild hypothermia and IPC, whereas the more clinically applicable RIC does not add cardioprotection beyond mild hypothermia.

The many faces of myocardial ischaemia and angina

Obstructive disease of the epicardial coronary arteries is the main cause of angina. However, a number of patients with anginal symptoms have normal coronaries or non-obstructive coronary artery disease (CAD) despite electrocardiographic evidence of ischaemia during stress testing. In addition to limited microvascular vasodilator capacity, the coronary microcirculation of these patients is particularly sensitive to vasoconstrictor stimuli, in a condition known as microvascular angina. This review briefly summarizes the determinants and control of coronary blood flow (CBF) and myocardial perfusion. It subsequently analyses the mechanisms responsible for transient myocardial ischaemia: obstructive CAD, coronary spasm and coronary microvascular dysfunction in the absence of epicardial coronary lesions, and variable combinations of structural anomalies, impaired endothelium-dependent and/or -independent vasodilation, and enhanced perception of pain. Lastly, we exemplify mechanism of angina during tachycardia. Distal to a coronary stenosis, coronary dilator reserve is already recruited and can be nearly exhausted at rest distal to a severe stenosis. Increased heart rate reduces the duration of diastole and thus CBF when metabolic vasodilation is no longer able to increase CBF. The increase in myocardial oxygen consumption and resulting metabolic vasodilation in adjacent myocardium without stenotic coronary arteries further acts to divert blood flow away from the post-stenotic coronary vascular bed through collaterals.

Novel Findings and Therapeutic Targets on Cardioprotection of Ischemia/ Reperfusion Injury in STEMI

Acute ST-segment elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality around the world. A large number of STEMI patients after the infarction gradually develop heart failure due to the infarcted myocardium. Timely reperfusion is essential to salvage ischemic myocardium from the infarction, but the restoration of coronary blood flow in the infarct-related artery itself induces myocardial injury and cardiomyocyte death, known as ischemia/reperfusion injury (IRI). The factors contributing to IRI in STEMI are complex, and microvascular obstruction, inflammation, release of reactive oxygen species, myocardial stunning, and activation of myocardial cell death are involved. Therefore, additional cardioprotection is required to prevent the heart from IRI. Although many mechanical conditioning procedures and pharmacological agents have been identified as effective cardioprotective approaches in animal studies, their translation into the clinical practice has been relatively disappointing due to a variety of reasons. With new emerging data on cardioprotection in STEMI over the past few years, it is mandatory to reevaluate the effectiveness of "old" cardioprotective interventions and highlight the novel therapeutic targets and new treatment strategies of cardioprotection.

Hypothermia in patients with acute myocardial infarction: a meta-analysis of randomized trials

BACKGROUND

In patients with acute myocardial infarction (MI) receiving percutaneous coronary intervention (PCI), the role of systemic therapeutic hypothermia remains controversial. We sought to investigate the role of systemic therapeutic hypothermia versus standard of care in patients with acute MI treated with PCI.

METHODS

This is a study-level meta-analysis of randomized trials. The primary outcome was all-cause death. The main secondary outcome was infarct size. Other secondary outcomes were recurrent MI, ischemia-driven target vessel revascularization (TVR), major adverse cardiovascular events, and bleeding.

RESULTS

A total of 1012 patients with acute MI receiving a PCI in nine trials (503 randomly assigned to hypothermia and 509 to control) were available for the quantitative synthesis. The weighted median follow-up was 30 days. As compared to controls, patients assigned to hypothermia had similar risk of all-cause death (risk ratio, [95% confidence intervals], 1.25 [0.80; 1.95], p = 0.32), with a trend toward higher risk of ischemia-driven TVR (3.55 [0.80; 15.87], p = 0.09) mostly due to acute or subacute stent thrombosis. Although in the overall cohort, infarct size was comparable between groups (standardized mean difference [95% Confidence intervals], 0.06 [- 0.92; 1.04], p = 0.92), patients effectively achieving the protocol-defined target temperature in the hypothermia group had smaller infarct size as compared to controls (p for interaction = 0.016). Treatment strategies did not differ with respect to the other outcomes.

CONCLUSIONS

As compared to standard of care, systemic therapeutic hypothermia in acute MI patients treated with PCI provided similar mortality with a signal toward more frequent repeat revascularization. Among patients assigned to hypothermia, those effectively achieving the protocol-defined target temperature displayed smaller infarct size.

TRIAL REGISTRATION

PROSPERO, CRD42019138754.

A pilot clinical study of adjunctive therapy with selective intracoronary hypothermia in patients with ST-segment elevation myocardial infarction

OBJECTIVES

We aimed to assess the effect of selective intracoronary hypothermia on outcomes in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

BACKGROUND

Intracoronary hypothermia, the feasibility and safety of which has been validated in humans, induced by selective trans-coronary infusion of saline at different temperatures can reduce infarct size (IS) prior to reperfusion in animal models of STEMI.

METHODS

Sixty STEMI patients presenting with thrombolysis in myocardial infarction (TIMI) flow grade 0/1 were randomized after coronary artery angiography. Intracoronary hypothermia was induced by selective trans-coronary infusion of saline at 4°C to the endangered myocardium in the 30 patients. The primary endpoint, absolute IS expressed as IS/myocardium at risk (MaR), was assessed by cardiac magnetic resonance imaging at day 7 post-PPCI in 50 patients. Clinical follow-up was undertaken at day 30 after procedure.

RESULTS

Intracoronary hypothermia was successfully performed in hypothermia group, without increase in arrhythmia or hemodynamic instability. The mean temperature reduction of 5.8 ± 1.1°C in distal coronary artery was achieved before reperfusion. Mean IS/MaR was predominantly reduced in the hypothermia group (44.85 ± 5.89% vs. 50.69 ± 10.75%, P = 0.022), especially in the anterior STEMI subgroup (46.12 ± 7.54% vs. 55.27 ± 11.175%, P = 0.023). The clinical events appeared no statistical difference between the two groups at the 30-day follow-up.

CONCLUSION

The statistical difference in IS/MaR by intracoronary hypothermia as adjunctive therapy to PPCI is an important observation and warrants a larger pivotal trial fully powered for efficacy.

Out-of-hospital initiation of hypothermia in ST-segment elevation myocardial infarction: a randomised trial

Objective

To evaluate the effect of prereperfusion hypothermia initiated in the out-of-hospital setting in awake patients with ST-segment elevation myocardial infarction (STEMI) on myocardial salvage measured by cardiac MRI (CMR).

Methods

Hypothermia was initiated within 6 hours of symptom onset by the emergency medical service with surface cooling pads and cold saline, and continued in the cath lab with endovascular cooling (target temperature: ≤35°C at time of reperfusion). Myocardial salvage index (using CMR) was compared in a randomised, controlled, open-label, endpoint blinded trial to a not-cooled group of patients at day 4±2 after the event.

Results

After postrandomisation exclusion of 19 patients a total of 101 patients were included in the intention-to-treat analysis (control group: n=54; hypothermia group: n=47). Target temperature was reached in 38/47 patients (81%) in the intervention group. Study-related interventions resulted in a delay in time from first medical contact to reperfusion of 14 min (control group 89±24 min; hypothermia group 103±21 min; p<0.01). Myocardial salvage index was 0.37 (±0.26) in the control group and 0.43 (±0.27) in the hypothermia group (p=0.27). No differences in cardiac biomarkers or clinical outcomes were found. In a CMR follow-up 6 months after the initial event no significant differences were detected.

Conclusion

Out-of-hospital induced therapeutic hypothermia as an adjunct to primary percutaneous coronary intervention did not improve myocardial salvage in patients with STEMI.

Trial registration number

NCT01777750

Emergency Neurological Life Support: Resuscitation Following Cardiac Arrest

Cardiac arrest is the most common cause of death in North America. An organized bundle of neurocritical care interventions can improve chances of survival and neurological recovery in patients who are successfully resuscitated from cardiac arrest. Therefore, resuscitation following cardiac arrest was chosen as an Emergency Neurological Life Support protocol. Key aspects of successful early post-arrest management include: prevention of secondary brain injury; identification of treatable causes of arrest in need of emergent intervention; and, delayed neurological prognostication. Secondary brain injury can be attenuated through targeted temperature management (TTM), avoidance of hypoxia and hypotension, avoidance of hyperoxia, hyperventilation or hypoventilation, and treatment of seizures. Most patients remaining comatose after resuscitation from cardiac arrest should undergo TTM. Treatable precipitants of arrest that require emergent intervention include, but are not limited to, acute coronary syndrome, intracranial hemorrhage, pulmonary embolism and major trauma. Accurate neurological prognostication is generally not appropriate for several days after cardiac arrest, so early aggressive care should never be limited based on perceived poor neurological prognosis.

Effects of endovascular cooling on infarct size in ST-segment elevation myocardial infarction: A patient-level pooled analysis from randomized trials

OBJECTIVES

This study sought to examine the relationship between temperature at reperfusion and infarct size.

BACKGROUND

Hypothermia consistently reduces infarct size when administered prior to reperfusion in animal studies, however, clinical results have been inconsistent.

METHODS

We performed a patient-level pooled analysis from six randomized control trials of endovascular cooling during primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) in 629 patients in which infarct size was assessed within 1 month after randomization by either single-photon emission computed tomography (SPECT) or cardiac magnetic resonance imaging (cMR).

RESULTS

In anterior infarct patients, after controlling for variability between studies, mean infarct size in controls was 21.3 (95%CI 17.4-25.3) and in patients with hypothermia <35°C it was 14.8 (95%CI 10.1-19.6), which was a statistically significant absolute reduction of 6.5%, or a 30% relative reduction in infarct size (P = 0.03). There was no significant difference in infarct size in anterior ≥35°C, or inferior infarct patients. There was no difference in the incidence of death, ventricular arrhythmias, or re-infarction due to stent thrombosis between hypothermia and control patients.

CONCLUSIONS

The present study, drawn from a patient-level pooled analysis of six randomized trials of endovascular cooling during primary PCI in STEMI, showed a significant reduction in infarct size in patients with anterior STEMI who were cooled to <35°C at the time of reperfusion. The results support the need for trials in patients with anterior STEMI using more powerful cooling devices to optimize the delivery of hypothermia prior to reperfusion.

Braun-Dullaeus R. Cardiogenic Causes of Fever

BACKGROUND

Persistent fever of unknown cause is only rarely of cardiac origin, but heart disease must be considered in the differential diagnosis. Aside from endocarditis, pericarditis and various other conditions may be responsible.

METHODS

This review is based on pertinent articles retrieved by a selective search in PubMed and Google Scholar employing the term "fever" in combination with "myocardial infarction," "pericarditis," "endocarditis," and "postcardiac injury," with additional consideration of current cardiological guidelines.

RESULTS

Endocarditis is associated with fever in 90% of cases, but 25-50% of patients also develop high body temperatures after acute myocardial infarction. In pericarditis, a temperature above 38°C indicates a poorer prognosis; if accompanied by other warning signs, it is an indication for hospitalization and pericardiocentesis. Fever can arise after cardiac surgical procedures as a manifestation of post - cardiotomy syndrome, a special type of perimyocarditis. There may be a latency period of up to 3 months.

CONCLUSION

Fever can have both infectious and non-infectious cardiac causes. Its interpretation depends on the clinical context. The evidence base for treatment is sparse, and controlled trials are needed.

Optimal course of treatment in acute cardiogenic shock complicating myocardial infarction

INTRODUCTION

About 5% of patients with myocardial infarction suffer from cardiogenic shock as a complication, with a mortality of ≥30%. Primary percutaneous coronary intervention as soon as possible is the most successful therapeutic approach. Prognosis depends not only on the extent of infarction, but also - and even more - on organ hypoperfusion with consequent development of multiple organ dysfunction syndrome. Areas covered: This review covers diagnostic, monitoring and treatment concepts relevant for caring patients with cardiogenic shock complicating myocardial infarction. All major clinical trials have been selected for review of the recent data. Expert commentary: For optimal care, not only primary percutaneous intervention of the occluded coronary artery is necessary, but also best intensive care medicine avoiding the development of multiple organ dysfunction syndrome and finally death. On contrary, intra-aortic balloon pump - though used for decades - is unable to reduce mortality of patients with cardiogenic shock complicating myocardial infarction.

Oxidative stress in ischemia and reperfusion: current concepts, novel ideas and future perspectives

Oxidative stress remains a major contributor to myocardial injury after ischemia followed by reperfusion (I/R) as the reperfusion of the myocardial infarction (MI) area inevitably leads to a cascade of I/R injury. This review focused on concepts of the antioxidative defense system and elucidates recent research using antioxidants like vitamin C, E and β-carotene or essential trace elements to activate compounds of antioxidative pathways in the circulation. In this context, important defense mechanisms like superoxide dismutase and glutathione peroxidase will be described. Furthermore, the different mechanisms through which myocardial protection can be addressed, like ischemic postconditioning in myocardial infarction or adjunctive measures like targeted temperature management as well as new theories, including the role of iron in I/R injury, will be discussed.