Post-Cardiac Arrest Hydrocortisone Use Ameliorates Cardiac Mitochondrial Injury in a Male Rat Model of Ventricular Fibrillation Cardiac Arrest

Impact of stress hyperglycemia ratio on mortality in patients with cardiac arrest: insight from American MIMIC-IV database

Background

Stress hyperglycemia ratio (SHR) has shown a predominant correlation with transient adverse events in critically ill patients. However, there remains a gap in comprehensive research regarding the association between SHR and mortality among patients experiencing cardiac arrest and admitted to the intensive care unit (ICU).

Methods

A total of 535 patients with their initial ICU admission suffered cardiac arrest, according to the American Medical Information Mart for Intensive Care (MIMIC)-IV database. Patients were stratified into four categories based on quantiles of SHR. Multivariable Cox regression models were used to evaluate the association SHR and mortality. The association between SHR and mortality was assessed using multivariable Cox regression models. Subgroup analyses were conducted to determine whether SHR influenced ICU, 1-year, and long-term all-cause mortality in subgroups stratified according to diabetes status.

Results

Patients with higher SHR, when compared to the reference quartile 1 group, exhibited a greater risk of ICU mortality (adjusted hazard ratio [aHR] = 3.029; 95% CI: 1.802-5.090), 1-year mortality (aHR = 3.057; 95% CI: 1.885-4.958), and long-term mortality (aHR = 3.183; 95% CI: 2.020-5.015). This association was particularly noteworthy among patients without diabetes, as indicated by subgroup analysis.

Conclusion

Elevated SHR was notably associated with heightened risks of ICU, 1-year, and long-term all-cause mortality among cardiac arrest patients. These findings underscore the importance of considering SHR as a potential prognostic factor in the critical care management of cardiac arrest patients, warranting further investigation and clinical attention.

Review of the Association Between Long-Term and Current Systemic Steroid Use With Electromechanical Complications and Inpatient Mortality After ST-Elevation Myocardial Infarction

Background The impact of long-term systemic steroid use on electrical and mechanical complications following ST-segment elevation myocardial infarction (STEMI) has not been extensively studied. Methods In a retrospective cohort study of the National Inpatient Sample (NIS) from 2018 to 2020, adults admitted with STEMI were dichotomized based on the presence of long-term (current) systemic steroid (LTCSS) use. The primary outcome was all-cause mortality. Secondary outcomes included a composite of mechanical complications, electrical, hemodynamic, and thrombotic complications, as well as revascularization complexity, length of stay (LOS), and total charge. Multivariate linear and logistic regressions were used to adjust for confounders. Results Out of 608,210 admissions for STEMI, 5,310 (0.9%) had LTCSS use. There was no significant difference in the odds of all-cause mortality (aOR: 0.89, 95%CI: 0.74-1.08, p-value: 0.245) and the composite of mechanical complications (aOR: 0.74, 95%CI: 0.25-2.30, p-value: 0.599). LTCSS use was associated with lower odds of ventricular tachycardia, atrioventricular blocks, new permanent-pacemaker insertion, cardiogenic shock, the need for mechanical circulatory support, mechanical ventilation, cardioversion, a reduced LOS by 1 day, and a reduced total charge by 34,512 USD (all p-values: <0.05). There were no significant differences in the revascularization strategy (coronary artery bypass graft (CABG) vs. percutaneous coronary interventions (PCI)) or in the incidence of composite thrombotic events. Conclusion LTCSS use among patients admitted with STEMI was associated with lower odds of electrical dysfunction and hemodynamic instability but no difference in the odds of mechanical complications, CABG rate, all-cause mortality, cardiac arrest, or thrombotic complications. Further prospective studies are needed to evaluate these findings further.

Effect of prehospital high-dose glucocorticoid on hemodynamics in patients resuscitated from out-of-hospital cardiac arrest: a sub-study of the STEROHCA trial

BACKGROUND

Following resuscitated out-of-hospital cardiac arrest (OHCA), inflammatory markers are significantly elevated and associated with hemodynamic instability and organ dysfunction. Vasopressor support is recommended to maintain a mean arterial pressure (MAP) above 65 mmHg. Glucocorticoids have anti-inflammatory effects and may lower the need for vasopressors. This study aimed to assess the hemodynamic effects of prehospital high-dose glucocorticoid treatment in resuscitated comatose OHCA patients.

METHODS

The STEROHCA trial was a randomized, placebo-controlled, phase 2 trial comparing one prehospital injection of methylprednisolone 250 mg with placebo immediately after resuscitated OHCA. In this sub-study, we included patients who remained comatose at admission and survived until intensive care unit (ICU) admission. The primary outcome was cumulated norepinephrine use from ICU admission until 48 h reported as mcg/kg/min. Secondary outcomes included hemodynamic status characterized by MAP, heart rate, vasoactive-inotropic score (VIS), and the VIS/MAP-ratio as well as cardiac function assessed by pulmonary artery catheter measurements. Linear mixed-model analyses were performed to evaluate mean differences between treatment groups at all follow-up times.

RESULTS

A total of 114 comatose OHCA patients were included (glucocorticoid: n = 56, placebo: n = 58) in the sub-study. There were no differences in outcomes at ICU admission. From the time of ICU admission up to 48 h post-admission, patients in the glucocorticoid group cumulated a lower norepinephrine use (mean difference - 0.04 mcg/kg/min, 95% CI - 0.07 to - 0.01, p = 0.02). Moreover, after 12-24 h post-admission, the glucocorticoid group demonstrated a higher MAP with mean differences ranging from 6 to 7 mmHg (95% CIs from 1 to 12), a lower VIS (mean differences from - 4.2 to - 3.8, 95% CIs from - 8.1 to 0.3), and a lower VIS/MAP ratio (mean differences from - 0.10 to - 0.07, 95% CIs from - 0.16 to - 0.01), while there were no major differences in heart rate (mean differences from - 4 to - 3, 95% CIs from - 11 to 3). These treatment differences between groups were also present 30-48 h post-admission but to a smaller extent and with increased statistical uncertainty. No differences were found in pulmonary artery catheter measurements between groups.

CONCLUSIONS

Prehospital treatment with high-dose glucocorticoid was associated with reduced norepinephrine use in resuscitated OHCA patients.

TRIAL REGISTRATION

EudraCT number: 2020-000855-11; submitted March 30, 2020. URL: https://www.

CLINICALTRIALS

gov ; Unique Identifier: NCT04624776.

A ventricular fibrillation cardiac arrest model with extracorporeal cardiopulmonary resuscitation in rats: 8 minutes arrest time leads to increased myocardial damage but does not increase neuronal damage compared to 6 minutes

Introduction

Extracorporeal cardiopulmonary resuscitation (ECPR) is an emerging strategy in highly selected patients with refractory cardiac arrest (CA). Animal models can help to identify new therapeutic strategies to improve neurological outcome and cardiac function after global ischemia in CA. Aim of the study was to establish a reproducible ECPR rat model of ventricular fibrillation CA (VFCA) that leads to consistent neuronal damage with acceptable long-term survival rates, which can be used for future research.

Materials and methods

Male Sprague Dawley rats were resuscitated with ECPR from 6 min (n = 15) and 8 min (n = 16) VFCA. Animals surviving for 14 days after return of spontaneous resuscitation (ROSC) were compared with sham operated animals (n = 10); neurological outcome was assessed daily until day 14. In the hippocampal cornu ammonis 1 region viable neurons were counted. Microglia and astrocyte reaction was assessed by Iba1 and GFAP immunohistochemistry, and collagen fibers in the myocardium were detected in Azan staining. QuPath was applied for quantification.

Results

Of the 15 rats included in the 6 min CA group, all achieved ROSC (100%) and 10 (67%) survived to 14 days; in the 8 min CA group, 15 (94%) achieved ROSC and 5 (31%) reached the endpoint. All sham animals (n = 10) survived 2 weeks. The quantity of viable neurons was significantly decreased, while the area displaying Iba1 and GFAP positive pixels was significantly increased in the hippocampus across both groups that experienced CA. Interestingly, there was no difference between the two CA groups regarding these changes. The myocardium in the 8 min CA group exhibited significantly more collagen fibers compared to the sham animals, without differences between 6- and 8-min CA groups. However, this significant increase was not observed in the 6 min CA group.

Conclusion

Our findings indicate a uniform occurrence of neuronal damage in the hippocampus across both CA groups. However, there was a decrease in survival following an 8-min CA. Consequently, a 6-min duration of CA resulted in predictable neurological damage without significant cardiac damage and ensured adequate survival rates up to 14 days. This appears to offer a reliable model for investigating neuroprotective therapies.

The relationship between the level of NMLR on admission and the prognosis of patients after cardiopulmonary resuscitation: a retrospective observational study

BACKGROUND

The inflammatory immune response is involved in the pathophysiology of the post-cardiac arrest syndrome and leads to high mortality. The admission (neutrophil + monocyte) to lymphocyte ratio (NMLR) can help us to assess the immune inflammatory status of patients. We aimed to identify factors that affect the prognosis and explore the association between NMLR and the prognosis of patients after cardiopulmonary resuscitation (CPR).

METHODS

This is a retrospective study based on the MIMIC-IV database. We assessed patients admitted to the ICU after cardiopulmonary resuscitation, included demographic characteristics, peripheral blood cell count and blood gas indicators for the first time after admission to the ICU, developed a multivariate COX proportional-hazards model to explore prognostic factors, and divided patients into High NMLR and Low NMLR groups by cutoff values of NMLR. Propensity score matching (PSM) was used to adjust confounding factors.

RESULTS

A total of 955 patients were included in the analysis, with 497 surviving and 458 dying during the follow-up period. In a multivariate Cox proportional-hazards model, age (RR 1.007, p = 0.0411), NMLR levels (RR 1.003, p = 0.0381), lactate (RR 1.097, p < 0.001) and hematocrit (RR 1.101, p < 0.001) were independent risk factors for patient death following CPR. Patients were divided into a high NMLR group (> 14.2) and a low NMLR group (≤ 14.2) based on the optimal threshold for NMLR. Compared to low NMLR group, high NMLR group had higher total vasoactive drugs and lower 28-day survival. After PSM, there were no differences in baseline characteristics. The high NMLR group still had a higher mortality rate (p = 0.001), lower 28-day survival (p = 0.001) and shorter length of stay (p = 0.005) compared to the low NMLR group.

CONCLUSIONS

Age, NMLR levels, lactate levels and hematocrit were independent risk factors for death in patients after CPR. NMLR > 14.2 was associated with higher mortality and was a potential predictor of clinical outcome in patients after CPR.

Inhibition of ERK downregulates autophagy via mitigating mitochondrial fragmentation to protect SH-SY5Y cells from OGD/R injury

BACKGROUND

Cerebral ischemia-reperfusion injury (CIRI) is the main cause leading to high mortality and neurological disability in patients with cardiac arrest/cardiopulmonary resuscitation (CA/CPR). Our previous study found that extracellular signal-regulated kinase (ERK) activation, dynamin-related protein1 (Drp1)/Mitofusin2 (Mfn2)-dependent mitochondrial dynamics imbalance, and excessive autophagy were involved in the mechanism of nerve injury after CA/CPR. However, the specific pathological signaling pathway is still unknown. This study aimed to explore the molecular function changes of ERK-Drp1/Mfn2-autophagy signaling pathway in SH-SY5Y cell oxygen-glucose deprivation/reoxygenation (OGD/R) model, to further clarify the pathophysiological mechanism of CIRI, and to provide a new strategy for cerebral protection after CIRI.

METHODS

SH-SY5Y cells were pretreated with drugs 24 h before OGD/R. The Drp1 and Mfn2 knockdown were adopted small interfering RNAs. The overexpression of p-Drp1S616 and Mfn2 were used recombinant plasmids. The expression levels of mitochondrial dynamics proteins (p-Drp1, Drp1, Mfn2, Mfn1 and Opa1) and autophagy markers (LC3, Beclin1 and p62) were measured with the Western blotting. The mRNA levels after transfection were determined by PCR. Cell injury and viability were evaluated with released LDH activity and CCK8 assay kits. Mitochondria morphology and autophagosome were observed under transmission electron microscopy. Mitochondrial function was detected by the mitochondrial permeability transition pore assay kit. The co-expression of p-ERK, p-Drp1 and LC3 was assessed with multiple immunofluorescences. One-way analysis of variance followed by least significance difference post hoc analysis (for equal homogeneity) or Dunnett's T3 test (for unequal homogeneity) were used for statistical tests.

RESULTS

ERK inhibitor-PD98059 (PD) protects SH-SY5Y cells from OGD/R-induced injury; while ERK activator-TPA had the opposite effect. Similar to autophagy inhibitor 3-MA, PD downregulated autophagy to improve cell viability; while autophagy activator-rapamycin further aggravated cell death. PD and Drp1-knockdown synergistically attenuated OGD/R-induced Drp1 activation, mPTP opening and cell injury; overexpression of Drp1S616E or ablating Mfn2 partly abolished the protective effects of PD. Multiple immunofluorescences showed that p-ERK, p-Drp1 and LC3 were co-expressed.

CONCLUSION

Inhibition of ERK downregulates autophagy via reducing Drp1/Mfn2-dependent mitochondrial fragmentation to antagonize mitochondrial dysfunction and promotes cell survival in the SH-SY5Y cells OGD/R model. Video Abstract.

Ginsenoside Rb1 Improves Post-Cardiac Arrest Myocardial Stunning and Cerebral Outcomes by Regulating the Keap1/Nrf2 Pathway

The prognosis of cardiac arrest (CA) is dismal despite the ongoing progress in cardiopulmonary resuscitation (CPR). ginsenoside Rb1 (Gn-Rb1) has been verified to be cardioprotective in cardiac remodeling and cardiac ischemia/reperfusion (I/R) injury, but its role is less known in CA. After 15 min of potassium chloride-induced CA, male C57BL/6 mice were resuscitated. Gn-Rb1 was blindly randomized to mice after 20 s of CPR. We assessed the cardiac systolic function before CA and 3 h after CPR. Mortality rates, neurological outcome, mitochondrial homeostasis, and the levels of oxidative stress were evaluated. We found that Gn-Rb1 improved the long-term survival during the post-resuscitation period but did not affect the ROSC rate. Further mechanistic investigations revealed that Gn-Rb1 ameliorated CA/CPR-induced mitochondrial destabilization and oxidative stress, partially via the activation of Keap1/Nrf2 axis. Gn-Rb1 improved the neurological outcome after resuscitation partially by balancing the oxidative stress and suppressing apoptosis. In sum, Gn-Rb1 protects against post-CA myocardial stunning and cerebral outcomes via the induction of the Nrf2 signaling pathway, which may offer a new insight into therapeutic strategies for CA.

Bio-physiological susceptibility of the brain, heart, and lungs to systemic ischemia reperfusion and hyperoxia-induced injury in post-cardiac arrest rats

Cardiac arrest (CA) patients suffer from systemic ischemia-reperfusion (IR) injury leading to multiple organ failure; however, few studies have focused on tissue-specific pathophysiological responses to IR-induced oxidative stress. Herein, we investigated biological and physiological parameters of the brain and heart, and we particularly focused on the lung dysfunction that has not been well studied to date. We aimed to understand tissue-specific susceptibility to oxidative stress and tested how oxygen concentrations in the post-resuscitation setting would affect outcomes. Rats were resuscitated from 10 min of asphyxia CA. Mechanical ventilation was initiated at the beginning of cardiopulmonary resuscitation. We examined animals with or without CA, and those were further divided into the animals exposed to 100% oxygen (CA_Hypero) or those with 30% oxygen (CA_Normo) for 2 h after resuscitation. Biological and physiological parameters of the brain, heart, and lungs were assessed. The brain and lung functions were decreased after CA and resuscitation indicated by worse modified neurological score as compared to baseline (222 ± 33 vs. 500 ± 0, P < 0.05), and decreased PaO2 (20 min after resuscitation: 113 ± 9 vs. baseline: 128 ± 9 mmHg, P < 0.05) and increased airway pressure (2 h: 10.3 ± 0.3 vs. baseline: 8.1 ± 0.2 mmHg, P < 0.001), whereas the heart function measured by echocardiography did not show significant differences compared before and after CA (ejection fraction, 24 h: 77.9 ± 3.3% vs. baseline: 82.2 ± 1.9%, P = 0.2886; fractional shortening, 24 h: 42.9 ± 3.1% vs. baseline: 45.7 ± 1.9%, P = 0.4658). Likewise, increases of superoxide production in the brain and lungs were remarkable, while those in the heart were moderate. mRNA gene expression analysis revealed that CA_Hypero group had increases in Il1b as compared to CA_Normo group significantly in the brain (P < 0.01) and lungs (P < 0.001) but not the heart (P = 0.4848). Similarly, hyperoxia-induced increases in other inflammatory and apoptotic mRNA gene expression were observed in the brain, whereas no differences were found in the heart. Upon systemic IR injury initiated by asphyxia CA, hyperoxia-induced injury exacerbated inflammation/apoptosis signals in the brain and lungs but might not affect the heart. Hyperoxia following asphyxia CA is more damaging to the brain and lungs but not the heart.

Effect of corticosteroid administration on cardiac arrest: a systematic review and network meta-analysis of the timing of administration

Corticosteroids may have a beneficial effect on the outcome of cardiac arrest (CA); however, it is not known whether the timing of corticosteroid use affects the outcome. We performed a systematic review and network meta-analysis to compare the efficacy of corticosteroid administration according to the timing. A favorable final outcome, as the primary study outcome, was defined as a combination of survival with good neurologic outcome and survival for 1 year. The secondary outcome was survival to discharge. Nine clinical studies were included. Corticosteroids administered during cardiopulmonary resuscitation (CPR; odds ratio [OR], 1.29; 95% confidence interval [CI], 1.11-1.51) and post-CA (OR, 1.47; 95% CI, 1.30-1.66) had a positive effect on the favorable final outcome compared to the control protocol (no corticosteroid administration), while those used prior to CA had a negative effect. Corticosteroids administered post-CA had a positive effect on survival to discharge compared to the control protocol (OR, 1.82; 95% CI, 1.02-3.27), while those used prior to CA and during CPR had no significant effect. Post-CA was evaluated to be the best administration timing for both outcomes. In conclusion, the timing of corticosteroid administration may be an important factor for the prognosis of CA. Corticosteroids administration post-CA and during CPR may have beneficial effects on CA outcomes.

The immunology of the post-cardiac arrest syndrome

Patients successfully resuscitated from cardiac arrest often have brain injury, myocardial dysfunction, and systemic ischemia-reperfusion injury, collectively termed the post-cardiac arrest syndrome (PCAS). To improve outcomes, potential therapies must be able to be administered early in the post-arrest course and provide broad cytoprotection, as ischemia-reperfusion injury affects all organ systems. Our understanding of the immune system contributions to the PCAS has expanded, with animal models detailing biologically plausible mechanisms of secondary injury, the protective effects of available immunomodulatory drugs, and how immune dysregulation underlies infection susceptibility after arrest. In this narrative review, we discuss the dysregulated immune response in PCAS, human trials of targeted immunomodulation therapies, and future directions for immunomodulation following cardiac arrest.

Post-Cardiac Arrest Hydrocortisone Use Ameliorates Cardiac Mitochondrial Injury in a Male Rat Model of Ventricular Fibrillation Cardiac Arrest

Background

Steroid use after cardiac arrest has been reported to improve survival and neurological outcome in cardiac arrest survivors. The study aimed to evaluate the effect of post‐arrest hydrocortisone use on myocardial damage and cardiac mitochondrial injury in a rat model of ventricular fibrillation cardiac arrest.

Methods and Results

Ventricular fibrillation cardiac arrest was induced and left untreated for 5 minutes in adult male Wistar rats. Cardiopulmonary resuscitation and electric shocks were then applied to achieve return of spontaneous circulation (ROSC). Successfully resuscitated animals were randomized into 3 groups: control, low‐dose hydrocortisone (2 mg/kg), and high‐dose hydrocortisone (8 mg/kg). The low‐dose hydrocortisone and high‐dose hydrocortisone (treatment) groups received intravenous hydrocortisone immediately after ROSC and the control group received saline as placebo. Each group consisted of 15 animals. Within 4 hours of ROSC, both treatment groups showed a higher cardiac output than the control group. At the fourth hour following ROSC, histological examination and transmission electron microscopy demonstrated less myocardial damage and mitochondrial injury in the animals treated with hydrocortisone. In the treatment groups, hydrocortisone mitigated the acceleration of Ca²⁺‐induced mitochondrial swelling and suppression of complex activity observed in the control group. At the 72nd hour after ROSC, a significantly higher proportion of animals treated with hydrocortisone survived and had good neurological recovery compared with those given a placebo.

Conclusions

Hydrocortisone use after cardiac arrest may mitigate myocardial injury and cardiac mitochondrial damage and thus improve survival, neurological and histological outcomes in a rat model of ventricular fibrillation cardiac arrest.