The Effect of Targeted Temperature Management on the Metabolome Following Out-of-Hospital Cardiac Arrest

Targeted temperature management (TTM) may moderate the injury from out-of-hospital cardiac arrest. Slowing the metabolism has been a suggested effect. Nevertheless, studies have found higher lactate levels in patients cooled to 33°C compared with 36°C even days from TTM cessation. Larger studies have not been performed on the TTM's effect on the metabolome. Accordingly, to explore the effect of TTM, we used ultra-performance liquid-mass spectrometry in a substudy of 146 patients randomized in the TTM trial to either 33°C or 36°C for 24 hours and quantified 60 circulating metabolites at the time of hospital arrival (T0) and 48 hours later (T48). From T0 to T48, profound changes to the metabolome were observed: tricarboxylic acid (TCA) cycle metabolites, amino acids, uric acid, and carnitine species all decreased. TTM significantly modified these changes in nine metabolites (Benjamini-Hochberg corrected false discovery rate <0.05): branched amino acids valine and leucine levels dropped more in the 33°C arm (change [95% confidence interval]: -60.9 μM [-70.8 to -50.9] vs. -36.0 μM [-45.8 to -26.3] and -35.5 μM [-43.1 to -27.8] vs. -21.2 μM [-28.7 to -13.6], respectively), whereas the TCA metabolites including malic acid and 2-oxoglutaric acid remained higher for the first 48 hours (-7.7 μM [-9.7 to -5.7] vs. -10.4 μM [-12.4 to -8.4] and -3 μM [-4.3 to -1.7] vs. -3.7 μM [-5 to -2.3]). Prostaglandin E2 only dropped in the TTM 36°C group. The results show that TTM affects the metabolism hours after normothermia have been reached. Clinical Trial Number: NCT01020916.

Soluble Urokinase-Type Plasminogen Activator Receptor in Comatose Survivors After Out-of-Hospital Cardiac Arrest Treated with Targeted Temperature Management

Exposure to whole-body ischemia/reperfusion after out-of-hospital cardiac arrest (OHCA) triggers a systemic inflammatory response where soluble urokinase plasminogen activator receptor (suPAR) is released. This study investigated serial levels of suPAR in differentiated target temperature management and the associations with mortality and 6-month neurological outcome. This is a single-center substudy of the randomized Targeted Temperature Management (TTM) for 24-hour versus 48-hour trial. In this analysis, we included 82 patients and measured serial levels of suPAR at 24, 48, and 72 hours after achievement of target temperature (32-34°C). We assessed all-cause mortality and neurological function evaluated by the Cerebral Performance Categories (CPC) at 6 months after OHCA. Levels of suPAR between TTH groups were evaluated in repeated measures mixed models. Mortality was assessed by the Kaplan-Meier method and serial measurements of suPAR (log2 transformed) were investigated by Cox proportional-hazards models. Good neurological outcome at 6 months was assessed by logistic regression analyses. Levels of suPAR were significantly different between TTH groups (pinteraction = 0.04) with the highest difference at 48 hours, 4.7 ng/mL (95% CI: 4.1-5.4 ng/mL) in the TTH24 group compared to 2.8 ng/mL (95% CI: 2.2-3.5 ng/mL) in the TTH48 group, p < 0.0001. Levels of suPAR above the median value were significantly associated with increased all-cause mortality at any time point (plog-rank<0.05). The interaction of suPAR levels and TTH group was not significant (pinteraction = NS). A twofold increase in levels of suPAR was significantly associated with a decreased odds ratio of a good neurological outcome in both unadjusted and adjusted analyses without interaction of TTH group (pinteraction = NS). Prolonged TTM of 48 hours versus 24 hours was associated with lower levels of suPAR. High levels of suPAR were associated with increased mortality and lower odds for good neurological outcome at 6 months with no significant interaction of TTH group.

Neuropsychological outcome after cardiac arrest: results from a sub-study of the targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (TTM2) trial

BACKGROUND

Cognitive impairment is common following out-of-hospital cardiac arrest (OHCA), but the nature of the impairment is poorly understood. Our objective was to describe cognitive impairment in OHCA survivors, with the hypothesis that OHCA survivors would perform significantly worse on neuropsychological tests of cognition than controls with acute myocardial infarction (MI). Another aim was to investigate the relationship between cognitive performance and the associated factors of emotional problems, fatigue, insomnia, and cardiovascular risk factors following OHCA.

METHODS

This was a prospective case-control sub-study of The Targeted Hypothermia versus Targeted Normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial. Eight of 61 TTM2-sites in Sweden, Denmark, and the United Kingdom included adults with OHCA of presumed cardiac or unknown cause. A matched non-arrest control group with acute MI was recruited. At approximately 7 months post-event, we administered an extensive neuropsychological test battery and questionnaires on anxiety, depression, fatigue, and insomnia, and collected information on the cardiovascular risk factors hypertension and diabetes.

RESULTS

Of 184 eligible OHCA survivors, 108 were included, with 92 MI controls enrolled. Amongst OHCA survivors, 29% performed z-score ≤ - 1 (at least borderline-mild impairment) in ≥ 2 cognitive domains, 14% performed z-score ≤ - 2 (major impairment) in ≥ 1 cognitive domain while 54% performed without impairment in any domain. Impairment was most pronounced in episodic memory, executive functions, and processing speed. OHCA survivors performed significantly worse than MI controls in episodic memory (mean difference, MD = - 0.37, 95% confidence intervals [- 0.61, - 0.12]), verbal (MD = - 0.34 [- 0.62, - 0.07]), and visual/constructive functions (MD = - 0.26 [- 0.47, - 0.04]) on linear regressions adjusted for educational attainment and sex. When additionally adjusting for anxiety, depression, fatigue, insomnia, hypertension, and diabetes, executive functions (MD = - 0.44 [- 0.82, - 0.06]) were also worse following OHCA. Diabetes, symptoms of anxiety, depression, and fatigue were significantly associated with worse cognitive performance.

CONCLUSIONS

In our study population, cognitive impairment was generally mild following OHCA. OHCA survivors performed worse than MI controls in 3 of 6 domains. These results support current guidelines that a post-OHCA follow-up service should screen for cognitive impairment, emotional problems, and fatigue.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03543371. Registered 1 June 2018.

Hypothermic versus Normothermic Temperature Control after Cardiac Arrest

Hypothermia versus Normothermia after Cardiac ArrestHolgersson et al. perform an individual patient data meta-analysis of the TTM and TTM2 trials of hypothermia after cardiac arrest and find no difference in 6-month mortality with hypothermia to 33°C versus normothermia.

MicroRNA-9-3p: a novel predictor of neurological outcome after cardiac arrest

AIMS

Resuscitated out-of-hospital cardiac arrest (OHCA) patients who remain comatose after hospital arrival are at high risk of mortality due to anoxic brain injury. MicroRNA are small-non-coding RNA molecules ultimately involved in gene-silencing. They show promise as biomarkers, as they are stable in body fluids. The microRNA 9-3p (miR-9-3p) is associated with neurological injury in trauma and subarachnoid haemorrhage.

METHODS AND RESULTS

This post hoc analysis considered all 171 comatose OHCA patients from a single centre in the target temperature management (TTM) trial. Patients were randomized to TTM at either 33°C or 36°C for 24 h. MicroRNA-9-3p (miR-9-3p) was measured in plasma sampled at admission and at 28, 48, and 72 h. There were no significant differences in age, gender, and pre-hospital data, including lactate level at admission, between miR-9-3p level quartiles. miR-9-3p levels changed markedly following OHCA with a peak at 48 h. Median miR-9-3p levels between TTM 33°C vs. 36°C were not different at any of the four time points. Elevated miR-9-3p levels at 48 h were strongly associated with an unfavourable neurological outcome [OR: 2.21, 95% confidence interval (CI): 1.64-3.15, P < 0.0001). MiR-9-3p was inferior to neuron-specific enolase in predicting functional neurological outcome [area under the curve: 0.79 (95% CI: 0.71-0.87) vs. 0.91 (95% CI: 0.85-0.97)].

CONCLUSION

MiR-9-3p is strongly associated with neurological outcome following OHCA, and the levels of miR-9-3p are peaking 48 hours following cardiac arrest.

Targeted plasma metabolomics in resuscitated comatose out-of-hospital cardiac arrest patients

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) is a leading cause of death. Even if successfully resuscitated, mortality remains high due to ischemic and reperfusion injury (I/R). The oxygen deprivation leads to a metabolic derangement amplified upon reperfusion resulting in an uncontrolled generation of reactive oxygen species in the mitochondria triggering cell death mechanisms. The understanding of I/R injury in humans following OHCA remains sparse, with no existing treatment to attenuate the reperfusion injury.

AIM

To describe metabolic derangement in patients following resuscitated OHCA.

METHODS

Plasma from consecutive resuscitated unconscious OHCA patients drawn at hospital admission were analyzed using ultra-performance-liquid-mass-spectrometry. Sixty-one metabolites were prespecified for quantification and studied.

RESULTS

In total, 163 patients were included, of which 143 (88%) were men, and the median age was 62 years (53-68). All measured metabolites from the tricarboxylic acid (TCA) cycle were significantly higher in non-survivors vs. survivors (180-days survival). Hierarchical clustering identified four clusters (A-D) of patients with distinct metabolic profiles. Cluster A and B had higher levels of TCA metabolites, amino acids and acylcarnitine species compared to C and D. The mortality was significantly higher in cluster A and B (A:62% and B:59% vs. C:21 % and D:24%, p < 0.001). Cluster A and B had longer time to return of spontaneous circulation (A:33 min (21-43), B:27 min (24-35), C:18 min (13-28), and D:18 min (12-25), p < 0.001).

CONCLUSION

Circulating levels of metabolites from the TCA cycle best described the variance between survivors and non-survivors. Four different metabolic phenotypes with significantly different mortality were identified.

Comparing Doppler Echocardiography and Thermodilution for Cardiac Output Measurements in a Contemporary Cohort of Comatose Cardiac Arrest Patients Undergoing Targeted Temperature Management

Measuring cardiac output is used to guide treatment during postresuscitation care. The aim of this study was to compare Doppler echocardiography (Doppler-CO) with thermodilution using pulmonary artery catheters (PAC-CO) for cardiac output estimation in a large cohort of comatose out-of-hospital cardiac arrest (OHCA) patients undergoing targeted temperature management (TTM). Single-center substudy of 141 patients included in the TTM trial randomly assigned to 33 or 36°C for 24 hours after OHCA. Per protocol, PAC-CO and Doppler-CO were measured simultaneously shortly after admission and again at 24 and 48 hours. Linear correlation was assessed between methods and positive predictive value (PPV) and negative predictive value (NPV) of Doppler to estimate low cardiac output (<3.5 L/min) was calculated. A total of 301 paired cardiac output measurements were available. Average cardiac output was 5.28 ± 1.94 L/min measured by thermodilution and 4.06 ± 1.49 L/min measured by Doppler with a mean bias of 1.22 L/min (limits of agreements -1.92 to 4.36 L/min). Correlation between methods was moderate (R² = 0.36). Using PAC-CO as the gold standard, PPV of a low cardiac output measurement (<3.5 L/min) by Doppler was 33%. However, the NPV was 92%. Hypothermia at 33°C did not negatively affect the correlations of CO methods. In the lowest quartile of Doppler, 13% had elevated lactate (>2 mmol/L). In the lowest quartile of thermodilution, 36% had elevated lactate (>2 mmol/L). In ventilated OHCA patients, the two methods for estimating cardiac output correlated moderately and there was a consistent underestimation of Doppler-CO. Absolute cardiac output values from Doppler-CO should be interpreted with caution. However, Doppler can be used to exclude low cardiac output with high accuracy. TTM at 33°C did not negatively affect the correlation or bias of cardiac output measurements. ClinicalTrials.gov ID: NCT01020916.

Repolarization and ventricular arrhythmia during targeted temperature management post cardiac arrest

BACKGROUND

Targeted temperature management (TTM) following out-of-hospital cardiac arrest (OHCA) prolongs the QT-interval but our knowledge of different temperatures and risk of arrhythmia is incomplete.

OBJECTIVE

To assess whether the QTc, QT-peak (QTp) and T-peak to T-end interval (TpTe) may be useful markers of ventricular arrhythmia in contemporary post cardiac arrest treatment.

METHODS

An ECG-substudy of the TTM-trial (TTM at 33 °C vs. 36 °C) with serial ECGs from 680 (94%) patients. Bazett's (B) and Fridericia's (F) formula were used for heart rate correction of the QT, QTp and TpTe. Ventricular arrhythmia (VT/VF) were registered during the first three days of post cardiac arrest care.

RESULTS

The QT, QTc and QTp intervals were prolonged more at 33 °C compared to 36 °C and restored to similar and lower levels after rewarming. The TpTe-interval remained between 92-100 ms throughout TTM in both groups. The QTc intervals were associated with ventricular arrhythmia, but not after adjustment for cardiac arrest characteristics. The QTp-interval was not associated with risk of ventricular arrhythmia. Heart rate corrected TpTe-intervals were associated with higher risk of arrhythmia (Odds ratio (OR): TpTe(B): 1.12 (1.02-1.23, p = 0.01 TpTe(F): 1.12 (1.02-1.23, p = 0.02) per 20 ms). Further a prolonged TpTe-interval ≥ 90 ms was consistently associated with higher risk (OR_adjusted: TpTe(B): 2.05 (1.25-3.37), p < 0.01, TpTe(F): 2.14 (1.32-3.49), p < 0.01).

CONCLUSIONS

TTM prolongs the QT-interval by prolongation of the QTp-interval without association to increased risk. The TpTe-interval is not significantly affected by core temperature, but heart rate corrected TpTe intervals are robustly associated with risk of ventricular arrhythmia.

TRIAL REGISTRATION

The TTM-trial is registered and accessible at ClinicalTrials.gov (Identifier: NCT01020916).

The complement lectin pathway protein MAp19 and out-of-hospital cardiac arrest: Insights from two randomized clinical trials

Aim:

Activation of the complement system is known to be a potent inducer of systemic inflammation, which is an important component of post-cardiac arrest syndrome. Mannan-binding-lectin associated protein of 19 kDa (MAp19) is suggested to be a regulatory component of the lectin pathway of complement activation. The aims of this study were to describe serial levels of MAp19 protein in comatose survivors of out-of-hospital cardiac arrest (OHCA), to evaluate the effect of two different regimes of targeted temperature management and to investigate the possible association between levels of MAp19 and mortality.

Methods:

In this post-hoc study, we analysed data from two large randomized controlled studies: ‘Targeted temperature management at 33 degrees C versus 36 degrees C after cardiac arrest’ (TTM) and ‘Targeted temperature management for 48 versus 24 h and neurological outcome after out-of-hospital cardiac arrest’ (TTH). We measured serial levels of MAp19 in 240 patients within 72 h after OHCA and in 82 healthy controls. The effect of targeted temperature management on MAp19 levels was analysed according to temperature allocation in main trials.

Results:

MAp19 levels were significantly lower in OHCA patients within 48 h after OHCA (p-values &lt;0.001) compared with healthy controls. A target temperature at 33°C compared with 36°C for 24 h was associated with significantly lower levels of MAp19 (–57 ng/mL (95% confidence interval (CI): –97 to −16 mg/mL), p=0.006). Target temperature at 33°C for 48 h compared with 24 h was not associated with a difference in MAp19 levels (–31 ng/mL (95% CI: –120 to 60 mg/mL), p=0.57). Low MAp19 levels at admission were associated with higher 30-day mortality (12% vs. 38%, plog-rank =0.0008), also in adjusted analysis (two-fold higher, hazard ratio =0.48 (95% CI: 0.31 to 0.75), p=0.001). Analysis of MAp19 levels at 24–72 h showed they were not associated with 30-day mortality.

Conclusion:

Survivors after OHCA have lower levels of MAp19 protein compared with healthy controls. A targeted temperature management at 33°C compared with 36°C was associated with significantly lower MAp19 levels, whereas target temperature at 33°C for 48 h compared with 24 h did not influence MAp19 protein levels. Low MAp19 levels at admission were independently associated with increased mortality.

Impact of Hypothermia on Oxygenation Variables and Metabolism in Survivors of Out-of-Hospital Cardiac Arrest Undergoing Targeted Temperature Management at 33°C Versus 36°C

Targeted temperature management (TTM) exerts substantial impact on hemodynamic function in out-of-hospital cardiac arrest (OHCA) patients. Whole-body oxygen consumption (VO₂) and delivery (DO₂) have not previously been investigated in a clinical setting during TTM at different levels of temperature after OHCA. A substudy of 151 patients randomized at a single center in the TTM-trial, where patients were randomly assigned TTM at 33°C (TTM33) or 36°C (TTM36) for 24 hours. We calculated VO₂ according to the principle of Fick (VO₂ = cardiac output*arteriovenous oxygen content difference). DO₂ was calculated as cardiac output*arterial oxygen content. Cardiac output was measured by pulmonary artery catheter with thermodilution. Arteriovenous oxygen content difference was calculated from arterial and mixed venous oxygen saturation and hemoglobin. Oxygen extraction ratio = VO₂/DO₂. At 24 hours, the VO₂ was 169 ± 59 mL O₂ per minute in TTM33 and 217 ± 53 mL O₂ per minute in TTM36 (p < 0.0001). During 24 hours of TTM, the overall difference was 53 mL O₂ minute (95% confidence interval [CI]: 31-74, p_group < 0.0001). After rewarming at 36 and 48 hours, there was no difference in VO₂ between the groups. DO₂ was overall 277 mL O₂ per minute (95% CI: 175-379, p_group < 0.0001) higher in the TTM36-group during TTM. Oxygen extraction ratio during TTM was not significantly different between the two groups (2% [95% CI: -0.1 to 5, p_group = 0.09]). VO₂ during the first 36 hours after OHCA correlated significantly with temperature, and VO₂ was 19 mL O₂ per minute lower per degree reduction in temperature (95% CI: 15-22), p < 0.0001. TTM at 33°C compared to 36°C after OHCA is associated with significantly lower VO₂ and DO₂, however, oxygen extraction ratio was not significantly different. For each degree lower body temperature, the VO₂ fell by 19 mL O₂ per minute.

P6383Cardiac output during targeted temperature management and renal function after out-of-hospital cardiac arrest

Background

After resuscitation from out-of-hospital cardiac arrest (OHCA), renal injury and hemodynamic instability are common. Low blood pressure during targeted temperature management (TTM) is associated with acute renal injury (AKI). The aim of this study is to test the hypothesis, that low cardiac output during TTM is associated with acute kidney injury after OHCA.

Methods

Single-center substudy of 171 patients included in the prospective, randomized TTM-trial. Hemodynamic evaluation was performed with serial measurements by pulmonary artery catheter. Mean arterial pressure ≥65 mmHg and central venous pressure of 10 to 15 mmHg were hemodynamic treatment goals. Acute kidney injury (AKI) was the primary endpoint and was defined according to the KDIGO-criteria. Differences between groups were tested by repeated measurements mixed models.

Measurements and main results

Of 152 patients with available hemodynamic data, 49 (32%) had AKI and 21 (14%) had AKI with need for renal replacement therapy (RRT) in the first three days. At admission, cardiac index was higher in the AKI-group (mean (confidence interval): 2.6 (2.2–3.0) L/min/m2 versus 2.2 (2.0–2.3) L/min/m2, p=0.003). During 24 hours of targeted temperature management, patients with AKI had increased heart rate (11 beats/min, pgroup<0.0001) and increased lactate (1 mmol/L, pgroup<0.0001) compared to patients without AKI. However, there was no overall difference in cardiac index (pgroup = 0.25) (Figure). In multivariate models, adjusting for potential confounders including targeted temperature, mean arterial pressure (odds ratio: 0.69 (0.50–0.96) per 5 mmHg increase, p=0.03), heart rate (1.04 (1.01–1.08) per beat/min increase, p=0.01) and lactate (1.59 (1.14–2.2) per mmol/L increase, p=0.006) were independently associated with AKI, but cardiac index remained unrelated with AKI.

Figure 1

Conclusions

Blood pressure, heart rate and lactate, but not cardiac output, during 24 hours of targeted temperature management were associated with renal injury in comatose OHCA-patients.

Acknowledgement/Funding

The research fund Gangstedfonden and the Research fund of Rigshospitalet has supported this study with unrestricted salary in Dr. Grand's PhD project.

5230Association of cardiac output during targeted temperature management with mortality after out-of-hospital cardiac arrest

Purpose

Myocardial dysfunction and low cardiac output are common after out-of-hospital cardiac arrest (OHCA) as part of the post-cardiac arrest syndrome. This study investigates the association of cardiac output during targeted temperature management (TTM) with mortality. We hypothesized that low cardiac output during TTM is associated with mortality.

Methods

In the TTM-trial, which randomly allocated patients to TTM of 33°C or 36°C for 24 hours, we prospectively and consecutively monitored 171 patients with protocolized measurements from pulmonary artery catheters (PAC). Clinical and hemodynamic variables were registered at pre-specified time points in addition to 30-day survival status. Lactate, heart rate and cardiac index were measured at 3 time-points during TTM and averaged. We defined low cardiac output as a cardiac index during TTM <2.4 l/min/m2 in the TTM36-group and <1.8 l/min/m2 in the TTM33-group, since hypothermia affects cardiac output. We further stratified patients according to serum lactate (above/below 2 mmol/L) and heart rate (above/below median, which was 65 beats/min.).

Results

Of 152 patients with available hemodynamic measurements, 71 (47%) had low cardiac output during TTM (TTM33: 38 (49%), TTM36: 33 (44%)). Low cardiac output was not associated with mortality in univariate analysis (hazard ratio (HR): 1.47 [0.83–2.59], p=0.19) or multivariate analysis adjusted for potential confounders (HRadjusted: 0.74 [0.38–1.44], p=0.37). Low cardiac output combined with HR>65 was associated with increased mortality (HR: 2.69 [1.51–4.79], p=0.0007) in univariate, but not in multivariate analysis (p=0.22) (Figure). Low cardiac output and HR<65 was associated with decreased mortality in multivariate analysis (HRadjusted: 0.36 [0.14–0.93], p=0.03). Low cardiac output and lactate>2mmol/L was associated with increased mortality (HR: 2.73 [1.49–4.99], p=0.001) in univariate, but not in multivariate analysis (p=0.53), whereas patients with low cardiac output and lactate<2mmol/L had low mortality (HRadjusted: 0.58 [0.27–1.24], p=0.16) compared to the rest of the population (Figure).

Figure 1

Conclusion

This study found, that a frequent symptom during TTM is low cardiac output, which was not associated with mortality. However, patients with low cardiac output combined with either increased lactate or heart rate seems to be a population at risk. Whether low cardiac output should be corrected by inotropes or mechanical support to reduce mortality remains to be studied in prospective trials, but the efficacy of goal-directed therapy to increase cardiac output during TTM may be modest, especially if lactate and heart rate are normal.

Acknowledgement/Funding

The research fund Gangstedfonden and the Research fund of Rigshospitalet has supported this study with unrestricted salary in Dr. Grand's PhD project.

Arterial blood pressure during targeted temperature management after out-of-hospital cardiac arrest and association with brain injury and long-term cognitive function

OBJECTIVES

During targeted temperature management after out-of-hospital cardiac arrest infusion of vasoactive drugs is often needed to ensure cerebral perfusion pressure. This study investigated mean arterial pressure after out-of-hospital cardiac arrest and the association with brain injury and long-term cognitive function.

METHODS

Post-hoc analysis of patients surviving at least 48 hours in the biobank substudy of the targeted temperature management trial with available blood pressure data. Patients were stratified in three groups according to mean arterial pressure during targeted temperature management (4-28 hours after admission; <70 mmHg, 70-80 mmHg, >80 mmHg). A biomarker of brain injury, neuron-specific enolase, was measured and impaired cognitive function was defined as a mini-mental state examination score below 27 in 6-month survivors.

RESULTS

Of the 657 patients included in the present analysis, 154 (23%) had mean arterial pressure less than 70 mmHg, 288 (44%) had mean arterial pressure between 70 and 80 mmHg and 215 (33%) had mean arterial pressure greater than 80 mmHg. There were no statistically significant differences in survival (P=0.35) or neuron-specific enolase levels (P=0.12) between the groups. The level of target temperature did not statistically significantly interact with mean arterial pressure regarding neuron-specific enolase (P_{interaction_MAP*TTM}=0.58). In the subgroup of survivors with impaired cognitive function (n=132) (35%) mean arterial pressure during targeted temperature management was significantly higher (P_group=0.03).

CONCLUSIONS

In a large cohort of comatose out-of-hospital cardiac arrest patients, low mean arterial pressure during targeted temperature management was not associated with higher neuron-specific enolase regardless of the level of target temperature (33°C or 36°C for 24 hours). In survivors with impaired cognitive function, mean arterial pressure during targeted temperature management was significantly higher.

Serum tau fragments as predictors of death or poor neurological outcome after out-of-hospital cardiac arrest

Background: Anoxic brain injury is the primary cause of death after resuscitation from out-of-hospital cardiac arrest (OHCA) and prognostication is challenging. The aim of this study was to evaluate the potential of two fragments of tau as serum biomarkers for neurological outcome. Methods: Single-center sub-study of 171 patients included in the Target Temperature Management (TTM) Trial randomly assigned to TTM at 33 °C or TTM at 36 °C for 24 h after OHCA. Fragments (tau-A and tau-C) of the neuronal protein tau were measured in serum 24, 48 and 72 h after OHCA. The primary endpoint was neurological outcome. Results: Median (quartile 1 - quartile 3) tau-A (ng/ml) values were 58 (43-71) versus 51 (43-67), 72 (57-84) versus 71 (59-82) and 76 (61-92) versus 75 (64-89) for good versus unfavourable outcome at 24, 48 and 72 h, respectively (p_group = 0.95). Median tau C (ng/ml) values were 38 (29-50) versus 36 (29-49), 49 (38-58) versus 48 (33-59) and 48 (39-59) versus 48 (36-62) (p_group = 0.95). Tau-A and tau-C did not predict neurological outcome (area under the receiver-operating curve at 48 h; tau-A: 0.51 and tau-C: 0.51). Conclusions: Serum levels of tau fragments were unable to predict neurological outcome after OHCA.

Mitochondrial dysfunction in adults after out-of-hospital cardiac arrest

BACKGROUND

While preclinical studies suggest that mitochondria play a pivotal role in ischaemia-reperfusion injury, the knowledge of mitochondrial function in human out-of-hospital cardiac arrest remains scarce. The present study sought to compare oxidative phosphorylation capacity in skeletal muscle biopsies from out-of-hospital cardiac arrest patients to healthy controls.

METHODS

This was a substudy of a randomised trial comparing targeted temperature management at 33°C versus 36°C for out-of-hospital cardiac arrest patients. Skeletal muscle biopsies were obtained from adult resuscitated comatose out-of-hospital cardiac arrest patients 28 hours after initiation of targeted temperature management, i.e. at target temperature prior to rewarming, and from age-matched healthy controls. Mitochondrial function was analysed by high-resolution respirometry. Maximal sustained respiration through complex I, maximal coupled respiration through complex I and complex II and maximal electron transport system capacity was compared.

RESULTS

A total of 20 out-of-hospital cardiac arrest patients and 21 controls were included in the analysis. We found no difference in mitochondrial function between temperature allocations. We found no difference in complex I sustained respiration between out-of-hospital cardiac arrest and controls (23 (18-26) vs. 22 (19-26) pmol O₂/mg/s, P=0.76), whereas coupled complex I and complex II respiration was significantly lower in out-of-hospital cardiac arrest patients versus controls (53 (42-59) vs. 64 (54-68) pmol O₂/mg/s, P=0.01). Furthermore, electron transport system capacity was lower in out-of-hospital cardiac arrest versus controls (63 (51-69) vs. 73 (66-78) pmol O₂/mg/s, P=0.005).

CONCLUSIONS

Mitochondrial oxidative phosphorylation capacity in skeletal muscle biopsies was reduced in out-of-hospital cardiac arrest patients undergoing targeted temperature management compared to age-matched, healthy controls. The role of mitochondria as risk markers and potential targets for post-resuscitation care remains unknown.

The association between plasma miR-122-5p release pattern at admission and all-cause mortality or shock after out-of-hospital cardiac arrest

BACKGROUND

Data suggests that the plasma levels of the liver-specific miR-122-5p might both be a marker of cardiogenic shock and a prognostic marker of out-of-hospital cardiac arrest (OHCA). Our aim was to characterize plasma miR-122-5p at admission after OHCA and to assess the association between miR-122-5p and relevant clinical factors such all-cause mortality and shock at admission after OHCA.

METHODS

In the pilot trial, 10 survivors after OHCA were compared to 10 age- and sex-matched controls. In the main trial, 167 unconscious survivors of OHCA from the Targeted Temperature Management (TTM) trial were included.

RESULTS

In the pilot trial, plasma miR-122-5p at admission after OHCA was 400-fold elevated compared to controls. In the main trial, plasma miR-122-5p at admission was independently associated with lactate and bystander cardiopulmonary resuscitation. miR-122-5p at admission was not associated with shock at admission (p = 0.14) or all-cause mortality (p = 0.35). Target temperature (33 °C vs 36 °C) was not associated with miR-122-5p levels at any time point.

CONCLUSIONS

After OHCA, miR-122-5p demonstrated a marked acute increase in plasma and was independently associated with lactate and bystander resuscitation. However, miR-122-5p at admission was not associated with all-cause mortality or shock at admission.

Importance of comorbidities in comatose survivors of shockable and non-shockable out-of-hospital cardiac arrest treated with target temperature management

OBJECTIVE

Comorbidity prior to out-of-hospital cardiac arrest (OHCA) and primary rhythm in relation to survival is not well established. We aimed to assess the prognostic importance of comorbidity in relation to primary rhythm in OHCA-patients treated with Target Temperature Management (TTM).

DESIGN

Consecutive comatose survivors of OHCA treated with TTM in hospitals in the Copenhagen area between 2002-2011 were included. Utstein-based pre- and in-hospital data collection was performed. Data on comorbidity was obtained from The Danish National Patient Register and patient charts, assessed by the Charlson Comorbidity Index (CCI).

RESULTS

A total of 666 patients were included. A third (n = 233, 35%) presented with non-shockable rhythm, and they were less often male (64% vs. 82%, p < .001), and OHCA in public, witnessed OHCA, and bystander cardiopulmonary resuscitation (CPR) were less common compared to patients with a shockable primary rhythm (public: 27% vs. 48%, p < .001, witnessed: 79% vs. 90%, p < .001, bystander CPR: 47% vs. 63%, p < .001). 30-day mortality was 62% compared to 28% in patients with non-shockable and shockable rhythm, respectively. By Cox-regression analyses, any comorbidity (CCI ≥1) was the only factor independently associated with 30-day mortality in patients with non-shockable rhythm (HR =1.9 (95% CI: 1.2-2.9), p < .01), whereas in patients with shockable rhythm comorbidity was not associated with outcome after adjustment for prognostic factors (HR = 0.82 (0.55-1.2), p = .34). No significant interaction between primary rhythm and comorbidity in terms of mortality was present.

CONCLUSION

A higher comorbidity burden was independently associated with a higher 30-day mortality rate in patients presenting with non-shockable primary rhythm but not in patients with shockable rhythm.

Women have a worse prognosis and undergo fewer coronary angiographies after out-of-hospital cardiac arrest than men

Background:

Out-of-hospital cardiac arrest is more often reported in men than in women.

Objectives:

We aimed to assess sex-related differences in post-resuscitation care; especially with regards to coronary angiography, percutaneous coronary intervention, mortality and functional status after out-of-hospital cardiac arrest.

Methods:

We included 704 consecutive adult out-of-hospital cardiac arrest-patients with cardiac aetiology in the Copenhagen area from 2007–2011. Utstein guidelines were used for the pre-hospital data. Vital status and pre-arrest comorbidities were acquired from Danish registries and review of patient charts. Logistic regression was used to assess differences in functional status and use of post-resuscitation care. Cox regression was used to assess differences in 30-day mortality. We used ‘smcfcs’ and ‘mice’ imputation to handle missing data.

Results:

Female sex was associated with higher 30-day mortality after adjusting for age and comorbidity (hazard ratio (HR): 1.42, confidence interval (CI): 1.13–1.79, p<0.01), this was not significant when adjusting for primary rhythm (HR: 1.12, CI: 0.88–1.42, p=0.37). Women less frequently received coronary angiography <24 h in multiple regression after out-of-hospital cardiac arrest (odds ratio (OR)CAG=0.55, CI: 0.31–0.97, p=0.041), however no difference in percutaneous coronary intervention was found (ORPCI=0.55, CI: 0.23–1.36, p=0.19). Coronary artery bypass grafting was less often performed in women (ORCABG: 0.10, CI: 0.01–0.78, p=0.03). There was no difference in functional status at discharge between men and women ( p=1).

Conclusion:

Female sex was not significantly associated with higher mortality when adjusting for confounders. Women less often underwent coronary angiography and coronary artery bypass grafting, but it is not clear whether this difference can be explained by other factors, or an actual under-treatment in women.

Single versus Serial Measurements of Neuron-Specific Enolase and Prediction of Poor Neurological Outcome in Persistently Unconscious Patients after Out-Of-Hospital Cardiac Arrest - A TTM-Trial Substudy

BACKGROUND

Prediction of neurological outcome is a crucial part of post cardiac arrest care and prediction in patients remaining unconscious and/or sedated after rewarming from targeted temperature management (TTM) remains difficult. Current guidelines suggest the use of serial measurements of the biomarker neuron-specific enolase (NSE) in combination with other predictors of outcome in patients admitted after out-of-hospital cardiac arrest (OHCA). This study sought to investigate the ability of NSE to predict poor outcome in patients remaining unconscious at day three after OHCA. In addition, this study sought to investigate if serial NSE measurements add incremental prognostic information compared to a single NSE measurement at 48 hours in this population.

METHODS

This study is a post-hoc sub-study of the TTM trial, randomizing OHCA patients to a course of TTM at either 33°C or 36°C. Patients were included from sites participating in the TTM-trial biobank sub study. NSE was measured at 24, 48 and 72 hours after ROSC and follow-up was concluded after 180 days. The primary end point was poor neurological function or death defined by a cerebral performance category score (CPC-score) of 3 to 5.

RESULTS

A total of 685 (73%) patients participated in the study. At day three after OHCA 63 (9%) patients had died and 473 (69%) patients were not awake. In these patients, a single NSE measurement at 48 hours predicted poor outcome with an area under the receiver operating characteristics curve (AUC) of 0.83. A combination of all three NSE measurements yielded the highest discovered AUC (0.88, p = .0002). Easily applicable combinations of serial NSE measurements did not significantly improve prediction over a single measurement at 48 hours (AUC 0.58-0.84 versus 0.83).

CONCLUSION

NSE is a strong predictor of poor outcome after OHCA in persistently unconscious patients undergoing TTM, and NSE is a promising surrogate marker of outcome in clinical trials. While combinations of serial NSE measurements may provide an increase in overall prognostic information, it is unclear whether actual clinical prognostication with low false-positive rates is improved by application of serial measurements in persistently unconscious patients. The findings of this study should be confirmed in another prospective cohort.

TRIAL REGISTRATION

NCT01020916.

Prevalence and Prognostic Implications of Bundle Branch Block in Comatose Survivors of Out-of-Hospital Cardiac Arrest

This study reports the prevalence and prognostic impact of right bundle branch block (RBBB) and left bundle branch block (LBBB) in the admission electrocardiogram (ECG) of comatose survivors of out-of-hospital cardiac arrest (OHCA). The present study is part of the predefined electrocardiographic substudy of the prospective randomized target temperature management trial, which found no benefit of targeting 33°C over 36°C in terms of outcome. Six-hundred eighty-two patients were included in the substudy. An admission ECG, which defined the present study population, was available in 602 patients (88%). These ECGs were stratified by the presence of LBBB, RBBB, or no-BBB (reference) on admission. End points were mortality and neurologic outcome 6 months after OHCA. RBBB was present in 79 patients (13%) and LBBB in 65 patients (11%), and the majority of BBBs (92%) had resolved 4 hours after admission. RBBB was associated with significantly higher 6 months mortality (RBBB: hazard ratio [HR]_unadjusted 1.78, 95% confidence interval [CI] 1.30 to 2.43; LBBB: HR_unadjusted 1.26, 95% CI 0.87 to 1.81), but this did not reach a level of significance in the adjusted model (HR_adjusted 1.33, 95% CI 0.94 to 1.87). Similar findings were seen for neurologic outcome in the unadjusted and adjusted analyses. RBBB was further independently associated with higher odds of unfavorable neurologic outcome (RBBB: adjusted odds ratio 1.97, 95% CI 1.05 to 3.71). In conclusion, BBBs after OHCA were transient in most patients, and RBBB was directly associated with higher mortality and independently associated with higher odds of unfavorable neurologic outcome. RBBB is seemingly an early indicator of an unfavorable prognosis after OHCA.

Usefulness of Serum B-Type Natriuretic Peptide Levels in Comatose Patients Resuscitated from Out-of-Hospital Cardiac Arrest to Predict Outcome

N-terminal pro-B-type natriuretic (NT-proBNP) is expressed in the heart and brain, and serum levels are elevated in acute heart and brain diseases. We aimed to assess the possible association between serum levels and neurological outcome and death in comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA). Of the 939 comatose OHCA patients enrolled and randomized in the Targeted Temperature Management (TTM) trial to TTM at 33°C or 36°C for 24 hours, 700 were included in the biomarker substudy. Of these, 647 (92%) had serum levels of NT-proBNP measured 24, 48, and 72 hours after return of spontaneous circulation (ROSC). Neurological outcome was evaluated by the Cerebral Performance Category (CPC) score and modified Rankin Scale (mRS) at 6 months. Six hundred thirty-eight patients (99%) had serum NT-proBNP levels ≥125 pg/ml. Patients with TTM at 33°C had significantly lower NT-proBNP serum levels (median 1,472 pg/ml) than those in the 36°C group (1,914 pg/ml) at 24 hours after ROSC, p <0.01 but not at 48 and 72 hours. At 24 hours, an increase in NT-proBNP quartile was associated with death (Plogrank <0.0001). In addition, NT-proBNP serum levels > median were independently associated with poor neurological outcome (odds ratio, ORCPC 2.02, CI 1.34 to 3.05, p <0.001; ORmRS 2.28, CI 1.50 to 3.46, p <0.001) adjusted for potential confounders. The association was diminished at 48 and 72 hours after ROSC. In conclusion, NT-proBNP serum levels are increased in comatose OHCA patients. Furthermore, serum NT-proBNP levels are affected by level of TTM and are associated with death and poor neurological outcome.

Early changes in left atrial volume after acute myocardial infarction. Relation to invasive hemodynamics at rest and during exercise

BACKGROUND

Dilatation of left atrium (LA) reflects chronic LA pressure or volume overload that possesses considerable prognostic information. Little is known regarding the interaction between LA remodeling after acute myocardial infarction (MI) and left atrial pressure at rest and during exercise. The objective was to assess changes in LA volume early after MI in patients with diastolic dysfunction and the relation to invasive hemodynamics and natriuretic peptides.

METHODS

62 patients with left ventricle ejection fraction (LVEF)≥45%, diastolic E/e'>8 and LA volume index >34ml/m² within 48h of MI were enrolled. After 1 and 4months blood sampling, echocardiography and right heart catheterization were performed during exercise test.

RESULTS

LA remodeling was considered in patients with a change from mild (35-41ml/m²), to severe (>48ml/m²) dilatation after 4months (Found in 22 patients (35%)). Patients with LA remodeling were characterized by lower a' (1month 8.9±2.0 vs. 10.4±2.5cm/s, p=0.002; 4month 8.8±2.0 vs. 10.4±2.4cm/s, p=0.007) and higher MR-proANP (1month 162±64 vs. 120±44pg/l, p=0.005; 4months 175±48 vs. 129±56pg/l, p=0.002). With exercise, pulmonary artery pressure, right atrial pressure and pulmonary capillary wedge pressure increased markedly in all patients. There were however, no significant differences in filling pressure at rest or during exercise irrespective of whether LA remodeling occurred.

CONCLUSION

Contrary to our hypothesis early LA dilatation after MI was weakly associated with resting and exercise induced changes in LA pressure overload. The dilatation was however associated with lower e' and higher MR-proANP.

Predictive value of interleukin-6 in post-cardiac arrest patients treated with targeted temperature management at 33 °C or 36 °C

AIM

Post-cardiac arrest syndrome (PCAS) is characterized by systemic inflammation, however data on the prognostic value of inflammatory markers is sparse. We sought to investigate the importance of systemic inflammation, assessed by interleukin-6 (IL-6) in comatose survivors of out-of-hospital cardiac arrest.

METHODS

A total of 682 patients enrolled in the Target Temperature Management (TTM) trial, surviving >24h with available IL-6 data were included. IL-6 was measured on days 1, 2 and 3 after return of spontaneous circulation. Severity of PCAS was assessed daily by the Sequential Organ Failure Assessment score. Survival status was recorded at 30 days.

RESULTS

High levels of IL-6 at day 1-3 (all p<0.0001) were independently associated with severity of PCAS with no interaction of target temperature (all p=NS). IL-6 levels did not differ between temperature groups (p(interaction)=0.99). IL-6 levels at day 2 (p<0.0001) and day 3 (p<0.0001) were associated with crude mortality. Adjusted Cox proportional-hazards analysis showed that a two-fold increase of IL-6 levels at day 2 (HR=1.15 (95% CI: 1.07-1.23), p=0.0002) and day 3 (HR=1.18 (95% CI: 1.09-1.27), p<0.0001) were associated with mortality. IL-6 levels at day 3 had the highest discriminative value in predicting mortality (AUC=0.66). IL-6 did not significantly improve 30-day mortality prediction compared to traditional prognostic factors (p=0.08).

CONCLUSIONS

In patients surviving >24h following cardiac arrest, IL-6 levels were significantly elevated and associated with severity of PCAS with no significant influence of target temperature. High IL-6 levels were associated with increased mortality. Measuring levels of IL-6 did not provide incremental prognostic value.

The effect of targeted temperature management on coagulation parameters and bleeding events after out-of-hospital cardiac arrest of presumed cardiac cause

AIMS

Targeted temperature management (TTM) is part of the standard treatment of comatose patients after out-of-hospital cardiac arrest (OHCA) to attenuate neurological injury. In other clinical settings, hypothermia promotes coagulopathy leading to an increase in bleeding and thrombosis tendency. Thus, concern has been raised as to whether TTM can be applied safely, as acute myocardial infarction requiring primary percutaneous coronary intervention (PCI) with the need of effective antiplatelet therapy is frequent following OHCA. This study investigated the influence of TTM at 33 or 36°C on various laboratory and coagulation parameters.

METHODS AND RESULTS

In this single-center predefined substudy of the TTM trial, 171 patients were randomized to TTM at either 33 or 36°C in the postresuscitation phase. The two subgroups were compared regarding standard laboratory coagulation parameters, thrombelastography (TEG), bleeding, and stent thrombosis events. Platelet counts were lower in the TTM33-group compared to TTM36 (p=0.009), but neither standard coagulation nor TEG-parameters showed any difference between the groups. TEG revealed a normocoagulable state in the majority of patients, while approximately 20% of the population presented as hypercoagulable. Adverse events included 38 bleeding events, one stent thrombosis, and one reinfarction, with no significant difference between the groups.

CONCLUSIONS

There was no evidence supporting the assumption that TTM at 33°C was associated with impaired hemostasis or increased the frequency of adverse bleeding and thrombotic events compared to TTM at 36°C. We found that TTM at either temperature can safely be applied in the postresuscitation phase after acute myocardial infarction and primary PCI.

Resuscitation and post resuscitation care of the very old after out-of-hospital cardiac arrest is worthwhile

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) is associated with a poor prognosis. As comorbidity and frailty increase with age; ethical dilemmas may arise when OHCA occur in the very old.

OBJECTIVES

We aimed to investigate mortality, neurological outcome and post resuscitation care in octogenarians (≥80) to assess whether resuscitation and post resuscitation care should be avoided.

METHODS

During 2007-2011 consecutive OHCA-patients were attended by the physician-based Emergency Medical Services-system in Copenhagen. Pre-hospital data based on Utstein-criteria, and data on post resuscitation care were collected. Primary outcome was successful resuscitation; secondary endpoints were 30-day mortality and neurological outcome (Cerebral Performance Category (CPC)).

RESULTS

2509 OHCA-patients with attempted resuscitation were recorded, 22% (n=558) were octogenarians/nonagenarians. 166 (30% of all octogenarians with resuscitation attempted) octogenarians were successfully resuscitated compared to 830 (43% with resuscitation attempted) patients <80 years. 30-day mortality in octogenarians was significantly higher after adjustment for prognostic factors (HR=1.61 CI: 1.22-2.13, p<0.001). Octogenarians received fewer coronary angiographies (CAG) (14 vs. 37%, p<0.001), and had lower odds of receiving CAG by multivariate logistic regression (OR: 0.19, CI: 0.08-0.44, p<0.001). A favorable neurological outcome (CPC 1/2) in survivors to discharge was found in 70% (n=26) of octogenarians compared to 86% (n=317, p=0.03) in the younger patients.

CONCLUSION

OHCA in octogenarians was associated with a significantly higher mortality rate after adjustment for prognostic factors. However, the majority of octogenarian survivors were discharged with a favorable neurological outcome. Withholding resuscitation and post resuscitation care in octogenarians does not seem justified.

Prognostic Implications of Level-of-Care at Tertiary Heart Centers Compared With Other Hospitals After Resuscitation From Out-of-Hospital Cardiac Arrest

Background—

Studies have found higher survival rates after out-of-hospital cardiac arrest and admission to tertiary heart centers. The aim was to examine the level-of-care at tertiary centers compared with nontertiary hospitals and the association with outcome after out-of-hospital cardiac arrest.

Methods and Results—

Consecutive out-of-hospital cardiac arrest patients (n=1078) without ST-segment–elevation myocardial infarction admitted to tertiary centers (54%) and nontertiary hospitals (46%) were included (2002–2011). Patient charts were reviewed focusing on level-of-care and comorbidity. Survival to discharge differed significantly with 45% versus 24% of patients discharged alive ( P <0.001), and after adjustment for prognostic factors admissions to tertiary centers were still associated with lower 30-day mortality (hazard ratio, 0.78 [0.64–0.96; P =0.02]), independent of comorbidity. The adjusted odds of predefined markers of level-of-care were higher in tertiary centers: admission to intensive care unit (odds ratio [OR], 1.8 [95% confidence interval, 1.2–2.5]), temporary pacemaker (OR, 6.4 [2.2–19]), vasoactive agents (OR, 1.5 [1.1–2.1]), acute (<24 hours) and late coronary angiography (OR, 10 [5.3–22] and 3.8 [2.5–5.7]), neurophysiological examination (OR, 1.8 [1.3–2.6]), and brain computed tomography (OR, 1.9 [1.4–2.6]), whereas no difference in therapeutic hypothermia was noted. Patients at tertiary centers were more often consulted by a cardiologist (OR, 8.6 [5.0–15]), had an echocardiography (OR, 2.8 [2.1–3.7]), and survivors more often had implantable cardioverter defibrillator’s implanted (OR, 2.1 [1.2–3.6]).

Conclusions—

Admissions to tertiary centers were associated with significantly higher survival after out-of-hospital cardiac arrest in patients without ST-segment–elevation myocardial infarction in the Copenhagen area even after adjustment for prognostic factors including comorbidity. Level-of-care seems higher in tertiary centers both in the early phase, during the intensive care unit admission, and in the workup before discharge. The varying level-of-care may contribute to the survival difference; however, differences in comorbidity do not seem to matter significantly.

Sympathoadrenal activation and endothelial damage are inter correlated and predict increased mortality in patients resuscitated after out-of-hospital cardiac arrest. a post Hoc sub-study of patients from the TTM-trial

Objective

Sympathoadrenal activation and endothelial damage are hallmarks of acute critical illness. This study investigated their association and predictive value in patients resuscitated from out-of-hospital cardiac arrest (OHCA).

Methods

Post-hoc analysis of patients included at a single site in The Targeted Temperature Management at 33 degrees versus 36 degrees after Cardiac Arrest (TTM) trial. The main study reported similar outcomes with targeting 33 versus 36 degrees. TTM main study ClinicalTrials.gov: NCT01020916. One hundred sixty three patients resuscitated from OHCA were included at a single site ICU. Blood was sampled a median 135 min (Inter Quartile Range (IQR) 103-169) after OHCA. Plasma catecholamines (adrenaline, noradrenaline) and serum endothelial biomarkers (syndecan-1, thrombomodulin, sE-selectin, sVE-cadherin) were measured at admission (immediately after randomization). We had access to data on demography, medical history, characteristics of the OHCA, patients and 180-day outcome.

Results

Adrenaline and noradrenaline correlated positively with syndecan-1 and thrombomodulin i.e., biomarkers reflecting endothelial damage (both p<0.05). Overall 180-day mortality was 35%. By Cox analyses, plasma adrenaline, serum sE-selectin, reflecting endothelial cell activation, and thrombomodulin levels predicted mortality. However, thrombomodulin was the only biomarker independently associated with mortality after adjusting for gender, age, rhythm (shockable vs. non-shockable), OHCA to return of spontaneous circulation (ROSC) time, shock at admission and ST elevation myocardial infarction (30-day Hazards Ratio 1.71 (IQR 1.05-2.77), p=0.031 and 180-day Hazards Ratio 1.65 (IQR 1.03-2.65), p=0.037 for 2-fold higher thrombomodulin levels).

Conclusions

Circulating catecholamines and endothelial damage were intercorrelated and predicted increased mortality. Interventions aiming at protecting and/or restoring the endothelium may be beneficial in OHCA patients.

Legislation hampers medical research in acute situations

INTRODUCTION

Informed consent in incapacitated adults is permitted in the form of proxy consent by both the patients' closest relative (next of kin, NOK) and general practitioner (GP). In research in acute situations not involving pharmaceuticals, Danish legislation allows for randomisation and subsequent proxy consent, as soon as possible. The aim of this study was to describe the delay associated with obtaining consent and to assess whether consent from NOK or GP/Danish Health and Medicines Authority is obtained with delays beyond the intervention.

METHODS

In a prospective study, 171 comatose out-of-hospital cardiac arrest (OHCA) patients were randomised to targeted temperature management. Patients were randomised before NOK could be informed, and proxy consent was obtained as soon as possible. Written consent from NOK and GP were our study data.

RESULTS

We obtained all legally required consent: 169 cases of consent were obtained from NOK, two patients gave consent before NOK, in no cases was consent denied by the proxy. Consent from NOK was obtained with a median delay of zero days (interquartile range (IQR): 0-1, max. 128 days). Delay from NOK consent to GP consent was a median of nine days (IQR: 6-23, max. 527 days).

CONCLUSION

NOK fully accepted participation in a clinical trial after OHCA with short delays in consent. Consent from GPs was associated with long delays beyond the intervention, which make GPs less appropriate for proxy consent of incapacitated adults in acute situations. The Ethics Committees' approval of the trial justified by their competence and authority, combined with the NOK´s insight into the patient's wishes may be a relevant and feasible alternative to the current consent procedure.

FUNDING

This work was supported by the European Regional Development Fund through the Interreg IV A OKS programme (NYPS ID: 167157) with regards to authors JHT, CH, NN and JK.

TRIAL REGISTRATION

not relevant.

Cognitive function in survivors of out-of-hospital cardiac arrest after target temperature management at 33°C versus 36°C

BACKGROUND

Target temperature management is recommended as a neuroprotective strategy after out-of-hospital cardiac arrest. Potential effects of different target temperatures on cognitive impairment commonly described in survivors have not been investigated sufficiently. The primary aim of this study was to evaluate whether a target temperature of 33°C compared with 36°C was favorable for cognitive function; the secondary aim was to describe cognitive impairment in cardiac arrest survivors in general.

METHODS AND RESULTS

Study sites included 652 cardiac arrest survivors originally randomized and stratified for site to temperature control at 33°C or 36°C within the Target Temperature Management trial. Survival until 180 days after the arrest was 52% (33°C, n=178/328; 36°C, n=164/324). Survivors were invited to a face-to-face follow-up, and 287 cardiac arrest survivors (33°C, n=148/36°C, n=139) were assessed with tests for memory (Rivermead Behavioural Memory Test), executive functions (Frontal Assessment Battery), and attention/mental speed (Symbol Digit Modalities Test). A control group of 119 matched patients hospitalized for acute ST-segment-elevation myocardial infarction without cardiac arrest performed the same assessments. Half of the cardiac arrest survivors had cognitive impairment, which was mostly mild. Cognitive outcome did not differ (P>0.30) between the 2 temperature groups (33°C/36°C). Compared with control subjects with ST-segment-elevation myocardial infarction, attention/mental speed was more affected among cardiac arrest patients, but results for memory and executive functioning were similar.

CONCLUSIONS

Cognitive function was comparable in survivors of out-of-hospital cardiac arrest when a temperature of 33°C and 36°C was targeted. Cognitive impairment detected in cardiac arrest survivors was also common in matched control subjects with ST-segment-elevation myocardial infarction not having had a cardiac arrest.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01946932.

Prognostic implication of out-of-hospital cardiac arrest in patients with cardiogenic shock and acute myocardial infarction

OBJECTIVES

To compare outcome in patients with acute myocardial infarction (MI) and cardiogenic shock (CS) presenting with and without out-of-hospital cardiac arrest (OHCA).

BACKGROUND

Despite general improvement in outcome after acute MI, CS remains a leading cause of death in acute MI patients with a high 30-day mortality rate. OHCA on top of cardiogenic shock may further increase mortality in these patients resulting in premature withdrawal of supportive therapy, but this is not known.

METHODS AND RESULTS

In a retrospective study from 2008 to 2013, 248 consecutive patients admitted alive to a tertiary centre with the diagnosis of CS and acute MI were enrolled, 118 (48%) presented with OHCA and 130 (52%) without (non-OHCA patients). Mean lactate level at admission was significantly higher in OHCA patients compared with non-OCHA patients (9mmol/l (SD 6) vs. 6mmol/l (SD 4) p<0.0001). Co-morbidities were more prevalent in the non-OHCA group. By univariate analysis age (Hazard ratio (HR)=1.02 [CI 1.00-1.03], p=0.01) and lactate at admission (HR=1.06 [CI 1.03-1.09], p<0.001), but not OHCA (HR=1.1 [CI 0.8-1.4], p=NS) was associated with mortality. In multivariate analysis, only age (HR=1.02 [CI 1.01-1.04], p=0.003) and lactate level at admission (HR=1.06 [1.03-1.09], p<0.001) were independent predictors of mortality. One-week mortality was 63% in the OHCA group and 56% in the non-OHCA group, p=NS.

CONCLUSION

OHCA is not an independent predictor of mortality in patients with acute MI complicated by cardiogenic shock. This should encourage active intensive treatment of CS patients regardless of OHCA.

Relationships between biomarkers and left ventricular filling pressures at rest and during exercise in patients after myocardial infarction

BACKGROUND

Increased pulmonary capillary wedge pressure (PCWP) is an independent prognostic predictor after myocardial infarction (MI), but PCWP is difficult to assess noninvasively in subjects with preserved ejection fraction (EF). We hypothesized that biomarkers would provide information regarding PCWP at rest and during exercise in subjects with preserved EF after MI.

METHODS AND RESULTS

Seventy-four subjects with EF >45% and recent MI underwent right heart catheterization at rest and during a symptom-limited semisupine cycle exercise test with simultaneous echocardiography. Plasma samples were collected at rest for assessment of midregional pro-A-type natriuretic peptide (MR-proANP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), galectin-3 (Gal-3), copeptin, and midregional pro-adrenomedullin (MR-proADM). Plasma levels of MR-proANP and PCWP were associated at rest (r = 0.33; P = .002) and peak exercise (r = 0.35; P = .002) as well as with changes in PCWP (r = 0.26; P = .03). Plasma levels of NT-proBNP and PCWP were weakly associated at rest (r = 0.23; P = .03) and peak exercise (r = 0.28; P = .02) but not with changes in PCWP (r = 0.20; P = .09). In a multivariable analysis, plasma levels of MR-proANP remained associated with rest and exercise PCWP (P < .01), whereas NT-proBNP did not. Plasma levels of Gal-3, copeptin, and MR-proADM were not associated with PCWP at rest or peak exercise.

CONCLUSIONS

In subjects recovering from an acute MI with preserved EF, plasma levels of natriuretic peptides, particularly MR-proANP, are associated with filling pressures at rest and during exercise.

[New studies question the cardiac safety of conducted electrical weapons]

Conducted electrical weapons (CEW) were invented in the 1970s and are now widely used by more than 16,000 military and law enforcement agencies worldwide. Recent studies have sug-gested that a causal relation of cardiac arrest in humans and utilization of CEW may exist and cardiac capture and fatal arrhythmia have been documented in animal studies. We believe, based on current knowledge, that CEW use may have caused human fatalities. Users should be aware of potential serious side effects and be able to provide basic life support.