International Cardiac Arrest Registry Research Articles

Abstract 348: Machine Learning Approaches for Early Outcome Risk Stratification Within 6 Hours of Cardiac Arrest

Background: Formal prognostication should be delayed at least 72 hours after cardiac arrest, but early stratification of risk severity provides important information for medical decision making, research enrollment, and precision medicine. Hypothesis: EEG-derived indices are valid biomarkers of severity of injury after cardiac arrest and contribute to early identification of risk. Aims: To assess the relative impact of early clinical data and processed EEG indices in the first 6 hours after recovery of spontaneous circulation (ROSC). Methods: Data from the first 6 hours after ROSC in the International Cardiac Arrest Registry (INTCAR) from Maine Medical Center including demographics, cardiac arrest data, admission vital signs and laboratory results and processed EEG indices at 6 hours after ROSC (bispectral index or BIS6 and suppression ratio or SR6) were extracted. Cerebral Performance Category (CPC) scores at hospital discharge and 6-month follow-up were dichotomized into good (CPC = 1-2) and poor (CPC = 3-5) outcomes. Three models were trained, one with INTCAR data, a second with EEG data, and the third combining INTCAR and BIS6-SR6. Six machine learning algorithms were applied: Catboost, random forest, Xgboost, Adaboost, support vector machine and logistic regression. Variable importance was analyzed by the decrease of impurity of random forest. Results: Among 913 included patients, median age was 59 years (95%CI 23-85), 623 (68%) were male, initial rhythm was shockable in 405 (44%) patients, and average time to ROSC was 23 (95%CI 3 - 73) minutes. Survival to hospital discharge occurred in 41% (364/893), and poor outcome occurred in 72.7% at 6-month follow-up (607/835). For CPC at discharge, area-under-the curve (AUC) was 0.85 for the combined INTCAR and EEG data, greater than INTCAR (AUC = 0.80) or EEG (AUC = 0.77). For the CPC at follow-up, the AUC was 0.88 for the combined data, greater than INTCAR (AUC = 0.83) or EEG (AUC = 0.79). Variable ranking analysis showed that BIS6 and SR6 were the two most informative features for both outcomes. Conclusions: The processed EEG variables BIS6 and SR6 significantly contribute to risk identification in the first 6 hours after ROSC, and combined with early clinical data provide reliable risk stratification.

Influence of circulatory shock at hospital admission on outcome after out-of-hospital cardiac arrest

Hypotension after cardiac arrest could aggravate prolonged hypoxic ischemic encephalopathy. The association of circulatory shock at hospital admission with outcome after cardiac arrest has not been well studied. The objective of this study was to investigate the independent association of circulatory shock at hospital admission with neurologic outcome, and to evaluate whether cardiovascular comorbidities interact with circulatory shock. 4004 adult patients with out-of-hospital cardiac arrest enrolled in the International Cardiac Arrest Registry 2006–2017 were included in analysis. Circulatory shock was defined as a systolic blood pressure below 90 mmHg and/or medical or mechanical supportive measures to maintain adequate perfusion during hospital admission. Primary outcome was cerebral performance category (CPC) dichotomized as good, (CPC 1–2) versus poor (CPC 3–5) outcome at hospital discharge. 38% of included patients were in circulatory shock at hospital admission, 32% had good neurologic outcome at hospital discharge. The adjusted odds ratio for good neurologic outcome in patients without preexisting cardiovascular disease with circulatory shock at hospital admission was 0.60 [0.46–0.79]. No significant interaction was detected with preexisting comorbidities in the main analysis. We conclude that circulatory shock at hospital admission after out-of-hospital cardiac arrest is independently associated with poor neurologic outcome.

Incidence of cardiac interventions and associated cardiac arrest outcomes in patients with nonshockable initial rhythms and no ST elevation post resuscitation

BackgroundOut of Hospital Cardiac arrest (OHCA) survivors with ST elevation (STE) with or without shockable rhythms often benefit from coronary angiography (CAG) and, if indicated, percutaneous coronary intervention (PCI). However, the benefits of CAG and PCI in OHCA survivors with nonshockable rhythms (PEA/asystole) and no STE are debated. MethodsUsing the International Cardiac Arrest Registry (INTCAR 2.0), representing 44 centers in the US and Europe, comatose OHCA survivors with known presenting rhythms and post resuscitation ECGs were identified. Survival to hospital discharge, neurological recovery on discharge, and impact of CAG with or without PCI on such outcome were assessed and compared with other groups (shockable rhythms with or without STE). ResultsTotal of 2113 OHCA survivors were identified and described as; nonshockable/no STE (Nsh-NST) (n = 940, 44.5%), shockable/no STE (Sh-NST) (n = 716, 33.9%), nonshockable/STE (Nsh-ST) (n = 110, 5.2%), and shockable/STE (Sh-ST) (n = 347, 16.4%). Of Nsh-NST, 13.7% (129) were previously healthy before CA and only 17.3% (161) underwent CAG; of those, 30.4% (52) underwent PCI. A total of 18.6% (174) Nsh-NST patients survived to hospital discharge, with 57.5% (100) of such survivors having good neurological recovery (cerebral performance category 1 or 2) on discharge. Coronary angiography was associated with improved odds for survival and neurological recovery among all groups, including those with NSh-NST. ConclusionsNonshockable initial rhythms with no ST elevation post resuscitation was the most common presentation after OHCA. Although most of these patients did not undergo coronary angiography, among those who did, 1 in 4 patients had a culprit lesion and underwent revascularization. Invasive CAG should be at least considered for all OHCA survivors, including those with nonshockable rhythms and no ST elevation post resuscitation. Brief abstractOut of hospital cardiac arrest (OHCA) survivors with ST elevation and/or shockable rhythms benefit from coronary angiography and revascularization. Nonshockable cardiac arrest survivors with no ST elevation have the worst prognosis and rarely undergo coronary angiography.Nonshockable rhythms with no ST elevation was the most common presentation after OHCA and among a small subgroup underwent coronary angiography, 1 in 4 patients with had culprit lesion and underwent revascularization. Coronary angiography was associated with high prevalence of acute culprit coronary lesions and should be considered for those with a probably cardiac cause for their arres.

Influence of sex on survival, neurologic outcomes, and neurodiagnostic testing after out-of-hospital cardiac arrest

AimPrevious studies evaluating the relationship between sex and post-resuscitation care and outcomes following out-of-hospital cardiac arrest (OHCA) are conflicting. We investigated the association between sex and outcomes as well as neurodiagnostic testing in a prospective multicenter international registry of patients admitted to intensive care units following OHCA. MethodsOHCA survivors enrolled in the International Cardiac Arrest Registry (INTCAR) from 2012 to 2017 were included. We assessed the independent association between sex and survival to hospital discharge, good neurologic outcome (Cerebral Performance Category 1 or 2), neurodiagnostic testing, and withdrawal of life-sustaining therapy (WLST). ResultsOf 2407 eligible patients, 809 (33.6%) were women. Baseline characteristics differed by sex, with less bystander CPR and initial shockable rhythms among women. Women were less likely to survive to hospital discharge, however significance abated following adjusted analysis (30.1% vs 42.7%, adjusted OR 0.85, 95% CI 0.67–1.08). Women were less likely to have good neurologic outcome at discharge (21.4% vs 34.0%, adjusted OR 0.74, 95% CI 0.57–0.96) and at six months post-arrest (16.7% vs 29.4%, adjusted OR 0.73, 95% CI 0.54–0.98) that persisted after adjustment. Neuroimaging (75.5% vs 74.3%, p = 0.54) and other neurophysiologic testing (78.8% vs 78.6%, p = 0.91) was similar across sex. Women were more likely to undergo WLST (55.6% vs 42.8%, adjusted OR 1.35, 95% CI 1.09–1.66). ConclusionsWomen with cardiac arrest have lower odds of good neurologic outcomes and higher odds of WLST, despite comparable rates of neurodiagnostic testing and after controlling for baseline differences in clinical characteristics and cardiac arrest features.

Risk Stratification Among Survivors of Cardiac Arrest Considered for Coronary Angiography

BackgroundThe American College of Cardiology Interventional Council published consensus-based recommendations to help identify resuscitated cardiac arrest patients with unfavorable clinical features in whom invasive procedures are unlikely to improve survival. ObjectivesThis study sought to identify how many unfavorable features are required before prognosis is significantly worsened and which features are most impactful in predicting prognosis. MethodsUsing the INTCAR (International Cardiac Arrest Registry), the impact of each proposed “unfavorable feature” on survival to hospital discharge was individually analyzed. Logistic regression was performed to assess the association of such unfavorable features with poor outcomes. ResultsSeven unfavorable features (of 10 total) were captured in 2,508 patients successfully resuscitated after cardiac arrest (ongoing cardiopulmonary resuscitation and noncardiac etiology were exclusion criteria in our registry). Chronic kidney disease was used in lieu of end-stage renal disease. In total, 39% survived to hospital discharge. The odds ratio (OR) of survival to hospital discharge for each unfavorable feature was as follows: age >85 years OR: 0.30 (95% CI: 0.15 to 0.61), time-to-ROSC >30 min OR: 0.30 (95% CI: 0.23 to 0.39), nonshockable rhythm OR: 0.39 (95% CI: 0.29 to 0.54), no bystander cardiopulmonary resuscitation OR: 0.49 (95% CI: 0.38 to 0.64), lactate >7 mmol/l OR: 0.50 (95% CI: 0.40 to 0.63), unwitnessed arrest OR: 0.58 (95% CI: 0.44 to 0.78), pH <7.2 OR: 0.78 (95% CI: 0.63 to 0.98), and chronic kidney disease OR: 0.96 (95% CI: 0.70 to 1.33). The presence of any 3 or more unfavorable features predicted <40% survival. Presence of the 3 strongest risk factors (age >85 years, time-to-ROSC >30 min, and non-ventricular tachycardia/ventricular fibrillation) together or ≥6 unfavorable features predicted a ≤10% chance of survival to discharge. ConclusionsPatients successfully resuscitated from cardiac arrest with 6 or more unfavorable features have a poor long-term prognosis. Delaying or even forgoing invasive procedures in such patients is reasonable.

The association of partial pressures of oxygen and carbon dioxide with neurological outcome after out-of-hospital cardiac arrest: an explorative International Cardiac Arrest Registry 2.0 study

BackgroundExposure to extreme arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) following the return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest (OHCA) is common and may affect neurological outcome but results of previous studies are conflicting.MethodsExploratory study of the International Cardiac Arrest Registry (INTCAR) 2.0 database, including 2162 OHCA patients with ROSC in 22 intensive care units in North America and Europe. We tested the hypothesis that exposure to extreme PaO2 or PaCO2 values within 24 h after OHCA is associated with poor neurological outcome at discharge. Our primary analyses investigated the association between extreme PaO2 and PaCO2 values, defined as hyperoxemia (PaO2 > 40 kPa), hypoxemia (PaO2 < 8.0 kPa), hypercapnemia (PaCO2 > 6.7 kPa) and hypocapnemia (PaCO2 < 4.0 kPa) and neurological outcome. The secondary analyses tested the association between the exposure combinations of PaO2 > 40 kPa with PaCO2 < 4.0 kPa and PaO2 8.0–40 kPa with PaCO2 > 6.7 kPa and neurological outcome. To define a cut point for the onset of poor neurological outcome, we tested a model with increasing and decreasing PaO2 levels and decreasing PaCO2 levels. Cerebral Performance Category (CPC), dichotomized to good (CPC 1–2) and poor (CPC 3–5) was used as outcome measure.ResultsOf 2135 patients eligible for analysis, 700 were exposed to hyperoxemia or hypoxemia and 1128 to hypercapnemia or hypocapnemia. Our primary analyses did not reveal significant associations between exposure to extreme PaO2 or PaCO2 values and neurological outcome (P = 0.13–0.49). Our secondary analyses showed no significant associations between combinations of PaO2 and PaCO2 and neurological outcome (P = 0.11–0.86). There was no PaO2 or PaCO2 level significantly associated with poor neurological outcome. All analyses were adjusted for relevant co-variates.ConclusionsExposure to extreme PaO2 or PaCO2 values in the first 24 h after OHCA was common, but not independently associated with neurological outcome at discharge.

Functional outcomes associated with varying levels of targeted temperature management after out-of-hospital cardiac arrest — An INTCAR2 registry analysis

IntroductionTargeted temperature management (TTM) after out-of-hospital cardiac arrest (OHCA) has been recommended in international guidelines since 2005. The TTM-trial published in 2013 showed no difference in survival or neurological outcome for patients randomised to 33 °C or 36 °C, and many hospitals have changed practice. The optimal utilization of TTM is still debated. This study aimed to analyse if a difference in temperature goal was associated with outcome in an unselected international registry population. MethodsThis is a retrospective observational study based on a prospective registry — the International Cardiac Arrest Registry 2. Patients were categorized as receiving TTM in the lower range at 32–34 °C (TTM-low) or at 35–37 °C (TTM-high). Primary outcome was good functional status defined as cerebral performance category (CPC) of 1–2 at hospital discharge and secondary outcome was adverse events related to TTM. A logistic regression model was created to evaluate the independent effect of temperature by correcting for clinical and demographic factors associated with outcome. ResultsOf 1710 patients included, 1242 (72,6%) received TTM-low and 468 (27,4%) TTM-high. In patients receiving TTM-low, 31.3% survived with good outcome compared to 28.8% in the TTM-high group. There was no significant association between temperature and outcome (p = 0.352). In analyses adjusted for baseline differences the OR for a good outcome with TTM-low was 1.27, 95% CI (0.94–1.73). Haemodynamic instability leading to discontinuation of TTM was more common in TTM-low. ConclusionsNo significant difference in functional outcome at hospital discharge was found in patients receiving lower- versus higher targeted temperature management.

Editorial introductions

Current Opinion in Critical Care was launched in 1995. It is one of a successful series of review journals whose unique format is designed to provide a systematic and critical assessment of the literature as presented in the many primary journals. The field of critical care is divided into 13 sections that are reviewed once a year. Each section is assigned a Section Editor, a leading authority in the area, who identifies the most important topics at that time. Here we are pleased to introduce the Section Editors for this issue. SECTION EDITORS Hans FribergHans FribergHans Friberg, MD, PhD, EDIC is a Professor of Anaesthesiology and Intensive Care Medicine at Lund University, Sweden and a senior consultant at Skåne University Hospital, Malmö, Sweden. Dr Friberg did his PhD-work at the Laboratory for Experimental Brain Research at Lund University, where he studied brain injury and mitochondrial dysfunction in rodent models of global and focal brain ischemia. Dr Friberg's present research area is post-resuscitation care and temperature management after cardiac arrest. He has published some 200 scientific papers. He is the senior author of the Targeted Temperature Management after cardiac arrest trial (TTM-trial) and also a senior author of the ongoing TTM2-trial. Dr Friberg is an initiator of the Hypothermia Network which has become the International Cardiac Arrest Registry (INTCAR), a transatlantic research collaboration with more than 6000 registered patients. He is the initiator of SWECRIT, a large regional biobank for critically ill patients in the ICU. Dr Friberg is a co-author of the ERC guidelines on post-resuscitation care and serves on the Board of the Swedish Resuscitation Council. Anthony S. McLeanAnthony S. McLeanAnthony S. McLean, BSc (Hons), MB.ChB (Otago), MD, FRACP, FCSANZ, FCICM, MRACMA is based at the Nepean Hospital, Sydney, Australia and is Head of Intensive Care Medicine and Professor with the University of Sydney, Australia. His research background ranges from critical care echocardiography and heart failure to genomics of sepsis in critically ill patients. He has been training basic and advanced echocardiographic techniques for many years, both nationally and internationally. He leads a dedicated research team into the use of echocardiography in the critically ill patient. Additionally, the Nepean Intensive Care Genomics team have been researching the utility of blood transcriptome analysis in septic patients for the past decade, developing international database networks with a particular interest in influenza and other respiratory viruses. He has over 130 publications in peer review journals, written books on both basic and advanced critical care echocardiography and has contributed multiple book chapters on aspects of Intensive Care Medicine. A strong believer in advancing Intensive Care medicine in the region he has participated in many scientific meetings and workshops in South East Asian countries. He is a past President of the Australian and New Zealand Society of Intensive Care and is also a past President of the Asia Pacific Association of Critical Care Medicine.

Variability in functional outcome and treatment practices by treatment center after out-of-hospital cardiac arrest: analysis of International Cardiac Arrest Registry.

Functional outcomes vary between centers after out-of-hospital cardiac arrest (OHCA) and are partially explained by pre-existing health status and arrest characteristics, while the effects of in-hospital treatments on functional outcome are less understood. We examined variation in functional outcomes by center after adjusting for patient- and arrest-specific characteristics and evaluated how in-hospital management differs between high- and low-performing centers. Analysis of observational registry data within the International Cardiac Arrest Registry was used to perform a hierarchical model of center-specific risk standardized rates for good outcome, adjusted for demographics, pre-existing functional status, and arrest-related factors with treatment center as a random effect variable. We described the variability in treatments and diagnostic tests that may influence outcome at centers with adjusted rates significantly above and below registry average. A total of 3855 patients were admitted to an ICU following cardiac arrest with return of spontaneous circulation. The overall prevalence of good outcome was 11-63% among centers. After adjustment, center-specific risk standardized rates for good functional outcome ranged from 0.47 (0.37-0.58) to 0.20 (0.12-0.26). High-performing centers had faster time to goal temperature, were more likely to have goal temperature of 33°C, more likely to perform unconscious cardiac catheterization and percutaneous coronary intervention, and had differing prognostication practices than low-performing centers. Center-specific differences in outcomes after OHCA after adjusting for patient-specific factors exist. This variation could partially be explained by in-hospital management differences. Future research should address the contribution of these factors to the differences in outcomes after resuscitation.

Early withdrawal of life support after resuscitation from cardiac arrest is common and may result in additional deaths

Aim“Early” withdrawal of life support therapies (eWLST) within the first 3 calendar days after resuscitation from cardiac arrest (CA) is discouraged. We evaluated a prospective multicenter registry of patients admitted to hospitals after resuscitation from CA to determine predictors of eWLST and estimate its impact on outcomes. MethodsCA survivors enrolled from 2012–2017 in the International Cardiac Arrest Registry (INTCAR) were included. We developed a propensity score for eWLST and matched a cohort with similar probabilities of eWLST who received ongoing care. The incidence of good outcome (Cerebral Performance Category of 1 or 2) was measured across deciles of eWLST in the matched cohort. Results2688 patients from 24 hospitals were included. Median ischemic time was 20 (IQR 11, 30) minutes, and 1148 (43%) had an initial shockable rhythm. Withdrawal of life support occurred in 1162 (43%) cases, with 459 (17%) classified as eWLST. Older age, initial non-shockable rhythm, increased ischemic time, shock on admission, out-of-hospital arrest, and admission in the United States were each independently associated with eWLST. All patients with eWLST died, while the matched cohort, good outcome occurred in 21% of patients. 19% of patients within the eWLST group were predicted to have a good outcome, had eWLST not occurred. ConclusionsEarly withdrawal of life support occurs frequently after cardiac arrest. Although the mortality of patients matched to those with eWLST was high, these data showed excess mortality with eWLST.

Variation in Sedation and Neuromuscular Blockade Regimens on Outcome After Cardiac Arrest.

Sedation and neuromuscular blockade protocols in patients undergoing targeted temperature management after cardiac arrest address patient discomfort and manage shivering. These protocols vary widely between centers and may affect outcomes. Consecutive patients admitted to 20 centers after resuscitation from cardiac arrest were prospectively entered into the International Cardiac Arrest Registry between 2006 and 2016. Additional data about each center's sedation and shivering management practice were obtained via survey. Sedation and shivering practices were categorized as escalating doses of sedation and minimal or no neuromuscular blockade (sedation and shivering practice 1), sedation with continuous or scheduled neuromuscular blockade (sedation and shivering practice 2), or sedation with as-needed neuromuscular blockade (sedation and shivering practice 3). Good outcome was defined as Cerebral Performance Category score of 1 or 2. A logistic regression hierarchical model was created with two levels (patient-level data with standard confounders at level 1 and hospitals at level 2) and sedation and shivering practices as a fixed effect at the hospital level. The primary outcome was dichotomized Cerebral Performance Category at 6 months. Cardiac arrest receiving centers in Europe and the United states from 2006 to 2016 PATIENTS:: Four-thousand two-hundred sixty-seven cardiac arrest patients 18 years old or older enrolled in the International Cardiac Arrest Registry. None. The mean age was 62 ± 15 years, 36% were female, 77% out-of-hospital arrests, and mean ischemic time was 24 (± 18) minutes. Adjusted odds ratio (for age, return of spontaneous circulation, location of arrest, witnessed, initial rhythm, bystander cardiopulmonary resuscitation, defibrillation, medical history, country, and size of hospital) was 1.13 (0.74-1.73; p = 0.56) and 1.45 (1.00-2.13; p = 0.046) for sedation and shivering practice 2 and sedation and shivering practice 3, respectively, referenced to sedation and shivering practice 1. Cardiac arrest patients treated at centers using as-needed neuromuscular blockade had increased odds of good outcomes compared with centers using escalating sedation doses and avoidance of neuromuscular blockade, after adjusting for potential confounders. These findings should be further investigated in prospective studies.

Derivation and Validation of the CREST Model for Very Early Prediction of Circulatory Etiology Death in Patients Without ST-Segment-Elevation Myocardial Infarction After Cardiac Arrest.

No practical tool quantitates the risk of circulatory-etiology death (CED) immediately after successful cardiopulmonary resuscitation in patients without ST-segment-elevation myocardial infarction. We developed and validated a prediction model to rapidly determine that risk and facilitate triage to individualized treatment pathways. With the use of INTCAR (International Cardiac Arrest Registry), an 87-question data set representing 44 centers in the United States and Europe, patients were classified as having had CED or a combined end point of neurological-etiology death or survival. Demographics and clinical factors were modeled in a derivation cohort, and backward stepwise logistic regression was used to identify factors independently associated with CED. We demonstrated model performance using area under the curve and the Hosmer-Lemeshow test in the derivation and validation cohorts, and assigned a simplified point-scoring system. Among 638 patients in the derivation cohort, 121 (18.9%) had CED. The final model included preexisting coronary artery disease (odds ratio [OR], 2.86; confidence interval [CI], 1.83-4.49; P≤0.001), nonshockable rhythm (OR, 1.75; CI, 1.10-2.77; P=0.017), initial ejection fraction<30% (OR, 2.11; CI, 1.32-3.37; P=0.002), shock at presentation (OR, 2.27; CI, 1.42-3.62; P<0.001), and ischemic time >25 minutes (OR, 1.42; CI, 0.90-2.23; P=0.13). The derivation model area under the curve was 0.73, and Hosmer-Lemeshow test P=0.47. Outcomes were similar in the 318-patient validation cohort (area under the curve 0.68, Hosmer-Lemeshow test P=0.41). When assigned a point for each associated factor in the derivation model, the average predicted versus observed probability of CED with a CREST score (coronary artery disease, initial heart rhythm, low ejection fraction, shock at the time of admission, and ischemic time >25 minutes) of 0 to 5 was: 7.1% versus 10.2%, 9.5% versus 11%, 22.5% versus 19.6%, 32.4% versus 29.6%, 38.5% versus 30%, and 55.7% versus 50%. The CREST model stratified patients immediately after resuscitation according to risk of a circulatory-etiology death. The tool may allow for estimation of circulatory risk and improve the triage of survivors of cardiac arrest without ST-segment-elevation myocardial infarction at the point of care.

Association of gender to outcome after out-of-hospital cardiac arrest--a report from the International Cardiac Arrest Registry.

IntroductionPrevious studies have suggested an effect of gender on outcome after out-of-hospital cardiac arrest (OHCA), but the results are conflicting. We aimed to investigate the association of gender to outcome, coronary angiography (CAG) and adverse events in OHCA survivors treated with mild induced hypothermia (MIH).MethodsWe performed a retrospective analysis of prospectively collected data from the International Cardiac Arrest Registry. Adult patients with a non-traumatic OHCA and treated with MIH were included. Good neurological outcome was defined as a cerebral performance category (CPC) of 1 or 2.ResultsA total of 1,667 patients, 472 women (28%) and 1,195 men (72%), met the inclusion criteria. Men were more likely to receive bystander cardiopulmonary resuscitation, have an initial shockable rhythm and to have a presumed cardiac cause of arrest. At hospital discharge, men had a higher survival rate (52% vs. 38%, P <0.001) and more often a good neurological outcome (43% vs. 32%, P <0.001) in the univariate analysis. When adjusting for baseline characteristics, male gender was associated with improved survival (OR 1.34, 95% CI 1.01 to 1.78) but no longer with neurological outcome (OR 1.24, 95% CI 0.92 to 1.67). Adverse events were common; women more often had hypokalemia, hypomagnesemia and bleeding requiring transfusion, while men had more pneumonia. In a subgroup analysis of patients with a presumed cardiac cause of arrest (n = 1,361), men more often had CAG performed on admission (58% vs. 50%, P = 0.02) but this discrepancy disappeared in an adjusted analysis.ConclusionsGender differences exist regarding cause of arrest, adverse events and outcome. Male gender was independently associated with survival but not with neurological outcome.

Abstract 17309: Validation of a Novel Prediction Tool for Circulatory Etiology Death After Cardiac Arrest

Introduction: Post-resuscitation cardiac arrest (CA) triage to urgent angiography, percutaneous intervention, and mechanical circulatory support is hampered by inconclusive risk stratification, especially among patients without ST elevation myocardial infarction (STEMI). We analyzed registry data to develop a prediction tool to determine the risk of circulatory-etiology (CV) death in patients without STEMI, and validated it in a separate cohort. Methods: Using the International Cardiac Arrest Registry (INTCAR)-Cardiology data set and stepwise linear regression with an inclusion rule of P≤0.1, we determined demographic and clinical factors independently associated with CV death, and created a weighted prediction model for patients presenting after CA without STEMI. The model was then validated in a separate, larger cohort from INTCAR. This project was approved by the Maine Medical Center IRB. Results: Of 468 patients in the derivation cohort, 90 met criteria for the endpoint. In the multivariable model, age greater than 65 (OR=2.4, p=0.0001), preexisting coronary disease (OR=1.9, P=0.0065), diabetes (OR=1.8, P=0.01), in-hospital arrest (OR=1.5, P=0.1), time from collapse to return of circulation (TTROSC) greater than 25 minutes (OR=1.7, p=0.02), shock at presentation (OR=3.9, P&lt;0.0001), and EF&lt;30% on first echo (OR=1.6, P=0.05) were independently associated with CV death. Using weighted predictors (age&gt;65 =1, prior CAD =1, diabetes =1, in-hospital arrest =1, TTROSC&gt;25 =1, admission LVEF&lt;30% =1, shock =2,), an additive score of 0-2 predicted CV death in 8.5% and ≥3 in 34% in the derivation cohort. In the validation cohort, which comprised 1197 patients, of whom 263 met criteria for CV death, a score of 0-2 was associated with 13.1% and ≥3 with 35.1% CV death, respectively. Conclusions: A simple bedside prediction tool can predict high (34-35.1%) vs. low (8.5-13.1%) risk of circulatory-etiology death in cardiac arrest survivors without STEMI. This model could be used to risk-stratify cardiac arrest survivors, and aid in the triage of patients to appropriate and cost-effective post-resuscitation treatments.

Neurologic outcomes and postresuscitation care of patients with myoclonus following cardiac arrest.

To evaluate the outcomes of cardiac arrest survivors with myoclonus receiving modern postresuscitation care. Retrospective review of registry data. Cardiac arrest receiving centers in Europe and the United States from 2002 to 2012. Two thousand five hundred thirty-two cardiac arrest survivors 18 years or older enrolled in the International Cardiac Arrest Registry. None. Eighty-eight percent of patients underwent therapeutic hypothermia and 471 (18%) exhibited myoclonus. Patients with myoclonus had longer time to professional cardiopulmonary resuscitation (8.6 vs 7.0 min; p < 0.001) and total ischemic time (25.6 vs 22.3 min; p < 0.001) and less often presented with ventricular tachycardia/ventricular fibrillation, a witnessed arrest, or had bystander cardiopulmonary resuscitation. Electroencephalography demonstrated myoclonus with epileptiform activity in 209 of 374 (55%), including status epilepticus in 102 of 374 (27%). Good outcome (Cerebral Performance Category 1-2) at hospital discharge was noted in 9% of patients with myoclonus, less frequently in myoclonus with epileptiform activity (2% vs 15%; p < 0.001). Patients with myoclonus with good outcome were younger (53.7 vs 62.7 yr; p < 0.001), had more ventricular tachycardia/ventricular fibrillation (81% vs 46%; p < 0.001), shorter ischemic time (18.9 vs 26.4 min; p = 0.003), more witnessed arrests (91% vs 77%; p = 0.02), and fewer "do-not-resuscitate" orders (7% vs 78%; p < 0.001). Life support was withdrawn in 330 of 427 patients (78%) with myoclonus and poor outcome, due to neurological futility in 293 of 330 (89%), at 5 days (3-8 d) after resuscitation. With myoclonus and good outcome, median ICU length of stay was 8 days (5-11 d) and hospital length of stay was 14.5 days (9-22 d). Nine percent of cardiac arrest survivors with myoclonus after cardiac arrest had good functional outcomes, usually in patients without associated epileptiform activity and after prolonged hospitalization. Deaths occurred early and primarily after withdrawal of life support. It is uncertain whether prolonged care would yield a higher percentage of good outcomes, but myoclonus of itself should not be considered a sign of futility.

Safety, feasibility, and outcomes of induced hypothermia therapy following in-hospital cardiac arrest-evaluation of a large prospective registry*.

Despite a lack of randomized trials, practice guidelines recommend that mild induced hypothermia be considered for comatose survivors of in-hospital cardiac arrest. This study describes the safety, feasibility, and outcomes of mild induced hypothermia treatment following in-hospital cardiac arrest. Prospective, observational, registry-based study. Forty-six critical care facilities in eight countries in Europe and the United States reporting in the Hypothermia Network Registry and the International Cardiac Arrest Registry. A total of 663 patients with in-hospital cardiac arrest and treated with mild induced hypothermia were included between January 2004 and February 2012. None. A cerebral performance category of 1 or 2 was considered a good outcome. At hospital discharge 41% of patients had a good outcome. At median 6-month follow-up, 34% had a good outcome. Among in-hospital deaths, 52% were of cardiac causes and 44% of cerebral cause. A higher initial body temperature was associated with reduced odds of a good outcome (odds ratio, 0.79; 95% CI, 0.68-0.92). Adverse events were common; bleeding requiring transfusion (odds ratio, 0.56; 95% CI, 0.31-1.00) and sepsis (odds ratio, 0.52; 95% CI, 0.30-0.91) were associated with reduced odds for a good outcome. In this registry study of an in-hospital cardiac arrest population treated with mild induced hypothermia, we found a 41% good outcome at hospital discharge and 34% at follow-up. Infectious complications occurred in 43% of cases, and 11% of patients required a transfusion for bleeding. The majority of deaths were of cardiac origin.

Moderate-dose sedation and analgesia during targeted temperature management after cardiac arrest.

Sedation and analgesia regimens during targeted temperature management (TTM), after cardiac arrest varies widely, are poorly described in the literature and may have a negative impact on outcome. Since implementing TTM in 2005, we have used moderate-dose sedation and describe our experience with this approach. In this retrospective review, we included patients treated with TTM for cardiac arrest at our institution for 2008-2012. Patients received TTM if they did not follow verbal commands following cardiac arrest, regardless of place of arrest or rhythm. Utstein-compatible data were prospectively entered into the International Cardiac Arrest Registry, supplemented by review of nursing, pharmacy, and physical therapy records. We report analgesic and sedative medications and doses during the 24h of active TTM at 33°C, resource utilization, and important clinical events. 166 patients treated with TTM after in- and out-of-hospital cardiac arrest with complete data were included. Overall survival was 42%, median time to following commands was 3h after rewarming (-6, 14), time to spontaneous breathing trial was 19h (5-35), time to extubation was 28h (9-60), and 59% of survivors were discharged directly home at 13 (10-20) days. The incidence of seizure was 6%, septic shock 4%, and pneumonia 32%. Four survivors required tracheostomy at 8, 8, 12, and 16days. A moderate-dose sedation and analgesia regimen was well tolerated and effective during therapeutic hypothermia after cardiac arrest and is an effective alternative to very deep sedation. We recommend more complete description of sedation and analgesia protocols in future studies, including expanded outcome reporting to include variables affected by sedation therapy. Further study is required to define which sedation approach for TTM may be best.

Abstract 228: Neurological Outcomes of Cardiac Arrest Survivors with Myoclonus Following Resuscitation

Objectives: Historically, myoclonus was thought to portend a hopeless prognosis after cardiac arrest (CA). We evaluated the outcomes and characteristics of CA survivors with myoclonus in a large prospective registry. Methods: Retrospective review of the International Cardiac Arrest Registry (INTCAR) Findings: Of 2564 patients entered into INTCAR between 12/2008-12/2011, 466 (18%) had myoclonus, with an average age of 61.8 (SD 15.9) years, 84% OHCA, initial rhythm VT/VF in 47%, asystole in 28%, and PEA in 21%. Mean “no flow” interval was 8.6 (7.2) minutes, “low flow” interval 17 (15.2) minutes, and total time to return of circulation (TTROSC) 25.6 (15.5) minutes. Therapeutic hypothermia (TH) was applied in 444 (95%) patients, and 334 (72%) had EEG monitoring. Good Outcome (GO) with CPC1-2 occurred in 27 patients at ICU discharge, increasing to 43 (9.2%) at hospital discharge. For patients with GO, mean age was 53.6 (15.6), 79% VT/VF, and TTROSC was 18.6 (12.8) minutes. The EEG showed continuous activity with diffuse slowing in 61% of GO patients, and median hospital LOS was 14.5 days [IQR 9-22]. Of 423 myoclonus patients with poor outcome (PO = CPC3-5), life support was withdrawn in 330 (78%); due to neurological futility in 293 (89%), and the EEG (n=306) showed burst suppression in 152 (49.7%), status epilepticus in 102 (33.3%), severe background attenuation in 75 (24.5%) and continuous activity with diffuse slowing in 75 (24.5%). Among PO patients, 49 (11.6%) did not receive or complete TH. Median hospital LOS in this cohort was 5 [IQR3-7] days. Of 293 patients that died of “neurological futility”, 131 (45%) died less than 5 days after CA. Conclusions: Myoclonus after cardiac arrest should not be considered uniformly fatal. Despite early withdrawal or less than fully aggressive life supportive measures in many patients, 9.2% of myoclonus patients in a large registry population had good outcomes.

Abstract 276: A Genetic Algorithm Prognostic Tool Nested Within a 2500-Patient Registry of Post--Cardiac Arrest Care

Objectives: Predicting outcome after cardiac arrest (CA) is challenging. With data collected in the International Cardiac Arrest Registry (INTCAR), a novel prediction tool based on genetic algorithm (GA) was developed. Methods: 2,564 adult, resuscitated, comatose CA patients were included from 35 sites in Europe and USA. Primary outcome was hospital discharge Cerebral Performance Category (CPC) dichotomized into good (GO=CPC1-2) and poor outcomes (PO=CPC 3-5). The GA-based models were constructed using Experlytics® software including all 180 candidate variables from the registry. A decision tree displaying the relation of the information carrying variables was evolved and pruned to a final model and optimized towards accuracy, sensitivity, specificity and Receiver-Operating Characteristic (ROC) value. Results: Median age was 64 (IQR 54-73) years, 30% were female, the CA was witnessed in 84%, and initial rhythm was VF/VT in 55%, asystole in 23%, PEA in 17%. Time to ROSC was 19 (10-30) min. 37% had a GO at hospital discharge. 35% had coronary disease, 14% insulin dependent diabetes mellitus (IDDM), 8 % non-IDDM and 14% pulmonary disease. The final tree (figure 1) had an accuracy of 85%, a sensitivity of 91% and a specificity of 72%. The area under the ROC curve was 87% (CI 83-90). Conclusions: A novel tool based on GA predicted outcome comparable to previous models. The GA could visually display the important information carrying variables and their relation. This model requires external validation, but represents a promising tool to better predict outcome and define the relationship between important risk factors Figure 1. Relation of variables in a decision tree displaying good and poor outcome. ACD, automatic compression decompression, CPC, cerebral performance category, CPR, cardiopulmonary resuscitation, GCS, Glasgow Coma Scale, IDDM, Insulin dependent diabetes mellitus, MRI , magnetic resonance imaging, ROSC, return of spontaneous circulation.

Effects of variation in temperature management on cerebral performance category scores in patients who received therapeutic hypothermia post cardiac arrest

AimTo assess differences in cerebral performance category (CPC) in patients who received therapeutic hypothermia post cardiac arrest by time to initiation, time to target temperature, and duration of therapeutic hypothermia (TH). MethodsA secondary data analysis was conducted using hospital-specific data from the international cardiac arrest registry (INTCAR) database. The analytic sample included 172 adult patients who experienced an out-of-hospital cardiac arrest and were treated in one Midwestern hospital. Measures included time from arrest to ROSC, arrest to TH, arrest to target temperature, and length of time target temperature was maintained. CPC was assessed at three points: transfer from ICU, discharge from hospital, and post discharge follow-up. ResultsAverage age was 63.6 years and 74.4% of subjects were male. Subjects had TH initiation a mean of 94.4min (SD 81.6) after cardiac arrest and reached target temperature after 309.0min (SD 151.0). In adjusted models, the odds of a poor neurological outcome increased with each 5min delay in initiating TH at transfer from ICU (OR=1.06, 95% C.I. 1.02–1.10). Similar results were seen for neurological outcomes at hospital discharge (OR=1.06, 95% C.I. 1.02–1.11) and post-discharge follow-up (OR=1.08, 95% C.I. 1.03–1.13). Additionally the odds of a poor neurological outcome increased for every 30min delay in time to target temperature at post-discharge follow-up (OR=1.17, 95% C.I. 1.01–1.36). ConclusionIn adults undergoing TH post cardiac arrest, delay in initiation of TH and reaching target temperature differentiated poor versus good neurologic outcomes. Randomized trials assessing the range of current recommended guidelines for TH should be conducted to establish optimal treatment protocols.