Ventricular Fibrillation Out-of-hospital Cardiac Arrest Research Articles

Instantaneous amplitude: Association of ventricular fibrillation waveform measures at time of shock with outcome in out-of-hospital cardiac arrest.

Prompt defibrillation is key to successful resuscitation from ventricular fibrillation out-of-hospital cardiac arrest (VF-OHCA). Preliminary evidence suggests that the timing of shock relative to the amplitude of the VF ECG waveform may affect the likelihood of resuscitation. We investigated whether the VF waveform amplitude at the time of shock (instantaneous amplitude) predicts outcome independent of other validated waveform measures. We conducted a retrospective study of VF-OHCA patients ≥18 old. We evaluated three VF waveform measures for each shock: instantaneous amplitude at the time of shock, and maximum amplitude and amplitude spectrum area (AMSA) over a 3-s window preceding the shock. Linear mixed-effects modeling was used to determine whether instantaneous amplitude was associated with shock-specific return of organized rhythm (ROR) or return of spontaneous circulation (ROSC) independent of maximum amplitude or AMSA. The 566 eligible patients received 1513 shocks, resulting in ROR of 62.0% (938/1513) and ROSC of 22.3% (337/1513). In unadjusted regression, an interquartile increase in instantaneous amplitude was associated with ROR (Odds ratio [OR][95% confidence interval]=1.27 [1.11-1.45]) and ROSC (OR=1.27 [1.14-1.42]). However, instantaneous amplitude was not associated with ROR (OR=1.13 [0.97-1.30]) after accounting for maximum amplitude, nor with ROR (OR=1.00 [0.87-1.15]) or ROSC (OR=1.05 [0.93-1.18]) after accounting for AMSA. By contrast, AMSA and maximum amplitude remained independently associated with ROR and ROSC. We did not observe an independent association between instantaneous amplitude and shock-specific outcomes. Efforts to time shock to the maximal amplitude of the VF waveform are unlikely to affect resuscitation outcome.

Abstract 238: A Machine Learning Algorithm To Predict Refractory Ventricular Fibrillation

Introduction: Guidelines for resuscitation of ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) advise drug therapy (epinephrine and antiarrhythmics) if a patient requires ≥3 shocks. Given that a higher number of shocks is associated with lower survival, the ability to predict which patients will require ≥3 shocks could enable preemptive, targeted intervention (antiarrhythmics or early hospital transport for invasive interventions) aimed at improving outcome. Aim: We sought to design an ECG-based algorithm to predict whether VF OHCA patients will require ≥3 shocks. Methods: We evaluated a cohort of adult VF OHCA from a metropolitan EMS system between 2008-2020. Patients were randomized 80%-20% for training-test. We trained an algorithm to predict whether a patient will require ≥3 shocks using 3-s ECG segments collected immediately before and within a minute after initial shock. The method uses a random forest classifier to predict shock count based on singular value decompositions of ECG wavelet transforms. Test performance was quantified by area under the receiver operating characteristic curve (AUC). Association between functional survival and shock count was evaluated with logistic regression. A sensitivity analysis assessed prediction of patients requiring ≥4 shocks. Results: Of 1376 VF OHCA patients, 311 (23%) were female; the median (IQR) shock count was 3 (1-6) and 591 (43%) achieved functional survival. Shock count was associated with lower functional survival with an odds ratio (95% CI) of 0.92 (0.89-0.95) for each additional shock. In 275 test patients, AUC (95% CI) was 0.80 (0.74-0.85) for predicting ≥3 shocks and 0.81 (0.75-0.85) for predicting ≥4 (Figure). Conclusions: A machine learning algorithm based on ECGs proximal to the initial shock predicts patients likely to experience refractory VF and high shock count, and could enable rescuers to preemptively administer interventions targeted to improve resuscitation outcome.

Myocardial scarring and recurrence of ventricular arrhythmia in patients surviving a ventricular fibrillation out of hospital cardiac arrest

Abstract Introduction Prediction of ventricular arrhythmia recurrence in survivors of ventricular fibrillation out of hospital cardiac arrest (VF-OHCA) is important, but currently difficult. Risk of recurrence may be related to presence of myocardial scarring and dedicated late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) software allows for characterization of left ventricular scarring, including differentiation between core, border zone (BZ) and BZ channels that represent potential electrical circuits of slow conductivity responsible for ventricular arrhythmic events. Purpose Our study aims to characterize myocardial scarring as defined by LGE-CMR in survivors of a VF-OCHA and investigate its potential role for the risk of new ventricular arrhythmia. Methods Between 2018 and 2021, a total of 130 VF-OHCA patients had CMR, of which we included 28 patients with LGE-CMR before ICD implantation for secondary prevention. A total of 15 (54%) patients had signs of acute or chronic ischemic heart disease (IHD); and 13 (46%) patients had arrhythmogenic cardiomyopathy (ACM). Scar tissue including core, BZ and BZ channels were automatically detected by specialized investigational software. To differentiate BZ from healthy tissue and BZ from core, thresholds of 40% ± 5% and 60% ± 5% of the maximum signal intensity were applied. A BZ channel in the LGE-CMR reconstruction was defined as a continuous corridor of BZ between 2 core areas or between a core area and a valve annulus (Figure 1A+B). Results The median age was 56 years; 86% were men and the median left ventricular ejection fraction was 50±11%. A total of 16 (57%) patients had an inferior scar on LGE-CMR, and 8 (29%) patients with IHD were incompletely revascularized. After a median follow-up of 98 days, 9 (32%) patients (6/9 with IHD, including 5/6 incompletely revascularized; 3/9 with ACM) had recurrence of ventricular arrhythmia (6/9 monomorphic ventricular tachycardia (VT)). A significantly higher number of patients with BZ channels had recurrence of ventricular arrhythmia compared with patients without BZ channels (7/11 vs. 2/17; P=0.01) (Figure 2). The number of BZ channels (3±1 vs. 2±1; P=0.13); scar mass (21±8g vs. 14±11g; P=0.21); core mass (7±4g vs. 4±5g; P=0.14); and BZ mass (11±5g vs. 9±7g; P=0.42) were insignificantly higher in patients with recurrent ventricular arrhythmia compared with patients without. Conclusion Borderzone channels analyzed by LGE-CMR were associated with subsequent recurrence of ventricular arrhythmia in patients with out of hospital cardiac arrest caused by ventricular fibrillation. Funding Acknowledgement Type of funding sources: None.

The impact of ventricular fibrillation amplitude on successful cardioversion, resuscitation duration, and survival after out-of-hospital cardiac arrest

Objective: We sought to examine the incidence of low amplitude ventricular fibrillation and its impact on successful cardioversion, duration of resuscitation, and survival to hospital discharge in patients with out-of-hospital cardiac arrest (OHCA). Design: Retrospective analysis from a statewide registry. Setting: Victoria, Australia. Participants: Consecutive initial ventricular fibrillation arrests with an emergency medical service (EMS)-attempted resuscitation between 1 February 2019 and 30 January 2020. Main outcome measures: Survival to hospital discharge, successful cardioversion, and duration of resuscitation. Results: Of the 471 initial ventricular fibrillation arrests, 429 (91.1%) had sufficient electrocardiogram data for review. The median initial and final ventricular fibrillation amplitude did not differ (0.3 mV; interquartile range [IQR], 0.2-0.5 mV). The final pre-shock amplitude was ≤ 0.1 mV (very fine) and ≤ 0.2 mV (fine) in 22.8% and 37.5% of cases respectively. In a multivariable analysis, only the time between emergency call and first defibrillation was associated with a low initial ventricular fibrillation amplitude ≤ 0.2 mV (adjusted odds ratio [aOR], 1.07; 95% CI, 1.02-1.13; P = 0.004). After adjustment for arrest factors, every 0.1 mV increase in final amplitude was independently associated with survival to hospital discharge (aOR, 1.26; 95% CI, 1.14-1.39; P < 0.001) and initial cardioversion success (aOR, 1.19; 95% CI, 1.07-1.32; P = 0.001). The duration of resuscitation also increased by 1.7 minutes (95% CI, 1.03-2.36; P < 0.001) for every 0.1 mV increase in final amplitude. Conclusion: More than one-third of initial ventricular fibrillation OHCA cases were low in amplitude. Comparative international data are needed to better understand how low amplitude ventricular fibrillation rhythms confound the measurement of OHCA interventions and international benchmarks for survival outcomes.

Long-term outcome of myocardial scarring and deformation with cardiovascular magnetic resonance in out of hospital cardiac arrest survivors

Cardiovascular magnetic resonance (CMR) is increasingly recognized as a diagnostic and prognostic tool in out of hospital cardiac arrest (OHCA) survivors. After assessing CMR findings early after ventricular fibrillation (VF) OHCA, we sought to explore the long-term outcome of myocardial scarring and deformation. We included 121 consecutive VF OHCA survivors (82% male, median 62 years) undergoing CMR within 2 weeks from cardiac arrest. Late gadolinium-enhancement (LGE) was quantified using the full width at half maximum method and tissue tracking analysis software was used to assess myocardial deformation. LGE was found in 71% of patients (median LGE mass 6.2% of the left ventricle, LV), mainly with an ischaemic pattern. Myocardial deformation was overall impaired and showed a significant correlation with LGE presence and extent (P < 0.001). A composite end-point of all-cause mortality and appropriate ICD discharge/anti-tachycardia pacing was met in 24% of patients. Patients meeting the end-point had significantly greater LGE extent (8.6% of LV myocardium vs. 4.1%, P = 0.02), while there was no difference with regards to myocardial deformation. Survival rate was significantly lower in patients with LGE (P = 0.05) and LGE mass >4.4% of the LV identified a group of patients at higher risk of adverse events (P = 0.005). We found a high prevalence of LGE, early after OHCA, and an overall impaired myocardial deformation. On long-term follow-up both LGE presence and extent showed a significant association with recurrent adverse events, while LV ejection fraction and myocardial deformation did not identify patients with an unfavourable outcome.

Merits of expanding the Utstein case definition for out of hospital cardiac arrest

BackgroundThe Utstein population is defined by non-traumatic, bystander-witnessed out-of-hospital cardiac arrest (OHCA) presenting with ventricular fibrillation (VF). It is used to compare resuscitation performance across emergency medical services (EMS) systems. We hypothesized a system-specific survival correlation between the current Utstein population and other VF populations defined by unwitnessed VF OHCA and VF OHCA after EMS arrival (EMS-witnessed). Expanding performance metrics to this more comprehensive population would make the Utstein definition more representative of the actual community burden and response to VF OHCA. MethodsWe performed a cohort investigation of all non-traumatic, VF OHCA in the Cardiac Arrest Registry to Enhance Survival from 1/1/2013-12/31/2018 among EMS agencies that treated > = 100 VF OHCA. We evaluated sample size and survival with the addition of the new VF populations. We used Pearson coefficient to assess whether there was a correlation of agency-specific survival outcomes between the current Utstein population and unwitnessed and EMS-witnessed VF OHCA. ResultsA total of 107 EMS agencies treated 38,836 VF arrests: 22,918 current Utstein, 11,297 unwitnessed VF, and 4621 EMS-witnessed VF OHCA. Overall, survival was 29.8% (11,567/38,836): 33.9% (7774/22,918) among current Utstein, 17.2% (1942/11,297) among unwitnessed VF, and 40.1% (1851/4621) among EMS-witnessed VF. For agency-specific survival outcome, the Pearson correlation was 0.52 between the current Utstein population versus combined unwitnessed and EMS-witnessed groups. For survival with Cerebral Performance Category 1–2, the Pearson correlation was 0.61. ConclusionExpanding the Utstein population to include unwitnessed and EMS-witnessed VF OHCA achieves a simpler, more inclusive case definition that minimizes variability in case determination and increases the number of survivors and eligible population by ∼50%, while still achieving a distinguishing metric of system-specific performance.

Abstract 273: Implications of Expanding the Utstein Case Definition for Out of Hospital Cardiac Arrest

Background: The Utstein population is defined by non-traumatic, bystander-witnessed out-of-hospital cardiac arrest (OHCA) presenting with ventricular fibrillation (VF). It is used to compare resuscitation performance across emergency medical services (EMS) systems. We hypothesized there being a system-specific survival correlation between the current Utstein and other VF populations inclusive of unwitnessed and EMS-witnessed VF OHCA that supports expanding performance metrics to this more comprehensive population that is more representative of the actual community burden of VF OHCA. Methods: We performed a cohort investigation of all non-traumatic, VF OHCA in the Cardiac Arrest Registry to Enhance Survival from 1/1/2013-12/31/2018 among EMS agencies that treated &gt;=100 VF OHCA. We evaluated sample size and survival with the addition of the new VF populations. We used the Pearson coefficient to assess the correlation of agency-specific survival between the current Utstein population and unwitnessed and EMS-witnessed VF OHCA. Results: A total of 107 EMS agencies treated 38,836 VF arrests: 22,918 current Utstein, 11,297 unwitnessed VF, and 4621 EMS-witnessed VF OHCA. Overall, survival was 29.8% (11,567/38,836): 33.9% (7,774/22,918) among current Utstein, 17.2% (1942/11,297) among unwitnessed VF, and 40.1% (1851/4621) among EMS-witnessed VF. For agency-specific survival outcome, the Pearson correlation was 0.52 between current the Utstein population versus combined unwitnessed and EMS-witnessed groups. For survival with Cerebral Performance Category 1-2, the Pearson correlation was 0.61. Conclusion: Expanding the Utstein population to include unwitnessed and EMS-witnessed VF OHCA achieves a simpler, more inclusive case definition that minimizes variability in case determination and increases the number of survivors and eligible population by ~50%, while still achieving a distinguishing metric of system-specific performance.

Abstract 253: Trajectory of Ventricular Fibrillation Prognostic Status During Cardiopulmonary Resuscitation

Background: Resuscitation from out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF) typically involves continuous CPR cycles interrupted every 2 minutes for rhythm analysis and potential defibrillation. Quantitative measures of the VF ECG waveform have been proposed to guide therapy for VF arrest because they are associated with myocardial energetics, are dynamic over the course of resuscitation, and predict outcome. However, while VF waveform measures have until recently have required CPR interruption to accurately gauge prognostic status, CPR interruptions are associated with a lower chance of survival. We used a novel waveform measure previously-validated during active CPR to estimate the course of VF status through the 2-minute CPR cycle between consecutive shocks. Methods: We conducted an observational study of patients with VF OHCA who experienced recurrent VF for at least 90 seconds following initial shock. We used the continuous defibrillator ECG to calculate the VF waveform measure as a function of predicted probability of survival-with-intact-neurologic-status at 1-s intervals over the course of resuscitation between shocks. Results: We collected 499 VF ECG segments (≥90 seconds) during CPR from 313 patients. The trajectory of the average prognostic VF measure had a 3-phase time-dependent pattern (Fig. 1). During CPR, the slope of the measure decreased during the initial 25 s of VF (slope = -12%/min) and was relatively flat during the subsequent 65-s interval of VF (slope = +1%/min). Furthermore, slope decreased sharply following the cessation of CPR for rhythm analysis, charge, and shock (slope = -23%/min). Conclusion: On average, a novel VF waveform measure assessed during the scheduled cycle of CPR and rhythm analysis between consecutive shocks was characterized by a period of decline, stabilization, and then decline. Whether these changes in VF status can be used to improve care for individual patients is uncertain.

Metrics of mechanical chest compression device use in out-of-hospital cardiac arrest.

ObjectiveThe quality of cardiopulmonary resuscitation (CPR) affects outcomes from cardiac arrest, yet manual CPR is difficult to administer. Although mechanical CPR (mCPR) devices offer high quality CPR, only limited data describe their deployment, their interaction with standard manual CPR (sCPR), and the consequent effects on chest compression continuity and patient outcomes. We sought to describe the interaction between sCPR and mCPR and the impact of the sCPR‐mCPR transition upon outcomes in adult out‐of‐hospital cardiac arrest (OHCA).MethodsWe analyzed all adult ventricular fibrillation OHCA treated by the Anchorage Fire Department (AFD) during calendar year 2016. AFD protocols include the immediate initiation of sCPR upon rescuer arrival and transition to mCPR, guided by patient status. We compared CPR timing, performance, and outcomes between those receiving sCPR only and those receiving sCPR transitioning to mCPR (sCPR + mCPR).ResultsAll 19 sCPR‐only patients achieved return of spontaneous circulation (ROSC) after a median of 3.3 (interquartile range 2.2–5.1) minutes. Among 30 patients remaining pulseless after sCPR (median 6.9 [5.3–11.0] minutes), transition to mCPR occurred with a median chest compression interruption of 7 (5–13) seconds. Twenty‐one of 30 sCPR + mCPR patients achieved ROSC after a median of 11.2 (5.7–23.8) additional minutes of mCPR. Survival differed between groups: sCPR only 14/19 (74%) versus sCPR + mCPR 13/30 (43%), P = 0.045.ConclusionIn this series, transition to mCPR occurred in patients unresponsive to initial sCPR with only brief interruptions in chest compressions. Assessment of mCPR must consider the interactions with sCPR.

The association of chronic health status and survival following ventricular fibrillation cardiac arrest: Investigation of a primary myocardial mechanism

IntroductionQuantitative waveform measures are a surrogate of the acute physiological status of the myocardium and predict survival following ventricular fibrillation out-of-hospital cardiac arrest (OHCA). We investigated whether the amplitude spectrum area (AMSA) waveform measure mediates the adverse relationship between increasing burden of chronic health conditions and lower likelihood of survival. MethodsWe performed a cohort investigation of persons > = 18 years who suffered ventricular fibrillation OHCA between 2008–2015 in a metropolitan emergency medical service (EMS) system. The count of chronic health conditions was determined using the Charlson Comorbidity Index (CCI). AMSA was calculated just prior to the initial shock. We used multivariable logistic regression to assess the relationship between CCI and survival-to-discharge in models first without and then with AMSA to determine the extent to which AMSA attenuated the CCI-survival association. ResultsOf the 716 eligible patients, 422/716 (59%) had at least one chronic health condition; 21.8% with one, 19.6% with two, 10.3% with 3, and 7.3% with ≥4. Survival-to-discharge was 45% (324/716). In the multivariable model adjusted for traditional Utstein characteristics, increasing CCI was associated with lower odds of survival (Odds ratio (OR) (95% confidence interval] = 0.82 [0.72, 0.93] for each additional chronic health condition). The addition of AMSA to the model only modestly attenuated the CCI-survival association (OR = 0.85 [0.74,0.98]). ConclusionThe waveform measure AMSA – a surrogate for the physiological status of the myocardium – mediated only a modest portion of the association between increasing burden of chronic health conditions and lower likelihood of survival following ventricular fibrillation OHCA.

The relationship between chronic health conditions and outcome following out-of-hospital ventricular fibrillation cardiac arrest

IntroductionThe cumulative burden of chronic health conditions could contribute to out-of-hospital cardiac arrest (OHCA) physiology and response to attempted resuscitation. Yet little is known about how chronic health conditions influence prognosis. We evaluated the relationship between cumulative comorbidity and outcome following ventricular fibrillation OHCA using 3 different scales. MethodsWe performed a cohort investigation of persons >=18years who suffered non-traumatic OHCA and presented with ventricular fibrillation between January 1, 2007 and December 31, 2013 in a metropolitan emergency medical service (EMS) system. Chronic conditions were ascertained from EMS reports. The primary relationship between cumulative comorbidity and outcome (survival to hospital discharge) used the Charlson Index and two other scales. Analyses used logistical regression (LR), multiple imputation and inverse probability weighting. ResultsDuring the study period 1166/1488 potential patients were included. The median Charlson Index was 1 (25th-75th%: 0–2). Overall survival was 43.9%. Comorbidity was associated with a dose-dependent decrease in the likelihood of survival. ompared to Charlson Score of 0, the odds ratio of survival was 0.68 (0.48–0.96) for Charslon of 1, 0.49 (0.35–0.69) for Charlson of 2, and 0.43 (0.30–0.61) for Charlson of >=3 after adjustment for Utstein predictors using multivariable LR. This inverse comorbidity-survival association was similar for the other 2 scales and was observed for different clinical outcomes (admission to hospital, functional survival, 30-day survival, and 1-year survival). ConclusionBased on these results, cumulative comorbidity can help explain survival variability and improve prognostic accuracy. Whether information about cumulative comorbidity or specific health conditions can inform resuscitation care is unknown though the results suggest comorbidity may influence acute pathophysiology and treatment response.

Availability and Accuracy of EMS Information about Chronic Health and Medications in Cardiac Arrest.

IntroductionField information available to emergency medical services (EMS) about a patient’s chronic health conditions or medication therapies could help direct patient care or be used to investigate outcome disparities. However, little is known about the field availability or accuracy of information of chronic health conditions or chronic medication treatments in emergent circumstances, especially when the patient cannot serve as an information resource. We evaluated the prehospital availability and accuracy of specific chronic health conditions and medication treatments among out-of-hospital cardiac arrest (OHCA) patients.MethodsThe investigation was a retrospective cohort study of adult persons suffering ventricular fibrillation OHCA treated by EMS in a large metropolitan county from January 1, 2007, to December 31, 2013. The study was designed to determine the availability and accuracy of EMS ascertainment of selected chronic health conditions and medication treatments. We evaluated chronic health conditions of “any heart disease,” congestive heart failure (CHF), and diabetes and medication treatments of beta blockers and loop diuretics using two distinct sources: 1) EMS report, and 2) hospital record specific to the OHCA event. Because hospital information was considered the gold standard, we restricted the primary analysis to those who were admitted to hospital.ResultsOf the 1,496 initially eligible patients, 387 could not be resuscitated and were pronounced dead in the field, one patient was left alive at scene due to Physician’s Orders for Life-sustaining Treatment (POLST) orders, 125 expired in the emergency department (n=125), and 983 were admitted to hospital. A total of 832 of 1,496 (55.6%) had both sources of data for comparison and comprised the primary analytic group. Using the hospital record as the gold standard, EMS ascertainment had a sensitivity of 0.79 (304/384) and a specificity of 0.88 (218/248) for any prior heart disease; sensitivity 0.45 (47/105) and specificity 0.87 (477/516) for CHF; sensitivity 0.71 (143/201) and specificity 0.98 (416/424) for diabetes; sensitivity 0.70 (118/169) and specificity 0.94 (273/290) for beta blockers; sensitivity 0.70 (62/89) and specificity 0.97 (358/370) for loop diuretics.ConclusionIn this cohort of OHCA, information about selected chronic health conditions and medication treatments based on EMS ascertainment was available for many patients, generally revealing moderate sensitivity and greater specificity.

A Randomised tRial of Expedited transfer to a cardiac arrest centre for non-ST elevation ventricular fibrillation out-of-hospital cardiac arrest: The ARREST pilot randomised trial

BackgroundWide variation exists in inter-hospital survival from out-of-hospital cardiac arrest (OHCA). Regionalisation of care into cardiac arrest centres (CAC) may improve this. We report a pilot randomised trial of expedited transfer to a CAC following OHCA without ST-elevation. The objective was to assess the feasibility of performing a large-scale randomised controlled trial. MethodsAdult witnessed ventricular fibrillation OHCA of presumed cardiac cause were randomised 1:1 to either: (1) treatment: comprising expedited transfer to a CAC for goal-directed therapy including access to immediate reperfusion, or (2) control: comprising current standard of care involving delivery to the geographically closest hospital. The feasibility of randomisation, protocol adherence and data collection of the primary (30-day all-cause mortality) and secondary (cerebral performance category (CPC)) and in-hospital major cardiovascular and cerebrovascular events (MACCE) clinical outcome measures were assessed. ResultsBetween November 2014 and April 2016, 118 cases were screened, of which 63 patients (53%) met eligibility criteria and 40 of the 63 patients (63%) were randomised. There were no protocol deviations in the treatment arm. Data collection of primary and secondary outcomes was achieved in 83%. There was no difference in baseline characteristics between the groups: 30-day mortality (Intervention 9/18, 50% vs. Control 6/15, 40%; P=0.73), CPC 1/2 (Intervention: 9/18, 50% vs. Control 7/14, 50%; P>0.99) or MACCE (Intervention: 9/18, 50% vs. Control 6/15, 40%; P=0.73). ConclusionsThese findings support the feasibility and acceptability of conducting a large-scale randomised controlled trial of expedited transfer to CAC following OHCA to address a remaining uncertainty in post-arrest care.

Changing target temperature from 33 °C to 36 °C in the ICU management of out-of-hospital cardiac arrest: A before and after study

IntroductionIn December 2013, our institution changed the target temperature management (TTM) for the first 24h in ventricular fibrillation out-of-hospital cardiac arrest (VF-OHCA) patients from 33°C to 36°C. This study aimed to examine the impact this change had on measured temperatures and patient outcomes. MethodsWe conducted a retrospective cohort study of consecutive VF-OHCA patients admitted to a tertiary referral hospital in Melbourne (Australia) between January 2013 and August 2015. Outcomes were adjusted for age and duration of cardiac arrest. ResultsOver the 30-month period, 76 VF-OHCA cases were admitted (24 before and 52 after the TTM change). Patient demographics, cardiac arrest features and hospital interventions were similar between the two periods. After the TTM change, less patients received active cooling (100% vs. 70%, p < 0.001), patients spent less time at target temperature (87% vs. 50%, p < 0.001), and fever rates increased (0% vs. 19%, p = 0.03). ​During the 36°C period, there was a decrease in the proportion of patients who were discharged: alive (71% vs. 58%, p=0.31), home (58% vs. 40%, p=0.08); and, with a favourable neurological outcome (cerebral performance category score 1-2: 71% vs. 56%, p=0.22). ConclusionAfter the change from a TTM target of 33°C to 36°C, we report low compliance with target temperature, higher rates of fever, and a trend towards clinical worsening in patient outcomes. Hospitals adopting a 36°C target temperature to need to be aware that this target may not be easy to achieve, and requires adequate sedation and muscle-relaxant to avoid fever.

Abstract 17799: Have We Abandoned Therapeutic Hypothermia Prematurely?

Introduction: Following the recent Targeted Temperature Management (TTM) Trial, many worldwide cardiac arrest centers have adjusted target temperatures from 330C to 360C. The aim of this study was to examine quality of post-arrest care in an expert cardiac center following the adoption of a TTM protocol. Methods: We conducted an audit of consecutive ventricular fibrillation out-of-hospital cardiac arrest (VF-OHCA) patients of presumed cardiac etiology, admitted to a quaternary referral cardiac hospital in Australia. Results: Over the two-year period there were 70 VF-OHCAs admitted (28 before TTM change and 42 after). Patient demographics, arrest features including witnessed arrest, bystander CPR and arrest duration were all similar, between the two periods. Post-arrest care including cardiology consults (93% vs 100%, p=0.15), coronary angiography (79% vs. 76%, p=0.82) and documented orders for TTM were all equivalent. Compliance, however, with temperature management was significantly worse in the 360C period; the average time at target temperature was significantly lower in this time (22hrs vs. 8hrs, p&lt;0.001). 50% of patients recorded temperatures &gt;37.1o in the first 24-hours in the 360C, compared to 0% of patients during the 330C period. Survival to hospital discharge (75% vs 69%, p = 0.59) and rates of discharge to home among (59% vs 45%, p = 0.32) were similar between 330C and 360C periods. After adjustment for arrest duration, an abnormal temperature (&gt;37.10C) in the first 24hours following hospital admission was associated with hypoxic brain injury (AOR=4.55, 95%CI: 1.08-19.09, p=0.039). Conclusion: Revision of the TTM protocol in an expert cardiac centre was associated with significant non-compliance with target temperatures, leading to increased febrile patients in the post arrest period and possible poorer outcomes.

Implantable cardioverter-defibrillator therapy in patients with ventricular fibrillation out of hospital cardiac arrest secondary to acute coronary syndrome.

BackgroundSurvivors of ventricular fibrillation out of hospital cardiac arrest (VF‐OHCA) due to a potentially reversible cause such as acute myocardial infarction (MI) or ischemia are considered to be at low risk of recurrent arrhythmia. Implantable cardioverter defibrillators (ICD) are not routinely recommended in such patients. However, the outcome of these patients in the era of rapid coronary revascularization and ICD therapy is not known.Methods and ResultsWe examined the outcome of 114 consecutive survivors of VF OHCA due to acute MI or ischemia in Olmsted County, MN from 1990 to 2011. An ICD was implanted in 45/114 patients. ICD recipients had lower EF [median (IQR) 38 (26 to 54) versus 48 (35 to 58) %, P=0.04]. During a median (IQR) follow‐up of 9.9 (4.4 to 14.6) years, ICD implantation was associated with reduced cardiac mortality (HR 0.24 [0.07 to 0.88], P=0.031) and a trend towards reduced all‐cause mortality (HR 0.56 [0.30 to 1.02], P=0.059) after adjusting for the first principal component. One or more appropriate ICD therapies were delivered in 19/45, with half of the patients receiving therapy within 1 year. Patients with EF ≤35% at discharge continued to be at long‐term risk for ICD therapy compared with those with EF >35% who were at increased risk predominantly in the first 8 months. EF and revascularization were not significantly associated with ICD therapy in the multivariable analysis.ConclusionsPatients with VF‐OHCA in the setting of acute MI or myocardial ischemia remain at high risk of recurrent ventricular arrhythmias, particularly if EF ≤35%. This suggests that ICD implantation may be reasonable if EF ≤35%.

Association of Amplitude Spectral Area of the Ventricular Fibrillation Waveform With Survival of Out-of-Hospital Ventricular Fibrillation Cardiac Arrest

BackgroundPrevious investigations of out-of-hospital cardiac arrest (OHCA) have shown that the waveform characteristic amplitude spectral area (AMSA) can predict successful defibrillation and return of spontaneous circulation (ROSC) but has not been studied previously for survival. ObjectivesTo determine whether AMSA computed from the ventricular fibrillation (VF) waveform is associated with pre-hospital ROSC, hospital admission, and hospital discharge. MethodsAdults with witnessed OHCA and an initial rhythm of VF from an Utstein style database were studied. AMSA was measured prior to each shock and averaged for each subject (AMSA-avg). Factors such as age, sex, number of shocks, time from dispatch to monitor/defibrillator application, first shock AMSA, and AMSA-avg that could predict pre-hospital ROSC, hospital admission, and hospital discharge were analyzed by logistic regression. ResultsEighty-nine subjects (mean age 62 ± 15 years) with a total of 286 shocks were analyzed. AMSA-avg was associated with pre-hospital ROSC (p = 0.003); a threshold of 20.9 mV-Hz had a 95% sensitivity and a 43.4% specificity. Additionally, AMSA-avg was associated with hospital admission (p < 0.001); a threshold of 21 mV-Hz had a 95% sensitivity and a 54% specificity and with hospital discharge (p < 0.001); a threshold of 25.6 mV-Hz had a 95% sensitivity and a 53% specificity. First-shock AMSA was also predictive of pre-hospital ROSC, hospital admission, and discharge. Time from dispatch to monitor/defibrillator application was associated with hospital admission (p = 0.034) but not pre-hospital ROSC or hospital discharge. ConclusionsAMSA is highly associated with pre-hospital ROSC, survival to hospital admission, and hospital discharge in witnessed VF OHCA. Future studies are needed to determine whether AMSA computed during resuscitation can identify patients for whom continuing current resuscitation efforts would likely be futile.

The patient journey through a hospital with high survival rates for ventricular fibrillation out-of-hospital cardiac arrest

Background: Little is known about the transition through hospital for patients presenting with ventricular fibrillation out-of-hospital cardiac arrest (VF-OHCA) beyond intensive care units (ICU). We aimed to describe the complete patient journey through a hospital with high survival rates for VF-OHCA.

Most Important Outcomes Research Papers on Cardiac Arrest and Cardiopulmonary Resuscitation

Cardiac arrest is a common and treatable cause of death and disability. Each year ≈424 000 people experience emergency medical services (EMS)-assessed out-of-hospital cardiac arrest (OHCA) in the United States.1 The actual burden of OHCA is likely significantly higher because a substantial number go unassessed. In a prospective analysis of deaths in a US county, 5.6% of annual mortality was attributable to cardiac arrest.2 Many patients who suffer OHCA do not receive prompt cardiopulmonary resuscitation (CPR). Among those who receive CPR, a large number do not survive because of an inability to restore spontaneous circulation, or anoxic cerebral injury even after restoration of circulation. Nevertheless, when timely interventions are provided, a small proportion of patients (10.4% of all EMS-treated OHCA) recover to resume normal lives. The key therapeutic interventions that make the difference between life and death, metaphorically characterized as the 5 links in a chain of survival by the American Heart Association, include: (1) immediate recognition of cardiac arrest and activation of the EMS, (2) early CPR with emphasis on chest compression, (3) rapid defibrillation, (4) effective advanced life support, and (5) integrated postcardiac arrest care.3 Resuscitation science has undergone major advances since the origins of modern CPR >50 years ago.4 The field continues to be dynamic with emergence of new therapies such as therapeutic hypothermia5 and improvements in systems of care. However, many questions remain on issues such as optimum compression rate, efficacy of chest compression only CPR (CCCPR), dispatcher-assisted CPR, and benefits of postresuscitation measures such as hypothermia. A critical challenge also lies in the translation of resuscitation science into practice. To improve outcomes, each of the links in the chain of survival needs to be executed promptly and effectively. There remain several lacunae, which need to be overcome to develop an …

Most Important Outcomes Research Papers on Device Therapies for Cardiomyopathies

Disorders of the cardiac muscle or cardiomyopathies are a broad, yet collectively common, group of conditions. Despite the heterogeneous etiologies, mode of death from these conditions is remarkably similar - progressive decline in cardiac function leading to intractable heart failure (HF) and sustained ventricular arrhythmias resulting in sudden cardiac death (SCD). Nearly 50% of patients die within 5 years of a HF diagnosis.1 Indeed, in the United States, HF alone is thought to cause 55,000 deaths per year2 and further contribute to 1 in 9 deaths overall.1 However, while advanced HF and the risk of SCD were once thought to be untreatable, technological advances has seen the emergence of device therapies as viable treatment options. Specifically, implantable cardioverter-defibrillator (ICD) therapy for treatment of ventricular arrhythmias, cardiac resynchronization therapy (CRT) for restoring cardiac synchrony and mechanical efficiency, and ventricular assist device (VAD) therapy to temporarily or permanently replace the function of the failing heart, have all emerged as highly efficacious therapies. The expanding use of device therapies, however, poses many challenges. First, while the indications for these devices are well summarized in clinical guidelines,3,4 considerable hurdles remain in ensuring eligible patients receive these therapies.5 By the same token, establishing the safety and effectiveness of these therapies in populations that are found in clinical practice, yet commonly excluded from trials, such as the elderly6 and uncommon forms of cardiomyopathies,7 is a high priority. Second, rapid dissemination of technologies frequently results in disparities in care. Indeed, age, gender, and racial disparities, in both receipt of these devices and outcomes following implantation, have been well documented. Whether these disparities have persisted, and the potential causative mechanisms underlying these disparities, however, are uncertain.8,9 Third, these devices are not without significant untoward effects; understanding …