Defibrillator Research Articles

PRECORDIAL THUMP AS A LIFE-SAVING RESUSCITATION MEASURE IN OBESE PATIENTS DURING OUT-OF-HOSPITAL CARDIAC ARREST

Introduction: The precordial thump (PT) was until recently recognized as a life-saving measure for confirmed and monitored shockable rhythm cardiac arrest (CA) cases when a defibrillator is not immediately vailable, but cardiopulmonary resuscitation guidelines no longer mention it. Objectives: We present the PT as a life-saving measure during CA in obese patient. Case report: The emergency medical team intervened on a 69-year-old man, with, complaining of chest pain lasting >1h. He was dyspneic, pale and clammy skin. RR 18/min, SatO2 89%, HR 76 bpm, BP of 80/50 mmHg. ECG: anterior ST elevation myocardial infarction with right bundle branch block. He was allergic to aspirin. He was treated with 180mg of oral ticagrelor, a 500ml saline solution IV and 4 l/min O2 by mask and then went into CA. Before the defibrillator became available, patient was treated with three PTs, an oropharyngeal airway placement, bag valve mask ventilation with 100% oxygen and the initiation of chest compressions. When the biphasic defibrillator arrived, the monitor showed coarse ventricular fibrillation. One DC shock with 200J of energy was delivered. After the shock, the patient regained consciousness, a pulse and spontaneous breathing. The ECG monitor showed a sinus rhythm of 143 bpm, BP 80/50 mmHg, and SatO2 89%. Conclusion: Although CPR guidelines no longer mention the PT, the question remains whether it could be an initial life-saving procedure during CA in obese patients.

Non-Pharmacological Therapy in Heart Failure and Management of Heart Failure in Special Populations-A Review.

Non-pharmacological therapies play an essential role in the management of heart failure, complementing pharmacological treatments to mitigate disease progression and improve patient outcomes. This review provides an updated perspective on non-pharmacological interventions with a focus on lifestyle modifications, device therapies, and the management of heart failure in special populations, such as the elderly, women, and patients with comorbid conditions like renal dysfunction and diabetes. Key lifestyle interventions, including sodium and fluid restriction, dietary changes, and physical activity, are explored for their impact on symptom reduction, hospital readmissions, and quality of life. Device therapies like cardiac resynchronization therapy (CRT) and implantable cardioverter defibrillators (ICD) are also evaluated for their effectiveness in reducing mortality in patients with advanced HF. Special attention is given to vulnerable populations, emphasizing the need for individualized approaches tailored to specific pathophysiological mechanisms and socioeconomic factors. By integrating these strategies, healthcare providers can optimize care and enhance patient adherence, reducing the overall burden of heart failure.

Impact of implantable cardioverter defibrillators on mortality in heart failure receiving quadruple guideline-directed medical therapy: a propensity score-matched study

BackgroundIn the contemporary management of heart failure with reduced ejection fraction (HFrEF), the recommended quadruple guideline-directed medical therapy (GDMT) consists of angiotensin receptor-neprilysin inhibitor (ARNI), evidence-based beta-blockers (BB), mineralocorticoid receptor antagonists (MRA), and sodium-glucose cotransporter-2 inhibitors (SGLT-2i). This study explored the impact of adding implantable cardioverter-defibrillator (ICD) therapy to this comprehensive regimen in HFrEF patients.MethodsUtilizing deidentified data from the National Electronic Database of the Turkish Ministry of Health, we conducted a nationwide retrospective cohort study on 5450 HFrEF patients receiving quadruple GDMT, including ARNI. Among them, 709 patients underwent additional ICD or cardiac resynchronization therapy defibrillator (CRT-D) implantation. Propensity score matching ensured balanced baseline characteristics between groups. Primary endpoint was determined as all-cause mortality.ResultsIn the matched cohort, all-cause mortality occurred in 108 out of 619 patients (17.4%) in the GDMT group and 101 out of 619 patients (16.3%) in the ICD group, with a hazard ratio (HR) of 0.74 and a 95% confidence interval (CI) ranging from 0.57 to 0.98. The median follow-up time was 1365 days in the matched cohort, 1283 days in the GDMT group. Subgroup analyses consistently demonstrated benefits, particularly among individuals aged 61 years and older (HR: 0.60, 95% CI: 0.42–0.87, p = 0.006), those with sinus rhythm (HR: 0.55, 95% CI: 0.34–0.89, p = 0.013), individuals not using amiodarone (HR: 0.61, 95% CI: 0.42–0.89, p = 0.011), and those with an estimated glomerular filtration rate lower than 61.9 (HR: 0.66, 95% CI: 0.48–0.91, p = 0.011).ConclusionsThis study may offer a glimmer of hope that even after achieving the best current optimal medical therapy, the addition of device therapy could still yield positive outcomes in the management of patients with HFrEF.Graphical

Abstract Su302: Impact of Time to Defibrillation on Mortality after In-Hospital Cardiac Arrest

Background: In-hospital cardiac arrest occurs in 290,000 patients annually in the United States, with less than 20% of these arrests featuring a shockable presenting rhythm. The three-phase model of CPR is separated into the electrical phase which occurs in the first 4 minutes, the circulatory phase which includes minutes 4-10, and the metabolic phase which is greater than 10 minutes from arrest onset. Defibrillation during the electrical phase has been proven to improve survival by approximately 50%. Current guidelines recommend defibrillation within the first 2 minutes of arrest in those with a rhythm of VT/VF. The purpose of this study was to determine the effect of time to defibrillation on mortality in patients with shockable rhythms. Methods: Full-disclosure rhythm strips for all cardiac arrests in non-ICU patients on telemetry were reviewed from Feb 2019 to April 2023. Time to defibrillation of shockable rhythms (VT/VF) was determined from the telemetry data and corresponding defibrillator data from the Zoll CodeNet electronic system. Results: We identified 32 of the 186 patients with cardiac arrest while on telemetry presenting with pulseless monomorphic VTor polymorphic VT/VF. The average time to defibrillation was 4.8 min ± 2.7 min. 34% of patients were defibrillated in 4 minutes or less from the onset of the arrythmia, 31% were defibrillated in more than 4 minutes from the onset of the arrythmia, and 34% were not defibrillated. Patients defibrillated in 4 minutes or less had a significantly lower mortality of 36.4% compared to a 50% mortality of those defibrillated in more than 4 minutes and 90.9% mortality in those not defibrillated (p<0.05).The patients who were not defibrillated were determined to have ongoing VT or poly VT/VF until telemetry was removed and the Zoll defibrillator pads were applied. They were ultimately deermined ot have PEA and were not shocked. Conclusions: Patients defibrillated in 4 minutes or less from the onset of a sustained shockable arrythmia experienced significantly lower mortality during hospitalization compared to those who were defibrillated in more than 4 minutes or were not defibrillated. 34% of patients with a shockable rhythm were not defibrillated due to a diagnosis of PEA after the Zoll pads were placed. Patients with sustained VT/VF causing in-hospital cardiac arrest should be defibrillated as soon as a defibrillator can be applied. Telemetry data should be clearly communicated to the code team.

Abstract Su507: Occurrence of Fibrillation in Out-of-hospital Cardiac Arrest Patients Presenting in a Non-shockable Rhythm when Treated with an Automated External Defibrillator

Background: Most out-of-hospital cardiac arrest (OHCA) patients who are initially treated with an automated external defibrillator (AED) and present in a non-shockable rhythm never receive a shock. This analysis reports on patients who presented in a non-shockable rhythm when the AED was initially applied and later transitioned into a shockable rhythm. Methods: Data from a convenience group of OHCA patients treated with a Philips HeartStart Home, Onsite or FRx AED were included. The AEDs were the first defibrillator on scene either in home, in public access or by a BLS team. Application of any medication during AED use was unlikely. Each patient’s heart rhythms were reviewed by an expert. All patients whose initial rhythm was non-shockable but later received at least one shock were identified and the rhythms were analyzed. Results: Out of 876 patients, 322 (36.8%) received at least one shock, of which five patients (1.6%) presented in a non-shockable rhythm and were later shocked. Three patients presented in an organized rhythm. The first patient degraded into Torsade de Pointe as shown in Figure 1; the post-shock rhythm was organized. The second patient received no CPR and A-V pacing was observed in the ECG recording. The pacing stopped when the rhythm transitioned into VF and restarted post shock. The third patient transitioned into VF during chest compressions and the post-shock rhythm was asystole. The remaining two patients presented in asystole and the rhythm evolved to fine VF after receiving chest compressions. After defibrillation, their rhythms returned to asystole. Conclusions: For OHCA patients treated with an AED, presenting in a non-shockable rhythm and later transitioning into a shockable rhythm is rare but possible. Lay-responder CPR may play a role in rhythm evolvement. The impact of rhythm changes on survivability of these patients is unknown.

Abstract Su304: The Effect of Time to DC Shock on Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest with Recurrent Shockable Rhythm

Objective: The optimal timing for defibrillation attempts in out-of-hospital cardiac arrest (OHCA) patients with recurrent shockable rhythms [ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT)] is uncertain. This study examined the association between "time to DC shock" and the return of spontaneous circulation (ROSC) in OHCA patients with recurrent shockable rhythms. Methods: This was a retrospective analysis of data from the Salt Lake City Fire Department (SLCFD) from 2012 to 2023. Rhythm-filtering technology, used since 2012, enabled real-time and accurate interpretation of cardiac rhythms during CPR, with local protocols allowing early defibrillation for recurrent VF/ pulseless VT cases. Patients who experienced four or five episodes of shockable rhythms and received defibrillation were included. Generalized estimating equation (GEE) analysis was used to evaluate the association between time to shock preceding recurrent defibrillation and ROSC. Results: A total of 142 patients were included, with a mean age of 59.7 ± 15 years; 105 (73.9%) were male, 63 (44.4%) arrested in public locations, and 101 (71.1%) had witnessed arrests. Adjusted GEE analysis revealed that longer time to shock was associated with lower odds of achieving ROSC (OR: 0.81, 95% CI: 0.72–0.93, p = 0.005). Every one-minute delay in defibrillation is predicted to decrease the likelihood of achieving ROSC by 19%. Conclusion: In patients with recurrent shockable rhythms, every one-minute delay in delivering a shock was associated with a statistically significant 19% reduction in the chance of achieving ROSC. This finding highlights the importance of reducing the time to defibrillation in managing recurrent shockable rhythms and suggests reevaluating the current recommendation of two-minute intervals for rhythm check and shock delivery.

Abstract Su502: Is 80% a Reasonable Minimal Goal for Defibrillation Efficacy of Out-of-Hospital Cardiac Arrest ?

Introduction: There is no clear goal defined by standards or learned societies on clinical performance related to defibrillation efficacy. In literature, monophasic shocks defibrillation efficacy is mainly >70% whereas biphasic is >80%. Resuscitation guidelines define efficient defibrillation as cessation of shockable rhythm at 5s post-shock and proceed to state that beyond 5s, shock outcomes are biased by known confounders (call to AED connection time (CallAEDTime), bystander, cardio-pulmonary resuscitation (CPR), drugs…). Thus, it is consistent that automated external defibrillator (AED) performance should be assessed in terms of defibrillation efficacy right after the shock rather than in terms of restoration of a spontaneous circulation or survival to hospital discharge. This study aimed to define an acceptable goal for validation of defibrillation efficacy. Method: In this observational retrospective study, we included AED tracings of adult non-traumatic out-of-hospital cardiac arrest (OHCA) patients with initial ventricular fibrillation (VF) rescued by basic life support teams (Paris Fire Brigade) from 01/2017 to 02/2022. Cardiac rhythm was examined during the 10 first minutes of connection of the AED (DGT7, Schiller Médical, France). Shockable rhythm is defined as coarse-VF with at least 200µV peak-to-peak amplitude (ptpA). Efficient defibrillation was defined as cessation of shockable rhythm at 5s post-shock. We fitted a linear mixed model to predict defibrillation efficacy using the 4s ptpA of pre-shock VF. The model included the patient as random effect and a p-value <0.05 was considered statistically significant. Results: We analyzed 1333 shocks from 547 patients, with: median age of 59 (interquartile range, IQR[49-71]), 78% male, 36% in public places, 72% with bystander CPR and median[IQR] CallAEDTime of 13min [10-15]min. The effect of the pre-shock ptpA of VF on the defibrillation efficacy is statistically significant: OR=1.023, 95% Confidence Interval (CI) [1.010,1.036], p<0.001. That means that for each 100µv increment in VF amplitude pre-shock, the probability of success at 5s post-shock increases by 2.3%. Adjusting for age, sex, location, CPR and CallAEDTime does not change the results. The logistic regression of Figure1, shows a defibrillation efficacy at 200µV ptpA of 79%, CI [75,82]%. Conclusion: Based on 1333 OHCA biphasic shocks, this study suggests defining 80% as a reasonable minimal goal for validation of the AED defibrillation efficacy.

Abstract Su804: Use of Machine Learning Models to Predict Neurologically Intact Survival for Advanced Age Adults Following Out-of-hospital Cardiac Arrest

Background: We recently published a multivariable logistic regression model that successfully predicted neurologic outcomes in advanced age adults (≥ 65 years old) who achieve return of spontaneous circulation following out-of-hospital cardiac arrest (OHCA). Prior to externally validating this model, we sought to compare the predictive performance of our logistic regression model against common machine learning (ML) algorithms using the same dataset. Methods: We performed a retrospective observational analysis of the Cardiac Arrest Registry to Enhance Survival database from 2013-2021. All non-traumatic OHCA occurring in adults (≥65 years) who survived to hospital admission were included. The primary outcome measure was neurologically intact survival defined as a cerebral performance category (CPC) score of 1 or 2 at hospital discharge. Our original logistic regression model was compared to Boosted Trees and Decision Tree ML algorithms and assessed using accuracy, Area Under the Receiver Operating Characteristic Curve (AUC-ROC) and Area Under the Precision-Recall Curve (AUC-PR). The model variables included age, gender, race/ethnicity, location, witnessed status, who initiated cardiopulmonary resuscitation, whether an automated external defibrillator was applied prior to emergency medical services arrival, and first monitored rhythm. Results: A total of 83,561 OHCA were included. Median age was 75 years (IQR 69-82), 58.9% were male, 53% were White, 67% experienced an OHCA at home, 52% were witnessed by a bystander, 44% received bystander CPR, and 34% were found in shockable rhythm. Neurologically intact survival (CPC 1 or 2) occurred in 23% of patients. The logistic regression model had an accuracy of 79.6%, AUC-PR 0.542, and AUC-ROC of 0.774. The Boosted Trees model had an accuracy of 79.2%, AUC-PR 0.555, and AUC-ROC of 0.774. The Decision Tree Model had an accuracy of 79.3%, AUC-PR 0.490, and AUC-ROC of 0.717. Conclusion: Boosted Trees and Decision Tree ML models performed comparably to the logistic regression model in predicting favorable versus unfavorable neurological outcomes following successful resuscitation from OHCA in advanced-age adults. Given their similar performance, logistic regression may be preferred for its simplicity and interpretability over alternative ML models. Future efforts to improve and ultimately externally validate the model are warranted.

Abstract Su908: Unfavorable prognostic features and temporal trends in Out-of-Hospital Cardiac Arrests (OHCA) presenting to an Academic Center at the Border in El Paso

Introduction: Early recognition of cardiac arrest with bystander cardiopulmonary resuscitation (CPR), and early defibrillation when appropriate, can improve outcomes after Out of Hospital Cardiac Arrest (OHCA). Data from the national registries indicate there are both regional as well racial and ethnic differences in rates of bystander CPR in witnessed OHCA cases with significantly lower rates of bystander CPR in non-white persons. However, Hispanic as well border populations are underrepresented in these studies. University Medical Center (UMC) El Paso, Texas is an academic medical center located 1 mile from the US- Mexico border which is also the only not for profit safety net hospital with a Level1 trauma center. Research Question: Outcomes after OHCA are strongly affected by peri-arrest circumstances including bystander CPR and certain features portend poor outcomes. We performed a descriptive observational study of OHCA cases presenting to UMC to analyze temporal trends in these factors in our community as local data from El Paso is currently not reported in any registries. Methods: We collaborated with the El Paso Fire Department (EPFD) to obtain resuscitation data on patients who suffered OHCA and were brought to the University Medical Center (UMC)Emergency Department (ED) and created a registry of patients who suffered OHCA in El Paso FROM 2017 to Nov 2021. Results: Initial analysis identified around 698 predominantly Hispanic patients who suffered OHCA. Of these 115 were due to non-cardiac causes such as trauma, and 583 were possible cardiac etiology. OHCA cases peaked in 2020 coinciding with COVID 19 surge. Less than one third (31.5%) had bystander CPR with only 11.9% having a shockable rhythm. 64% did not achieve Return of spontaneous circulation in the field. 39% expired in the ED or in the field. We also performed a temporal analysis of these features and bystander CPR rates peaked in 2019 (38.1%to 24.8% in 2021). Conclusion: In our Hispanic underserved population in El Paso, we identified poor outcomes after OHCA, with non-shockable rhythm being the most common adverse feature and decreased rates of bystander CPR (31.5%) with further decrease after 2019. Local community level data which is critical for appropriate local resource allocation to improve OHCA outcomes is missing from underserved populations and additional resources are required improve outcomes.

Abstract Su503: Relationships Between Quantitative ECG Measures and Defibrillation Success in Early Ventricular Fibrillation

Introduction: Rapid termination of ventricular fibrillation (VF) has long been recognized as the cornerstone of effective cardiac arrest resuscitation. In recent years, amplitude spectral area (AMSA) has been shown to be highly associated with defibrillation success, and AMSA has been experimentally used to personalize defibrillation timing and strategy. However, questions remain about whether the interpretation of AMSA holds uniformly in varied conditions, such as ultra-early or prolonged cardiac arrest or after anti-arrhythmic administration. Hypothesis: AMSA is greater after 20 seconds of untreated VF compared to 50 seconds of untreated VF; a higher AMSA predicts greater first-defibrillation success. Methods: VF was induced in adult swine (n = 3) with a bipolar pacing catheter placed in the right ventricle. Animals were randomized to 20- or 50-second-long episodes of VF (n = 123), followed by standard 150 J biphasic defibrillation. In MATLAB, AMSA was calculated as the summed product of frequency and square root of power after Fast Fourier Transform for the four second period of VF immediately prior to defibrillation. Results were analyzed by a two-sided Chi-squared test or ANOVA with Tukey’s HSD in R; a p-value < 0.05 was considered significant. Results: First shock success was lower in the 20-second-VF group compared to the 50 second group (31/78 (39.7%) vs 31/45 (68.8%), p = 0.003). The AMSA at 20 seconds was significantly higher for successful compared to unsuccessful first defibrillation (8.20 vs. 7.31 mV-Hz, p = 0.034). The AMSA at 50 seconds was not statistically different between successful and unsuccessful defibrillations (6.32 vs. 5.67 mV-Hz, p = 0.470). Evaluating the AMSA after a duration of VF irrespective of shock success, AMSA was higher at 20 seconds compared to 50 seconds (7.66 vs 6.12 mV-Hz, p < 0.001). Conclusion(s): AMSA decreases from 20 to 50 seconds of untreated VF, and higher AMSA at a given time point is associated with greater first defibrillation success. However, first defibrillation success was higher after 50 seconds of untreated VF compared to 20 seconds, raising questions about special cases, such as edge effects, that may influence AMSA interpretation.

Abstract Su906: Patient and Arrest Characteristics Associated with Rearrest and Mortality Following Out of Hospital Cardiac Arrest

Background: Cardiac rearrest post-return of spontaneous circulation (ROSC) is a critical concern in emergency care, as it is associated with worse outcomes. Patient characteristics and arrest factors associated with rearrest remain poorly understood, making predicting rearrest after out of hospital cardiac arrest (OHCA) challenging. Aim: To examine rearrest patterns, identify patient-specific risk factors for rearrest, and assess the impact of rearrest on patient outcomes. Hypothesis: Patients that experience rearrest after OHCA will have greater cardiac comorbidities, unfavorable arrest characteristics, and greater mortality. Methods: We performed an observational single-site clinical trial of consecutive adult EMS OHCA patients with ROSC (1/01/2018 to 3/31/24). EMS reports, continuous EMS ECG recordings, and electronic health records were analyzed to determine rearrest occurrence at any time during EMS and ED care. Patient demographics, comorbidities, and arrest/rearrest characteristics were determined. The primary outcome was survival at 6 months. Statistical significance was determined using Chi-square and logistic regression (LR) analyses. Results: We examined 344 patients with OHCA and ROSC, of whom 173 patients rearrested and 171 did not. Patients experiencing rearrest were older (p<0.003) and more likely to be female (p<0.013). They were also more likely to have ED resuscitation medications and interventions (epinephrine, amiodarone, lidocaine, defibrillation, all p<0.001) and a higher incidence of underlying cardiovascular comorbidities, including HTN and CAD (p<0.03). Notably, PEA and asystole were the most common rearrest rhythms, and time from arrest to ROSC was greater (30±16 vs. 25±15 min, p<0.007) in rearrest patients vs. those who did not rearrest. Patients with rearrest were less likely to receive TTM (p<0.003) and importantly, had higher rates of in-hospital and six-month mortality (both p<0.001). In a LR model, no rearrest (OR 2.4, 1.1-5.2), shockable arrest rhythm (OR 9.3, 4-22), female sex (OR 3.3, 1.6-6.5), and therapeutic hypothermia (OR 3.3, 1.7-6.4), were associated with survival (all p<0.04). Conclusions: Rearrest is independently associated with mortality. Increased age, male sex, and underlying cardiac comorbidities were associated with rearrest. Patient and arrest characteristics may predict rearrest. Improved understanding of why these factors promote rearrest will be important to prevent rearrest to enhance OHCA outcomes.

Abstract Su704: Body Mass Index and Outcomes of In-Hospital Cardiac Arrest

Background: Although previous studies have reported an association between a patient’s body mass index (BMI) and outcomes for various cardiovascular conditions, the relationship between BMI and survival for in-hospital cardiac arrest (IHCA), a condition for which emergent response is required, has not been fully described. Aims: Examine the association between BMI and survival outcomes for IHCA. Methods: Within the Get With The Guidelines®-Resuscitation, we identified 56,411 patients with IHCA and available BMI data during 2005-2012 when weight and height data were collected in the registry. BMI was classified as underweight [<18.5 kg/m 2 ], normal [18.5 to 24.9 kg/m 2 ], overweight [25.0 to 29.9 kg/m 2 ], obese [30.0 to 34.9 kg/m 2 ], and very obese [≥35.0 kg/m 2 ]). Using multivariable hierarchical models with hospital as a random effect, we examined the association between BMI and survival to discharge, stratified by cardiac arrest rhythm type (shockable and non-shockable). As secondary outcomes, we examined rates of sustained return of spontaneous circulation for > 20 minutes (ROSC) and favorable neurological survival (i.e., survival to discharge without severe neurological disability). Results: Among 10,219 patients with a shockable arrest rhythm, 3,964 (38.7%) survived to discharge. After multivariable adjustment, compared with overweight patients, those who were underweight, of normal weight, and very obese had lower survival rates, whereas obese patients had similar survival rates ( Table ). Underweight patients also had a lower rate of ROSC and favorable neurologic survival ( Table ). Among 46,192 patients with a non-shockable arrest rhythm, 7,331 (15.8%) survived to discharge. After multivariable adjustment, all BMI groups had similar rates of survival, ROSC, and favorable neurologic survival, except for underweight patients ( Table ). Conclusions: Although the association between BMI and survival outcomes for IHCA varied by initial rhythm, underweight patients consistently had lower survival rates of survival. Very obese patients generally had similar outcomes to other weight groups, underscoring that morbid obesity was not a negative predictor of survival outcomes for IHCA.

Abstract Su1205: The Effect of Targeted Temperature Management on Five-Year Mortality in Comatose Out-of-Hospital Cardiac Arrest Survivors: A Real-World Experience

Background: Hypothermia-Induced Targeted Temperature Management (TTM) is a neuroprotective treatment after the return of spontaneous circulation (ROSC) in comatose survivors of out-of-hospital cardiac arrest (OHCA). However, its effectiveness in all patient subpopulations is debated. While short-term survival has been well studied, the impact of TTM on long-term survival is still unknown. Methods: In a prospective cohort study, 98 comatose survivors of non-traumatic OHCA were recruited from four tertiary-level hospitals in Buffalo, Western New York and followed up for five years. Patients with active cancer, infection, cardiac pathology or surgery in three-month prior to presentation, were excluded. Cardiac arrest characteristics, demographics, comorbidities, and therapeutic interventions were recorded. According to TTM protocols, a target body temperature of 33°C was reached and maintained for 24 hours using either an intravascular cooling catheter or a surface cooling system. This was followed by gradual controlled rewarming over 12-24 hours to normothermia. Factors associated with the receipt of TTM were determined. The effect of TTM on five-year survival was studied using cox-regression analysis. Results: Among comatose patients with mean age of 60.1±14.9 years, 49% received TTM. Females were significantly less likely to receive TTM (35.1% vs 59.3%, p=0.021). In TTM group, the time to ROSC was significantly longer: median [IQR] 14.5 mins (5-19.7) vs 20 mins (12-27), p=0.018. TTM group was more likely to have a history of coronary artery disease (CAD) (12.5% vs 35.4%, p=0.009). Overall, 5-year mortality did not differ significantly between TTM vs. non-TTM: 72.9% vs 66.0%, (HR: 1.134, 95% CI: 0.705-1.826, p=0.603) in univariate and multivariate Cox-regression analysis (Table 1). Conclusion: While females are less likely to receive TTM treatment, TTM is more likely to be used in patients with a longer time to ROSC and a history of CAD. The overall five-year survival remains high in both treatment groups in all eligible patients, as well as in shockable and non-shockable rhythm groups studied separately. Larger cohort studies are needed to determine the patients who may benefit most from TTM.

Abstract 4135273: Frailty increases the risk of in-hospital mortality and post-procedural complications in patients undergoing Cardiac Implantable Electronic Devices placement

Background: Heart failure with reduced ejection fraction (HFrEF) often necessitates the use of cardiac implantable electronic devices (CIED) such as cardiac resynchronization therapy defibrillators (CRT-D) or implantable cardioverter-defibrillators (ICD). These devices are proven to reduce mortality, prevent hospitalizations, and improve symptoms and quality of life. Frailty, characterized by an age-associated decline in physiological reserve, significantly impacts outcomes in these patients. This study uses the Hospital Frailty Risk Score (HFRS) to assess the effect of frailty on mortality and post-procedural complications in HFrEF patients undergoing CIED implantation. Hypothesis: Frail patients with HFrEF have worse in-hospital outcomes after CIED placement Methods: We conducted a retrospective cohort study using the 2020 National Inpatient Sample database from the Healthcare Utilization Project. Our population included patients aged 18 years or older with HFrEF who underwent CRT-D or ICD placement, identified using ICD-10 procedure codes. The primary risk factor was frailty, classified by an HFRS score of ≥5 (frail) or <5 (not frail). The primary outcome was in-hospital mortality, and the secondary outcome was the composite of post-procedural complications. Multivariate regression analysis was used to estimate the odds ratio. Results: Out of 24,809 patients who underwent ICD or CRT-D placement, 48.8% were frail. Non-Frail patients had lower mean age compared to Frail patients (66.2 vs 67.3 years old, p=0.003). In-hospital mortality was 1.1%, and 7% experienced post-procedural complications. In-hospital mortality was higher in frail patients compared to non-frail patients (2% vs 0.3%, p<0.001). In the multivariate analysis, frail patients had higher odds of in-hospital mortality compared to the non-frail group subset (OR=5.97; 95% CI: 2.77-12.88, p<0.001). Additionally, frailty was associated with higher odds of post-procedural complications (OR=1.28; 95% CI: 1.01-1.63, p<0.001), increased length of stay (5 vs 11.6 days, p<0.001), and total hospital charges (215,668 vs 324,474 , p<0.001). Conclusion: Frailty significantly increases the risk of in-hospital mortality and post-procedural complications in HFrEF patients. This highlights the importance of considering frailty as part of a pre-procedural risk stratification assessment and tailoring management strategies to improve outcomes for these high-risk patients.

Abstract 4136884: Incidence and Characteristics of Peri-Procedural Complications of Cardiac Implantable Electrical Devices in Breast Cancer Survivors

Introduction: Breast cancer (BC) is the most common non-cutaneous cancer in women. Several BC treatments increase the risk of conduction abnormalities and heart failure, potentially requiring cardiac implantable electrical devices (CIEDs). Due to vascular access devices, surgical management, and chest wall radiation, these patients are subject to upper extremity vascular alterations. There is limited data regarding CIED use in this population. Research question: Do patients with BC and CIEDs have different procedural approaches or complications compared to the general population? Aims: This study aimed to evaluate CIED placement and periprocedural complications in patients with a history of BC. Methods: This was a retrospective study of CIEDs placed at our institution between 2005 and 2023. Patients with a diagnosis of BC prior to time of placement were included. Complications included those within 30 days of the procedure. Results: We analyzed 109 female patients (median age of 73 years, IQR 66-80) who received pacemaker (PPM, 58.7%), cardiac resynchronization therapy defibrillator (CRT-D, 22%), implantable cardioverter defibrillator (ICD, 16.5%), or cardiac resynchronization therapy pacemaker (CRT-P, 2.8%). The median time from cancer diagnosis to device placement was 13 years (IQR 7-21). Oncologic therapies are included in Figure 1. In patients with unilateral cancer, most devices (78.4%) were placed contralaterally, with 32% of all devices being right sided. Anatomy related to chemotherapy port altered intraoperative approach in 2 cases and bilateral lymph node dissection necessitated subcutaneous ICD in 1 case. Complications were noted in 12 patients (11%) and included hematoma, lead revision, upper extremity DVT, pericardial effusion, stress cardiomyopathy, perforation, site infection, and worsening of chronic lymphedema. Conclusions: BC survivors undergoing CIED placement appear to be at higher risk of periprocedural complications when compared to the general population. They are more likely to undergo right sided device placement to avoid vascular access ipsilateral to prior surgery or radiation. Further studies are required to understand the long-term outcomes of CIED placement in this cohort of patients.

Abstract Sa1103: Utility of early Computed Tomography after out-of-hospital cardiac arrest resuscitation

Background: Initial care after out-of-hospital cardiac arrest (OHCA) poses major challenges to clinical teams due to diverse arrest etiologies and the potential need for time-sensitive interventions. Emergency department-based evaluation of these patients is crucial for identifying treatable causes of arrest. Recent data from one academic hospital highlights the potential importance of initial broad computed tomography (CT) immediately following resuscitation. Objective: To assess the ability of early post-arrest CT imaging to diagnose potential etiologies and sequelae of OHCA. Methods: We employed a registry of consecutive OHCA cases admitted to 3 hospitals within the University of Pennsylvania Health System between 1/2019-10/2020, collecting demographic, arrest, and post-arrest clinical data. Inclusion criteria included age >18 y, OHCA with return of spontaneous circulation (ROSC). We abstracted CT data including findings, contrast use, and timing, and subsequent clinical notes to assess for interventions performed based on CT findings from the EHR. KDIGO definition was used for acute kidney injury (AKI). SAS software was used for data analysis. Results: A total of 161 OHCA patients were included (mean age 60.8±15.6y; 42% female). Initial shockable rhythms were present in 16%, with 70% witnessed and 39% receiving bystander CPR. 154 patients survived to admission, and 41 survived to discharge. 117 patients underwent CT imaging in the ED: 117 underwent head CT, 87 chest CT, and 64 abdomen/pelvis CT. Median time to any first CT was 2.0h (IQR:1.4,2.8). Intracranial hemorrhage was diagnosed in 5/117 patients (4.3%); 3 received conservative therapy. Cerebral edema was found in 30/117 patients (25.6%), 10 received treatment. Pulmonary embolism was diagnosed in 8/87 cases (9.2%), 7 of which were acute and treated pharmacologically and/or mechanically. Aspiration and/or pneumonia, pneumonitis, bronchitis, bronchiolitis was found on 65/84 cases (74.7%), 30 received antibiotics. Deep venous thrombosis was detected in 3/64 patients (4.7%), 2 received anticoagulation. We found no significant differences in AKI rates with the use of contrast compared to patients receiving no contrast (p=0.93). Conclusion: These results confirm and extend other reports emphasizing the potential value for routine use of CT imaging post-ROSC. Implementing larger scale prospective studies comparing such protocols and standard-of-care is important to determine impact on OHCA outcomes.

Abstract 4137905: The association between prehospital epinephrine administration and short-term outcomes in patients with shockable out-of-hospital cardiac arrest and extracorporeal cardiopulmonary resuscitation: a propensity matched analysis

Background: In out-of-hospital cardiac arrest (OHCA) patients with an initial shockable rhythm, epinephrine increases the likelihood of return of spontaneous circulation (ROSC), but its effect on neurological outcome remains uncertain. Epinephrine administered before extracorporeal resuscitation (ECPR), which is a non-pharmacological method to obtain ROSC, may have worsened neurological outcome. Aim: To evaluate the impact of prehospital epinephrine administration on the prognosis of OHCA patients undergoing ECPR. Methods: This is a retrospective analysis of a cohort study from a multicenter, prospective registry of 81234 OHCA patients between 2014 and 2021. After the application of exclusion criteria, 1061 OHCA patients with an initial shockable rhythm and who underwent ECPR were eligible for this study. The primary outcome was favorable neurological outcome at 30 days after the OHCA and the secondary outcome was ROSC during transfer. Patients who did and did not receive prehospital epinephrine were propensity score-matched on the basis of age, gender, witness arrest, bystander-initiated CPR, dispatcher-assisted CPR, advanced airway management, call-to-defibrillation interval, year and district. Results: Among 1061 eligible patients, 442 patients received epinephrine and 619 patients did not. Matching was successful in achieving covariate balance as shown by a standardized difference of <10% for all variables (329 matched pairs). The proportion of patients with prehospital ROSC was significantly higher in those who received prehospital epinephrine than those who did not (36 [8%] vs 31 [5%]; adjusted odds ratio [OR] after propensity score-matching, 1.96 [95% CI 1.05-3.67], p=0.03). The proportion of patients with favorable neurological outcome at 30 days was not significantly lower in those who received prehospital epinephrine than those who did not (34 [8%] vs 78 [13%]; adjusted OR after propensity score-matching, 0.78 [95% CI 0.45-1.37], p=0.39). Conclusion: In patients with shockable OHCA and ECPR, prehospital epinephrine administration was significantly associated with increased ROSC before hospital arrival and not significantly with decreased favorable neurological outcome at 30 days.

Abstract 4120249: What Happens to Automated External Defibrillator Rhythm Strips after a Cardiac Arrest?

Background: Following an out of hospital cardiac arrest (OHCA), rhythm strips stored on an automated external defibrillator (AED) help guide important medical decisions, including possible implantable cardioverter defibrillator (ICD) implantation. However, this information is often difficult to obtain. Objective: To evaluate how frequently AED rhythm strips are reviewed following an OHCA prior to placing an ICD. Methods: Using the Cardiac Arrest Registry to Enhance Survival (CARES), we identified patients from 1/2015-12/2023 who were transferred to our institution following an OHCA. Patients were excluded if resuscitation was not attempted, death occurred during the hospitalization or patient identifying information was not available. Results: Of 907 OHCAs identified, 119 patients ( Table 1 ) met the inclusion criteria. The AED rhythm strip was in the electronic medical record on hospital arrival in 22% of cases and only after provider initiation in 6% of cases. None of the rhythm strips from a bystander-only delivered AED shock (n=17) were available on arrival, with only 24% retrieved during the hospitalization, taking 4.5±2.1 days from the date of arrest. Patients with an AED rhythm strip available (n=34) were more likely than those without a rhythm strip (n=85) to have a cardiac MRI (38% v. 13%, p=0.02) and genetic testing (15% v. 1%, p=0.02) done and have an ICD placed (53% v. 27%, p=0.04) or be discharged on a new anti-arrhythmic drug (15% v. 4%, p=0.04). Figure 1 Of the 42 patients who had an ICD placed during the index hospitalization, 54% were implanted without knowing the type of shockable rhythm or confirmation that an appropriate AED shock had been delivered. Conclusion: Rhythm strips help guide clinical decisions when assessing the need for ICD implantation. There is a systems gap in the process of transferring rhythm strips from AEDs to hospital providers following an OHCA.

Abstract Su204: Association between delta E T CO 2 and Return of Spontaneous Circulation in a National US Cohort

Introduction: International guidelines support use of end-tidal carbon dioxide (E T CO 2 ) for monitoring resuscitation in out-of-hospital cardiac arrest (OHCA). Specific E T CO 2 cutoffs have been proposed for termination of resuscitation, though data on rates of ROSC based on changes in E T CO 2 is limited. We aimed to evaluate the relationship between change in E T CO 2 in OHCA and its relationship to return of spontaneous circulation (ROSC) using a US national database. Methods: This retrospective analysis of National Emergency Medical Services Information System (NEMSIS) datasets from 2020 to 2022 evaluated all adult patients who underwent resuscitation for OHCA and had multiple E T CO 2 measurements. We excluded cases with missing data. The highest difference between two sequential E T CO 2 measurements (MΔE T CO 2 ) and total difference between minimum and maximum E T CO 2 measurements [TΔE T CO 2 ] were calculated for each case. ΔE T CO 2 groups were stratified into 10-unit increments and we compared rates of ROSC between groups. We then used multivariable logistic regression to evaluate the association between each 5 unit increase in ΔE T CO 2 and ROSC. We adjusted for age, sex, location, witness status, initial shockable rhythm, and CPR or AED prior to EMS arrival. Results: We included 274,516 total patients with 1,686,390 E T CO 2 measurements. The median number of E T CO 2 measurements was 5 (IQR 3-8). Median age was 65, 62.8% were male, 60.1% had witnessed arrests, and 78.3% received CPR and 32.3% received AED placement prior to EMS arrival. ROSC rates based on MΔE T CO 2 were 0-10 mmHg [33.3%], 10-20 mmHg [42.3%], 20-30 mmHg [49.7%], 30-40 mmHg [53.2%], and >40 mmHg [56.6%]. ROSC rates for TΔE T CO 2 were 0-10 mmHg [29.6%], 10-20 mmHg [36.7%], 20-30 mmHg [43.5%], 30-40 mmHg [48.9%], and >40 mmHg [54.6%]. Adjusted odds of ROSC per 10 mmHg increase in MΔE T CO 2 was 1.21 [1.21-1.22] and TΔE T CO 2 was 1.19 [1.19-1.19]. Conclusions: Increasing max and overall ΔE T CO 2 was associated with increased rates and odds of ROSC for OHCA.

Abstract Su603: Out-of-hospital cardiac arrest presenting with ST-segment elevation myocardial infarction: Real world assessment and treatment

Background: Coronary artery disease is a common cause of out-of-hospital cardiac arrest (OHCA). Early recognition myocardial infarction (MI) and initiating appropriate therapy has been shown to improve outcomes in OHCA. While early coronary intervention is part of guidelines-based care, the implementation of these recommendation in actual US practice remains poorly described. Objectives: This study aims to characterize patients presenting with OHCA and MI in a cohort from 4 hospitals, to assess care of these patients in actual practice. Methods: We employed a database of OHCA patients admitted to four hospitals within the University of Pennsylvania Hospital System between 01/2019-12/2023. For this study, we included all patients that were diagnosed with STEMI during emergency department evaluation, and collected demographic, arrest, coronary angiographic, and ECG data from electronic health records. SAS was used for statistical analysis. Results: A total of 43 MI cases were included; mean age was 60.6±11.8 y, 65% male, mean BMI 30.0±6.3, 58.1% African American, 27.9% White or Caucasian, and 16.3% had a medical history of myocardial infarction. 74.4% were witnessed, and 44.2% received bystander CPR[BA1]. Initial shockable rhythm was present in 34.9%. 38 survived to hospital admission, and 9 were discharged alive. The first obtained 12-lead ECG (median time to ECG: 13min, (IQR: 3.5-26.5)) found that ST-segment elevations were present in 88.4%, ST-segment depressions in 44.2%, T-wave inversions in 4.7%, QT prolongation in 9.3%, and wide QRS in 18.6%. Sinus rhythm was most common (41.9%), followed by junctional rhythm (9.3%). Left and right bundle branch blocks (4.3% and 7%, respectively) and AV block (7%) were recorded. Coronary angiography (median time to angiography: 1.95hr (IQR: 1.3-4.2)) was performed in 29 patients and revealed that left anterior descending artery (28.6%) was the most common location for a culprit lesion, followed by the right coronary artery (21.4%), and left circumflex artery (10.7%). Notably, in 21.4% of cases, no culprit lesion was identified. 13 patients underwent angioplasty with stent, 4 received balloon angioplasty, and 1 underwent aspiration thrombectomy. Conclusion: This study highlights important attributes of OHCA patients presenting with MI. This paves the way for larger studies comparing ECG and coronary angiography findings between MI and control populations to help identify and improve acute care for OHCA MI patients.