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Background: There is no specific treatment for sudden cardiac arrest (SCA) manifesting as pulseless electric activity (PEA) and survival rates are low; unlike ventricular fibrillation (VF), which is treatable by defibrillation. Development of novel treatments requires fundamental clinical studies, but access to the true initial rhythm has been a limiting factor., Methods: Using demographics and detailed clinical variables, we trained and tested an AI model (extreme gradient boosting) to differentiate PEA-SCA versus VF-SCA in a novel setting that provided the true initial rhythm. A subgroup of SCAs are witnessed by emergency medical services personnel, and because the response time is zero, the true SCA initial rhythm is recorded. The internal cohort consisted of 421 emergency medical services-witnessed out-of-hospital SCAs with PEA or VF as the initial rhythm in the Portland, Oregon metropolitan area. External validation was performed in 220 emergency medical services-witnessed SCAs from Ventura, CA., Results: In the internal cohort, the artificial intelligence model achieved an area under the receiver operating characteristic curve of 0.68 (95% CI, 0.61-0.76). Model performance was similar in the external cohort, achieving an area under the receiver operating characteristic curve of 0.72 (95% CI, 0.59-0.84). Anemia, older age, increased weight, and dyspnea as a warning symptom were the most important features of PEA-SCA; younger age, chest pain as a warning symptom and established coronary artery disease were important features associated with VF., Conclusions: The artificial intelligence model identified novel features of PEA-SCA, differentiated from VF-SCA and was successfully replicated in an external cohort. These findings enhance the mechanistic understanding of PEA-SCA with potential implications for developing novel management strategies., Competing Interests: Disclosures None.

Study Objective: The proportion of nonshockable sudden cardiac arrests (pulseless electrical activity and asystole) continues to rise. Survival is lower than shockable (ventricular fibrillation [VF]) sudden cardiac arrests, but there is little community-based information on temporal trends in the incidence and survival from sudden cardiac arrests based on presenting rhythms. We investigated community-based temporal trends in sudden cardiac arrest incidence and survival by presenting rhythm., Methods: We prospectively evaluated the incidence of each presenting sudden cardiac arrest rhythm and survival outcomes for out-of-hospital events in the Portland, Oregon metro area (population of approximately 1 million, 2002 to 2017). We limited inclusion to cases of likely cardiac cause with resuscitation attempted by emergency medical services., Results: Out of 3,723 overall sudden cardiac arrest cases, 908 (24%) presented with pulseless electrical activity, 1,513 (41%) with VF, and 1,302 (35%) with asystole. The incidence of pulseless electrical activity-sudden cardiac arrest remained stable over 4-year periods (9.6/100,000 in 2002 to 2005, 7.4/100,000 in 2006 to 2009, 5.7/100,000 in 2010 to 2013, and 8.3/100,000 in 2014 to 2017; unadjusted beta [β] -0.56; 95% confidence interval [CI], -3.98 to 2.85). The incidence of VF-sudden cardiac arrests decreased over time (14.6/100,000 in 2002 to 2005, 13.4/100,000 in 2006 to 2009, 12.0/100,000 in 2010 to 2013, and 11.6/100,000 in 2014 to 2017; unadjusted β -1.05; 95% CI, -1.68 to -0.42) and asystole-sudden cardiac arrests (8.6/100,000 in 2002 to 2005, 9.0/100,000 in 2006 to 2009, 10.3/100,000 in 2010 to 2013, and 15.7/100,000 in 2014 to 2017; unadjusted β 2.25; 95% CI -1.24 to 5.73) did not change significantly over time. Survival increased over time for pulseless electrical activity-sudden cardiac arrests (5.7%, 4.3%, 9.6%, 13.6%; unadjusted β 2.8%; 95% CI 1.3 to 4.4) and VF-sudden cardiac arrests (27.5%, 29.8%, 37.9%, 36.6%; unadjusted β 3.5%; 95% CI 1.4 to 5.6), but not for asystole-sudden cardiac arrests (1.7%, 1.6%, 4.0%, 2.4%; unadjusted β 0.3%; 95% CI, -0.4 to 1.1). Enhancements in the emergency medical services system's pulseless electrical activity-sudden cardiac arrest management were temporally associated with the increasing pulseless electrical activity survival rates., Conclusions: Over a 16-year period, the incidence of VF/ventricular tachycardia decreased over time, but pulseless electrical activity incidence remained stable. Survival from both VF-sudden cardiac arrests and pulseless electrical activity-sudden cardiac arrests increased over time with a more than 2-fold increase for pulseless electrical activity-sudden cardiac arrests., (Copyright © 2023 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.)

Background: Early during the coronavirus disease 2019 (COVID-19) pandemic, higher sudden cardiac arrest (SCA) incidence and lower survival rates were reported. However, ongoing effects on SCA during the evolving pandemic have not been evaluated., Objective: The purpose of this study was to assess the impact of COVID-19 on SCA during 2 years of the pandemic., Methods: In a prospective study of Ventura County, California (2020 population 843,843; 44.1% Hispanic), we compared SCA incidence and outcomes during the first 2 years of the COVID-19 pandemic to the prior 4 years., Results: Of 2222 out-of-hospital SCA cases identified, 907 occurred during the pandemic (March 2020 to February 2022) and 1315 occurred prepandemic (March 2016 to February 2020). Overall age-standardized annual SCA incidence increased from 39 per 100,000 (95% confidence [CI] 37-41) prepandemic to 54 per 100,000 (95% CI 50-57; P <.001) during the pandemic. Among Hispanics, incidence increased by 77%, from 38 per 100,000 (95% CI 34-43) to 68 per 100,000 (95% CI 60-76; P <.001). Among non-Hispanics, incidence increased by 26%, from 39 per 100,000 (95% CI 37-42; P <.001) to 50 per 100,000 (95% CI 46-54). SCA incidence rates closely tracked COVID-19 infection rates. During the pandemic, SCA survival was significantly reduced (15% to 10%; P <.001), and Hispanics were less likely than non-Hispanics to receive bystander cardiopulmonary resuscitation (45% vs 55%; P = .005) and to present with shockable rhythm (15% vs 24%; P = .003)., Conclusion: Overall SCA rates remained consistently higher and survival outcomes consistently lower, with exaggerated effects during COVID infection peaks. This longer evaluation uncovered higher increases in SCA incidence among Hispanics, with worse resuscitation profiles. Potential ethnicity-specific barriers to acute SCA care warrant urgent evaluation and intervention., (Copyright © 2023 Heart Rhythm Society. All rights reserved.)

Objective: The proportion of sudden cardiac arrests (SCA) manifesting with pulseless electrical activity (PEA) has increased significantly, and the survival rate remains lower than ventricular fibrillation (VF). However, a subgroup of PEA-SCA cases does survive and may yield key predictors of improved outcomes when compared to non-survivors. We aimed to identify key predictors of survival from PEA-SCA., Methods: Our study sample is drawn from two ongoing community-based, prospective studies of out-of-hospital SCA: Oregon SUDS from the Portland, OR metro area (Pop. approx. 1 million; 2002-2017) and Ventura PRESTO from Ventura County, CA (Pop. approx. 850,000, 2015-2021). For the present sub-study, we included SCA cases with PEA as the presenting rhythm where emergency medical services (EMS) personnel attempted resuscitation., Results: We identified 1,704 PEA-SCA cases, of which 173 (10.2%) were survivors and 1,531 (89.8%) non-survivors. Patients whose PEA-SCA occurred in a healthcare unit (16.9%) or public location (18.1%) had higher survival than those whose PEA-SCA occurred at home (9.3%) or in a care facility (5.7%). Young age, witness status, PEA-SCA location and pre-existing COPD/asthma were independent predictors of survival. Among witnessed cases the survival rate was 10% even if EMS response time was >10 minutes., Conclusions: Key determinants for survival from PEA-SCA were young age, witnessed status, public location and pre-existing COPD/asthma. Survival outcomes in witnessed PEA cases were better than expected, even with delayed EMS response., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Despite improvements in management following survival from sudden cardiac arrest (SCA) and wide availability of implantable cardioverter defibrillators for secondary prevention, a subgroup of individuals will suffer multiple distinct episodes of SCA. The objective of this study was to characterize and evaluate the burden of recurrent out-of-hospital SCA among survivors of SCA in a single large US community., Methods: SCA cases were prospectively ascertained in the Oregon Sudden Unexpected Death Study. Individuals that experienced recurrent SCA were identified both prospectively and retrospectively., Results: We ascertained 6649 individuals with SCA (2002-2020) and 924 (14%) survived to hospital discharge. Of these, 88 survivors (10%) experienced recurrent SCA. Of the nonsurvivors (n=5725), 35 had suffered a recurrent SCA. Of the total 123 SCA cases with recurrent SCA, >60% occurred at least 1 year after the initial SCA (median 23 months, range: 6 days to 31 years). SCA occurred despite a secondary prevention implantable cardioverter defibrillator in 22% (n=26). Prevalence of coronary disease (36% versus 25%), hypertension (69% versus 43%), diabetes (44% versus 21%), and chronic kidney disease (35% versus 14%) was significantly higher in recurrent SCA versus single SCA survivors (n=80, P =0.01). Among individuals with no secondary prevention implantable cardioverter defibrillators before recurrent SCA, the majority had apparently reversible etiologies identified at initial SCA, with one-quarter undergoing coronary revascularization and over half diagnosed with noncoronary cardiac etiologies., Conclusions: At least 10% of SCA survivors had recurrent SCA, and a large subgroup suffered their repeat SCA despite treatment for an apparently reversible etiology. A renewed focus on careful assessment of cardiac substrate as well as management of coronary disease, hypertension, diabetes, and chronic kidney disease in SCA survivors could reduce recurrent SCA.

Out-of-hospital cardiac arrest (OHCA) remains a major public health problem. Even in high-income countries, survival rates have plateaued in the range of ten percent, stimulating an ongoing interest in developing novel approaches to resuscitation. Emergency Medical Services (EMS)-witnessed OHCAs constitute a subgroup of overall OHCA that occur after the arrival of EMS, leading to rapid initiation of resuscitation and significantly improved survival. In this narrative review we summarize and interpret recent developments in knowledge of EMS-witnessed OHCA regarding prevalence, demographics, location, circumstances, survival outcomes and clinical profile. We examine the possibility of informing novel resuscitation approaches and enhancing mechanistic knowledge by studying EMS-witnessed OHCA, with the goal of improving overall survival from OHCA., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Objectives: This study aimed to develop a novel clinical prediction algorithm for avertable sudden cardiac death., Background: Sudden cardiac death manifests as ventricular fibrillation (VF)/ ventricular tachycardia (VT) potentially treatable with defibrillation, or nonshockable rhythms (pulseless electrical activity/asystole) with low likelihood of survival. There are no available clinical risk scores for targeted prediction of VF/VT., Methods: Subjects with out-of-hospital sudden cardiac arrest presenting with documented VF or pulseless VT (33% of total cases) were ascertained prospectively from the Portland, Oregon, metro area with population ≈1 million residents (n = 1,374, 2002-2019). Comparisons of lifetime clinical records were conducted with a control group (n = 1,600) with ≈70% coronary disease prevalence. Prediction models were constructed from a training dataset using backwards stepwise logistic regression and applied to an internal validation dataset. Receiver operating characteristic curves (C statistic) were used to evaluate model discrimination. External validation was performed in a separate, geographically distinct population (Ventura County, California, population ≈850,000, 2015-2020)., Results: A clinical algorithm (VFRisk) constructed with 13 clinical, electrocardiogram, and echocardiographic variables had very good discrimination in the training dataset (C statistic = 0.808; [95% CI: 0.774-0.842]) and was successfully validated in internal (C statistic = 0.776 [95% CI: 0.725-0.827]) and external (C statistic = 0.782 [95% CI: 0.718-0.846]) datasets. The algorithm substantially outperformed the left ventricular ejection fraction (LVEF) ≤35% (C statistic = 0.638) and performed well across the LVEF spectrum., Conclusions: An algorithm for prediction of sudden cardiac arrest manifesting with VF/VT was successfully constructed using widely available clinical and noninvasive markers. These findings have potential to enhance primary prevention, especially in patients with mid-range or preserved LVEF., Competing Interests: Funding Support and Author Disclosures Dr Chugh has received funding from National Institutes of Health, National Heart, Lung, and Blood Institute Grants R01HL126938 and R01HL145675 for this work; and holds the Pauline and Harold Price Chair in Cardiac Electrophysiology at Cedars-Sinai, Los Angeles. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to evaluate the potential impact of the coronavirus disease-2019 (COVID-19) pandemic on out-of-hospital cardiac arrest (OHCA) responses and outcomes in 2 U.S. communities with relatively low infection rates., Background: Studies in areas with high COVID-19 infection rates indicate that the pandemic has had direct and indirect effects on community responses to OHCA and negative impacts on survival. Data from areas with lower infection rates are lacking., Methods: Cases of OHCA in Multnomah County, Oregon, and Ventura County, California, with attempted resuscitation by emergency medical services (EMS) from March 1 to May 31, 2020, and from March 1 to May 31, 2019, were evaluated., Results: In a comparison of 231 OHCA in 2019 to 278 in 2020, the proportion of cases receiving bystander cardiopulmonary resuscitation (CPR) was lower in 2020 (61% to 51%, respectively; p = 0.02), and bystander use of automated external defibrillators (AEDs) declined (5% to 1%, respectively; p = 0.02). EMS response time increased (6.6 ± 2.0 min to 7.6 ± 3.0 min, respectively; p < 0.001), and fewer OHCA cases survived to hospital discharge (14.7% to 7.9%, respectively; p = 0.02). Incidence rates did not change significantly (p > 0.07), and coronavirus infection rates were low (Multnomah County, 143/100,000; Ventura County, 127/100,000 as of May 31) compared to rates of ∼1,600 to 3,000/100,000 in the New York City region at that time., Conclusions: The community response to OHCA was altered from March to May 2020, with less bystander CPR, delays in EMS response time, and reduced survival from OHCA. These results highlight the pandemic's indirect negative impact on OHCA, even in communities with relatively low incidence of COVID-19 infection, and point to potential opportunities for countering the impact., Competing Interests: Author Disclosures Dr. Chugh was funded by National Institutes of Health, National Heart Lung and Blood Institute (NHLBI) grants R01 HL147358 and R01 HL145675. Dr. Chugh holds the Pauline and Harold Price Chair in Cardiac Electrophysiology at Cedars-Sinai, Los Angeles. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Prevention of sudden cardiac arrest (SCA) in the young remains a largely unsolved public health problem, and sports activity is an established trigger. Although the presence of standard cardiovascular risk factors in the young can link to future morbidity and mortality in adulthood, the potential contribution of these risk factors to SCA in the young has not been evaluated., Methods: We prospectively ascertained subjects who experienced SCA between the ages of 5 and 34 years in the Portland, Oregon, metropolitan area (2002-2015, catchment population ≈1 million). We assessed the circumstances, resuscitation outcomes, and clinical profile of subjects who had SCA by a detailed evaluation of emergency response records, lifetime clinical records, and autopsy examinations. We specifically evaluated the association of standard cardiovascular risk factors and SCA, and sports as a trigger for SCA in the young., Results: Of 3775 SCAs in all age groups, 186 (5%) occurred in the young (mean age 25.9±6.8, 67% male). In SCA in the young, overall prevalence of warning signs before SCA was low (29%), and 26 (14%) were associated with sports as a trigger. The remainder (n=160) occurred in other settings categorized as nonsports. Sports-related SCAs accounted for 39% of SCAs in patients aged ≤18, 13% of SCAs in patients aged 19 to 25, and 7% of SCAs in patients aged 25 to 34. Sports-related SCA cases were more likely to present with shockable rhythms, and survival from cardiac arrest was 2.5-fold higher in sports-related versus nonsports SCA (28% versus 11%; P =0.05). Overall, the most common SCA-related conditions were sudden arrhythmic death syndrome (31%), coronary artery disease (22%), and hypertrophic cardiomyopathy (14%). There was an unexpectedly high overall prevalence of established cardiovascular risk factors (obesity, diabetes mellitus, hypertension, hyperlipidemia, smoking) with ≥1 risk factors in 58% of SCA cases., Conclusions: Sports was a trigger of SCA in a minority of cases, and, in most patients, SCA occurred without warning symptoms. Standard cardiovascular risk factors were found in over half of patients, suggesting the potential role of public health approaches that screen for cardiovascular risk factors at earlier ages., (© 2017 American Heart Association, Inc.)

Background: Health insurance has many benefits including improved financial security, greater access to preventive care, and better self-perceived health. However, the influence of health insurance on major health outcomes is unclear. Sudden cardiac arrest prevention represents one of the major potential benefits from health insurance, given the large impact of sudden cardiac arrest on premature death and its potential sensitivity to preventive care., Methods and Results: We conducted a pre-post study with control group examining out-of-hospital cardiac arrest (OHCA) among adult residents of Multnomah County, Oregon (2015 adult population 636 000). Two time periods surrounding implementation of the Affordable Care Act were evaluated: 2011-2012 ("pre-expansion") and 2014-2015 ("postexpansion"). The change in OHCA incidence for the middle-aged population (45-64 years old) exposed to insurance expansion was compared with the elderly population (age ≥65 years old) with constant near-universal coverage. Rates of OHCA among middle-aged individuals decreased from 102 per 100 000 (95% CI: 92-113 per 100 000) to 85 per 100 000 (95% CI: 76-94 per 100 000), P value 0.01. The elderly population experienced no change in OHCA incidence, with rates of 275 per 100 000 (95% CI: 250-300 per 100 000) and 269 per 100 000 (95% CI: 245-292 per 100 000), P value 0.70., Conclusions: Health insurance expansion was associated with a significant reduction in OHCA incidence. Based on this pilot study, further investigation in larger populations is warranted and feasible., (© 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

Objective: To identify the incidence and prehospital predictors of ventricular tachycardia/ventricular fibrillation (VT/VF) as the initial arrhythmia in patients with out-of-hospital cardiac arrest (OHCA) in central Taiwan., Patients and Methods: The Taichung Sudden Unexpected Death Registry program encompasses the Taichung metropolitan area in central Taiwan, with a population of 2.7 million and 17 destination hospitals for patients with OHCA. We performed a detailed analysis of demographic characteristics, circumstances of cardiac arrest, and emergency medical service records using the Utstein Style., Results: From May 1, 2013, through April 30, 2014, resuscitation was attempted in 2013 individuals with OHCA, of which 384 were excluded due to trauma and noncardiac etiologies. Of the 1629 patients with presumed cardiogenic OHCA, 7.9% (n=129) had initial shockable rhythm; this proportion increased to 18.8% (61 of 325) in the witnessed arrest subgroup. Male sex (odds ratio [OR], 2.45; 95% CI, 1.46-4.12; P<.001), age younger than 65 years (OR, 2.39, 95% CI, 1.58-3.62; P<.001), public location of arrest (OR, 4.61; 95% CI, 2.86-7.44; P<.001), and witnessed status (OR, 3.98; 95% CI, 2.62-6.05; P<.001) were independent predictors of VT/VF rhythm., Conclusion: The proportion of patients with OHCA presenting with VT/VF was generally low in this East Asian population. Of the prehospital factors associated with VT/VF, public location of OHCA was the strongest predictor of VT/VF in this population, which may affect planning and deployment of emergency medical services in central Taiwan., (Copyright © 2016 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Background: Sports-associated sudden cardiac arrests (SCAs) occur mostly during middle age. We sought to determine the burden, characteristics, and outcomes of SCA during sports among middle-aged residents of a large US community., Methods and Results: Patients with SCA who were 35 to 65 years of age were identified in a large, prospective, population-based study (2002-2013), with systematic and comprehensive assessment of their lifetime medical history. Of the 1247 SCA cases, 63 (5%) occurred during sports activities at a mean age of 51.1±8.8 years, yielding an incidence of 21.7 (95% confidence interval, 8.1-35.4) per 1 million per year. The incidence varied significantly by sex, with a higher incidence among men (relative risk, 18.68; 95% confidence interval, 2.50-139.56) for sports SCAs compared with all other SCAs (relative risk 2.58; 95% confidence interval, 2.12-3.13). Sports SCA was also more likely to be a witnessed event (87% versus 53%; P<0.001) with cardiopulmonary resuscitation (44% versus 25%; P=0.001) and ventricular fibrillation (84% versus 51%; P<0.0001). Survival to hospital discharge was higher for sports-associated SCA (23.2% versus 13.6%; P=0.04). Sports SCA cases presented with known preexisting cardiac disease in 16% and ≥1 cardiovascular risk factors in 56%, and overall, 36% of cases had typical cardiovascular symptoms during the week preceding the SCA., Conclusions: Sports-associated SCA in middle age represents a relatively small proportion of the overall SCA burden, reinforcing the idea of the high-benefit, low-risk nature of sports activity. Especially in light of current population aging trends, our findings emphasize that targeted education could maximize both safety and acceptance of sports activity in the older athlete., (© 2015 American Heart Association, Inc.)

Background: There has been a paradigm shift in the manifestation of sudden cardiac arrest (SCA), with steadily decreasing rates of ventricular fibrillation/tachycardia (VF/VT) and a significant increase in the proportion of pulseless electrical activity (PEA) and asystole., Objective: Since PEA is marked by failure of myocardial contractility, we evaluated the potential role of drugs that affect cardiac contractility in the pathophysiology of human PEA., Methods: Subjects with out-of-hospital SCA (aged≥18 years) who underwent attempted resuscitation were evaluated in the ongoing Oregon Sudden Unexpected Death Study (2002-2009). Specific classes of medications with either negative or positive cardiac inotropic effects were evaluated for association with occurrence of PEA vs VF/VT by using Pearson χ(2) tests and logistic regression., Results: PEA cases (n = 309) were older than VF/VT cases (n = 509; 68±14 years vs 64±15 years; P<.0001) and were more likely to be women (39% vs 25%; P<.0001). In a logistic regression model adjusting for age, sex, comorbidities, disease burden, and resuscitation variables, antipsychotic drugs (odds ratio 2.40; 95% confidence interval 1.26-4.53) were significant predictors of PEA vs VF/VT. Conversely, use of digoxin was associated with the occurrence of VF/VT (P<.0001)., Conclusions: When drugs modifying myocardial contractility were evaluated in a comprehensive analysis of patients who suffered SCA, use of antipsychotic agents was a significant and independent predictor of manifestation with PEA., (Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)