An ECG-based artificial intelligence model for assessment of sudden cardiac death risk.

BACKGROUND: Conventional ECG-based algorithms could contribute to sudden cardiac death (SCD) risk stratification but demonstrate moderate predictive capabilities. Deep learning (DL) models use the entire digital signal and could potentially improve predictive power. We aimed to train and validate a 12 lead ECG-based DL algorithm for SCD risk assessment. METHODS: Out-of-hospital SCD cases were prospectively ascertained in the Portland, Oregon, metro area. A total of 1,827 pre- cardiac arrest 12 lead ECGs from 1,796 SCD cases were retrospectively collected and analyzed to develop an ECG-based DL model. External validation was performed in 714 ECGs from 714 SCD cases from Ventura County, CA. Two separate control group samples were obtained from 1342 ECGs taken from 1325 individuals of which at least 50% had established coronary artery disease. The DL model was compared with a previously validated conventional 6 variable ECG risk model. RESULTS: The DL model achieves an AUROC of 0.889 (95% CI 0.861-0.917) for the detection of SCD cases vs. controls in the internal held-out test dataset, and is successfully validated in external SCD cases with an AUROC of 0.820 (0.794-0.847). The DL model performs significantly better than the conventional ECG model that achieves an AUROC of 0.712 (0.668-0.756) in the internal and 0.743 (0.711-0.775) in the external cohort. CONCLUSIONS: An ECG-based DL model distinguishes SCD cases from controls with improved accuracy and performs better than a conventional ECG risk model. Further detailed investigation is warranted to evaluate how the DL model could contribute to improved SCD risk stratification.

Sudden cardiac death (SCD) occurs when there are problems with the electrical activity within the heart. It is a common cause of death throughout the world so it would be beneficial to be able to easily identify individuals that are at high risk of SCD. Electrocardiograms are a cheap and widely available way to measure electrical activity in the heart. We developed a computational method that can use electrocardiograms to determine whether a person is at increased risk of having a SCD. Our computational method could allow clinicians to screen large numbers of people and identify those at a higher risk of SCD. This could enable regular monitoring of these people and might enable SCDs to be prevented in some individuals.

Artificial Intelligence Model Predicts Sudden Cardiac Arrest Manifesting With Pulseless Electric Activity Versus Ventricular Fibrillation.

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.

Dynamic electrocardiogram changes are a novel risk marker for sudden cardiac death.

BACKGROUND AND AIMS: Electrocardiogram (ECG) abnormalities have been evaluated as static risk markers for sudden cardiac death (SCD), but the potential importance of dynamic ECG remodelling has not been investigated. In this study, the nature and prevalence of dynamic ECG remodelling were studied among individuals who eventually suffered SCD. METHODS: The study population was drawn from two prospective community-based SCD studies in Oregon (2002, discovery cohort) and California, USA (2015, validation cohort). For this present sub-study, 231 discovery cases (2015-17) and 203 validation cases (2015-21) with ≥2 archived pre-SCD ECGs were ascertained and were matched to 234 discovery and 203 validation controls based on age, sex, and duration between the ECGs. Dynamic ECG remodelling was measured as progression of a previously validated cumulative six-variable ECG electrical risk score. RESULTS: Oregon SCD cases displayed greater electrical risk score increase over time vs. controls [+1.06 (95% confidence interval +0.89 to +1.24) vs. -0.05 (-0.21 to +0.11); P < .001]. These findings were successfully replicated in California [+0.87 (+0.7 to +1.04) vs. -0.11 (-0.27 to 0.05); P < .001]. In multivariable models, abnormal dynamic ECG remodelling improved SCD prediction over baseline ECG, demographics, and clinical SCD risk factors in both Oregon [area under the receiver operating characteristic curve 0.770 (95% confidence interval 0.727-0.812) increased to area under the receiver operating characteristic curve 0.869 (95% confidence interval 0.837-0.902)] and California cohorts. CONCLUSIONS: Dynamic ECG remodelling improved SCD risk prediction beyond clinical factors combined with the static ECG, with successful validation in a geographically distinct population. These findings introduce a novel concept of SCD dynamic risk and warrant further detailed investigation.

Risk Factors for Sudden Cardiac Arrest Among Hispanic or Latino Adults in Southern California: Ventura PRESTO and HCHS/SOL.

Background Out-of-hospital sudden cardiac arrest (SCA) is a leading cause of mortality, making prevention of SCA a public health priority. No studies have evaluated predictors of SCA risk among Hispanic or Latino individuals in the United States. Methods and Results In this case-control study, adult SCA cases ages 18-85 (n=1,468) were ascertained in the ongoing Ventura Prediction of Sudden Death in Multi-Ethnic Communities (PRESTO) study (2015-2021) in Ventura County, California. Control subjects were selected from 3033 Hispanic or Latino participants who completed Visit 2 examinations (2014-2017) at the San Diego site of the HCHS/SOL (Hispanic Community Health Survey/Study of Latinos). We used logistic regression to evaluate the association of clinical factors with SCA. Among Hispanic or Latino SCA cases (n=295) and frequency-matched HCHS/SOL controls (n=590) (70.2% men with mean age 63.4 and 61.2 years, respectively), the following clinical variables were associated with SCA in models adjusted for age, sex, and other clinical variables: chronic kidney disease (odds ratio [OR], 7.3 [95% CI, 3.8-14.3]), heavy drinking (OR, 4.5 [95% CI, 2.3-9.0]), stroke (OR, 3.1 [95% CI, 1.2-8.0]), atrial fibrillation (OR, 3.7 [95% CI, 1.7-7.9]), coronary artery disease (OR, 2.9 [95% CI, 1.5-5.9]), heart failure (OR, 2.5 [95% CI, 1.2-5.1]), and diabetes (OR, 1.5 [95% CI, 1.0-2.3]). Conclusions In this first population-based study, to our knowledge, of SCA risk predictors among Hispanic or Latino adults, chronic kidney disease was the strongest risk factor for SCA, and established cardiovascular disease was also important. Early identification and management of chronic kidney disease may reduce SCA risk among Hispanic or Latino individuals, in addition to prevention and treatment of cardiovascular disease.

Warning symptoms associated with imminent sudden cardiac arrest: a population-based case-control study with external validation.

BACKGROUND: Sudden cardiac arrest is a global public health problem with a mortality rate of more than 90%. Prearrest warning symptoms could be harnessed using digital technology to potentially improve survival outcomes. We aimed to estimate the strength of association between symptoms and imminent sudden cardiac arrest. METHODS: We conducted a case-control study of individuals with sudden cardiac arrest and participants without sudden cardiac arrest who had similar symptoms identified from two US community-based studies of patients with sudden cardiac arrest in California state, USA (discovery population; the Ventura Prediction of Sudden Death in Multi-Ethnic Communities [PRESTO] study), and Oregon state, USA (replication population; the Oregon Sudden Unexpected Death Study [SUDS]). Participant data were obtained from emergency medical services reports for people aged 18-85 years with witnessed sudden cardiac arrest (between Feb 1, 2015, and Jan 31, 2021) and an inclusion symptom. Data were also obtained from corresponding control populations without sudden cardiac arrest who were attended by emergency medical services for similar symptoms (between Jan 1 and Dec 31, 2019). We evaluated the association of symptoms with sudden cardiac arrest in the discovery population and validated our results in the replication population by use of logistic regression models. FINDINGS: We identified 1672 individuals with sudden cardiac arrest from the PRESTO study, of whom 411 patients (mean age 65·7 [SD 12·4] years; 125 women and 286 men) were included in the analysis for the discovery population. From a total of 76 734 calls to emergency medical services, 1171 patients (mean age 61·8 [SD 17·3] years; 643 women, 514 men, and 14 participants without data for sex) were included in the control group. Patients with sudden cardiac arrest were more likely to have dyspnoea (168 [41%] of 411 vs 262 [22%] of 1171; p<0·0001), chest pain (136 [33%] vs 296 [25%]; p=0·0022), diaphoresis (50 [12%] vs 90 [8%]; p=0·0059), and seizure-like activity (43 [11%] vs 77 [7%], p=0·011). Symptom frequencies and patterns differed significantly by sex. Among men, chest pain (odds ratio [OR] 2·2, 95% CI 1·6-3·0), dyspnoea (2·2, 1·6-3·0), and diaphoresis (1·7, 1·1-2·7) were significantly associated with sudden cardiac arrest, whereas among women, only dyspnoea was significantly associated with sudden cardiac arrest (2·9, 1·9-4·3). 427 patients with sudden cardiac arrest (mean age 62·2 [SD 13·5]; 122 women and 305 men) were included in the analysis for the replication population and 1238 patients (mean age 59·3 [16·5] years; 689 women, 548 men, and one participant missing data for sex) were included in the control group. Findings were mostly consistent in the replication population; however, notable differences included that, among men, diaphoresis was not associated with sudden cardiac arrest and chest pain was associated with sudden cardiac arrest only in the sex-stratified multivariable analysis. INTERPRETATION: The prevalence of warning symptoms was sex-specific and differed significantly between patients with sudden cardiac arrest and controls. Warning symptoms hold promise for prediction of imminent sudden cardiac arrest but might need to be augmented with additional features to maximise predictive power. FUNDING: US National Heart Lung and Blood Institute.

Temporal Trends in Incidence and Survival From Sudden Cardiac Arrest Manifesting With Shockable and Nonshockable Rhythms: A 16-Year Prospective Study in a Large US Community.

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 [ß] -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 ß -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 ß 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 ß 2.8%; 95% CI 1.3 to 4.4) and VF-sudden cardiac arrests (27.5%, 29.8%, 37.9%, 36.6%; unadjusted ß 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 ß 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.

Sudden cardiac arrest during the COVID-19 pandemic: A two-year prospective evaluation in a North American community.

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.

Sudden Cardiac Arrest During Sports Activity in Older Adults.

BACKGROUND: Sports activity among older adults is rising, but there is a lack of community-based data on sports-related sudden cardiac arrest (SrSCA) in the elderly. OBJECTIVES: In this study, the authors investigated the prevalence and characteristics of SrSCA among subjects ≥65 years of age in a large U.S. METHODS: All out-of-hospital sudden cardiac arrests (SCAs) were prospectively ascertained in the Portland, Oregon, USA, metro area (2002-2017), and Ventura County, California, USA (2015-2021) (catchment population ∼1.85 million). Detailed information was obtained for SCA warning symptoms, circumstances, and lifetime clinical history. Subjects with SCA during or within 1 hour of cessation of sports activity were categorized as SrSCA. RESULTS: Of 4,078 SCAs among subjects ≥65 years of age, 77 were SrSCA (1.9%; 91% men). The crude annual SrSCA incidence among age ≥65 years was 3.29/100,000 in Portland and 2.10/100,000 in Ventura. The most common associated activities were cycling, gym activity, and running. SrSCA cases had lower burden of cardiovascular risk factors (P = 0.03) as well as comorbidities (P < 0.005) compared with non-SrSCA. Based on conservative estimates of community residents ≥65 years of age who participate in sports activity, the SrSCA incidence was 28.9/100,000 sport participation years and 18.4/100,000 sport participation years in Portland and Ventura, respectively. Crude survival to hospital discharge rate was higher in SrSCA, but the difference was nonsignificant after adjustment for confounding factors. CONCLUSIONS: Among free-living community residents age ≥65 years, SrSCA is uncommon, predominantly occurs in men, and is associated with lower disease burden than non-SrSCA. These results suggest that the risk of SrSCA is low, and probably outweighed by the high benefit of exercise.

Recurrent Out-of-Hospital Sudden Cardiac Arrest: Prevalence and Clinical Factors.

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.

Ethnicity-Specific Effects on Cardiac Arrest During the COVID-19 Pandemic: A Two-Year Prospective Evaluation in a North American Community.

Background: Out-of-hospital sudden cardiac arrest (SCA) is a major public health problem with mortality >90%, and incidence has increased during the COVID-19 pandemic. Information regarding ethnicity-specific effects on SCA incidence and survival is lacking. Methods: In a prospective, population-based study of Ventura County, CA residents (2020 Pop. 843,843; 44.1% Hispanic), we compared SCA incidence and outcomes during the first two years of the COVID-19 pandemic to the prior four years, overall and by ethnicity (Hispanic vs non-Hispanic). Findings: Of 2,222 OHCA cases identified, 907 occurred during the pandemic (March 2020 - Feb 2022) and 1315 occurred pre-pandemic (March 2016 - Feb 2020). Overall age-standardized annual SCA incidence increased from 38.9/100,000 [95% CI 36.8-41.0] pre-pandemic to 53.8/100,00 [95% CI 50.3 - 57.3, p<0.001] during the pandemic. Among Hispanics, incidence increased by 77%, from 38.2/100,00 [95% CI 33.8-42.5] to 67.7/100,00 [95% CI 59.5- 75.8, p<0.001]. Among non-Hispanics, incidence increased by 26% from 39.4/100,000 [95% CI 36.9-41.9, p<0.001] to 49.8/100,00 [95% CI 45.8-53.8]. SCA incidence rates closely tracked COVID-19 infection rates. During the pandemic, SCA survival was significantly reduced (15.3% to 10.0%, p<0.001) and Hispanics were less likely than non-Hispanics to have bystander CPR (44.6% vs. 54.7%, p=0.005) and shockable rhythm (15.3% vs. 24.1%, p=0.003). Interpretation: Hispanic residents experienced higher SCA rates during the pandemic with less favorable resuscitation profiles. These findings implicate potential ethnicity-specific barriers to acute care and represent an urgent call to action at the community and health-system levels. Funding: National Heart Lung and Blood Institute Grants R01HL145675 and R01HL147358.

Survivors of Sudden Cardiac Arrest Presenting With Pulseless Electrical Activity: Clinical Substrate, Triggers, Long-Term Prognosis.

BACKGROUND: The proportion of sudden cardiac arrest (SCA) presenting as pulseless electrical activity (PEA) is rising, and survival remains low. The pathophysiology of PEA-SCA is poorly understood, and current clinical practice lacks specific options for the management of survivors. OBJECTIVES: In this study, the authors sought to investigate clinical profile, triggers, and long-term prognosis in survivors of SCA presenting with PEA. METHODS: The community-based Oregon SUDS (Sudden Unexpected Death Study) (since 2002) and Ventura PRESTO (Prediction of Sudden Death in Multi-ethnic Communities) (since 2015) studies prospectively ascertain all out-of-hospital SCAs of likely cardiac etiology. Lifetime clinical history and detailed evaluation of SCA events is available. We evaluated all SCA survivors with PEA as the presenting rhythm. RESULTS: The study population included 201 PEA-SCA survivors. Of these, 97 could be contacted for access to their clinical records. Among the latter, the mean age was 67 ± 17 years and 58 (60%) were male. After in-hospital examinations, 29 events (30%) were associated with acute myocardial infarction, and 5 (5%) had bradyarrhythmias. Among the remaining 63 patients (65%), specific triggers remained undetermined, although 31 (49%) had a previous history of heart failure. Of the 201 overall survivors, 91 (45%) were deceased after a mean follow-up of 4.2 ± 4.0 years. Survivors under the age of 40 years had an excellent long-term prognosis. CONCLUSIONS: Survivors of PEA-SCA are a heterogeneous group with high prevalence of multiple comorbidities, especially heart failure. Surprisingly good long-term survival was observed in young individuals. Acute myocardial infarction as the precipitating event was common, but triggers remained undetermined in the majority. Provision of individualized care to PEA survivors requires a renewed investigative focus on PEA-SCA.

Prediction of Sudden Cardiac Death Manifesting With Documented Ventricular Fibrillation or Pulseless Ventricular Tachycardia.

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.

Evaluation of Sudden Cardiac Arrest by Race/Ethnicity Among Residents of Ventura County, California, 2015-2020.

Importance: Sudden cardiac arrest (SCA) is a major public health problem. Owing to a lack of population-based studies in multiracial/multiethnic communities, little information is available regarding race/ethnicity-specific epidemiologic factors of SCA. Objective: To evaluate the association of race/ethnicity with burden, outcomes, and clinical profile of individuals experiencing SCA. Design, Setting, and Participants: A 5-year prospective, population-based cohort study of out-of-hospital SCA was conducted from February 1, 2015, to January 31, 2020, among residents of Ventura County, California (2018 population, 848 112: non-Hispanic White [White], 45.8%; Hispanic/Latino [Hispanic], 42.4%; Asian, 7.3%; and Black, 1.7% individuals). All individuals with out-of-hospital SCA of likely cardiac cause and resuscitation attempted by emergency medical services were included. Exposures: Data on circumstances and outcomes of SCA from prehospital emergency medical services records and data on demographics and pre-SCA clinical history from detailed archived medical records, death certificates, and autopsies. Main Outcomes and Measures: Annual age-adjusted SCA incidence by race and ethnicity and SCA circumstances and outcomes by ethnicity. Clinical profile (cardiovascular risk factors, comorbidity burden, and cardiac history) by ethnicity, overall, and stratified by sex. Results: A total of 1624 patients with SCA were identified (1059 [65.2%] men; mean [SD] age, 70.9 [16.1] years). Race/ethnicity data were available for 1542 (95.0%) individuals, of whom 1022 (66.3%) were White, 381 (24.7%) were Hispanic, 86 (5.6%) were Asian, 31 (2.0%) were Black, and 22 (1.4%) were other race/ethnicity. Annual age-adjusted SCA rates per 100 000 residents of Ventura County were similar in White (37.5; 95% CI, 35.2-39.9), Hispanic (37.6; 95% CI, 33.7-41.5; P = .97 vs White), and Black (48.0; 95% CI, 30.8-65.2; P = .18 vs White) individuals, and lower in the Asian population (25.5; 95% CI, 20.1-30.9; P = .006 vs White). Survival to hospital discharge following SCA was similar in the Asian (11.8%), Hispanic (13.9%), and non-Hispanic White (13.0%) (P = .69) populations. Compared with White individuals, Hispanic and Asian individuals were more likely to have hypertension (White, 614 [76.3%]; Hispanic, 239 [79.1%]; Asian, 57 [89.1%]), diabetes (White, 287 [35.7%]; Hispanic, 178 [58.9%]; Asian, 37 [57.8%]), and chronic kidney disease (White, 231 [29.0%]; Hispanic, 123 [40.7%]; Asian, 33 [51.6%]) before SCA. Hispanic individuals were also more likely than White individuals to have hyperlipidemia (White, 380 [47.2%]; Hispanic, 165 [54.6%]) and history of stroke (White, 107 [13.3%]; Hispanic, 55 [18.2%]), but less likely to have a history of atrial fibrillation (White, 251 [31.2%]; Hispanic, 59 [19.5%]). Conclusions and Relevance: The results of this study suggest that the burden of SCA was similar in Hispanic and White individuals and lower in Asian individuals. The Asian and Hispanic populations had shared SCA risk factors, which were different from those of the White population. These findings underscore the need for an improved understanding of race/ethnicity-specific differences in SCA risk.

Out-of-Hospital Cardiac Arrest Response and Outcomes During the COVID-19 Pandemic.

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.

Sudden cardiac death during nighttime hours.

BACKGROUND: In the absence of apparent triggers, sudden cardiac death (SCD) during nighttime hours is a perplexing and devastating phenomenon. There are few published reports in the general population, with insufficient numbers to perform sex-specific analyses. Smaller studies of rare nocturnal SCD syndromes suggest a male predominance and implicate sleep-disordered breathing. OBJECTIVE: The purpose of this study was to identify mechanisms of nighttime SCD in the general population. METHODS: From the population-based Oregon Sudden Unexpected Death Study, we evaluated SCD cases that occurred in the community between 10 PM and 6 AM (nighttime) and compared them with daytime cases. Univariate comparisons were evaluated using Pearson χ2 tests and independent samples t tests. Logistic regression was used to further assess independent SCD risk. RESULTS: A total of 4126 SCD cases (66.2% male, 33.8% female) met criteria for analysis and 22.3% (n = 918) occurred during nighttime hours. Women were more likely to present with nighttime SCD than men (25.4% vs 20.6%; P < .001). In a multivariate regression model, female sex (odds ratio [OR] 1.3 [confidence interval (CI) 1.1-1.5]; P = .001), medications associated with somnolence/respiratory depression (OR 1.2 [CI 1.1-1.4]; P = .008) and chronic obstructive pulmonary disease/asthma (OR 1.4 [CI 1.1-1.6]; P < .001) were independently associated with nighttime SCD. Women were taking more central nervous system-affecting medications than men (1.9 ± 1.7 vs 1.4 ± 1.4; P = .001). CONCLUSION: In the general population, women were more likely than men to suffer SCD during nighttime hours and female sex was an independent predictor of nighttime events. Respiratory suppression is a concern, and caution is advisable when prescribing central nervous system-affecting medications to patients at an increased risk of SCD, especially women.

Remodeling of the 12-lead electrocardiogram in immediate survivors of sudden cardiac arrest.

BACKGROUND: The ECG is a critical diagnostic tool for the management of immediate sudden cardiac arrest (SCA) survivors, but can be altered as a consequence of the SCA event. A limited number of studies report that electrical remodeling post SCA is due to prolonged myocardial repolarization, but a better understanding of this phenomenon is needed. AIM: To identify specific ECG abnormalities that follow SCA in immediate survivors. METHODS: SCA survivors with a pre-arrest ECG and an ECG obtained within 48 h post-SCA were prospectively collected in the Oregon Sudden Unexpected Death Study (Portland metro region) from 2002-2015. Ventricular depolarization and repolarization measurements were compared between pre-arrest and post-arrest ECGs using paired t-tests and assessed for association with survival using unpaired t-tests and Pearson's chi-square tests. RESULTS: A pre-arrest ECG and post-arrest ECG were available for 297 SCA cases (67.8 ±â€¯13.4 years; 65.3% male). From the pre- to post-arrest setting, there was a significant mean increase in QRS (21 ms, p < 0.001) and QTc (35 ms, p < 0.001) in each SCA case, while there was no significant change in the JTc (4 ms, p = 0.361). Post-arrest QRS duration was significantly shorter in cases who survived to hospital discharge compared with those who did not survive (mean QRSD 115 ±â€¯29 ms vs 127 ±â€¯34 ms; p = 0.006). CONCLUSIONS: Contrary to expectations, electrical remodeling of the ECG due to SCA occurs due to prolongation of ventricular depolarization (QRSD), and not repolarization (JTc). Prolonged QRSD may also assist with prognostication and warrants further evaluation.

Experience With Hydroxychloroquine and Azithromycin in the Coronavirus Disease 2019 Pandemic: Implications for QT Interval Monitoring.

Background Despite a lack of clinical evidence, hydroxychloroquine and azithromycin are being administered widely to patients with verified or suspected coronavirus disease 2019 (COVID-19). Both drugs may increase risk of lethal arrhythmias associated with QT interval prolongation. Methods and Results We analyzed a case series of COVID-19-positive/suspected patients admitted between February 1, 2020, and April 4, 2020, who were treated with azithromycin, hydroxychloroquine, or a combination of both drugs. We evaluated baseline and postmedication QT interval (corrected QT interval [QTc]; Bazett) using 12-lead ECGs. Critical QTc prolongation was defined as follows: (1) maximum QTc ≥500 ms (if QRS <120 ms) or QTc ≥550 ms (if QRS ≥120 ms) and (2) QTc increase of ≥60 ms. Tisdale score and Elixhauser comorbidity index were calculated. Of 490 COVID-19-positive/suspected patients, 314 (64%) received either/both drugs and 98 (73 COVID-19 positive and 25 suspected) met study criteria (age, 62±17 years; 61% men). Azithromycin was prescribed in 28%, hydroxychloroquine in 10%, and both in 62%. Baseline mean QTc was 448±29 ms and increased to 459±36 ms (P=0.005) with medications. Significant prolongation was observed only in men (18±43 ms versus -0.2±28 ms in women; P=0.02). A total of 12% of patients reached critical QTc prolongation. Changes in QTc were highest with the combination compared with either drug, with much greater prolongation with combination versus azithromycin (17±39 ms versus 0.5±40 ms; P=0.07). No patients manifested torsades de pointes. Conclusions Overall, 12% of patients manifested critical QTc prolongation, and the combination caused greater prolongation than either drug alone. The balance between uncertain benefit and potential risk when treating COVID-19 patients should be carefully assessed.

Unexpected shift in circadian and septadian variation of sudden cardiac arrest: the Oregon Sudden Unexpected Death Study.

BACKGROUND: Earlier studies have reported both early morning and Monday peaks in occurrence of sudden cardiac arrest (SCA) in the community and appropriate defibrillator shocks in patients with an implantable cardioverter-defibrillator (ICD). However, a more recent analysis of ICD shocks reported absence of these peaks. OBJECTIVE: The purpose of this study was to perform a contemporary evaluation of the circadian and septadian variation of SCA in the general population. METHODS: The analysis was performed from an ongoing, population-based study of SCA in a Northwestern US community of approximately 1 million residents. To maximize accuracy, we focused on consecutive patients who presented with witnessed SCA and were attended by emergency medical services (EMS). The specific time of each SCA event was determined based on the time of the 911 call to EMS. RESULTS: During 2002-2014, we identified 1535 patients age ≥18 years who suffered witnessed SCA, with time of first EMS contact recorded. There was no morning (6 AM to 12 PM) peak, and we observed a nadir in SCA events during 12 AM to 6 AM, with only 13.9% of events occurring during this 6-hour block (P <.0001). There was no peak on Mondays, but a nadir was observed on Sundays that accounted for only 11.3% of SCA events during the week (P = .004). CONCLUSION: in this contemporary community-based study, we failed to observe the expected morning peak or the Monday peak in SCA, duplicating recent findings in primary prevention defibrillator patients. The significant public health implications of these findings merit further investigation.