Association between Conversion to Shockable Rhythms and Survival with Favorable Neurological Outcomes for Out-of-Hospital Cardiac Arrests.

BACKGROUND: The initial cardiac rhythm in out-of-hospital cardiac arrest (OHCA) portends different prognoses and affects treatment decisions. Initial shockable rhythms are associated with good survival and neurological outcomes but there is conflicting evidence for those who initially present with non-shockable rhythms. The aim of this study is to evaluate if OHCA with conversion from non-shockable (i.e., asystole and pulseless electrical activity) rhythms to shockable rhythms compared to OHCA remaining in non-shockable rhythms is associated with better survival and neurological outcomes. METHOD: OHCA cases from the Pan-Asian Resuscitation Outcomes Study registry in 13 countries between January 2009 and February 2018 were retrospectively analyzed. Cases with missing initial rhythms, age <18 years, presumed non-medical cause of arrest, and not conveyed by emergency medical services were excluded. Multivariable logistic regression analysis was performed to evaluate the relationship between initial and subsequent shockable rhythm, survival to discharge, and survival with favorable neurological outcomes (cerebral performance category 1 or 2). RESULTS: Of the 116,387 cases included. 11,153 (9.6%) had initial shockable rhythms and 9,765 (8.4%) subsequently converted to shockable rhythms. Japan had the lowest proportion of OHCA patients with initial shockable rhythms (7.3%). For OHCA with initial shockable rhythm, the adjusted odds ratios (aOR) for survival and good neurological outcomes were 8.11 (95% confidence interval [CI] 7.62-8.63) and 15.4 (95%CI 14.1-16.8) respectively. For OHCA that converted from initial non-shockable to shockable rhythms, the aORs for survival and good neurological outcomes were 1.23 (95%CI 1.10-1.37) and 1.61 (95%CI 1.35-1.91) respectively. The aORs for survival and good neurological outcomes were 1.48 (95%CI 1.22-1.79) and 1.92 (95%CI 1.3 - 2.84) respectively for initial asystole, while the aOR for survival in initial pulseless electrical activity patients was 0.83 (95%CI 0.71-0.98). Prehospital adrenaline administration had the highest aOR (2.05, 95%CI 1.93-2.18) for conversion to shockable rhythm. CONCLUSION: In this ambidirectional cohort study, conversion from non-shockable to shockable rhythm was associated with improved survival and neurologic outcomes compared to rhythms that continued to be non-shockable. Continued advanced resuscitation may be beneficial for OHCA with subsequent conversion to shockable rhythms.

The Effect of Building-Level Socioeconomic Status on Bystander Cardiopulmonary Resuscitation: A Retrospective Cohort Study.

OBJECTIVE: Understanding the social determinants of bystander cardiopulmonary resuscitation (CPR) receipt can inform the design of public health interventions to increase bystander CPR. The association of socioeconomic status with bystander CPR is generally poorly understood. We evaluated the relationship between socioeconomic status and bystander CPR in cases of out-of-hospital cardiac arrest (OHCA). METHODS: This was a retrospective cohort study based on the Singapore cohort of the Pan-Asian Resuscitation Outcomes Study registry between 2010 and 2018. We categorized patients into low, medium, and high Singapore Housing Index (SHI) levels-a building-level index of socioeconomic status. The primary outcome was receipt of bystander CPR. The secondary outcomes were prehospital return of spontaneous circulation and survival to discharge. RESULTS: A total of 12,730 OHCA cases were included, the median age was 71 years, and 58.9% were male. The bystander CPR rate was 56.7%. Compared to patients in the low SHI category, those in the medium and high SHI categories were more likely to receive bystander CPR (medium SHI: adjusted odds ratio [aOR] 1.48, 95% CI 1.30-1.69; high SHI: aOR 1.93, 95% CI 1.67-2.24). High SHI patients had higher survival compared to low SHI patients on unadjusted analysis (OR 1.79, 95% CI 1.08-2.96), but not adjusted analysis (adjusted for age, sex, race, witness status, arrest time, past medical history of cancer, and first arrest rhythm). When comparing high with low SHI, females had larger increases in bystander CPR rates than males. CONCLUSIONS: Lower building-level socioeconomic status was independently associated with lower rate of bystander CPR, and females were more susceptible to the effect of low socioeconomic status on lower rate of bystander CPR.

myResponder Smartphone Application to Crowdsource Basic Life Support for Out-of-Hospital Cardiac Arrest: The Singapore Experience.

OBJECTIVE: The Singapore myResponder is a novel smartphone application developed by the Singapore Civil Defence Force (SCDF) that notifies volunteer first responders of a suspected out-of-hospital cardiac arrest (OHCA) case and locations of Automated External Defibrillators (AED) in the vicinity so that they can assist with resuscitation. We aimed to examine the performance of this application, challenges encountered, and future directions. Methods: We analyzed data from the myResponder app since its launch from April 2015 to July 2019. The number of installations, registered community first responders, suspected OHCA cases, notifications sent by the app, percentage of responders who accepted activation and arrived at scene were reviewed. A subgroup of taxi driving responders (within a 1.5-kilometer response radius) carrying an AED under a subsequent pilot program was also analyzed. Results: By July 2019, 46,689 responders were registered in the myResponder app. There were a total of 19,189 cases created for suspected OHCA, with a median of 358 cases per month (IQR 330-430), in which 10,073 responders accepted activation from myResponder and 4,955 arrived on-scene. A total of 135,599 notifications were sent for these cases, with a median of 7.1 notifications per case (IQR 4.3-8.7). In 2019, the percentages of responders who accepted notification and arrived on scene were 45.8% and 24.1%, respectively. 43% (1110/2581) of responders arrived before EMS crew. Conclusion: The myResponder mobile application is a feasible smart technology solution to improve community response to OHCA, and to increase bystander CPR and AED use. Future directions include increasing the number of active responders, improving response rates, app performance, and better data capture for quality improvement.

Improved Out-of-Hospital Cardiac Arrest Survival with a Comprehensive Dispatcher-Assisted CPR Program in a Developing Emergency Care System.

OBJECTIVE: Out-of-hospital cardiac arrest (OHCA) is associated with poor survival. Studies have demonstrated improved survival with early bystander cardiopulmonary resuscitation (BCPR). This study evaluated the impact of a dispatcher-assisted CPR (DA-CPR) program on BCPR rate and outcomes of OHCA in a developing emergency medical services (EMS) system setting. METHODS: Data were extracted from the national cardiac arrest registry. A before-after analysis was performed between OHCA cases with cardiac etiology conveyed by EMS from April 2010-June 2012 (pre-intervention) and July 2012-December 2015 (post-intervention). Primary outcomes were survival-to-discharge/30 days post-arrest and favorable cerebral performance (Glasgow-Pittsburgh cerebral performance categories 1 and 2). RESULTS: 6365 OHCA cases were analyzed with 2129 in the pre-intervention and 4236 in the post-intervention group. In the post-intervention group, there was an increase in BCPR rates from 24.8% to 53.8% (p < 0.001), adjusted OR 3.67 (aOR; 95%CI: 3.26-4.13). OHCA outcomes also improved with survival-to-discharge rates increasing from 3.0%-4.5% (p < 0.01), aOR 2.10 (95%CI: 1.40-3.17) and favorable cerebral performance increasing from 1.6% to 2.7% (p < 0.05), aOR 2.82 (95%CI: 1.65-4.82). In patients with initial shockable rhythm, BCPR without dispatcher assistance was associated with significantly higher odds of survival-to-discharge (aOR 1.67, 95%CI: 1.06-2.64) and favorable cerebral performance (aOR 2.32, 95%CI: 1.26-4.27) compared to no BCPR. CONCLUSION: Our study showed that a simplified DA-CPR program can be successfully implemented in a developing EMS system and can contribute to higher BCPR rate and in turn, improve OHCA survival. Future studies can examine bystanders' characteristics and quality of the CPR performed to understand their impact on survival.

Coronavirus disease 2019 (COVID-19): an evidence map of medical literature.

BACKGROUND: Since the beginning of the COVID-19 outbreak in December 2019, a substantial body of COVID-19 medical literature has been generated. As of June 2020, gaps and longitudinal trends in the COVID-19 medical literature remain unidentified, despite potential benefits for research prioritisation and policy setting in both the COVID-19 pandemic and future large-scale public health crises. METHODS: In this paper, we searched PubMed and Embase for medical literature on COVID-19 between 1 January and 24 March 2020. We characterised the growth of the early COVID-19 medical literature using evidence maps and bibliometric analyses to elicit cross-sectional and longitudinal trends and systematically identify gaps. RESULTS: The early COVID-19 medical literature originated primarily from Asia and focused mainly on clinical features and diagnosis of the disease. Many areas of potential research remain underexplored, such as mental health, the use of novel technologies and artificial intelligence, pathophysiology of COVID-19 within different body systems, and indirect effects of COVID-19 on the care of non-COVID-19 patients. Few articles involved research collaboration at the international level (24.7%). The median submission-to-publication duration was 8 days (interquartile range: 4-16). CONCLUSIONS: Although in its early phase, COVID-19 research has generated a large volume of publications. However, there are still knowledge gaps yet to be filled and areas for improvement for the global research community. Our analysis of early COVID-19 research may be valuable in informing research prioritisation and policy planning both in the current COVID-19 pandemic and similar global health crises.

Heart rate n-variability (HRnV) and its application to risk stratification of chest pain patients in the emergency department.

BACKGROUND: Chest pain is one of the most common complaints among patients presenting to the emergency department (ED). Causes of chest pain can be benign or life threatening, making accurate risk stratification a critical issue in the ED. In addition to the use of established clinical scores, prior studies have attempted to create predictive models with heart rate variability (HRV). In this study, we proposed heart rate n-variability (HRnV), an alternative representation of beat-to-beat variation in electrocardiogram (ECG), and investigated its association with major adverse cardiac events (MACE) in ED patients with chest pain. METHODS: We conducted a retrospective analysis of data collected from the ED of a tertiary hospital in Singapore between September 2010 and July 2015. Patients > 20 years old who presented to the ED with chief complaint of chest pain were conveniently recruited. Five to six-minute single-lead ECGs, demographics, medical history, troponin, and other required variables were collected. We developed the HRnV-Calc software to calculate HRnV parameters. The primary outcome was 30-day MACE, which included all-cause death, acute myocardial infarction, and revascularization. Univariable and multivariable logistic regression analyses were conducted to investigate the association between individual risk factors and the outcome. Receiver operating characteristic (ROC) analysis was performed to compare the HRnV model (based on leave-one-out cross-validation) against other clinical scores in predicting 30-day MACE. RESULTS: A total of 795 patients were included in the analysis, of which 247 (31%) had MACE within 30 days. The MACE group was older, with a higher proportion being male patients. Twenty-one conventional HRV and 115 HRnV parameters were calculated. In univariable analysis, eleven HRV and 48 HRnV parameters were significantly associated with 30-day MACE. The multivariable stepwise logistic regression identified 16 predictors that were strongly associated with MACE outcome; these predictors consisted of one HRV, seven HRnV parameters, troponin, ST segment changes, and several other factors. The HRnV model outperformed several clinical scores in the ROC analysis. CONCLUSIONS: The novel HRnV representation demonstrated its value of augmenting HRV and traditional risk factors in designing a robust risk stratification tool for patients with chest pain in the ED.

Randomized controlled trial of internal and external targeted temperature management methods in post- cardiac arrest patients.

BACKGROUND: Targeted temperature management post-cardiac arrest is currently implemented using various methods, broadly categorized as internal and external. This study aimed to evaluate survival-to-hospital discharge and neurological outcomes (Glasgow-Pittsburgh Score) of post-cardiac arrest patients undergoing internal cooling verses external cooling. METHODOLOGY: A randomized controlled trial of post-resuscitation cardiac arrest patients was conducted from October 2008-September 2014. Patients were randomized to either internal or external cooling methods. Historical controls were selected matched by age and gender. Analysis using SPSS version 21.0 presented descriptive statistics and frequencies while univariate logistic regression was done using R 3.1.3. RESULTS: 23 patients were randomized to internal cooling and 22 patients to external cooling and 42 matched controls were selected. No significant difference was seen between internal and external cooling in terms of survival, neurological outcomes and complications. However in the internal cooling arm, there was lower risk of developing overcooling (p=0.01) and rebound hyperthermia (p=0.02). Compared to normothermia, internal cooling had higher survival (OR=3.36, 95% CI=(1.130, 10.412), and lower risk of developing cardiac arrhythmias (OR=0.18, 95% CI=(0.04, 0.63)). Subgroup analysis showed those with cardiac cause of arrest (OR=4.29, 95% CI=(1.26, 15.80)) and sustained ROSC (OR=5.50, 95% CI=(1.64, 20.39)) had better survival with internal cooling compared to normothermia. Cooling curves showed tighter temperature control for internal compared to external cooling. CONCLUSION: Internal cooling showed tighter temperature control compared to external cooling. Internal cooling can potentially provide better survival-to-hospital discharge outcomes and reduce cardiac arrhythmia complications in carefully selected patients as compared to normothermia.

Comparison of epidemiology, treatments and outcomes of ST segment elevation myocardial infarction between young and elderly patients.

BACKGROUND: With an ageing population, there is a need to understand the relative risk/benefit of interventions for elderly ST segment elevation myocardial infarction (STEMI) patients. The primary aim of this study was to compare epidemiology, treatments and outcomes between young and elderly STEMI patients. Our secondary aim was to determine the cut-off age when the benefits of primary percutaneous coronary intervention (PCI) were less pronounced. METHODS: Data were collected by the Singapore Myocardial Infarction Registry. Patients were categorised into young (age <65 years) and elderly STEMI (age ≥65 years) patients. RESULTS: We analysed 14 006 STEMI cases collected between January 2007 and December 2014; 33.9% were elderly STEMI patients. Elderly STEMI patients had longer median door to balloon (73 vs 64 min, P<0.001) time and were less likely to receive PCI (proportion difference=-23.6%, 95% CI -25.3 to -22.0). In the absence of PCI, elderly STEMI patients had a higher mortality within 30 days (elderly: HR 1.65, 95% CI 1.36 to 1.99, P<0.001; young: HR 1.10, 95% CI 0.79 to 1.54, P=0.573) and 1 year (elderly: HR 1.83, 95% CI 1.57 to 2.14, P<0.001; young: HR 1.41, 95% CI 1.09 to 1.83, P=0.009) of admission. The 1 year survival benefit of PCI started to decline after the age of 65 years. CONCLUSION: Elderly STEMI patients were less likely to receive PCI and had longer door to balloon times. Survival benefit of PCI decreased after the age of 65 years, with the decline most evident from age 85 years onwards. The risks of PCI need to be weighed carefully against its benefits, especially in very elderly patients.

Conversion to shockable rhythms during resuscitation and survival for out-of hospital cardiac arrest.

BACKGROUND: In out of hospital cardiac arrest (OHCA), the prognostic influence of conversion to shockable rhythms during resuscitation for initially non-shockable rhythms remains unknown. This study aimed to assess the relationship between initial and subsequent shockable rhythm and post-arrest survival and neurological outcomes after OHCA. METHODOLOGY: This was a retrospective analysis of all OHCA cases collected from the Pan-Asian Resuscitation Outcomes Study (PAROS) registry in 7 countries in Asia between 2009 and 2012. We included OHCA cases of presumed cardiac etiology, aged 18-years and above and resuscitation attempted by EMS. We performed multivariate logistic regression analyses to assess the relationship between initial and subsequent shockable rhythm and survival and neurological outcomes. 2-stage seemingly unrelated bivariate probit models were developed to jointly model the survival and neurological outcomes. We adjusted for the clustering effects of country variance in all models. RESULTS: 40,160 OHCA cases met the inclusion criteria. There were 5356 OHCA cases (13.3%) with initial shockable rhythm and 33,974 (84.7%) with initial non-shockable rhythm. After adjustment of baseline and prehospital characteristics, OHCA with initial shockable rhythm (odds ratio/OR=6.10, 95% confidence interval/CI=5.06-7.34) and subsequent conversion to shockable rhythm (OR=2.00,95%CI=1.10-3.65) independently predicted better survival-to-hospital-discharge outcomes. Subsequent shockable rhythm conversion significantly improved survival-to-admission, discharge and post-arrest overall and cerebral performance outcomes in the multivariate logistic regression and 2-stage analyses. CONCLUSION: Initial shockable rhythm was the strongest predictor for survival. However, conversion to subsequent shockable rhythm significantly improved post-arrest survival and neurological outcomes. This study suggests the importance of early resuscitation efforts even for initially non-shockable rhythms which has prognostic implications and selection of subsequent post-resuscitation therapy.

Emergency Medical Services Utilization among Patients with ST-Segment Elevation Myocardial Infarction: Observations from the Singapore Myocardial Infarction Registry.

OBJECTIVE: Early activation of emergency medical services (EMS), rapid transport, and treatment of patients experiencing ST-segment elevation myocardial infarction (STEMI) can improve outcomes. The Singapore Myocardial Infarction Registry (SMIR) is a nation-wide registry that collects data on STEMI. We aimed to determine the prevalence, predictors, and outcomes of EMS utilization among STEMI patients presenting to Emergency Departments (ED) in Singapore. METHODS: We analyzed STEMI patients enrolled by SMIR from January 2010 to December 2012. We excluded patients who were transferred, developed STEMI in-hospital or suffered cardiac arrest out-of-hospital or in the ED. Primary outcome was process-of-care timings. Secondary outcomes included the occurrence of cardiac complications. Multivariate analysis was used to examine independent factors associated with EMS transport. RESULTS: 6412 patients were enrolled into the study; 4667 patients were eligible for analysis. 49.8% of patients utilized EMS transport. EMS transport was associated with higher rate of reperfusion therapy (74.3% vs. 65.1%, p < 0.01), shorter median symptom-to-door time (119 vs. 182 minutes, p < 0.01), door-to-balloon time (59 vs. 70 minutes, p < 0.01), and symptom-to-balloon time (185 vs. 233 minutes, p < 0.01). EMS transport had more patients with Killip Class 4 (7.5% vs 4.0%, p < 0.01) and was associated with greater presentation of heart failure, arrhythmias, and complete heart block. Independent predictors of EMS transport were age, syncope and Killip score; after-office-hour presentation was a negative predictor. CONCLUSION: Less than half of STEMI patients utilized EMS and EMS patients had faster receipt of initial reperfusion therapies. Targeted public education to reduce time to treatment may improve the care of STEMI patients.

Prehospital Trauma Care in Singapore.

Prehospital emergency care in Singapore has taken shape over almost a century. What began as a hospital-based ambulance service intended to ferry medical cases was later complemented by an ambulance service under the Singapore Fire Brigade to transport trauma cases. The two ambulance services would later combine and come under the Singapore Civil Defence Force. The development of prehospital care systems in island city-state Singapore faces unique challenges as a result of its land area and population density. This article defines aspects of prehospital trauma care in Singapore. It outlines key historical milestones and current initiatives in service, training, and research. It makes propositions for the future direction of trauma care in Singapore. The progress Singapore has made given her circumstances may serve as lessons for the future development of prehospital trauma systems in similar environments. Key words: Singapore; trauma; prehospital emergency care; emergency medical services.

Incidence and Long-Term Outcomes of Acute Myocardial Infarction Among Survivors of Out-of-Hospital Cardiac Arrest.

BACKGROUND: Despite the increasing long-term survival after out-of-hospital cardiac arrest (OHCA), the risk of subsequent acute myocardial infarction (AMI) remains poorly understood. We aimed to determine the incidence, predictors, and long-term outcomes of AMI among survivors of OHCA. METHODS AND RESULTS: We assembled a retrospective cohort of 882 patients with OHCA who survived to 30 days or discharge from the hospital between 2010 and 2019. Survivors of OHCA had an increased risk of subsequent AMI, defined as AMI occurring 30 days after index OHCA or following discharge from the hospital after OHCA, compared with the general population when matched for age and sex (standardized incidence ratio, 4.64 [95% CI, 3.52-6.01]). Age-specific risks of subsequent AMI for men (standardized incidence ratio, 3.29 [95% CI, 2.39-4.42]) and women (standardized incidence ratio, 6.15 [95% CI, 3.27-10.52]) were significantly increased. A total of 7.2%, 8.3%, and 14.3% of survivors of OHCA had a subsequent AMI at 3 years, 5 years, and end of follow-up, respectively. Age at OHCA (hazard ratio [HR], 1.04 [95% CI, 1.02-1.06]) and past medical history of prior AMI, defined as any AMI preceding or during the index OHCA event (HR, 1.84 [95% CI, 1.05-3.22]), were associated with subsequent AMI, while an initial shockable rhythm was not (HR, 1.00 [95% CI, 0.52-1.94]). Survivors of OHCA with subsequent AMI had a higher risk of death (HR, 1.58 [95% CI, 1.12-2.22]) than those without. CONCLUSIONS: Survivors of OHCA are at an increased risk of subsequent AMI compared with the general population. Prior AMI, but not an initial shockable rhythm, increases this risk, while subsequent AMI predicts death. Preventive measures for AMI including cardiovascular risk factor control and revascularization may thus improve outcomes in selected patients with cardiac pathogenesis.

Nationwide improvement of door-to-balloon times in patients with acute ST-segment elevation myocardial infarction requiring primary percutaneous coronary intervention with out-of-hospital 12-lead ECG recording and transmission.

STUDY OBJECTIVE: Reducing door-to-balloon times for acute ST-segment elevation myocardial infarction (STEMI) patients has been shown to improve long-term survival. We aim to reduce door-to-balloon time for STEMI patients requiring primary percutaneous coronary intervention by adoption of out-of-hospital 12-lead ECG transmission by Singapore's national ambulance service. METHODS: This was a nationwide, before-after study of STEMI patients who presented to the emergency departments (ED) and required percutaneous coronary intervention. In the before phase, chest pain patients received 12-lead ECGs in the ED. In the after phase, 12-lead ECGs were performed by ambulance crews and transmitted from the field to the ED. Patients whose ECG showed greater than or equal to 2 mm ST-segment elevation in anterior or greater than or equal to 1 mm ST-segment elevation in inferior leads for 2 or more contiguous leads and symptom onset of less than 12 hours' duration were eligible for percutaneous coronary intervention activation before arrival. RESULTS: ECGs (2,653) were transmitted by the ambulance service; 180 (7%) were suspected STEMI. One hundred twenty-seven patients from the before and 156 from the after phase met inclusion criteria for analysis. Median door-to-balloon time was 75 minutes in the before and 51 minutes in the after phase (median difference=23 minutes; 95% confidence interval 18 to 27 minutes). Median door-to-balloon times were significantly reduced regardless of presentation hours. Overall, there was significant reduction in door-to-activation, door-to-ECG, and door-to-cardiovascular laboratory times. No significant difference was found pertaining to adverse events. CONCLUSION: This study describes a nationwide implementation of out-of-hospital ECG transmission resulting in reduced door-to-balloon times, regardless of presentation hours. Out-of-hospital ECG transmission should be adopted as best practice for management of chest pain.

Barriers and facilitators for developing a prehospital emergency care system evaluation tool (PEC-SET) for low-resource settings: a qualitative analysis.

OBJECTIVES: Strengthening of emergency care systems, including prehospital systems, can reduce death and disability. We aimed to identify perspectives on barriers and facilitators relating to the development and implementation of a prehospital emergency care system assessment tool (PEC-SET) from prehospital providers representing several South and Southeast (SE) Asian countries. DESIGN: We conducted a qualitative study using focus group discussions (FGD) informed by the Consolidated Framework for Implementation Research (CFIR). FGDs were conducted in English, audioconferencing/videoconferencing was recorded, transcribed verbatim and coded using an inductive and deductive approach. Participants suggested specific elements to be measured within three main 'pillars' of disease conditions proposed by the research team of the tool being developed (cardiovascular, trauma and perinatal emergencies). SETTING: We explored the perspectives of medical directors in six low-income and middle-income countries (LMICs) in South and SE Asia. PARTICIPANTS: A total of 16 participants were interviewed (1 Vietnam, 4 Philippines, 4 Thailand, 5 Malaysia, 1 Indonesia and 1 Pakistan) as a part of 4 focus groups. RESULTS: Themes identified within the four CFIR constructs included: (1) Intervention characteristics: importance of developing an contextually specific tool, need for generalisability, trialling in one geographical area or with one pillar before expanding; (2) Inner setting: data transfer barriers, workforce shortages; (3) Outer setting: underdevelopment of EMS nationally; need for further EMS system development prior to implementing a tool and (4) Individual characteristics: lack of buy-in by prehospital personnel. Elements proposed by participants included both process and outcome measures. CONCLUSIONS: Through the CFIR framework, we identified several themes which can provide a basis for codeveloping a PEC-SET for LMICs with local stakeholders. This work may inform development of quality improvement tools in LMIC PEC systems.

Determinants of health-related quality of life after out-of-hospital cardiac arrest (OHCA): A systematic review.

OBJECTIVE: With a growing number of out-of-hospital cardiac arrest (OHCA) survivors globally, the focus of OHCA management has now broadened to survivorship. An outcome central to survivorship is health-related quality of life (HRQoL). This systematic review aimed to synthesise evidence related to the determinants of HRQoL of OHCA survivors. METHODS: We systematically searched MEDLINE, Embase, and Scopus from inception to 15 August 2022 to identify studies investigating the association of at least one determinant and HRQoL in adult OHCA survivors. All articles were independently reviewed by two investigators. We abstracted data pertaining to determinants and classified them using a well-established HRQoL theoretical framework - the Wilson and Cleary (revised) model. RESULTS: 31 articles assessing a total of 35 determinants were included. Determinants were classified into the five domains in the HRQoL model. 26 studies assessed determinants related to individual characteristics (n = 3), 12 studied biological function (n = 7), nine studied symptoms (n = 3), 16 studied functioning (n = 5), and 35 studied characteristics of the environment (n = 17). In studies that included multivariable analyses, most reported that individual characteristics (older age, female sex), symptoms (anxiety, depression), and functioning (impaired neurocognitive function) were significantly associated with poorer HRQoL. CONCLUSIONS: Individual characteristics, symptoms, and functioning played significant roles in explaining the variability in HRQoL. Significant non-modifiable determinants such as age and sex could be used to identify populations at risk of poorer HRQoL, while significant modifiable determinants such as psychological health and neurocognitive functioning could serve as targets for post-discharge screening and rehabilitation plans. PROSPERO registration number: CRD42022359303.

Long term survival and disease burden from out-of-hospital cardiac arrest in Singapore: a population-based cohort study.

Background: Understanding the long-term outcomes and disability-adjusted life years (DALY) after out-of-hospital cardiac arrest (OHCA) is important to understand the overall health and disease burden of OHCA respectively, but data in Asia remains limited. We aimed to quantify long-term survival and the annual disease burden of OHCA within a national multi-ethnic Asian cohort. Methods: We conducted an open cohort study linking the Singapore Pan-Asian Resuscitation Outcomes Study (PAROS) and the Singapore Registry of Births and Deaths from 2010 to 2019. We performed Cox regression, constructed Kaplan-Meier curves, and calculated DALYs and standardised mortality ratios (SMR) for each year of follow-up. Results: We analysed 802 cases. The mean age was 56.0 (SD 17.8). Most were male (631 cases, 78,7%) and of Chinese ethnicity (552 cases, 68.8%). At one year, the SMR was 14.9 (95% CI:12.5-17.8), decreasing to 1.2 (95% CI:0.7-1.8) at three years, and 0.4 (95% CI:0.2-0.8) at five years. Age at arrest (HR:1.03, 95% CI:1.02-1.04, p < 0.001), shockable presenting rhythm (HR:0.75, 95% CI:0.52-0.93, p = 0.015) and CPC category (HR:4.62, 95% CI:3.17-6.75, p < 0.001) were independently associated with mortality. Annual DALYs due to OHCA varied from 304.1 in 2010 to 849.7 in 2015, then 547.1 in 2018. Mean DALYs decreased from 12.162 in 2010 to 3.599 in 2018. Conclusions: OHCA survivors had an increased mortality rate for the first three years which subsequently normalised compared to that of the general population. Annual OHCA disease burden in DALY trended downwards from 2010 to 2018. Improved surveillance and OHCA treatment strategies may improve long-term survivorship and decrease its global burden. Funding: National Medical Research Council, Singapore, under the Clinician Scientist Award (NMRC/CSA-SI/0014/2017) and the Singapore Translational Research Investigator Award (MOH-000982-01).

Impact of time-to-compression on out-of-hospital cardiac arrest survival outcomes: A national registry study.

OBJECTIVE: We aimed to quantify the association of no-flow interval in out-of-hospital cardiac arrests (OHCA) with the odds of neurologically favorable survival and survival to hospital discharge/ 30th day. Our secondary aim was to explore futility thresholds to guide clinical decisions, such as prehospital termination of resuscitation. METHODS: All OHCAs from 2012 to 2017 in Singapore were extracted. We examined the association between no-flow interval (continuous variable) and survival outcomes using univariate and multivariable logistic regressions. The primary outcome was survival with favorable cerebral performance (Glasgow-Pittsburgh Cerebral Performance Categories 1/2), the secondary outcome was survival to hospital discharge/ 30th day if not discharged. To determine futility thresholds, we plotted the adjusted probability of good neurological outcomes to no-flow interval. RESULTS: 12,771 OHCAs were analyzed. The per-minute adjusted OR when no-flow interval was incorporated as a continuous variable in the multivariable model was: good neurological function- aOR 0.98 (95%CI: 0.97-0.98); survival to discharge- aOR 0.98 (95%CI: 0.98-0.99). Taking the 1% futility of survival line gave a no-flow interval cutoff of 12 mins (NPV 99%, sensitivity 85% and specificity 42%) overall and 7.5 mins for witnessed arrests. CONCLUSION: We demonstrated that prolonged no-flow interval had a significant effect on lower odds of favorable neurological outcomes, with medical futility occurring when no-flow interval was >12 mins (>7.5 mins for witnessed arrest). Our study adds to the literature of the importance of early CPR and EMS response and provided a threshold beyond traditional 'down-times', which could aid clinical decisions in TOR or OHCA management.

Ambient temperature and hospital admissions for non-ST segment elevation myocardial infarction in the tropics.

BACKGROUND: Myocardial infarction is an important cause of cardiovascular mortality and can be precipitated by climatic factors. The temperature dependence of myocardial infarction risk has been well examined in temperate settings. Fewer studies have investigated this in the tropics where thermal amplitudes are narrower. This study investigated how ambient temperature influenced the risk of non-ST segment elevation myocardial infarction (NSTEMI), an increasingly common type of myocardial infarction, in the tropical city-state of Singapore. METHODS: All nationally reported NSTEMI cases from 2009 to 2018 were included and assessed for its short-term association with ambient temperature using conditional Poisson regression models that comprised a three-way interaction term with year, month and day of the week and adjusted for relative humidity. The Distributed Lag Non-Linear Modelling (DLNM) was used to account for the immediate and lagged effects of environmental exposures. Stratified analysis by sex and age groups was undertaken to assess potential effect modification. RESULTS: There were 60,643 reports of NSTEMI. Temperature decline (cool effect) was associated with a delayed cumulative, non-linear increase in NSTEMI risk over 10 days post exposure [Relative Risk (RRlag0-10, 10th percentile: 1.12, 95%CI: 1.02-1.24)]. Those aged 65 years and above were potentially more susceptible (RR lag0-10, 10th percentile: 1.19, 95 % CI: 1.06-1.33) to the cool effect compared to those below that age (RRlag0-10, 10th percentile: 1.00, 95 % CI: 0.85-1.18) (p-value for difference = 0.087). CONCLUSION: Short-term temperature fluctuations were independently associated with NSTEMI incidence in the tropics, with age as a potential effect modifier of this association. An increase in the frequency of climate change driven temperature events may trigger more instances of NSTEMI in tropical cosmopolitan cities.

Association of air pollution with acute ischemic stroke risk in Singapore: a time-stratified case-crossover study.

BACKGROUND: Air quality is an important determinant of cardiovascular health such as ischemic heart disease and acute ischemic stroke (AIS) with substantial mortality and morbidity reported across the globe. However, associations between air quality and AIS in the current literature remain inconsistent, with few studies undertaken in cosmopolitan cities located in the tropics. OBJECTIVES: We evaluated the associations between individual ambient air pollutants and AIS. METHODS: We performed a nationwide, population-based, time-stratified case-crossover analysis on all AIS cases reported to the Singapore Stroke Registry from 2009 to 2018. We estimated the incidence rate ratio (IRR) of AIS across different concentrations of each pollutant by quartiles (referencing the 25th percentile), in single-pollutant conditional Poisson models adjusted for time-varying meteorological effects. We stratified our analysis by predetermined subgroups deemed at higher risk. RESULTS: A total of 51,675 episodes of AIS were included. Ozone (O3) (IRR4th quartile: 1.05, 95% confidence interval (CI): 1.01-1.08) and carbon monoxide (CO) (IRR2nd quartile: 1.05, 95% CI: 1.02-1.08, IRR3rd quartile: 1.07, 95% CI: 1.04-1.10, IRR4th quartile: 1.07, 95% CI: 1.04-1.11) were positively associated with AIS incidence. The increased incidence of AIS due to O3 and CO persisted for 5 days after exposure. Those under 65 years of age were more likely to experience AIS when exposed to CO. Individuals with atrial fibrillation (AF) were more susceptible to exposure from O3, CO, and PM10. Current/ex-smokers were more vulnerable to the effect of O3. CONCLUSION: Air pollution increases the incidence of AIS, especially in those with AF and in those who are current or ex-smokers.