Stress and burnout amongst mental health professionals in Singapore during Covid-19 endemicity

The COVID-19 pandemic has exerted a huge emotional strain on mental health professionals (MHP) in Singapore. As Singapore transited into an endemic status, it is unclear whether the psychological strain has likewise lessened. The aims of this study were to investigate the levels of stress and burnout experienced by MHP working in a tertiary psychiatric hospital in Singapore during this phase of COVID-19 endemicity (2022) in comparison to the earlier pandemic years (2020 and 2021) and to identify factors which contribute to as well as ameliorate stress and burnout. A total of 282 MHP participated in an online survey in 2022, which included 2 validated measures, namely the Perceived Stress Scale and the Oldenburg Burnout Inventory (OLBI). Participants were also asked to rank factors that contributed the most to their stress and burnout. Between-group comparisons were conducted regarding stress and burnout levels among MHP across different demographic groupings and working contexts. In addition, OLBI data completed by MHP in 2020 and 2021 were extracted from 2 published studies, and trend analysis was conducted for the proportion of MHP meeting burnout threshold across 3 time points. We found that the proportion of MHP meeting burnout threshold in 2020, 2021 and 2022 were 76.9%, 87.6% and 77.9% respectively. Professional groups, age, years of experience and income groups were associated with stress and/or burnout. High clinical workload was ranked as the top factor that contributed to stress and burnout while flexible working arrangement was ranked as the top area for improvement so as to reduce stress and burnout. As such, policy makers and hospital management may want to focus on setting clear mental health targets and facilitate manageable clinical workload, build manpower resiliency, optimize resources and provide flexible work arrangements to alleviate stress and burnout among MHP.

Comparing the Impact of Stenting vs. Medical Therapy for Intracranial Arterial Stenosis : A Systematic Review and One-stage and Two-stage Meta-Analysis of Randomized Clinical Trials

PURPOSE

In the treatment of intracranial arterial stenosis (ICAS), controversies remain regarding the optimal treatment strategy. Our study aims to conduct an individual patient-level data meta-analysis of existing RCTs comparing PTAS versus best medical therapy and to identify differences in outcomes such as incidence of ischemic stroke or death.

METHODS

Randomised controlled trials comparing the outcomes of stenting versus best medical therapy for patients who had symptomatic ICAS of >50%. Excluded studies included case reports, case series, reviews, observational studies,  letters or studies evaluating isolated angioplasty techniques without stenting. Data was extracted in accordance with PRISMA guidelines.

RESULTS

7 studies involving 1425 participants were included. There was an increased risk in the incidence of stroke and death within the first 30 days post-procedure for patients treated with PTAS over best medical therapy (RR = 2.22 [1.28-3.86], I² = 0%). Patients who underwent stenting also had a significantly higher risk of intracranial haemorrhage (RR = 12.66 [2.41-66.45], I² = 0%) and death (RR = 5.41 [1.20-24.28], I² = 0%).Under the shared frailty model, stenting when compared to medical therapy has a HR of 1.81 (95% CI:1.25-2.6) of stroke or death across 1 year. Under the parametric Royston-Parmar model, stenting has a significant decrease in the RMST(-0.83 months; 95% CI: -1.30-0.37). Stenting continued to show worse outcomes up to the 3 year mark with a HR of 1.60 (95% CI: 1.11-2.32).

CONCLUSIONS AND RELEVANCE

There is an increased risk of peri- and post-procedural stroke and death over best medical therapy in patients with symptomatic ICAS who undergo PTAS. Further work is required to refine patient selection and mitigate peri-procedural risks.

Revolutionizing the Management of Large-Core Ischaemic Strokes: Decoding the Success of Endovascular Therapy in the Recent Stroke Trials

Endovascular therapy (EVT) has revolutionized the management of acute ischaemic strokes with large vessel occlusion, with emerging evidence suggesting its benefit also in large infarct core volume strokes. In the last two years, four randomised controlled trials have been published on this topic-RESCUE-Japan LIMIT, ANGEL-ASPECT, SELECT2 and TENSION, with overall results showing that EVT improves functional and neurological outcomes compared to medical management alone. This review aims to summarise the recent evidence presented by these four trials and highlight some of the limitations in our current understanding of this topic.

Safety attitudes, burnout and well-being among healthcare workers during the COVID-19 pandemic: an Indo-Pacific regional cross-sectional study

Introduction

The coronavirus disease 2019 (COVID-19) pandemic has had an unprecedented impact in Asia and has placed significant burden on already stretched healthcare systems. We examined the impact of COVID-19 on the safety attitudes among healthcare workers (HCWs), as well as their associated demographic and occupational factors, and measures of burnout, depression and anxiety.

Methods

A cross-sectional survey study utilising snowball sampling was performed involving doctors, nurses and allied health professions from 23 hospitals in Singapore, Malaysia, India and Indonesia between 29 May 2020 and 13 July 2020. This survey collated demographic data and workplace conditions and included three validated questionnaires: the Safety Attitudes Questionnaire (SAQ), Oldenburg Burnout Inventory and Hospital Anxiety and Depression Scale. We performed multivariate mixed-model regression to assess independent associations with the SAQ total percentage agree rate (PAR).

Results

We obtained 3,163 responses. The SAQ total PARs were found to be 35.7%, 15.0%, 51.0% and 3.3% among the respondents from Singapore, Malaysia, India and Indonesia, respectively. Burnout scores were highest among respondents from Indonesia and lowest among respondents from India (70.9%-85.4% vs. 56.3%-63.6%, respectively). Multivariate analyses revealed that meeting burnout and depression thresholds and shifts lasting ≥12 h were significantly associated with lower SAQ total PAR.

Conclusion

Addressing the factors contributing to high burnout and depression and placing strict limits on work hours per shift may contribute significantly towards improving safety culture among HCWs and should remain priorities during the pandemic.

Sex-based comparisons of clinical characteristics and outcomes of patients with embolic stroke of undetermined source with implantable loop recorders

Funding Acknowledgements

Type of funding sources: None.

Introduction

Embolic strokes of undetermined source (ESUS) constitute a significant proportion of all ischemic strokes, but sex-based comparisons of clinical characteristics and outcomes of ESUS patients have not been well explored. As such, we aimed to examine how sex influences outcomes of ESUS patients.

Methods

Retrospective cohort study performed on consecutive ESUS patients with an implanted ILR between December 2013 to September 2021. We obtained information on the patients’ characteristics, treatments, and outcomes from the electronic medical records. Cox regression was used to investigate whether sex was independently associated with outcomes.

Results

There were 176 patients included in this study. The mean duration of follow-up was 1254 ± 724 days. Mean age was 60.8 ± 12.0 and 47 (26.7%) of patients were female. On univariable Cox regression analysis for subsequent atrial fibrillation (AF) on implantable loop recorder (ILR), patients with subsequent AF on ILR were more likely to be female (HR 2.19, 95% CI 1.04–4.63, p = 0.040), older (HR 1.07, 95% CI 1.03–1.12, p = 0.001), have a lower glomerular filtration rate (eGFR) (HR 0.98, 95% CI 0.97– 0.99, p = 0.004), and have previous percutaneous coronary intervention (PCI) (HR 2.60, 95% CI 1.05–6.46, p = 0.039). On multivariable Cox regression, after adjustment for age, eGFR and previous PCI status, female sex remained independently associated with the development of subsequent AF on ILR. Female sex was not associated with other outcomes including mortality, subsequent acute myocardial infarction, stroke/transient ischemic attack and heart failure.

Conclusions

In this cohort of ESUS patients with ILR implantation, female sex was independently associated with a higher risk of development of AF on ILR. However, female sex was not a predictor of mortality, subsequent acute myocardial infarction, stroke/transient ischemic attack and heart failure.

Abnormal left atrial strain is associated with eventual diagnosis of atrial fibrillation in patients with embolic stroke of undetermined source

Funding Acknowledgements

Type of funding sources: None.

Background

Patients with embolic stroke of undetermined source (ESUS) have no immediate attributable cause despite initial evaluation. Occult paroxysmal atrial fibrillation (pAF) diagnosed on prolonged electrocardiographic monitoring may be subsequently found in 20% of patients initially classified as ESUS [1]. Anatomic and functional alterations of left atrium (LA) are known to predict pAF in the general population [2]. Recent studies have suggested that LA dysfunction is linked to the risk of development of pAF in stroke patients and may precede LA enlargement [1]. LA strain analysis may be helpful to predict the development of pAF as it can detect subclinical functional impairment [2]. The aim of this study was to analyse whether LA strain can be a marker for the development of new-onset AF in patients with ESUS and sinus rhythm.

Methods

Our single-centre observational cohort study examined 157 patients hospitalised for ESUS in our tertiary hospital between October 2014 and October 2017 who underwent AF monitoring with an implantable loop recorder (ILR). These patients were followed up for occurrence of new-onset pAF and recurrence of ischaemic stroke. All patients underwent transthoracic echocardiography (TTE) during index hospitalisation as part of the workup for ESUS. Echocardiographic images were obtained and analysed post-hoc for two-dimensional (2D) speckle tracing deformation parameters. These LA strain parameters were analysed against the primary outcome of AF detection and secondary outcome of recurrent ischaemic stroke.

Results

A total of 157 ESUS patients, with a mean age of 61.0 (±11.6) years, were followed up for a median duration of 3.5 (interquartile range 3.29) years. ILR monitoring detected AF in 27 patients (17.2%). 27 patients developed recurrent ischaemic strokes. Of the 27 patients with newly diagnosed AF on ILR, 24 (88.9%) were commenced on oral anticoagulation; the remaining 3 patients were not on anticoagulation due to high bleeding risk and frailty.

Patients who had newly diagnosed AF had more impaired left atrial reservoir strain (LASr; 23.5% ± 10.3%, P = 0.042) and left atrial conduit strain (LAScd; -10.5% ± 5.3%, P = 0.003) compared with patients who remained in sinus rhythm. Multivariable logistic regression analysis adjusting for age, sex, hypertension, hyperlipidaemia, diabetes mellitus and left ventricular ejection fraction (LVEF) showed that LAScd was associated with occult AF (adjusted odds ratio [aOR] = 1.110, 95% CI, 1.019-1.209, P = 0.017) and the composite outcome of AF and recurrent ischaemic stroke (OR = 1.069, 95% CI, 1.014-1.138, P = 0.038). Abnormal LAScd was significantly associated with occult AF even when stratified by normal LA volume index (LAVI) (OR = 2.672, 95% CI, 1.035-8.548, P = 0.048) and high LAVI (OR = 1.713, 95% CI, 1.023-2.869, P = 0.041).

Conclusion

Impaired left atrial strain was associated with occult AF detection in patients with ESUS undergoing ILR monitoring.

Characteristics and outcomes of aortic stenosis patients with and without stroke

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Sia CH was supported by the National University of Singapore Yong Loo Lin School of Medicine’s Junior Academic Faculty Scheme

Background

Aortic stenosis (AS) is related to several atherosclerosis risk factors and is associated with an increased risk of ischaemic stroke. Some reports suggest that aortic valve calcification may predispose to embolic stroke although this is not well-studied. The literature is also sparse regarding individual stroke subtypes and predictors of stroke in AS.

Purpose

We aimed to 1) Describe rates of ischaemic stroke in AS including specific stroke subtypes; 2) Compare clinical and echocardiographic characteristics of patients with AS who subsequently developed ischaemic stroke versus those who did not, and 3) Identify independent variables associated with subsequent stroke in AS.

Methods

Patients with AS were recruited from an echocardiography database from September 2011 to December 2015 at a single tertiary centre. The primary study endpoint was acute ischaemic stroke. Clinical characteristics and echocardiographic parameters were compared between patients who suffered a stroke after AS diagnosis and those who did not. Multivariable Cox regression analysis was used to identify factors associated with subsequent stroke.

Results

A total of 703 patients with AS were studied, with a median follow-up duration of 3.0 (IQR 0.5, 5.0) years. Twenty-two patients (3.1%) developed stroke following AS diagnosis (large vessel, 18.2%; cardioembolic, 50.0%; small vessel, 18.2%; other determined ischaemic stroke, 13.6%). These patients had a greater prevalence of previous stroke or transient ischaemic attack (TIA) (50.0%) compared to patients who did not develop subsequent stroke (20.9%), p<0.001. Patients with AS who developed subsequent stroke also more commonly had atrial fibrillation at the time of indexed echocardiography (40.0%) compared to their counterparts who did not develop stroke (13.5%), p=0.004 (Table 1). Other cardiovascular risk factors and traditional echocardiographic parameters of AS severity were similar between the 2 groups. Degenerative calcified aortic valve was not associated with the development of all types of ischaemic stroke or cardioembolic stroke. AS severity was also not associated with development of stroke. Multivariable Cox regression analysis found previous stroke or TIA (HR 8.00, 95% CI 2.70–23.58, p<0.001) and atrial fibrillation at time of echocardiography (HR 8.81, 95% CI 1.34–10.80, p=0.012) to be independent predictors of subsequent stroke in AS. The key findings of our study are summarised in Figure 1.

Conclusions

Cardioembolic stroke is the most common stroke subtype in patients with AS. Previous history of stroke or TIA and atrial fibrillation at time of diagnostic echocardiography are independent predictors of subsequent stroke in AS. Calcified aortic valve was not found to be a risk factor for all types of ischaemic stroke or cardioembolic stroke.

Interplay between post-myocardial infarction ejection fraction and atrial fibrillation: implications for ischemic stroke

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Singapore Ministry of Health’s National Medical Research Council

Background

There are little data on the interplay between post-acute myocardial infarction (MI), left ventricular systolic dysfunction and atrial fibrillation (AF) and the impact on subsequent acute ischemic stroke (AIS), particularly among patients with moderately reduced ejection fraction (EF).

Purpose

We aimed to study the association between low EF, AF and the risk and severity of AIS.

Methods

This study linked national, population-based data from the Singapore Myocardial Infarction Registry with the Singapore Stroke Registry from 2007 to 2018. The EF and AF status were recorded during the index MI hospitalization. Patients were grouped based on an EF of ≥50% or <50%. An additional grouping of patients with AMI in 2008 to 2018 and EF of ≥50% (normal EF), 40-49% (mildly reduced EF) or <40% (reduced EF) was done. The primary outcome of interest was the risk of developing an AIS after an AMI. The secondary outcome of interest was the National Institute of Health Stroke Scale (NIHSS) across the different strata of EF among AMI patients with subsequent AIS.

Results

There were 64512 patients available for analysis. The median age was 65.7 and 69.5% were male. The median duration from MI to AIS was 16.9 (IQR 1.6-46.1) months. Low EF <40% was independently associated with subsequent AIS (adjusted HR 1.18, 95% CI 1.10-1.27), as was EF 40-49% (adjusted HR 1.16, 95% CI 1.06-1.27). Among patients with AF, EF<50% was not a statistically significant predictor of AIS (adjusted HR 1.08, 95% CI 0.96-1.23). In patients without AF, the mildly reduced EF group had an increased aHR of AIS of 1.18 (95% CI 1.06-1.31), but not those with AF (aHR 1.03, 95% CI 0.87-1.23). The cubic spline curves of continuous EF against relative hazard for stroke stratified by presence of AF is shown in Figure 1. Patients with low EF without AF had highest median NIHSS score during subsequent AIS (EF <40% NIHSS 6-9; EF 40-49% NIHSS 4; EF ≥50% NIHSS 4).

Conclusions

Reduced and moderately reduced EF post-MI was independently associated with subsequent AIS and was associated with increased AIS severity in patients without AF but not in those with AF. Further research is needed to mitigate the risk of late AIS among post-MI patients with reduced EF along with AF.

Clinical characteristics, echocardiographic features and long-term outcomes of patients with ischaemic versus non-ischaemic left ventricular thrombus

Background

Left ventricular thrombus (LVT) may develop in patients following myocardial infarction (MI), as well as in ischaemic and non-ischaemic cardiomyopathies, and may result in acute ischaemic stroke. Smaller studies comparing LVT associated with ischaemic and non-ischaemic aetiologies only reported 1-year outcomes or focused on specific subpopulations. We aimed to compare the clinical and echocardiographic characteristics and longer-term outcomes in a large population of patients with ischaemic versus non-ischaemic LVT.

Methods

This was a retrospective study of 552 consecutive patients with echocardiographically-identified LVT from March 2011 to January 2021 at a tertiary centre. Ischaemic LVT included LVT associated with MI and ischaemic cardiomyopathy. Non-ischaemic LVT included cases without evidence of ischaemia. Echocardiographic images were interpreted by trained cardiologists. We studied thrombus resolution as well as 5-year rates of ischaemic stroke and all-cause mortality.

Results

Of the 552 patients, mean age was 59.9 years and 84.4% were male. 492 patients had ischaemic LVT and 60 patients had non-ischaemic LVT. Ischaemic LVT was associated with older age (60.4 versus 55.3 years), male sex (86.8% versus 65.0%), smoking (49.2% versus 25.0%) and hyperlipidaemia (54.3% versus 28.3%). Left ventricular ejection fraction (LVEF) was lower in non-ischaemic LVT (28.9% versus 31.9%). LVEF ≤35% was associated with increased mortality in ischaemic LVT (HR 2.11, 95% CI 1.32–3.38). Rates of thrombus resolution, stroke and all-cause mortality were similar in the 2 groups. Anticoagulation was associated with a lower risk of stroke in ischaemic LVT (HR 0.32, 95% CI 0.16–0.66) and lower mortality in both ischaemic (HR 0.44, 95% CI 0.26–0.72) and non-ischaemic LVT (HR 0.14, 95% CI 0.03–0.61).

Conclusion

Patients with ischaemic LVT were more often older, male, smokers and had cardiovascular co-morbidities compared to those with non-ischaemic LVT. Thrombus resolution, stroke and all-cause mortality rates were similar in both groups. Anticoagulation was associated with lower mortality but this needs to be investigated in future prospective studies.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): CHS was supported by the National University of Singapore Yong Loo Lin School of Medicine's Junior Academic Faculty Scheme

Stress hyperglycaemia is associated with poor functional outcomes in patients with acute ischaemic stroke after intravenous thrombolysis

BACKGROUND

Transient hyperglycaemia in the context of illness with or without known diabetes has been termed as 'stress hyperglycaemia'. Stress hyperglycaemia can result in poor functional outcomes in patients with acute ischaemic stroke (AIS) who underwent mechanical thrombectomy. We investigated the association between stress hyperglycaemia and clinical outcomes in AIS patients undergoing intravenous thrombolysis (IVT).

METHODS

We examined 666 consecutive patients with AIS who underwent IVT from 2006 to 2018. All patients had a glycated haemoglobin level (HbA1c) and fasting venous blood glucose measured within 24 h of admission. Stress hyperglycaemia ratio (SHR) was defined as the ratio of the fasting glucose to the HbA1c. Univariate and multivariate analyses were employed to identify predictors of poor functional outcomes (modified Rankin Scale 3-6 at 3 months) after IVT.

RESULTS

Three-hundred and sixty-one patients (54.2%) had good functional outcomes. These patients tended to be younger (60.7 ± 12.7 vs. 70 ± 14.4 years, P < 0.001), male (70.7% vs. 51.5%, P < 0.001), had lower prevalence of atrial fibrillation (13.0% vs. 20.7%, P = 0.008) and lower SHR (0.88 ± 0.20 vs. 0.99 ± 26, P < 0.001). Patients with high SHR (≥0.97) were slightly older than those with low SHR (<0.97) and were more likely to have diabetes mellitus. On multivariate analysis, higher SHR was independently associated with poor functional outcomes (adjusted odds ratio 3.85, 95% confidence interval 1.59-9.09, P = 0.003).

CONCLUSION

SHR appears to be an important predictor of functional outcomes in patients with AIS undergoing IVT. This may have important implications on the role of glycaemic control in the acute management of ischaemic stroke.

Preprocedural Imaging : A Review of Different Radiological Factors Affecting the Outcome of Thrombectomy

BACKGROUND

Endovascular treatment (EVT) has strong evidence for its effectiveness in treatment of acute ischemic stroke (AIS); however, up to half of the patients who undergo EVT still do not have good functional outcomes. Various prethrombectomy radiological factors have been shown to be associated with good clinical outcomes and may be the key to better functional outcomes, reduced complications, and reduced mortality. In this paper, we reviewed the current literature on these imaging parameters so they can be employed to better estimate the probability of procedural success, therefore allowing for more effective preprocedural planning of EVT strategies. We reviewed articles in the literature related to imaging factors which have been shown to be associated with EVT success. The factors which are reviewed in this paper included: anatomical factors such as 1) the type of aortic arch and its characteristics, 2) the characteristics of the thrombus such as length, clot burden, permeability, location, 3) the middle cerebral artery features including the tortuosity and underlying intracranial stenosis, 4) perfusion scans estimating the volume of infarct and the penumbra and 5) the effect of collaterals on the procedure. The prognostic effect of each factor on the successful outcome of EVT is described. The identification of preprocedural thrombectomy imaging factors can help to improve the chances of recanalization, functional outcomes, and mortality. It allows the interventionist to make time-sensitive decisions in the treatment of acute ischemic stroke.

Prevalence and diagnostic yield of investigating t wave inversion in a large unselected pre-participation cohort of young Asian males

Background/Introduction

T wave inversion (TWI) is a potentially abnormal finding on pre-participation screening electrocardiography (ECG), as it may suggest an underlying cardiomyopathy that should be risk stratified appropriately to minimise the risk of sports-related sudden cardiac death. Existing international guidelines prescribe criteria for investigating TWI in athletes. However, it is not established if these criteria can be extrapolated to screening unselected individuals. There is also evidence recommending against investigating specific patterns of anterior TWI in certain subsets of athletes due to low diagnostic yield; whether these exemptions may apply to non-athletes is uncertain. Given the importance of physical activity for primary prevention of cardiovascular disease in the general population, more evidence to guide pre-participation ECG screening of unselected individuals is needed.

Purpose

Firstly, to determine the epidemiology of abnormal TWI in a large unselected pre-participation cohort of young males of predominantly Asian ethnicity. Secondly, to determine the diagnostic yield of an echocardiography-guided approach to investigating individuals with abnormal TWI for a cardiomyopathy.

Methods

All individuals who attended a national centre for pre-enlistment cardiac screening over 39 months from 2017 were examined. Demographic data, anthropometric data and standardised physical fitness test scores were collected. Resting 12-lead ECG was performed for all individuals. Those with abnormal TWI, defined as a negatively deflected T wave of at least 0.1 mV amplitude in two contiguous leads, were referred to tertiary centres for echocardiography.

Results

69,714 consecutive males of mean age 17.9±1.1 years were screened. 562 individuals (0.8%) displayed abnormal TWI. Better aerobic fitness, but not muscular strength, was associated with a higher prevalence of abnormal TWI in general and specifically in the anterior territory, although not beyond leads V1-V2. Aerobic fitness had no association with abnormal TWI in the inferior territory or lateral territory. Of those with abnormal TWI, 12 individuals (2.1%) were newly diagnosed with a cardiomyopathy. Significant factors associated with a cardiomyopathy diagnosis were abnormal TWI in the lateral territory, abnormal TWI in the anterior territory beyond lead V2, deeper maximum TWI depth, presence of hypertension and higher body mass index. No individual presenting with TWI restricted to solely leads V1-V2 and/or two inferior leads without abnormal TWI in other contiguous leads was diagnosed with a cardiomyopathy.

Conclusion

Investigating abnormal TWI in an unselected pre-participation cohort of young Asian males had a significant yield, particularly in individuals manifesting abnormal TWI in the lateral territory and the anterior territory beyond lead V2. The ECG finding of anterior TWI in an unselected population may not be as benign as that in athletic populations.

Funding Acknowledgement

Type of funding sources: None. Abnormal TWI: Prevalence and Yield

Abstract P471: Ipsilateral Asymmetrical Internal Cerebral Vein on Multiphasic Computed Tomography for Acute Anterior Circulation Ischemic Stroke Thrombectomy is an Independent Predictor of Poor Functional Outcome

Background: National Institute of health stroke scale(NIHSS) and collateral circulation are well-established predictors for functional outcomes of endovascular thrombectomy (EVT) patients in acute ischemic stroke (AIS), nonetheless additional prognostic markers can improve the prediction of stroke outcomes. The inflow and drainage into the internal cerebral veins (ICV) can be seen consistently on multiphasic computed tomography angiography (mCTA). Thus, we hypothesize that asymmetry of ICV in the mCTA in large vessel occlusion AIS can be used as an adjunctive predictor of functional outcomes and complications.

Method: We enrolled 185 consecutive anterior circulation AIS patients who underwent EVT that presented to our hospital between 2017 and 2019. The collateral circulation was defined by the university of Calgary mCTA collateral flow assessment in stroke. The ICV on the ipsilateral occlusion side was compared with the contralateral side according to a binary scale: 1 (less than contralateral or absent) or 2(equal or greater than contralateral). The primary outcome was modified Rankin scale at 3 months (mRS), and secondary outcomes included symptomatic intracranial hemorrhage and mortality.

Result: Among 185 patients, 53% were men, the median age 70 years (range 29-91) and the median NIHSS score on arrival (NIHSS OA) was 19 (range 4-34). 82 patients (44.3%) had good functional outcomes at 3 months. Ipsilateral asymmetry in all three stages of mCTA were statistically significantly associated with good functional outcomes. The 1 st delay phase of mCTA showed the strongest association. On multivariate analysis, high NIHSS OA (OR 1.09, 95% CI 1.02-1.15, P = 0.007), good mCTA collateral score (OR 0.30, 95% CI .16- .53, P < .001), ipsilateral asymmetrical ICV on the 1 st delay phase of mCTA (OR 2.64, 95% CI 1.17-5.96, P = 0.01) were independent predictors of poor functional outcome. Ipsilateral asymmetry was not associated with mortality or symptomatic intracranial hemorrhage on multivariate analysis.

Conclusion: Ipsilateral assymetrical ICV is a novel radiological marker associated with functional outcomes after thrombectomy even after correction for the collateral circulation. Further studies should be done to validate this finding in different datasets.

Neurology of COVID-19 in Singapore

PURPOSE

To describe the spectrum of COVID-19 neurology in Singapore.

METHOD

We prospectively studied all microbiologically-confirmed COVID-19 patients in Singapore, who were referred for any neurological complaint within three months of COVID-19 onset. Neurological diagnoses and relationship to COVID-19 was made by consensus guided by contemporaneous literature, refined using recent case definitions.

RESULTS

47,572 patients (median age 34 years, 98% males) were diagnosed with COVID-19 in Singapore between 19 March to 19 July 2020. We identified 90 patients (median age 38, 98.9% males) with neurological disorders; 39 with varying certainty of relationship to COVID-19 categorised as: i) Central nervous system syndromes-4 acute disseminated encephalomyelitis (ADEM) and encephalitis, ii) Cerebrovascular disorders-19 acute ischaemic stroke and transient ischaemic attack (AIS/TIA), 4 cerebral venous thrombosis (CVT), 2 intracerebral haemorrhage, iii) Peripheral nervous system-7 mono/polyneuropathies, and a novel group, iv) Autonomic nervous system-4 limited dysautonomic syndromes. Fifty-one other patients had pre/co-existent neurological conditions unrelated to COVID-19. Encephalitis/ADEM is delayed, occurring in critical COVID-19, while CVT and dysautonomia occurred relatively early, and largely in mild infections. AIS/TIA was variable in onset, occurring in patients with differing COVID-19 severity; remarkably 63.2% were asymptomatic. CVT was more frequent than expected and occurred in mild/asymptomatic patients. There were no neurological complications in all 81 paediatric COVID-19 cases.

CONCLUSION

COVID-19 neurology has a wide spectrum of dysimmune-thrombotic disorders. We encountered relatively few neurological complications, probably because our outbreak involved largely young men with mild/asymptomatic COVID-19. It is also widely perceived that the pandemic did not unduly affect the Singapore healthcare system.

Time-Stratified Case Crossover Study of the Association of Outdoor Ambient Air Pollution With the Risk of Acute Myocardial Infarction in the Context of Seasonal Exposure to the Southeast Asian Haze Problem

Background

Prior studies have demonstrated the association of air pollution with cardiovascular deaths. Singapore experiences seasonal transboundary haze. We investigated the association between air pollution and acute myocardial infarction (AMI) incidence in Singapore.

Methods and Results

We performed a time‐stratified case‐crossover study on all AMI cases in the Singapore Myocardial Infarction Registry (2010–2015). Exposure on days where AMI occurred (case days) were compared with the exposure on days where AMI did not occur (control days). Control days were chosen on the same day of the week earlier and later in the same month and year. We fitted conditional Poisson regression models to daily AMI incidence to include confounders such as ambient temperature, rainfall, wind‐speed, and Pollutant Standards Index. We assessed relationships between AMI incidence and Pollutant Standards Index in the entire cohort and subgroups of individual‐level characteristics. There were 53 948 cases. Each 30‐unit increase in Pollutant Standards Index was association with AMI incidence (incidence risk ratio [IRR] 1.04, 95% CI 1.03–1.06). In the subgroup of ST‐segment–elevation myocardial infarction the IRR was 1.00, 95% CI 0.98 to 1.03, while for non–ST‐segment–elevation myocardial infarction, the IRR was 1.08, 95% CI 1.05 to 1.10. Subgroup analyses showed generally significant. Moderate/unhealthy Pollutant Standards Index showed association with AMI occurrence with IRR 1.08, 95% CI 1.05 to 1.11 and IRR 1.09, 95% CI 1.01 to 1.18, respectively. Excess risk remained elevated through the day of exposure and for >2 years after.

Conclusions

We found an effect of short‐term air pollution on AMI incidence, especially non–ST‐segment–elevation myocardial infarction and inpatient AMI. These findings have public health implications for primary prevention and emergency health services during haze.

P263 Characterisation of patients with acute myocardial infarction complicated by left ventricular thrombus

Funding Acknowledgements

None

Background/Introduction

Left ventricular (LV) thrombus is a widely recognized complication of acute myocardial infarction (AMI).  Limited data are available from South East Asian patients with this post-infarction complication nor on whether patients with non-ST segment elevation myocardial infarction (NSTEMI) or STEMI with associated LV thrombosis exhibit differing clinical characteristics and/or outcomes. Left Ventricular Ejection Fraction (LVEF) ≤ 40% is a recognized predictor of LV thrombus formation, but there is limited data on LV thrombus patients with EF &gt; 40% or in NSTEMI patients.

Purpose

This study aims to investigate and compare the clinical characteristics, treatment and outcomes of post-AMI patients with LV thrombus formation, with a particular emphasis on those with EF ≤ 40% and in NSTEMI patients. 

Methods

Among 5829 consecutive echocardiogram results containing the keyword "thrombus" from August 2006 to September 2017, we identified 289 post-AMI patients with acute LV thrombus formation. Demographics, treatment and outcome measures were analysed.

Results

Cardiovascular risk factors such as dyslipidaemia (54.0%) and hypertension (50.5%) were commonly present in post-AMI patients with LV thrombus. Mean LVEF was 33.0 ± 10.4%. The majority (68.0%) of patients received triple therapy and 59.5% achieved thrombus resolution. NSTEMI patients had greater number of co-morbidities including heart failure (p &lt; 0.01), documented history of  ischaemic heart disease preceding the AMI leading to thrombus formation (p &lt; 0.01) and lower LVEF (28.3 ± 9.3% vs. 34.8 ± 10.3% , p &lt; 0.01) compared with STEMI cases. On multivariate analysis, having a lower EF was a significant independent predictor of stroke (HR 0.96, 95% CI 0.93-1.00, p = 0.03) and all-cause mortality (HR 0.95, 95% CI 0.92-0.99, p &lt; 0.01). The categories of STEMI and NSTEMI did not predict thrombus resolution, stroke events or all-cause mortality after adjustment.

Conclusion(s)

  Post-AMI LV thrombus patients with NSTEMI and STEMI differed in terms of their co-morbidities in their demographics and co-morbidities but it was a lower EF that was associated with an increased risk of stroke and all-cause mortality. Further studies on this topic are required.

P910An Asian perspective on left ventricular outflow tract cut-offs and the resulting discrepancy in severity grading of aortic stenosis

Objectives

Inconsistencies in grading of aortic stenosis (AS) severity have been reported based on measurement of left ventricular outflow tract diameter (LVOTd), but this remains to be studied in an Asian population. We investigated consistency of grading AS severity at various LVOTd, and subsequently postulated alternative cut-offs for more consistent grading of AS severity.

Methods

350 consecutive patients with index echocardiographic diagnosis of severe AS were divided them into three groups based on LVOTd: “small” (<20mm), “average” (20–22mm), “large” (>22mm). In each group, the consistency of flow-dependent (transaortic mean pressure gradient (MG)) and flow-independent parameters (AVA) were used for classification of AS severity.

Results

Of 350 patients, 51.7% had small LVOTd, while 30.8% and 17.5% had average and large LVOTd respectively. Consistent grading by LVOTd based on AVA and MG, was seen in 33.7% of patients with small, 47.6% with average, 57.7% with large LVOTd. When the hypothetical AVA cut-off of 0.9cm2 was used, consistent grading improved to 38.0% in small, 56.5% in average and 70% in large LVOTd. At an AVA cut-off of 0.8cm2, there was further incremental improvement in the small LVOTd group to 54.1% (p<0.05).

Table 1. Consistent grading by LVOTd based on current guidelines Small LVOTd (<20mm, n=181) Average LVOTd (20–22mm, n=108) Large LVOTd (>22mm, n=61) Consistent grading AVA < cut-off MG >40 Consistency (%) Consistent grading AVA < cut-off MG >40 Consistency (%) Consistent grading AVA < cut-off MG >40 Consistency (%) n=61 33.7 n=51 47.6 n=35 57.7 n=69 38 n=61 56.5 n=43 70* n=98 54.1*+ n=70 65.1* n=43 70.8* *p-value <0.05 when compared with AVA cut-off 0.8cm2 for each LVOTd category; +p-value <0.05 when compared with AVA cut-off 0.9cm2 for each LVOTd category.

Figure 1

Conclusion

Current severe AS guidelines are most consistent with those in the large LVOTd group. However, the majority of the study's Asian population is in the small LVOTd group, which is the group most susceptible to discrepancy in AS grading. Improved consistency in echocardiographic grading may be attained with a lower AVA cut-off in this Asian cohort.

P308Utility of a prominent R wave in lead V1 of a resting electrocardiogram for detecting significant cardiac pathology in an unselected population of young males

Background

Pre-participation electrocardiogram (ECG) screening is proposed as a means to detect cardiac pathology in asymptomatic individuals, and to select individuals for further cardiac investigation. Isolated ECG finding of Right Ventricular Hypertrophy (RVH) does not require further investigation based on the recent 2017 International Criteria. However, a prominent R wave in V1 has been described in cardiac abnormalities such as Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, cardiomyopathy in Duchenne muscular dystrophy, arrhythmogenic right ventricular cardiomyopathy (ARVC), atrial septal defect and pulmonary hypertension.

Purpose

We sought to examine the utility of a prominent R wave in V1 as a screening criterion in an asymptomatic young male population of predominantly non-athletes, to detect significant structural cardiac pathology.

Methods

As part of the Singapore Armed Forces Electrocardiographic and Echocardiographic (SAFE) Protocol Study, pre-military enlistment screening ECG data was collected from 144,346 males between the ages of 16 to 22 from November 2009 to December 2014. Patients with ECGs with a prominent R wave, defined as an R wave ≥0.5mV in lead V1 with an R/S ratio of ≥1, were sent to a tertiary medical facility for a detailed transthoracic echocardiogram and subsequent cardiologist review. Any cardiac pathology identified was deemed significant if it led to the patient being excluded from participation in vigorous physical activity.

Results

1,144 patients with an isolated prominent R wave in V1 were studied. The mean age was 18.2±1.09 years and 81% were of Chinese ethnicity. None of the patients had echocardiographic evidence of RVH, 5 patients had a dilated right ventricle and 3 individuals had an elevated pulmonary artery systolic pressure. 11 patients (0.96%) had significant structural heart disease known to be associated with a prominent R wave in V1 that excluded them from participation in physical activity. These included large atrial septal defects (n=8), pulmonary stenosis (n=1), total anomalous pulmonary venous return (n=1) and hypertrophic cardiomyopathy (n=1). The test has a sensitivity of 21.6%, specificity of 93.4%, positive predictive value of 0.96% and negative predictive value of 99.8%,

Performance As Screening Criteria Number of Patients With Cardiac Pathology In Those Tested Positive Number of Patients With Cardiac Pathology In Those Tested Negative Positive Predictive Value (%) Negative Predictive Value (%) Sensitivity (%) Specificity (%) 11 40 0.96 99.8 21.6 93.4

Significant Cardiac Pathology Identified

Conclusion

A prominent R in V1 is not associated with echocardiographic RVH, or ARVC even in a large predominantly non-athletic male population. However, 0.96% of such patients would have other significant cardiac pathologies such as a large atrial septal defect.