Meteorological gaps in audits of pedestrian environments: a scoping review

BACKGROUND

Weather and season are determinants of physical activity. Therefore, it is important to ensure built environments are designed to mitigate negative impacts of weather and season on pedestrians to prevent these losses. This scoping review aims to identify built environment audits of pedestrian environments developed for use during a specific weather condition or season. Secondly, this review aims to investigate gaps in the inclusion of relevant weather mitigating built environment features in pedestrian environment audit tools.

METHODS

Following a standard protocol, a systematic search was executed in CINAHL, Medline and Web of Science to identify built environment audit tools of pedestrian spaces. These databases were chosen since they are well-known to comprehensively cover health as well as multi-disciplinary research publications relevant to health. Studies were screened, and data were extracted from selected documents by two independent reviewers (e.g., psychometric properties and audit items included). Audit items were screened for the inclusion of weather mitigating built environment features, and the tool's capacity to measure temperature, precipitation, seasonal and sustainability impacts on pedestrians was calculated.

RESULTS

The search returned 2823 documents. After screening and full text review, 27 articles were included. No tool was found that was developed specifically for use during a specific weather condition or season. Additionally, gaps in the inclusion of weather mitigating items were found for all review dimensions (thermal comfort, precipitation, seasonal, and sustainability items). Poorly covered items were: (1) thermal comfort related (arctic entry presence, materials, textures, and colours of buildings, roads, sidewalk and furniture, and green design features); (2) precipitation related (drain presence, ditch presence, hazards, and snow removal features); (3) seasonal features (amenities, pedestrian scale lighting, and winter destinations and aesthetics); and (4) sustainability features (electric vehicle charging stations, renewable energy, car share, and bike share facilities).

CONCLUSIONS

Current built environment audit tools do not adequately include weather / season mitigating items. This is a limitation as it is important to investigate if the inclusion of these items in pedestrian spaces can promote physical activity during adverse weather conditions. Because climate change is causing increased extreme weather events, a need exists for the development of a new built environment audit tool that includes relevant weather mitigating features.

Exploring adherence to an early rule-out pathway for myocardial infarction in the emergency department using mixed-methods

Background

Incorporating a high-sensitivity cardiac troponin assay into a care pathway for the assessment of suspected acute coronary syndrome has enabled myocardial infarction to be ruled out earlier.

Purpose

Using mixed methods, we explored adherence to an early rule-out pathway in the HiSTORIC (High-Sensitivity Cardiac Troponin on Presentation to Rule Out Myocardial Infarction) randomised controlled trial.

Methods

In 16,972 consecutive patients we evaluated clinician adherence to an early rule-out pathway for the assessment of suspected acute coronary syndrome. Adherence was defined in patients with presentation cardiac troponin I concentrations <5ng/L and symptom onset >2 hours from presentation without serial troponin testing (type 1 adherence); presentation troponin <5ng/L and symptom onset ≤2 hours from presentation with serial testing (type 2 adherence); or presentation troponin between 5ng/L and sex-specific 99th centile with serial testing (type 3 adherence). Semi-structured interviews were conducted with 23 clinicians to aid interpretation of the quantitative analysis. Qualitative data were coded and organized into themes.

Results

In patients with troponin <5ng/L presenting >2hr from symptom onset, adherence was achieved in 81% of patients. In patients presenting ≤2hr from symptom onset, 35% of patients had a second troponin test. In patients with an initial troponin concentration between 5ng/L and the 99th centile, 65% of patients had a second troponin test. Compared to patients managed by clinicians who were adherent to the pathway, patients with troponin over-testing (type 1 non-adherence) were more likely to be older (mean age 52±16 years versus 58±14, P<0.001) and have a history of coronary disease (11% versus 27%, P<0.001). In contrast, patients with under testing (type 2 non-adherence) tended to be younger (mean age 49±16 versus 63±15, P<0.001), female (50% versus 37%, P<0.001) and have lower presentation troponin levels (median concentration 1.0ng/L IQR 1.0 to 2.0, versus 5.0ng/L IQR 2.0–10.0) compared to those in whom testing was performed according to pathway recommendations. Semi-structured interview data revealed how pathway adherence was influenced by five main themes: guideline characteristics, patient characteristics, the healthcare practitioner, the healthcare system and scientific evidence. Clear visual pathway layout was fundamental in achieving optimal adherence. Strong clinical suspicion of acute coronary syndrome promoted repeat troponin testing and deviation from the pathway was felt to be justifiable by more senior clinicians.

Conclusion

This analysis revealed successful implementation of the early rule-out pathway with interview data aiding interpretation of trial data. Younger patients with lower troponin concentrations were less likely to receive pathway recommended serial troponin testing. Clinical judgement is one of the main reasons for discontinuation of pathway recommendations.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Machine learning to optimise use of cardiac troponin in the diagnosis of acute myocardial infarction

Background

Guidelines recommend fixed cardiac troponin thresholds for the assessment of patients with suspected acute coronary syndrome, however, performance varies in important patient groups as concentrations are influenced by age, sex and comorbidities. This limitation can be addressed using machine learning algorithms.

Methods

Machine learning algorithms were developed that integrate cardiac troponin concentrations at presentation or on serial testing with age, sex and clinical features in 10,038 consecutive emergency patients with suspected acute coronary syndrome. The primary outcome was an adjudicated diagnosis of type 1, type 4b or type 4c myocardial infarction. The best performing algorithm was selected for the CoDE-ACS (Collaboration for the Diagnosis and Evaluation of Acute Coronary Syndrome) decision-support tool, and performance was externally validated in 3,035 patients pooled from three prospective studies.

Findings

CoDE-ACS had excellent discrimination and calibration using cardiac troponin at presentation (area under curve [AUC] 0.959, 95% confidence interval 0.948–0.971, Brier score 0.040), in the pooled external validation cohort. At presentation, the rule-out score identified 62.1% (1,885/3,035) of all patients as low-probability of myocardial infarction with a 99.5% (99.1–99.7%) negative predictive value and 97.0% (96.3–97.6%) sensitivity. The rule-in score identified 8.3% (252/3,035) of patients as high-probability with an 83.7% (82.4–85.0%) positive predictive value and 98.5% (98.0–98.9%) specificity. Performance of the rule-out and rule-in scores was consistent across patient subgroups (Figure 1 and Figure 2). CoDE-ACS incorporating a second cardiac troponin measurement also had excellent discrimination and calibration (AUC 0.971 [0.962–0.980], Brier score 0.039) and refined the individualised probabilities in the 29.5% (898/3,035) of patients neither ruled-out or ruled-in at presentation to guide further investigation.

Conclusions

We developed and externally validated the CoDE-ACS decision-support tool using machine learning to aid in the diagnosis of myocardial infarction. CoDE-ACS had excellent diagnostic performance to rule-out and rule-in myocardial infarction at presentation, performed consistently across patient subgroups, and provided individualised probabilities to guide further care in those who require serial troponin measurements.

Conclusions

We developed and externally validated the CoDE-ACS decision-support tool using machine learning to aid in the diagnosis of myocardial infarction. CoDE-ACS had excellent diagnostic performance to rule-out and rule-in myocardial infarction at presentation, performed consistently across patient subgroups, and provided individualised probabilities to guide further care in those who require serial troponin measurements.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health ResearchBritish Heart Foundation

Impact of patient selection on performance of an early rule-out pathway for myocardial infarction: from research to the real world

Background

Early rule-out pathways for myocardial infarction using high-sensitivity cardiac troponin are widely recommended in the assessment of patients with suspected acute coronary syndrome. Although developed in selected patients participating in research studies, these pathways are applied more widely in clinical practice where the diagnostic performance and effectiveness of these pathways may differ.

Purpose

To evaluate the performance of an early rule-out pathway for myocardial infarction using high-sensitivity cardiac troponin in selected and consecutive unselected patients with suspected acute coronary syndrome.

Methods

Presentation and serial high-sensitivity cardiac troponin I concentrations were measured in two cohorts of patients with suspected acute coronary syndrome presenting to the Emergency Departments across three acute care hospitals in Scotland. In the unselected cohort, electronic health record data were collected on consecutive patients in whom the usual care clinician measured cardiac troponin for suspected acute coronary syndrome. In the selected cohort, patients with suspected acute coronary syndrome were approached between 8am and 8pm by research staff and written informed consent obtained. In both cohorts, the performance of the High-STEACS early rule-out pathway was evaluated for an adjudicated diagnosis of myocardial infarction (type 1, type 4b or type 4c) during the index hospital admission.

Results

The unselected and selected patient cohorts comprised of 1,242 (median age 60 [interquartile range 47–75] years, 46% women) and 1,695 (median age 61 [52–73] years, 40% women) patients respectively. Myocardial infarction was diagnosed in 6% (74/1,242) and 14% (232/1,695) of patients in the unselected and selected patient cohorts respectively. More patients had myocardial infarction ruled-out in the unselected (74% [828/1,112] versus 66% [1,102/1,678]; P<0.001), with similar negative predictive value (99.9% [95% CI 99.7%-100%] versus 99.7% [95% CI 99.4%-99.0%) and sensitivity (99.3% [95% CI 97.4%-100%] versus 98.9% [95% CI 97.6%-99.9%]; Figure 1). In the selected cohort, more patients had intermediate troponin concentrations requiring serial testing (36% versus 29%) or had myocardial infarction diagnosed (34% versus 26%; P<0.001 for both). In contrast, the positive predictive value for myocardial infarction was lower in unselected patients (26.1% [95% CI 21.2%-31.4%] versus 39.9% [95% CI 35.9%-44.0%]).

Conclusion

The prevalence of myocardial infarction is lower in patients with suspected acute coronary syndrome evaluated in routine practice compared to those selected to participate in a research study. Whilst more patients have myocardial infarction accurately ruled out, the positive-predictive value in those ruled in is lower resulting in more hospital admissions with elevated cardiac troponin due to other conditions.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart FoundationMedical Research Council

Machine learning to aid in the diagnosis of acute heart failure in the emergency department

Background

B-type natriuretic peptide (BNP) and mid-regional pro-atrial natriuretic peptide (MRproANP) testing are recommended to aid in the diagnosis of acute heart failure. However, the application of these biomarkers for optimal diagnostic performance is uncertain.

Methods

We performed a systematic review and harmonised individual patient-level data to evaluate the diagnostic performance of BNP and MRproANP for the diagnosis of acute heart failure using random-effects meta-analysis. We subsequently developed and externally validated a decision-support tool called CoDE-HF for both BNP and MRproANP that combines the natriuretic peptide concentrations with clinical variables using machine learning to report the probability of acute heart failure for an individual patient.

Results

Fourteen studies from 12 countries provided individual patient-level data in 8,493 patients for BNP and 3,847 patients for MRproANP, in whom, 48.3% (4,105/8,493) and 41.3% (1,611/3899) had an adjudicated diagnosis of acute heart failure, respectively. The negative and positive predictive values of guideline-recommended thresholds for BNP (100 pg/mL) and MR-proANP (120 pg/mL) were 93.6% (95% confidence interval 88.4–96.6%) and 68.8% (62.9–74.2%), and 95.6% (92.2–97.6%) and 64.8% (56.3–72.5%), respectively. However, we observed significant heterogeneity in the diagnostic performance across important patient subgroups (Figure 1). In the external validation cohort, CoDE-HF was well calibrated with excellent discrimination in those without prior acute heart failure for both BNP and MRproANP (area under the curve of 0.946 [0.933–0.958] and 0.943 [0.921–0.964], and Brier scores of 0.105 and 0.073, respectively). CoDE-HF performed consistently across all subgroups for both BNP and MRproANP, and identified 30% and 65.7% at low-probability (negative predictive value of 99.1% [98.8–99.3%] and 99.1% [98.8–99.4%]), and 30% and 17.3% at high-probability (positive predictive value of 91.3% [90.7–91.9%] and 70.0% [68.5–71.4%]) in those without prior heart failure, respectively (Figure 2).

Conclusion

In an international collaborative analysis, we observed that guideline-recommended thresholds for BNP and MRproANP to diagnose acute heart failure varied significantly across patient subgroups. A decision-support tool using machine learning to combine natriuretic peptides as a continuous measure and other clinical variables provides a more accurate and individualised approach.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Medical Research Council and British Heart Foundation Figure 1. NPV of BNP threshold (100 pg/mL)Figure 2. NPV of the CoDE-HF rule-out score

Mechanisms of myocardial injury and clinical outcomes in patients hospitalised with suspected COVID-19

Background

Myocardial injury is associated with adverse outcomes in patients with COVID-19. However, the prognostic role of myocardial injury in COVID-19 compared to other acute illnesses and the underlying mechanisms of injury are poorly understood.

Methods

In a prospective, multi-centre, cohort study conducted in secondary and tertiary care hospitals in Scotland, all consecutive patients with suspected COVID-19 underwent cardiac troponin (ARCHITECTSTAT high-sensitive troponin I (hs-cTnI) assay; Abbott Laboratories) testing in plasma that was surplus to clinical requirements. The results were not reported unless required by the attending clinician. We evaluated the prevalence of myocardial injury, mechanisms and outcomes in all patients. In those with any hs-cTnI concentration above the sex-specific 99th centile the diagnosis was adjudicated according to the 4th Universal Definition of Myocardial Infarction. The primary outcome of all-cause mortality was compared in those with and without myocardial injury and COVID-19 by cox regression adjusted for age, sex, renal function and co-morbidities.

Results

A total of 2,916 (median age 69 [interquartile range, IQR 54–79] years, 53% women) consecutive patients with suspected COVID-19 were followed up for 228 [IQR 203–249] days. Myocardial injury occurred in 26% (750/2,916) with a median troponin concentration of 66 [35–178] ng/L; the prevalence was 41% (46/112) and 25% (704/2,804) in those with and without COVID-19, respectively. The most common mechanism was acute non-ischaemic myocardial injury occurring in 80% (37/46) and 71% (502/704) of patients with and without COVID-19, respectively. Type 1 myocardial infarction (2% and 4%), type 2 myocardial infarction (7% and 14%) and chronic myocardial injury (11% and 11%) were less common and only one patient had confirmed myocarditis. In patients with myocardial injury mortality was increased compared to those without (P<0.001 log rank), whether they had COVID-19 (54% [25/46] versus 26% [17/66]) or not (35% [248/704] versus 14% [294/2100]). Myocardial injury was an independent predictor of death in all patients (adjusted hazard ratio [aHR] 2.04, 95% confidence interval [CI] 1.71 to 2.43), but this excess risk was not higher in patients with COVID-19 (aHR 1.58, 95% CI 0.75 to 3.15) compared to those without the condition (aHR 2.01, 95% CI 1.81 to 2.49).

Conclusion

Myocardial injury is common in hospitalised patients with suspected COVID-19 whether or not COVID-19 was the cause of their presentation. The majority of patients had acute non-ischaemic myocardial injury rather than a defined cardiac condition. Despite this the presence of myocardial injury was an independent predictor of death in all hospitalised patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation Kaplan-Meier curve for all-cause death

247Safety and efficacy of high-sensitivity cardiac troponin for risk stratification in patients with suspected acute coronary syndrome

Background

Guidelines acknowledge the emerging role of high-sensitivity cardiac troponin (hs-cTn) assays for the risk stratification and rapid rule-out of myocardial infarction, but multiple approaches have been described. We previously demonstrated the utility of a single hs-cTnI concentration <5 ng/L at presentation to risk stratify patients with suspected acute coronary syndrome (ACS).

Purpose

To assess the safety and efficacy of a hs-cTnI concentration <5 ng/L at presentation in consecutive patients included in the High-STEACS (High-SensitivityTroponin in the Evaluation of patients with Acute Coronary Syndrome) randomised controlled trial.

Methods

The High-STEACS trial was a stepped wedge cluster randomised controlled trial in ten hospitals across Scotland that included 48,282 patients in whom high-sensitivity cardiac troponin was requested by the attending clinician for evaluation of suspected ACS. Patients with ST-segment elevation myocardial infarction (STEMI) were excluded. We evaluated the negative predictive value (NPV) and sensitivity of a presentation hs-cTnI <5 ng/L for a composite outcome of type 1 myocardial infarction, or subsequent type 1 myocardial infarction or cardiac death at 30 days. To assess safety, we report the one-year risk of type 1 myocardial infarction or cardiac death. To assess efficacy, we report the proportion of patients with cardiac troponin <5 ng/L at presentation.

Results

We included 47,101 consecutive patients in the analysis (mean 61±17 years old, 47% female). Of these patients, 27,500 (58%) had a cardiac troponin <5 ng/L at presentation. Overall, 4,313/47,101 (9%) patients had a composite outcome at 30 days, but the event rate was only 0.4% in those with troponin <5 ng/L (98/27,500). The NPV for the composite outcome in those <5 ng/L was 99.7% (95% confidence intervals [CI] 99.6–99.7) and the sensitivity was 98.0% (95% CI 97.6–98.4). In those without evidence of myocardial injury at presentation (hs-cTnI <99thcentile), type 1 myocardial infarction or cardiac death at one year occurred in 197 (0.7%) patients with cardiac troponin <5 ng/L, compared to 647 (5.5%) of those ≥5 ng/L. The NPV was unchanged across all age groups, although efficacy fell as fewer older patients had hs-cTnI concentrations below the risk stratification threshold (see Figure).

Conclusion

A hs-cTnI concentration <5 ng/L at presentation identifies the majority of patients with suspected ACS as low-risk of early or late cardiac events. Although the proportion identified as low risk is reduced in older populations, the safety of this risk stratification approach is maintained across patients of all ages.

Acknowledgement/Funding

British Heart Foundation

3325Incidence, outcomes and microbiology in patients with infective endocarditis

Introduction

Despite recent improvements in management, infective endocarditis remains associated with high morbidity and mortality. Over the last few decades, several factors have impacted on both the incidence and outcomes following infective endocarditis.

Purpose

Using a national linkage approach, we describe the changing age- and sex-stratified incidence and outcomes of infective endocarditis in Scotland over the last 25 years.

Methods

We conducted a consecutive retrospective individual patient linkage study across multiple national databases. Using data extracted from the Scottish hospital discharge dataset held by the Information Services Division of NHS National Services Scotland, we extracted episodes for all patients aged 20 years or older who were admitted with infective endocarditis between January 1, 1990, and December 31, 2014 in Scotland, UK. Patient episodes with infective endocarditis were linked to national prescribing and microbiology databases. The primary outcome was 1-year mortality following the index presentation. Generalised additive models were constructed to estimate the crude and age- and sex-stratified incidence rates (using a poison distribution) as well as trends in mortality (using a binomial distribution) adjusted for age, sex and comorbidity.

Results

Across 12,446 individual patients, there were a total of 12,667 hospitalisations (mean age 68±17 years, 55% females) with infective endocarditis using a 5-year look back period. The estimated crude rate of hospitalisation increased from 7.38 per 100,000 (95% CI 6.58 to 8.28) in 1990 to 15.09 per 100,000 (95% CI 13.90 to 16.39) in 2014 (p<0.001). Over the period of the study, 31% (3,877/12,667) of people admitted to hospital with infective endocarditis died within one year of admission. Case fatality fell markedly in both men and women from 1990 to 2014 (Figure). Microbiology was status was available for 34% of all hospitalisations with staphylococcus cultures associated with worse outcomes.

Conclusions

Despite the crude incidence of infective endocarditis doubling over the last 25 years and case fatality remaining high, the risk of death has markedly fallen over the last two decades. Staphylococcus cultures remain an independent marker of poor prognosis in this cohort.

Acknowledgement/Funding

British Heart Foundation

P1578Outcomes in patients with renal impairment and myocardial injury or infarction identified by high-sensitivity cardiac troponin testing: a secondary analysis of the High-STEACS trial

Background

Patients with renal impairment are at increased risk of myocardial infarction (MI), but the interpretation of cardiac troponin is challenging in this setting. The use of high-sensitivity cardiac troponin (hs-cTn) assays increases the detection of myocardial injury, yet may contribute to uncertainty in the diagnosis of MI in those with renal impairment.

Purpose

To describe the diagnosis and outcomes of patients with myocardial injury or infarction identified using a hs-cTnI assay, stratified by renal function.

Methods

In a pre-specified secondary analysis of a stepped-wedge cluster-randomised controlled trial, we identified consecutive patients with a hs-cTnI concentration greater than the sex-specific 99th centile between June 2013 and March 2016. The diagnoses of type 1 or type 2 MI were adjudicated and classified according to the 4th Universal Definition of Myocardial Infarction. Renal impairment was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73m2.The primary outcome of type 1 or type 4b MI or cardiovascular death was compared in patients with and without renal impairment at 1 year.

Results

A measure of renal function was available in 47,334 (98.0%) patients, of whom 7,933 (16.8%) had renal impairment (mean age 76±12 years; 54% female). Plasma hs-cTnI concentrations were >99th centile in 47.9% (3,800/7,933) of patients with renal impairment and 16.3% (6,439/39,401) of patients with normal renal function. In those with and without renal impairment, the adjudicated diagnosis was type 1 MI in 35.2% (1,336/3,800) and 55.8% (3,596/6,439) of patients, and type 2 MI in 12.6% (480/3,800) and 9.7% (626/6,439) of patients, respectively (P<0.001 for both). In patients with hs-cTnI concentrations >99th centile, the primary outcome occurred in 24.9% (945/3,800) of patients with renal impairment, compared to 12.1% (779/6,439) of patients with normal renal function (P<0.001). In patients with type 1 MI, the primary outcome occurred in 32.6% (436/1,336) of those with renal impairment and 11.7% (419/3,596) of those without (P<0.001). In patients with type 2 MI, the primary outcome occurred in 20.4% (98/480) and 9.9% (62/626) of patients with and without renal impairment, respectively (P<0.001).

Conclusion

Almost half of all patients with suspected acute coronary syndrome and renal impairment have hs-cTnI concentrations greater than the sex-specific 99th centile. Whilst only one in three had a diagnosis of type 1 MI, an elevated troponin concentration was associated with a poorer prognosis in those with concomitant renal impairment compared to those without, irrespective of the index diagnosis.

Acknowledgement/Funding

British Heart Foundation

P1731High-sensitivity troponin with sex-specific thresholds in suspected acute coronary syndrome

Background/Introduction

Major disparities between women and men in the diagnosis, management and outcome of acute coronary syndrome are well recognised. Whether sex-specific diagnostic thresholds for myocardial infarction will address these differences is uncertain.

Purpose

To evaluate the impact of implementing a high-sensitivity cardiac troponin I (hs-cTnI) assay with sex-specific diagnostic thresholds for myocardial infarction in women and men with suspected acute coronary syndrome.

Methods

In a stepped-wedge, cluster-randomized controlled trial across ten hospitals we evaluated the implementation of a hs-cTnI assay in 48,282 (47% women) consecutive patients with suspected acute coronary syndrome. During a validation phase the hs-cTnI assay results were suppressed and a contemporary cTnI assay with a single threshold was used to guide care. Myocardial injury was defined as any hs-cTnI concentration >99th centile of 16 ng/L in women and 34 ng/L in men. The primary outcome was myocardial infarction after the initial presentation or cardiovascular death at 1 year. In this prespecified analysis, we evaluated outcomes in men and women before and after implementation of the hs-cTnI assay.

Results

Use of the hs-cTnI assay with sex-specific thresholds increased myocardial injury in women by 42% (from 3,521 (16%) to 4,991 (22%)) and by 6% in men (from 5,068 (20%) to 5,369 (21%)). Whilst treatment increased in both sexes, women with myocardial injury remained less likely than men to undergo coronary revascularisation (15% versus34%), or to receive dual anti-platelet (26% versus43%), statin (16% versus26%) or other preventative therapies (P<0.001 for all). The primary outcome occurred in 18% (369/2,072) and 17% (488/2,919) of women with myocardial injury during the validation and implementation phase respectively (adjusted hazard ratio 1.11, 95% confidence interval 0.92 to 1.33), compared to 18% (370/2,044) and 15% (513/3,325) of men (adjusted hazard ratio 0.85, 95% confidence interval 0.71 to 1.01).

Patient management

Conclusion

Use of sex-specific thresholds identified five-times more additional women than men with myocardial injury, such that the proportion of women and men with myocardial injury is now similar. Despite this increase, women received approximately half the number of treatments for coronary artery disease as men and their outcomes were not improved.

Acknowledgement/Funding

The British Heart Foundation

P3593Improving the performance of high-sensitivity cardiac troponin for the diagnosis of myocardial infarction

Background

The Universal Definition of Myocardial Infarction (UDMI) mandates a rise and/or fall in high-sensitivity cardiac troponin (hs-cTn) concentration with at least one measure above the 99th centile of a healthy reference population. However, the 99th centile varies by age, sex, and prevalence of comorbid disease within reference populations, and the application of a single threshold may create diagnostic uncertainty in unselected patients attending the Emergency Department.

Purpose

To compare performance of hs-cTnI at the 99th centile with a model that includes additional clinical variables, for the diagnosis of type 1 myocardial infarction.

Methods

The High-Sensitivity Troponin in the Evaluation of patients with Acute Coronary Syndrome (High-STEACS trial) was a stepped wedge cluster randomised controlled trial of 48,282 consecutive patients across 10 hospitals in Scotland. We evaluated the positive predictive value (PPV) of a hs-cTnI >99th centile for a diagnosis of type 1 myocardial infarction. Patients with ST-segment elevation myocardial infarction (STEMI) were excluded, and all were adjudicated according to the 4th UDMI. The study population was randomly divided into derivation (80%) and internal validation (20%) cohorts. Using generalised additive modelling, we tested the effect of adding clinically relevant variables to hs-cTnI for the prediction of type 1 myocardial infarction in the derivation cohort, and assessed performance of the final model in the validation cohort.

Results

We included 47,101 consecutive patients (61±17 years, 47% female), of whom 9,057 (19%) had at least one hs-cTnI >99th centile (7,207 in derivation and 1,850 in validation cohorts). There were 4,087 (45%) patients with type 1 myocardial infarction, with 3239 (45%) and 848 (46%) in the derivation and validation cohorts, respectively. Across the study population, PPV for type 1 myocardial infarction reduced markedly with increasing age (Figure). Age, sex, chest pain, ischaemia on the electrocardiogram, creatinine and rate of change of hs-cTnI were included in the model. Comorbidities (ischaemic heart disease, diabetes, stroke and hyperlipidaemia) did not improve model performance. In the validation cohort, the area under the curve (AUC) for type 1 myocardial infarction using the 99th centile alone was 0.72 (95% CI 0.70–0.74), whereas the AUC for the optimised model was 0.84 (95% CI 0.82–0.85) (p<0.001 by DeLong's test for difference, see Figure).

Figure 1

Conclusion

The diagnostic performance of the 99th centile for type 1 myocardial infarction is poor, particularly in older populations. A simple model including readily available clinical features improves diagnostic performance and with further external validation could support more individualised treatment decisions.

Acknowledgement/Funding

British Heart Foundation

249High-sensitivity cardiac troponin and the universal definition of myocardial infarction: a randomised controlled trial

Background

The Universal Definition of Myocardial Infarction recommends the 99th centile diagnostic threshold using a high-sensitivity cardiac troponin (hs-cTn) assay and the classification of patients by the etiology of myocardial injury. Whether implementation of this definition improves risk stratification, treatment or outcomes is unknown.

Methods

In a stepped-wedge cluster randomized controlled trial, we implemented a high-sensitivity troponin assay and the recommendations of the Universal Definition in 48,282 consecutive patients with suspected acute coronary syndrome across ten hospitals. In a pre-specified secondary analysis, we compared the primary outcome of myocardial infarction or cardiovascular death, and secondary outcome of non-cardiovascular death at one year across diagnostic categories as per the Fourth Universal Definition. We applied competing risks methodology in all analyses, using a cumulative incidence function and determining the cause-specific hazard ratio (csHR) for competing outcomes.

Results

Cardiac troponin concentrations were elevated in 21.5% (10,360/48,282) of all trial participants. Implementation increased the diagnosis of type 1 myocardial infarction by 11% (510/4,471), type 2 myocardial infarction by 22% (205/916), acute myocardial injury by 36% (443/1,233) and chronic myocardial injury by 43% (389/898). The risk and rate of the primary outcome was highest in those with type 1 myocardial infarction, whereas the risk and rate of non-cardiovascular death was highest in those with acute myocardial injury (Table, Figure). Despite increases in anti-platelet therapy and coronary revascularization after implementation, the primary outcome was unchanged in patients with type 1 myocardial infarction (csHR 1.00, 95% CI 0.82 to 1.21), or in any other category.

Adjusted csHR for competing outcomes Myocardial infarction or cardiovascular death Non-cardiovascular death Adjusted csHR (95% CI) Adjusted csHR (95% CI) Type 1 myocardial infarction 5.64 (5.12 to 6.22) 0.83 (0.72 to 0.96) Type 2 myocardial infarction 3.50 (2.94 to 4.15) 1.72 (1.44 to 2.06) Acute myocardial injury 4.38 (3.80 to 5.05) 2.65 (2.33 to 3.00) Chronic myocardial injury 3.88 (3.31 to 4.55) 2.06 (1.77 to 2.40) Cox regression models adjusted for age, sex, diabetes, ischaemic heart disease, season, days since trial onset and site of recruitment (as a random effect).

Cumulative incidence and number at risk

Conclusions

Implementation of the recommendations of the Universal Definition identified patients with different risks of future cardiovascular and non-cardiovascular events, but did not improve outcomes. Greater understanding of the underlying mechanisms and effective strategies for the investigation and treatment of patients with myocardial injury and infarction are required if we are to improve outcomes.

Acknowledgement/Funding

British Heart Foundation

Prevalence and Clinical Relevance of Exon 2 Deletion of COMMD1 in Bedlington Terriers in Korea

BACKGROUND

Deletion of exon 2 of copper metabolism domain containing 1 (COMMD1) results in copper toxicosis in Bedlington terriers (CT-BT).

OBJECTIVES

This study was conducted to identify the prevalence and clinical relevance of the COMMD1 mutation in Bedlington terriers in Korea.

ANIMALS

A total of 105 purebred Bedlington terriers (50 males, 55 females) from the kennels and pet dog clubs in Korea were examined during the period 2008-2013.

METHODS

A multiplex PCR was carried out to detect exon 2 deletion of COMMD1. Clinical analysis was performed on each genetic group, and clinical status of the dogs was followed up to estimate survival probability.

RESULTS

Of the 105 samples, 52 (49%) were wild-type homozygote, 47 (45%) were heterozygote, and 6 (6%) were mutant-type homozygote. Plasma alanine aminotransferase (ALT) activity was increased in the mutant-type homozygous group >2 years of age (P < .0001). The survival probability of 6 mutant-type homozygotes surviving 2.5 years was 0.67, and 4 years was 0.5.

CONCLUSIONS AND CLINICAL IMPORTANCE

Results show the prevalence and clinical relevance of exon 2 deletion of COMMD1 and could help establish a structured selective breeding program to prevent CT-BT in Korea.

A secular increase in BMD in Chinese women

Population-based studies have revealed a decline in the incidence of age-adjusted hip fractures in southern Chinese women during the past decade. To determine whether there was a secular change in population characteristics that accounted for this decline, we compared the bone mineral density (BMD) and lifestyle habits of two cohorts of women who were more than 50 years of age and who were recruited from 1995 to 2000 and 2005 to 2010. The BMD levels in the 2005-2010 cohort were significantly higher at the spine and hip and ranged from 3.6 to 17.8% among the different age groups. Additionally, a significantly lower prevalence of subjects with osteoporosis and osteopenia was observed. Longer reproductive years, higher levels of physical activity, higher estradiol and 25(OH) vitamin D levels, and lower alkaline phosphatase levels were found in the 2005-2010 cohort. After adjusting for bone-determining factors, significant differences were detected in the BMD levels at the lumbar spine, femoral neck, and total hip (4.17, 9.02, and 9.34%, respectively) in women >50 years of age but not in women ≤50 years of age. The secular increase in BMD and healthier lifestyles most likely led to the decline in the incidence of age-adjusted fractures.

Anti-elastase and anti-hyaluronidase of phenolic substance from Areca catechu as a new anti-ageing agent

We have previously screened 150 medicinal plants for the inhibition of elastase and found significant inhibitory effects of the extracts of Areca catechu L. on the ageing and inflammation of skin tissues. To isolate and identify the compounds having biological activity, they were further purified by each fraction of solvents, silica gel column chromatography, preparative TLC and reversed-phase HPLC. The peak in HPLC, which coincided with the inhibitory activity against elastase, was identified as a phenolic substance by using various colorimetric methods, UV and IR. IC(50) values of this phenolic substance were 26.9 mug mL(-1) for porcine pancreatic elastase (PPE) and 60.8 mug mL(-1) for human neutrophil elastase (HNE). This phenolic substance showed more potent activity than that of reference compounds, oleanolic acid (76.5 mug mL(-1) for PPE, 219.2 mug mL(-1) for HNE) and ursolic acid (31.0 mug mL(-1) for PPE, 118.6 mug mL(-1) for HNE). According to the Lineweaver-Burk plots, the inhibition against both PPE and HNE by this phenolic substance was competitive inhibition with the substrate. The phenolic substance from A. catechu effectively inhibited hyaluronidase activity (IC(50) : 210 mug mL(-1) ). These results suggest that the phenolic substance purified from A. catechu has an anti-ageing effect by protecting connective tissue proteins.