Scholars@Duke
Alexander Tan Limkakeng Jr.

Alexander Tan Limkakeng Jr.

Professor of Emergency Medicine
Emergency Medicine
2301 Erwin Road Box 3096, Durham, NC 27710
ORCID iDhttps://orcid.org/0000-0002-9822-5595
2301 Erwin Road, Box 3096, Durham, NC 27710

Featured Works

Stress-Delta B-Type Natriuretic Peptide Does Not Exclude ACS in the ED.

Journal article J Appl Lab Med · September 1, 2022 Featured Publication BACKGROUND: There are many detectable changes in circulating biomarkers in the setting of myocardial ischemia. We hypothesize that there are associated changes in circulating B-type natriuretic peptide (BNP) level after stress-induced myocardial ischemia, ... Full text Link to item Cite

Predictors of Stress-Delta High-Sensitivity Troponin T in Emergency Department Patients Undergoing Stress Testing.

Journal article Cureus · September 2022 Featured Publication Background and objective Elevations in high-sensitivity troponin T (hs-TnT) are frequently observed following extreme physical exercise. In light of this, we sought to determine whether specific clinical characteristics are associated with this phenomenon ... Full text Open Access Link to item Cite

A precision medicine approach to stress testing using metabolomics and microribonucleic acids.

Journal article Per Med · July 2022 Featured Publication Both transcriptomics and metabolomics hold promise for identifying acute coronary syndrome (ACS) but they have not been used in combination, nor have dynamic changes in levels been assessed as a diagnostic tool. We assessed integrated analysis of periphera ... Full text Link to item Cite

Untapped Potential for Emergency Department Observation Unit Use: A National Hospital Ambulatory Medical Care Survey (NHAMCS) Study.

Journal article West J Emerg Med · January 18, 2022 Featured Publication INTRODUCTION: Millions of people present to the emergency department (ED) with chest pain annually. Accurate and timely risk stratification is important to identify potentially life-threatening conditions such as acute coronary syndrome (ACS). An ED-based ... Full text Open Access Link to item Cite

Impact of dispatcher-assisted cardiopulmonary resuscitation on performance of termination of resuscitation criteria.

Journal article Resuscitation · January 2022 Featured Publication BACKGROUND: Current Advanced Life Support Termination of Resuscitation (TOR) guidelines suggest when to cease cardiopulmonary resuscitation (CPR). With the significant increase of Dispatch-Assisted CPR (DA-CPR) programs, the impact of DA-CPR on the TOR cri ... Full text Link to item Cite

United States Emergency Department Use of Medications with Pharmacogenetic Recommendations.

Journal article West J Emerg Med · September 23, 2021 Featured Publication INTRODUCTION: Emergency departments (ED) use many medications with a range of therapeutic efficacy and potential significant side effects, and many medications have dosage adjustment recommendations based on the patient's specific genotype. How frequently ... Full text Open Access Link to item Cite

Immune response profiling in patients with traumatic injuries associated with alcohol ingestion.

Journal article Clin Transl Sci · September 2021 Featured Publication Traumatic injuries afflict more than 5 million people globally every year. Current and past animal research has demonstrated association among alcohol, trauma, and impaired immune function, whereas human registries have shown association between alcohol an ... Full text Open Access Link to item Cite

Machine Learning and Precision Medicine in Emergency Medicine: The Basics.

Journal article Cureus · September 2021 Featured Publication As machine learning (ML) and precision medicine become more readily available and used in practice, emergency physicians must understand the potential advantages and limitations of the technology. This narrative review focuses on the key components of mach ... Full text Open Access Link to item Cite

Ideal high sensitivity troponin baseline cutoff for patients with renal dysfunction.

Journal article Am J Emerg Med · August 2021 Featured Publication OBJECTIVE: High-sensitivity cardiac troponin assays (hs-cTn) aid in diagnosis of myocardial infarction (MI). These assays have lower specificity for non-ST Elevation MI (NSTEMI) in patients with renal disease. Our objective was to determine an optimized cu ... Full text Link to item Cite

A hypothetical implementation of 'Termination of Resuscitation' protocol for out-of-hospital cardiac arrest.

Journal article Resusc Plus · June 2021 Featured Publication BACKGROUND: Out-of-hospital cardiac arrests with negligible chance of survival are routinely transported to hospital and many are pronounced dead thereafter. This leads to some potentially avoidable costs. The 'Termination of Resuscitation' protocol allows ... Full text Open Access Link to item Cite

Outpatient versus observation/inpatient management of emergency department patients rapidly ruled-out for acute myocardial infarction: Findings from the HIGH-US study.

Journal article Am Heart J · January 2021 Featured Publication BACKGROUND: The actual Emergency Department (ED) dispositions of patients enrolled in observational studies and meeting criteria for rapid acute myocardial infarction (AMI) rule-out are unknown. Additionally, their presenting clinical profiles, cardiac tes ... Full text Open Access Link to item Cite

Biomarkers Enhance Discrimination and Prognosis of Type 2 Myocardial Infarction.

Journal article Circulation · October 20, 2020 Featured Publication BACKGROUND: The observed incidence of type 2 myocardial infarction (T2MI) is expected to increase with the implementation of increasingly sensitive cTn assays. However, it remains to be determined how to diagnose, risk-stratify, and treat patients with T2M ... Full text Link to item Cite

302 Biomarker Profiling for Obstructive Coronary Artery Disease: A PROMISE Substudy

Conference Annals of Emergency Medicine · October 2020 Featured Publication Full text Cite

Performance of Novel High-Sensitivity Cardiac Troponin I Assays for 0/1-Hour and 0/2- to 3-Hour Evaluations for Acute Myocardial Infarction: Results From the HIGH-US Study.

Conference Ann Emerg Med · July 2020 Featured Publication STUDY OBJECTIVE: We determine the accuracy of high-sensitivity cardiac troponin I (hs-cTnI), European-derived, rapid, acute myocardial infarction, rule-out/rule-in algorithms applied to a US emergency department (ED) population. METHODS: Adults presenting ... Full text Open Access Link to item Cite

The 99th percentile upper reference limit for the 5th generation cardiac troponin T assay in the United States.

Journal article Clin Chim Acta · May 2020 Featured Publication BACKGROUND: Determining diagnostic thresholds for cardiac troponin assays is key to interpreting their clinical performance. We describe the calculation of 99th percentile upper reference limits (URLs) for the Elecsys® Troponin T Gen 5 (TnT Gen 5) assay. M ... Full text Open Access Link to item Cite

Pivotal findings for a high-sensitivity cardiac troponin assay: Results of the HIGH-US study.

Journal article Clin Biochem · April 2020 Featured Publication BACKGROUND: Cardiac troponin (cTn) is the keystone for diagnosis of acute myocardial infarction (AMI). We examined the analytical and diagnostic accuracy of the Atellica IM TnIH assay to determine high-sensitivity performance and appropriate diagnostic per ... Full text Link to item Cite

Stress-delta B-type Natriuretic Peptide Levels as a Test for Inducible Myocardial Ischemia: A Systematic Review and Meta-Analysis.

Journal article Cureus · March 2, 2020 Featured Publication Background Cardiac ischemia induces myocardial dysfunction and ventricular wall stretch, which causes the release of B-type natriuretic peptide (BNP) into the bloodstream. However, it is unclear whether inducible ischemia produces a significant change in B ... Full text Open Access Link to item Cite

A Precision Medicine Approach to Stress Testing Using Metabolomics and Microribonucleic Acids

Journal article · 2020 Featured Publication ABSTRACTBackground Acute coronary syndrome (ACS) is a growing global health problem, and precision medicine techniques hold promise for the development of diagnostic indicators of ACS. In this pilot, we sought to assess the utility of ... Full text Cite

Damage- and pathogen-associated molecular patterns play differential roles in late mortality after critical illness.

Journal article JCI Insight · August 22, 2019 Featured Publication Multiple organ failure (MOF) is the leading cause of late mortality and morbidity in patients who are admitted to intensive care units (ICUs). However, there is an epidemiologic discrepancy in the mechanism of underlying immunologic derangement dependent o ... Full text Open Access Link to item Cite

Copeptin to rule out myocardial infarction in Blacks versus Caucasians.

Journal article Eur Heart J Acute Cardiovasc Care · August 2019 Featured Publication BACKGROUND: Copeptin in combination with troponin has been shown to have incremental value for the early rule-out of myocardial infarction, but its performance in Black patients specifically has never been examined. In light of a potential for wider use, d ... Full text Link to item Cite

Analytical performance evaluation of the Elecsys® Troponin T Gen 5 STAT assay.

Journal article Clin Chim Acta · August 2019 Featured Publication BACKGROUND: We report the analytical performance of the Elecsys® Troponin T Gen 5 STAT (TnT Gen 5 STAT; Roche Diagnostics) assay. METHODS: Measuring limits/ranges were determined in lithium-heparin plasma samples per Clinical and Laboratory Standards Insti ... Full text Open Access Link to item Cite

Myocardial Infarction Risk Stratification With a Single Measurement of High-Sensitivity Troponin I.

Journal article J Am Coll Cardiol · July 23, 2019 Featured Publication BACKGROUND: Limited data exist on rapid risk-stratification strategies using the U.S. Food and Drug Administration-cleared high-sensitivity cardiac troponin I (hs-cTnI) assays. OBJECTIVES: This study sought to examine single measurement hs-cTnI to identify ... Full text Link to item Cite

Pilot study of myocardial ischemia-induced metabolomic changes in emergency department patients undergoing stress testing.

Journal article PLoS One · 2019 Featured Publication BACKGROUND: The heart is a metabolically active organ, and plasma acylcarnitines are associated with long-term risk for myocardial infarction. We hypothesized that myocardial ischemia from cardiac stress testing will produce dynamic changes in acylcarnitin ... Full text Open Access Link to item Cite

Implementation of the HEART Pathway: Using the Consolidated Framework for Implementation Research.

Journal article Crit Pathw Cardiol · December 2018 Featured Publication OBJECTIVE: The HEART Pathway is an evidence-based decision tool for identifying emergency department (ED) patients with acute chest pain who are candidates for early discharge, to reduce unhelpful and potentially harmful hospitalizations. Guided by the Con ... Full text Open Access Link to item Cite

Unexpected Cardiac MRI Findings in Patients Presenting to the Emergency Department for Possible Acute Coronary Syndrome.

Journal article Crit Pathw Cardiol · September 2018 Featured Publication BACKGROUND: Stress cardiac magnetic resonance imaging (CMR) has become increasingly used in patients presenting to the emergency department (ED) with symptoms concerning for acute coronary syndrome (ACS). We hypothesized that CMR detects a number of altern ... Full text Open Access Link to item Cite

Are Well-Informed Potential Trial Participants More Likely to Participate?

Journal article J Empir Res Hum Res Ethics · December 2017 Featured Publication Bearing in mind the importance of the informed consent, flaws in this process may be a barrier to participants' recruitment. Our objective was to determine the relationship between the degree of comprehension of the informed consent document plus the impor ... Full text Open Access Link to item Cite

Care of the Patient with Chest Pain in the Observation Unit.

Journal article Emerg Med Clin North Am · August 2017 Featured Publication Care of the patient presenting to an emergency department (ED) with chest pain remains a common yet challenging aspect of emergency medicine. Acute coronary syndrome presents in nonspecific fashion. The development and evolution of the ED-based observation ... Full text Open Access Link to item Cite

Myocardial Ischemia on Exercise Stress Echocardiography Testing Is Not Associated with Changes in Troponin T Concentrations.

Journal article J Appl Lab Med · March 1, 2017 Featured Publication BACKGROUND: Some posit that any amount of myocardial ischemia can be detected by high-sensitivity cardiac troponin assays. We hypothesized that patients with myocardial ischemia induced by exercise stress would have significantly higher increases in high-s ... Full text Open Access Link to item Cite

Necessity of hospitalization and stress testing in low risk chest pain patients.

Journal article Am J Emerg Med · February 2017 Featured Publication BACKGROUND: Copeptin is a marker of endogenous stress including early myocardial infarction(MI) and has value in early rule out of MI when used with cardiac troponin I(cTnI). OBJECTIVES: The goal of this study was to demonstrate that patients with a normal ... Full text Link to item Cite

Systematic Molecular Phenotyping: A Path Toward Precision Emergency Medicine?

Journal article Acad Emerg Med · October 2016 Featured Publication Precision medicine is an emerging approach to disease treatment and prevention that considers variability in patient genes, environment, and lifestyle. However, little has been written about how such research impacts emergency care. Recent advances in anal ... Full text Open Access Link to item Cite

Evaluation of T-Wave Morphology in Patients With Left Bundle Branch Block and Suspected Acute Coronary Syndrome.

Journal article J Emerg Med · September 2016 Featured Publication BACKGROUND: T-wave morphology in the setting of left bundle branch block (LBBB) has been proposed as an indicator of myocardial ischemia. OBJECTIVES: We sought to identify T-wave morphology findings in patients with LBBB that predict non-ST-segment elevati ... Full text Open Access Link to item Cite

Potential Cost-effectiveness of Early Identification of Hospital-acquired Infection in Critically Ill Patients.

Journal article Ann Am Thorac Soc · March 2016 Featured Publication RATIONALE: Limitations in methods for the rapid diagnosis of hospital-acquired infections often delay initiation of effective antimicrobial therapy. New diagnostic approaches offer potential clinical and cost-related improvements in the management of these ... Full text Open Access Link to item Cite

Serial sampling of copeptin levels improves diagnosis and risk stratification in patients presenting with chest pain: results from the CHOPIN trial.

Journal article Emerg Med J · January 2016 Featured Publication BACKGROUND: Copeptin has demonstrated a role in early rule out for acute myocardial infarction (AMI) in combination with a negative troponin. However, management of patients with chest pain with a positive copeptin in the setting of a negative troponin is ... Full text Link to item Cite

Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study.

Journal article Am Heart J · December 2015 Featured Publication BACKGROUND: The modified Sgarbossa criteria were proposed in a derivation study to be superior to the original criteria for diagnosing acute coronary occlusion (ACO) in left bundle branch block (LBBB). The new rule replaces the third criterion (5 mm of exc ... Full text Open Access Link to item Cite

Improving the Emergency Care Research Investigator Pipeline: SAEM/ACEP Recommendations.

Journal article Acad Emerg Med · July 2015 Featured Publication As representatives of the Society for Academic Emergency Medicine (SAEM) and American College of Emergency Physicians (ACEP) Research Committees, we offer commentary regarding the reasons for, and possible solutions to, the low number of EM applications fo ... Full text Open Access Link to item Cite

Midregional proadrenomedullin predicts mortality and major adverse cardiac events in patients presenting with chest pain: results from the CHOPIN trial.

Journal article Acad Emerg Med · May 2015 Featured Publication OBJECTIVES: Chest pain is a common complaint to emergency departments (EDs) and clinical risk factors are used to predict which patients are at risk for worse outcomes and mortality. The goal was to assess the novel biomarker midregional proadrenomedullin ... Full text Link to item Cite

A randomized trial of protocol-based care for early septic shock.

Other N Engl J Med · May 1, 2014 Featured Publication BACKGROUND: In a single-center study published more than a decade ago involving patients presenting to the emergency department with severe sepsis and septic shock, mortality was markedly lower among those who were treated according to a 6-hour protocol of ... Full text Open Access Link to item Cite

Acute myocardial infarction in sub-Saharan Africa: the need for data.

Journal article PLoS One · 2014 Featured Publication BACKGROUND: Trends in the prevalence of acute myocardial infarction in sub-Saharan Africa have not been well described, despite growing recognition of the increasing burden of cardiovascular disease in low- and middle-income countries. The aim of this syst ... Full text Open Access Link to item Cite

Thrombolysis in myocardial infarction risk score in an observation unit setting.

Journal article Crit Pathw Cardiol · September 2013 Featured Publication OBJECTIVE: The Thrombolysis in Myocardial Infarction (TIMI) score is a validated tool for risk stratification of acute coronary syndrome. We hypothesized that the TIMI risk score would be able to risk stratify patients in observation unit for acute coronar ... Full text Open Access Link to item Cite

Copeptin helps in the early detection of patients with acute myocardial infarction: primary results of the CHOPIN trial (Copeptin Helps in the early detection Of Patients with acute myocardial INfarction).

Journal article J Am Coll Cardiol · July 9, 2013 Featured Publication OBJECTIVES: The goal of this study was to demonstrate that copeptin levels <14 pmol/L allow ruling out acute myocardial infarction (AMI) when used in combination with cardiac troponin I (cTnI) <99 th percentile and a nondiagnostic electrocardiogram at the ... Full text Link to item Cite

Utility of observation units for young emergency department chest pain patients.

Journal article J Emerg Med · February 2013 Featured Publication BACKGROUND: Determining which patients presenting to the Emergency Department (ED) require further work-up for acute coronary syndrome (ACS) can be difficult. The utility of routine observation for cardiac testing in low-risk young adult patients has been ... Full text Open Access Link to item Cite

Willingness to participate in clinical trials among patients of Chinese heritage: a meta-synthesis.

Journal article PLoS One · 2013 Featured Publication BACKGROUND: Subjects of Chinese heritage have been found to participate in clinical research at lower rates than other groups despite growing in numbers as a population. While much research has examined research participants' motivation, there has not been ... Full text Open Access Link to item Cite

Cardiac evaluation for structural abnormalities may not be required in patients presenting with syncope and a normal ECG result in an observation unit setting.

Journal article Ann Emerg Med · October 2012 Featured Publication STUDY OBJECTIVE: Patients with syncope are frequently managed in observation units and receive serial examinations, monitoring for arrhythmias, and structural analysis of the heart. The primary aim of this study is to determine the utility of structural an ... Full text Link to item Cite

Are patients with longer emergency department wait times less likely to consent to research?

Journal article Acad Emerg Med · April 2012 Featured Publication OBJECTIVES: There are unique challenges to enrolling patients in emergency department (ED) clinical research studies, including the time-sensitive nature of emergency conditions, the acute care environment, and the lack of an established relationship with ... Full text Open Access Link to item Cite

Left ventricular dysfunction screening in hypertensive patients with N-terminal pro-B-type natriuretic peptide and electrocardiogram.

Journal article Am J Emerg Med · January 2012 Featured Publication OBJECTIVE: Early recognition of left ventricular hypertrophy is important because antihypertensive treatment decreases morbidity and mortality. The ideal screening method for left ventricular hypertrophy in hypertensive emergency department (ED) patients h ... Full text Open Access Link to item Cite

An observation unit may help improve an institution's Press Ganey satisfaction score.

Journal article Crit Pathw Cardiol · June 2011 Featured Publication BACKGROUND: : Hospitals measure patient satisfaction through Press Ganey (PG) surveys. The impact of an emergency department observation unit (EDOU) on patient satisfaction has not been reported to date. We hypothesize that an EDOU has a positive impact on ... Full text Link to item Cite

A multicenter analysis of the ED diagnosis of pneumonia.

Journal article Am J Emerg Med · October 2010 Featured Publication OBJECTIVES: The objective of this study was to describe the prevalence of pneumonia-like signs and symptoms in patients admitted from the emergency department (ED) with a diagnosis of community acquired pneumonia (CAP) but subsequently discharged from the ... Full text Link to item Cite

Impact of renal dysfunction on acute coronary syndrome evaluation in observation unit patients.

Journal article Am J Emerg Med · July 2010 Featured Publication OBJECTIVES: The impact of renal disease on risk stratification of patients at low risk for potential acute coronary syndrome has not been well defined. The objective of this study was to document the prevalence of renal dysfunction and assess the associati ... Full text Open Access Link to item Cite

Emergency physician high pretest probability for acute coronary syndrome correlates with adverse cardiovascular outcomes.

Journal article Acad Emerg Med · August 2009 Featured Publication OBJECTIVES: The value of unstructured physician estimate of risk for disease processes, other than acute coronary syndrome (ACS), has been demonstrated. The authors sought to evaluate the predictive value of unstructured physician estimate of risk for ACS ... Full text Open Access Link to item Cite

Unsuspected pulmonary embolism in observation unit patients.

Journal article West J Emerg Med · August 2009 Featured Publication OBJECTIVE: Many emergency department (ED) patients with cardiopulmonary symptoms such as chest pain or dyspnea are placed in observation units but do not undergo specific diagnostic testing for pulmonary embolism (PE). The role of observation units in the ... Link to item Cite

Preferences for cardiac tests and procedures may partially explain sex but not race disparities.

Journal article Am J Emerg Med · June 2008 Featured Publication OBJECTIVE: There are known race and sex differences in emergent cardiac care. Many feel these differences reflect a bias from the physician. We hypothesized these differences may be the result of patient preferences. METHODS: Emergency department (ED) pati ... Full text Link to item Cite

Sixty-four-slice multidetector computed tomography: the future of ED cardiac care.

Journal article Am J Emerg Med · May 2007 Featured Publication Multidetector computed tomography (MDCT) imaging, a technological advance over traditional CT, is a promising possible alternative to cardiac catheterization for evaluating patients with chest pain in the emergency department (ED). In comparison with tradi ... Full text Link to item Cite

Combination of Goldman risk and initial cardiac troponin I for emergency department chest pain patient risk stratification.

Journal article Acad Emerg Med · July 2001 Featured Publication BACKGROUND: Accurate identification of low-risk emergency department (ED) chest pain patients who may be safe for discharge has not been well defined. Goldman criteria have reliably risk-stratified patients but have not identified any subset safe for ED re ... Full text Link to item Cite