1
|
Engström A, Mokhtari A, Ekelund U. Direct Comparison of the European Society of Cardiology 0/1-Hour Vs. 0/2-Hour Algorithms in Patients with Acute Chest Pain. J Emerg Med 2024; 66:e651-e659. [PMID: 38789353 DOI: 10.1016/j.jemermed.2024.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 01/21/2024] [Accepted: 02/02/2024] [Indexed: 05/26/2024]
Abstract
BACKGROUND The recent guidelines from the European Society of Cardiology recommends using high-sensitivity cardiac troponin (hs-cTn) in either 0/1-h or 0/2-h algorithms to identify or rule out acute myocardial infarction (AMI). Several studies have reported good diagnostic accuracy with both algorithms, but few have compared the algorithms directly. OBJECTIVE We aimed to compare the diagnostic accuracy of the algorithms head-to-head, in the same patients. METHODS This was a secondary analysis of data from a prospective observational study; 1167 consecutive patients presenting with chest pain to the emergency department at Skåne University Hospital (Lund, Sweden) were enrolled. Only patients with a hs-cTnT sample at presentation AND after 1 AND 2 h were included in the analysis. We compared sensitivity, specificity, and negative (NPV) and positive predictive value (PPV). The primary outcome was index visit AMI. RESULTS A total of 710 patients were included, of whom 56 (7.9%) had AMI. Both algorithms had a sensitivity of 98.2% and an NPV of 99.8% for ruling out AMI, but the 0/2-h algorithm ruled out significantly more patients (69.3% vs. 66.2%, p < 0.001). For rule-in, the 0/2-h algorithm had higher PPV (73.4% vs. 65.2%) and slightly better specificity (97.4% vs. 96.3%, p = 0.016) than the 0/1-h algorithm. CONCLUSION Both algorithms had good diagnostic accuracy, with a slight advantage for the 0/2-h algorithm. Which algorithm to implement may thus depend on practical issues such as the ability to exploit the theoretical time saved with the 0/1-h algorithm. Further studies comparing the algorithms in combination with electrocardiography, history, or risk scores are needed.
Collapse
Affiliation(s)
- Agnes Engström
- Department of Emergency and Internal Medicine, Skåne University Hospital, Lund, Sweden; Department of Clinical Sciences at Lund, Lund University, Lund, Sweden.
| | - Arash Mokhtari
- Department of Clinical Sciences at Lund, Lund University, Lund, Sweden; Department of Cardiology, Skåne University Hospital, Lund, Sweden
| | - Ulf Ekelund
- Department of Emergency and Internal Medicine, Skåne University Hospital, Lund, Sweden; Department of Clinical Sciences at Lund, Lund University, Lund, Sweden
| |
Collapse
|
2
|
Suh EH, Probst MA, Tichter AM, Ranard LS, Amaranto A, Chang BC, Huynh PA, Kratz A, Lee RJ, Rabbani LE, Sacco DL, Einstein AJ. Flexible-Interval High-Sensitivity Troponin Velocity for the Detection of Acute Coronary Syndromes. Am J Cardiol 2023; 203:240-247. [PMID: 37506670 DOI: 10.1016/j.amjcard.2023.06.080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/14/2023] [Accepted: 06/24/2023] [Indexed: 07/30/2023]
Abstract
Many algorithms for emergency department (ED) evaluation of acute coronary syndrome (ACS) using high-sensitivity troponin assays rely on the detection of a "delta," the difference in concentration over a predetermined interval, but collecting specimens at specific times can be difficult in the ED. We evaluate the use of troponin "velocity," the rate of change of troponin concentration over a flexible short interval for the prediction of major adverse cardiac events (MACEs) at 30 days. We conducted a prospective, observational study on a convenience sample of 821 patients who underwent ACS evaluation at a high-volume, urban ED. We determined the diagnostic performance of a novel velocity-based algorithm and compared the performance of 1- and 2-hour algorithms adapted from the European Society of Cardiology (ESC) using delta versus velocity. A total of 7 of 332 patients (2.1%) classified as low risk by the velocity-based algorithm experienced a MACE by 30 days compared with 35 of 221 (13.8%) of patients classified as greater than low risk, yielding a sensitivity of 83.3% (95% confidence interval [CI] 68.6% to 93.0%) and negative predictive value (NPV) of 97.9% (95% CI 95.9% to 98.9%). The ESC-derived algorithms using delta or velocity had NPVs ranging from 98.4% (95% CI 96.4% to 99.3%) to 99.6% (95% CI 97.0% to 99.9%) for 30-day MACEs. The NPV of the novel velocity-based algorithm for MACE at 30 days was borderline, but the substitution of troponin velocity for delta in the framework of the ESC algorithms performed well. In conclusion, specimen collection within strict time intervals may not be necessary for rapid evaluation of ACS with high-sensitivity troponin.
Collapse
Affiliation(s)
- Edward Hyun Suh
- Department of Emergency Medicine, Columbia University Irving Medical Center, New York, New York.
| | - Marc A Probst
- Department of Emergency Medicine, Columbia University Irving Medical Center, New York, New York
| | - Aleksandr M Tichter
- Department of Emergency Medicine, Baylor College of Medicine, Houston, Texas
| | - Lauren S Ranard
- Seymour, Paul, and Gloria Milstein Division of Cardiology, Columbia University Irving Medical Center, New York, New York
| | - Andrew Amaranto
- Department of Emergency Medicine, Hackensack School of Medicine, Hackensack, New Jersey
| | - Betty C Chang
- Department of Emergency Medicine, Columbia University Irving Medical Center, New York, New York
| | - Phong Anh Huynh
- Department of Emergency Medicine, Baylor College of Medicine, Houston, Texas
| | - Alexander Kratz
- Department of Pathology and Cell Biology, New York-Presbyterian Hospital, Columbia University Irving Medical Center, New York, New York
| | - Rebekah J Lee
- Stony Brook University School of Medicine, Stony Brook, New York
| | - Leroy E Rabbani
- Seymour, Paul, and Gloria Milstein Division of Cardiology, Columbia University Irving Medical Center, New York, New York
| | - Dana L Sacco
- Department of Emergency Medicine, Columbia University Irving Medical Center, New York, New York
| | - Andrew J Einstein
- Seymour, Paul, and Gloria Milstein Division of Cardiology, Columbia University Irving Medical Center, New York, New York
| |
Collapse
|
3
|
Ohtake H, Terasawa T, Zhelev Z, Iwata M, Rogers M, Peters JL, Hyde C. Serial high-sensitivity cardiac troponin testing for the diagnosis of myocardial infarction: a scoping review. BMJ Open 2022; 12:e066429. [PMID: 36414302 PMCID: PMC9685223 DOI: 10.1136/bmjopen-2022-066429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES We aimed to assess the diversity and practices of existing studies on several assays and algorithms for serial measurements of high-sensitivity cardiac troponin (hs-cTn) for risk stratification and the diagnosis of myocardial infarction (MI) and 30-day outcomes in patients suspected of having non-ST-segment elevation MI (NSTEMI). METHODS We searched multiple databases including MEDLINE, EMBASE, Science Citation Index, the Cochrane Database of Systematic Reviews and the CENTRAL databases for studies published between January 2006 and November 2021. Studies that assessed the diagnostic accuracy of serial hs-cTn testing in patients suspected of having NSTEMI in the emergency department (ED) were eligible. Data were analysed using the scoping review method. RESULTS We included 86 publications, mainly from research centres in Europe, North America and Australasia. Two hs-cTn assays, manufactured by Abbott (43/86) and Roche (53/86), dominated the evaluations. The studies most commonly measured the concentrations of hs-cTn at two time points, at presentation and a few hours thereafter, to assess the two-strata or three-strata algorithm for diagnosing or ruling out MI. Although data from 83 studies (97%) were prospectively collected, 0%-90% of the eligible patients were excluded from the analysis due to missing blood samples or the lack of a final diagnosis in 53 studies (62%) that reported relevant data. Only 19 studies (22%) reported on head-to-head comparisons of alternative assays. CONCLUSION Evidence on the accuracy of serial hs-cTn testing was largely derived from selected research institutions and relied on two specific assays. The proportions of the eligible patients excluded from the study raise concerns about directly applying the study findings to clinical practice in frontline EDs. PROSPERO REGISTRATION NUMBER CRD42018106379.
Collapse
Affiliation(s)
- Hirotaka Ohtake
- Department of Emergency and General Internal Medicine, Fujita Health University, Toyoake, Aichi, Japan
| | - Teruhiko Terasawa
- Department of Emergency and General Internal Medicine, Fujita Health University, Toyoake, Aichi, Japan
| | - Zhivko Zhelev
- University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Mitsunaga Iwata
- Department of Emergency and General Internal Medicine, Fujita Health University, Toyoake, Aichi, Japan
| | - Morwenna Rogers
- NIHR CLAHRC South West Peninsula, University of Exeter, Exeter, UK
| | - Jaime L Peters
- Peninsula Technology Assessment Group (PenTAG), University of Exeter, Exeter, UK
- Peninsula Technology Assessment Group (PenTAG), University of Exeter, Exeter, UK
| | - Chris Hyde
- Exeter Test Group, University of Exeter, Exeter, UK
| |
Collapse
|
4
|
Zhuo MF, Zhang KL, Shen XB, Lin WC, Hu B, Cai HP, Huang G. Postoperative adverse cardiac events in acute myocardial infarction with high thrombus load and best time for stent implantation. World J Clin Cases 2022; 10:2106-2114. [PMID: 35321185 PMCID: PMC8895172 DOI: 10.12998/wjcc.v10.i7.2106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/17/2021] [Accepted: 01/22/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Myocardial infarction is one of the most common types of coronary heart disease. It is mainly caused by the rupture of coronary atherosclerotic plaque, which leads to platelet agglutination and thrombosis. The occlusion of coronary arteries and vessels leads to insufficient myocardial blood supply, subsequently causing cardiac interstitial fibrosis, gradual enlargement of ventricles, and heart failure, which affects the quality of life and safety of patients.
AIM To investigate the effects of emergency percutaneous interventional therapy (PCI) and delayed stenting in acute myocardial infarction with high thrombotic load and identify factors related to major adverse cardiovascular events (MACE).
METHODS A total of 164 patients with acute myocardial infarction and high thrombotic load who received PCI were included. Of them, 92 patients were treated with delayed stent implantation (delayed group) and 72 patients received emergency PCI (immediate group). Myocardial perfusion after stent implantation was compared between the two groups. Patients were followed up for 12 mo, and the occurrence of MACE was used as the endpoint. Univariate and multivariate models were used to analyze the factors affecting MACE occurrence.
RESULTS After stent implantation, 66 (71.74%) patients in the delayed group and 40 (55.56%) patients in the immediate group had thrombolysis in myocardial infarction (TIMI) flow grade 3 (P < 0.05), while 61 (66.30%) patients in the delayed group and 39 (54.17%) patients in the immediate group reached TIMI myocardial perfusion grade 3 (P > 0.05). MACE occurred in 29 patients. There were statistically significant differences between the MACE and non-MACE groups in diabetes rate, TIMI grading, stent implantation timing, intraoperative use of tirofiban, and the levels of white blood cells (WBC), neutrophils, red blood cell distribution width (RDW), and uric acid, and high-sensitivity C-reactive protein (hs-CRP) at admission (P < 0.05). Logistic regression analysis showed that TIMI grade 3 and intraoperative use of tirofiban effectively reduced the risk of MACE (P < 0.05), while immediate stent implantation, increased WBC, hs-CRP and RDW on admission increased the risk of MACE (P < 0.05).
CONCLUSION Delayed stent implantation outweighs emergency PCI in improving postoperative myocardial perfusion in acute myocardial infarction with high thrombotic load, and effectively reduces MACE in these patients.
Collapse
Affiliation(s)
- Ming-Feng Zhuo
- Department of Emergency, Shishi General Hospital, Shishi 362700, Fujian Province, China
| | - Ke-Lian Zhang
- Department of Cardiovascular, Quanzhou First Hospital, Quanzhou 362000, Fujian Province, China
| | - Xue-Bin Shen
- Department of Cardiology, Affiliated Nanping First Hospital, Fujian Medical University, Nanping 353000, Fujian Province, China
| | - Wen-Can Lin
- Department of Emergency, Shishi General Hospital, Shishi 362700, Fujian Province, China
| | - Bin Hu
- Department of Emergency, Shishi General Hospital, Shishi 362700, Fujian Province, China
| | - Hua-Peng Cai
- Department of Emergency, Shishi General Hospital, Shishi 362700, Fujian Province, China
| | - Gang Huang
- Department of Emergency, Shishi General Hospital, Shishi 362700, Fujian Province, China
| |
Collapse
|
5
|
Chiang CH, Chiang CH, Pickering JW, Stoyanov KM, Chew DP, Neumann JT, Ojeda F, Sörensen NA, Su KY, Kavsak P, Worster A, Inoue K, Johannessen TR, Atar D, Amann M, Hochholzer W, Mokhtari A, Ekelund U, Twerenbold R, Mueller C, Bahrmann P, Buttinger N, Dooley M, Ruangsomboon O, Nowak RM, DeFilippi CR, Peacock WF, Neilan TG, Liu MA, Hsu WT, Lee GH, Tang PU, Ma KSK, Westermann D, Blankenberg S, Giannitsis E, Than MP, Lee CC. Performance of the European Society of Cardiology 0/1-Hour, 0/2-Hour, and 0/3-Hour Algorithms for Rapid Triage of Acute Myocardial Infarction : An International Collaborative Meta-analysis. Ann Intern Med 2022; 175:101-113. [PMID: 34807719 DOI: 10.7326/m21-1499] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND The 2020 European Society of Cardiology (ESC) guidelines recommend using the 0/1-hour and 0/2-hour algorithms over the 0/3-hour algorithm as the first and second choices of high-sensitivity cardiac troponin (hs-cTn)-based strategies for triage of patients with suspected acute myocardial infarction (AMI). PURPOSE To evaluate the diagnostic accuracies of the ESC 0/1-hour, 0/2-hour, and 0/3-hour algorithms. DATA SOURCES PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus from 1 January 2011 to 31 December 2020. (PROSPERO: CRD42020216479). STUDY SELECTION Prospective studies that evaluated the ESC 0/1-hour, 0/2-hour, or 0/3-hour algorithms in adult patients presenting with suspected AMI. DATA EXTRACTION The primary outcome was index AMI. Twenty unique cohorts were identified. Primary data were obtained from investigators of 16 cohorts and aggregate data were extracted from 4 cohorts. Two independent authors assessed each study for methodological quality. DATA SYNTHESIS A total of 32 studies (20 cohorts) with 30 066 patients were analyzed. The 0/1-hour algorithm had a pooled sensitivity of 99.1% (95% CI, 98.5% to 99.5%) and negative predictive value (NPV) of 99.8% (CI, 99.6% to 99.9%) for ruling out AMI. The 0/2-hour algorithm had a pooled sensitivity of 98.6% (CI, 97.2% to 99.3%) and NPV of 99.6% (CI, 99.4% to 99.8%). The 0/3-hour algorithm had a pooled sensitivity of 93.7% (CI, 87.4% to 97.0%) and NPV of 98.7% (CI, 97.7% to 99.3%). Sensitivity of the 0/3-hour algorithm was attenuated in studies that did not use clinical criteria (GRACE score <140 and pain-free) compared with studies that used clinical criteria (90.2% [CI, 82.9 to 94.6] vs. 98.4% [CI, 88.6 to 99.8]). All 3 algorithms had similar specificities and positive predictive values for ruling in AMI, but heterogeneity across studies was substantial. Diagnostic performance was similar across the hs-cTnT (Elecsys; Roche), hs-cTnI (Architect; Abbott), and hs-cTnI (Centaur/Atellica; Siemens) assays. LIMITATION Diagnostic accuracy, inclusion and exclusion criteria, and cardiac troponin sampling time varied among studies. CONCLUSION The ESC 0/1-hour and 0/2-hour algorithms have higher sensitivities and NPVs than the 0/3-hour algorithm for index AMI. PRIMARY FUNDING SOURCE National Taiwan University Hospital.
Collapse
Affiliation(s)
- Cho-Han Chiang
- Harvard Medical School, Boston, Massachusetts, and National Taiwan University College of Medicine, Taipei, Taiwan (Cho-Han Chiang)
| | - Cho-Hung Chiang
- Taipei Tzu Chi Hospital, Buddhist Tzu Chi Foundation, New Taipei City, Taiwan (Cho-Hung Chiang)
| | - John W Pickering
- Christchurch Hospital and University of Otago Christchurch, Christchurch, New Zealand (J.W.P.)
| | - Kiril M Stoyanov
- University Hospital of Heidelberg, Heidelberg, Germany (K.M.S., E.G.)
| | - Derek P Chew
- Flinders University of South Australia, Adelaide, Australia (D.P.C.)
| | - Johannes T Neumann
- Monash University, Melbourne, Australia, and University Heart & Vascular Center Hamburg, Hamburg, Germany (J.T.N.)
| | - Francisco Ojeda
- University Heart & Vascular Center Hamburg, Hamburg, Germany (F.O., N.A.S., D.W., S.B.)
| | - Nils A Sörensen
- University Heart & Vascular Center Hamburg, Hamburg, Germany (F.O., N.A.S., D.W., S.B.)
| | - Ke-Ying Su
- National Taiwan University Hospital, Taipei, Taiwan (K.S., G.H.L., P.T.)
| | - Peter Kavsak
- McMaster University, Hamilton, Ontario, Canada (P.K., A.W.)
| | - Andrew Worster
- McMaster University, Hamilton, Ontario, Canada (P.K., A.W.)
| | - Kenji Inoue
- Juntendo University Nerima Hospital, Tokyo, Japan (K.I.)
| | - Tonje R Johannessen
- University of Oslo and Oslo Accident and Emergency Outpatient Clinic, Oslo, Norway (T.R.J.)
| | - Dan Atar
- Oslo University Hospital, Ullevaal, and University of Oslo, Oslo, Norway (D.A.)
| | - Michael Amann
- University Heart Center Freiburg-Bad Krozingen, Bad Krozingen, Germany (M.A., W.H.)
| | - Willibald Hochholzer
- University Heart Center Freiburg-Bad Krozingen, Bad Krozingen, Germany (M.A., W.H.)
| | - Arash Mokhtari
- Skåne University Hospital, Lund University, Lund, Sweden (A.M., U.E.)
| | - Ulf Ekelund
- Skåne University Hospital, Lund University, Lund, Sweden (A.M., U.E.)
| | - Raphael Twerenbold
- University of Basel, Basel, Switzerland, University Heart and Vascular Center Hamburg, Hamburg, Germany, and German Center for Cardiovascular Research (DZHK) Partner Site Hamburg-Kiel-Lübeck (R.T.)
| | | | - Philipp Bahrmann
- Friedrich-Alexander-University Erlangen-Nuremberg, Nuremberg, Germany (P.B.)
| | - Nicolas Buttinger
- Brighton and Sussex University Hospitals NHS Trust, Brighton, United Kingdom (N.B., M.D.)
| | - Maureen Dooley
- Brighton and Sussex University Hospitals NHS Trust, Brighton, United Kingdom (N.B., M.D.)
| | | | | | | | | | - Tomas G Neilan
- Cardiovascular Imaging Research Center, Massachusetts General Hospital, Boston, Massachusetts (T.G.N.)
| | - Michael A Liu
- Warren Alpert Medical School of Brown University, Providence, Rhode Island (M.A.L.)
| | - Wan-Ting Hsu
- Harvard School of Public Health, Boston, Massachusetts (W.H.)
| | - Gin Hoong Lee
- National Taiwan University Hospital, Taipei, Taiwan (K.S., G.H.L., P.T.)
| | - Pui-Un Tang
- National Taiwan University Hospital, Taipei, Taiwan (K.S., G.H.L., P.T.)
| | - Kevin Sheng-Kai Ma
- Center for Global Health, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, and National Taiwan University, Taipei, Taiwan (K.S.M.)
| | - Dirk Westermann
- University Heart & Vascular Center Hamburg, Hamburg, Germany (F.O., N.A.S., D.W., S.B.)
| | - Stefan Blankenberg
- University Heart & Vascular Center Hamburg, Hamburg, Germany (F.O., N.A.S., D.W., S.B.)
| | | | - Martin P Than
- Christchurch Hospital and Christchurch Heart Institute, University of Otago Christchurch, Christchurch, New Zealand (M.P.T.)
| | - Chien-Chang Lee
- The Centre for Intelligent Healthcare, National Taiwan University Hospital, Taipei, Taiwan (C.L.)
| |
Collapse
|
6
|
O'Rielly CM, Andruchow JE, McRae AD. External validation of a low HEAR score to identify emergency department chest pain patients at very low risk of major adverse cardiac events without troponin testing. CAN J EMERG MED 2022; 24:68-74. [PMID: 34273102 DOI: 10.1007/s43678-021-00159-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 06/05/2021] [Indexed: 12/23/2022]
Abstract
BACKGROUND The history, ECG, age, risk factor (HEAR) score has been proposed to identify patients at sufficiently low risk of acute coronary syndrome that they may not require troponin testing. The objective of this study was to externally validate a low HEAR score to identify emergency department (ED) patients with chest pain at very low risk of 30-day major adverse cardiac events (MACE). METHODS This was a secondary analysis of a prospective cohort of patients requiring troponin testing to rule out myocardial infarction (MI) in a large urban ED. HEAR scores were calculated in two cohorts: (1) patients with no known history of coronary artery disease (CAD); and (2) all eligible patients. The proportion of patients classified as very low risk, sensitivity, specificity, predictive values and likelihood ratios at each cut-off were quantified for index acute myocardial infarction (AMI) and 30-day MACE at HEAR = 0 and HEAR ≤ 1 thresholds. RESULTS Of the 1150 patients included in this study, 820 (71.3%) had no history of CAD, 97 (8.4%) had index AMI and 123 (10.7%) had 30-day MACE. In patients with no prior history of CAD, HEAR ≤ 1 identified 202 (24.6%) of patients as very low risk for 30-day MACE with 98.4% (95% CI 91.6-99.9%) sensitivity. Among all patients, HEAR ≤ 1 identified 202 (17.6%) patients as very low risk for 30-day MACE with 99.2% (95% CI 95.6-99.9%) sensitivity. CONCLUSIONS A HEAR score ≤ 1 can identify more than 17% of all patients as very low risk for index AMI and 30-day MACE and unlikely to benefit from troponin testing. Broad implementation of this strategy could lead to significant resource savings.
Collapse
Affiliation(s)
- Connor M O'Rielly
- Department of Emergency Medicine, Cumming School of Medicine, University of Calgary, 3280 Hospital Drive NW, Room 3E34, Calgary, AB, T2N 4Z6, Canada
| | - James E Andruchow
- Department of Emergency Medicine, Cumming School of Medicine, University of Calgary, 3280 Hospital Drive NW, Room 3E34, Calgary, AB, T2N 4Z6, Canada
| | - Andrew D McRae
- Department of Emergency Medicine, Cumming School of Medicine, University of Calgary, 3280 Hospital Drive NW, Room 3E34, Calgary, AB, T2N 4Z6, Canada.
| |
Collapse
|