This document discusses high sensitivity troponins and their use in the emergency department setting. It notes that high sensitivity troponins can detect very small amounts of myocardial necrosis and outlines debates around their interpretation and what constitutes a "normal" level. It also summarizes research showing that using high sensitivity troponins can safely allow some low-risk chest pain patients to be discharged early from the emergency department, while others may benefit from closer monitoring in a CCU. However, there are ongoing discussions around what miss rates are acceptable and how troponins should best be used to determine patient disposition.

1. HIGH SENSITIVITY
TROPONINS

2. WHAT ARE TROPONINS?
 Cardiac regulating protein controlling Ca mediated interaction between
actin & myosin-not an enzyme!
 Troponin-Tropomyosin complex – 3 subunits : T,I,C
 Troponin I not found outside heart muscle – highly specific
 Troponin T also expressed in skeletal muscle - differentiated from
skeletal isoforms by monoclonal antibodies
 Raised in myocardial injury of any mechanism, initial cytosolic loss,
more sustained with contractile apparatus destruction

3. WHAT ARE HS TROPONINS?
 ‘When troponin was a lousy assay it was a great test, now that it is a great
assay it is a lousy test’-Robert Jesse
 ‘Low specificity troponins’ –Joe Lex
 Can detect <1g of myocardial necrosis (microscopic zone)
 Old test-99th centile at limits of detection

5. WHAT IS ‘NORMAL’
 ‘Normal’ from healthy population, 1% abnormal by chance
 Below study from GP population with co-morbidities , 99th centile
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7. KNOW YOUR ASSAY

8. WHY DO WE NEED THEM?
 Clinician ‘Gestalt’
• http://intensivecarenetwork.com/heart-stress-body
• Character of pain-no change to PTP, radiation to left arm, no change in
PTP, RF-no change, asking doctors on likelihood scale-poor
 ECG-Too insensitive, 28 % but 97% specific

9. INTERPRETATION OF HS
 Always in clinical context
 Significant change rise/fall
• Increase in >20% if 1st troponin elevated (European
Society of Cardiology)
• Better evidence with delta value of 10
• No clear evidence of % rise if troponins ‘normal’
•
-

11. UTILITY OF HST FOR ED
PHYSICIANS
1) Disposition
• Home-safely and quickly
• Studies largely confined to low risk
patients
• CCU
2) Treat patients
• Not much utility except home/ward quicker

12. DISPOSITION-IMPORTANT FOR
THE PATIENT AND NEAT
 Bayley et al. The financial burden of emergency department
congestion and hospital crowding for chest pain patients awaiting
admission. Ann Emerge Med 2005: 45; 110-7
 Pines et al. The association between emergency department
crowding and adverse cardiovascular outcomes in patients with chest
pain. Acad emerge Med 2009 Jun 22

13. NUMERATORS VS
DENOMINATORS
 ED physicians
• Work with denominators/uncertainty
• We are very proficient with working with numerators
 Ward physicians
• Work with numerators
• What happens when we ask them to work with denominators?

15. ED DISPOSITION-HOME-
MOST ‘LOW RISK’
 1635 patients, 30d follow up for MACE
• Non ischaemic ECG, TIMI 0, neg 0 & 2/24 troponin, 0% MACE
with sens 100%, spec 23.1, NPV 100%
• As above with TIMI 0 or 1, 0.8% MACE, sens 99.2, spec 48.7, NPV
99.7
• Allowed early discharge in 40% of suspected ACS presentations

16. ED DISPOSITION-HOME
 Results
• Swedish study, Mean age 55
• 61% (8883) had hs-TnT <5ng/L
• 39 had MI and 2 died at 1/12, 15 of whom had no ECG changes
• If Hs TnT<5 with no ECG changes, absolute MI risk 0.17, no
difference in death at 12/12 between discharged & admitted

18. ED DISPOSITION-HOME
 Strategy to maximize advantage of lower detection rate
• 703 patients, 28% had TnT <3ng/L at presentation (less than
detection threshold)
• Overall MI rate 19%
• No MI at 1/12 in undetectable cohort
 Authors-’Pending further validation studies’

19. WHAT IS AN ACCEPTABLE
‘MISS RATE’

20. WHAT HAPPE NS WHE N YOU SE ND THE M
HOME ? ‘ DIRE CONSE QUE NCES’
 They die! ?
• 10689 patients, 17% ACS, 2% sent home=2% miss rate, death rate
doubled c/w hospitalized if ‘risk adjusted’ but absolute risk the same
(but confidence interval wide and includes 1)
• Readmission hospitalized 17%, not hospitalized 72%

21. YOU CAN’T EVEN MISS
SILENT INFARCTS

22. ED DISPOSITION-CCU
 Sensitivity improves from 73% to 91% drop on specificity form
94% to 90%

23. ED DISPOSITION-CCU
 Reichlin, T et al. Early Diagnosis of Myocardial infarction with
sensitive cardiac troponin assays. N Engl J Med 2009: 361:858-67
• Multicentre study, 718 patients
• AUC at 3/24 93% vs 76%

24. ED DISPOSITION-CCU
 Sensitivity similar at 3 or 6 hours compared to previous 12 hour
sampling

25. COMING TO HELP…

26. DOES THIS HELP OR
HINDER?