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  1. Theinvestigation of possible cardiac chest painMARTIN THANDirector of Emergency Medicine ResearchChristchurch Hospital New Zealand

  2. Thank you For inviting me to speak

  3. An abbreviation • ED = Emergency Department

  4. LEARNING OBJECTIVES • What are the challenges in the assessment of possible cardiac chest pain? • How is cardiac troponin (cTn) used? • What’s the strategies for assessing chest pain? • Understand a bit about highly sensitive troponins

  5. LECTURE SUMMARY • Background – chest pain and overcrowding • Objectives in the assessment of chest pain • Challenges of chest pain assessment • Use of cTn • Integrating cTn into diagnostic strategy • A perspective on HS-cTn

  6. BACKGROUND • The greatest challenges in medicine is not about the rapid diagnosis and treatment of critically ill patients. • It is about decisions not to admit patients to hospital and not to doinvestigations

  7. BACKGROUND • One of the greatest fears of any clinician involved in acute care is for a patient to come unexpectedly to harm, • soon after hospital discharge, • from the medical complaint with which they initially presented to hospital for help.

  8. Thereis logical pressure to admit patients The missed AMI rate is inversely proportional to the admission rate for chest pain patients Kontos MC & Jesse RL. Am J Cardiol 2000;85:32B-39B

  9. Chest pain and Hospital overcrowding • This is a major issue

  10. Overcrowding • Now proven to be associated with poor patient outcomes • Death • Increased adverse events • Delayed treatment • Delayed pain relief

  11. Patients with chest pain and possible ACS • Very common type of presenting problem to the ED • First or second most common complaint in many ED’s

  12. Other consequences of prolonged chest pain assessment • Duplication • Risk from multiple handovers • Competing demand for staff time

  13. BACKGROUND - Summary • Patients with possible ACS are common yet most will not have an ACS. • The challenge is ‘rule-out’ rather than ‘rule-in’, • Rule-out is difficult to achieve and consumes a lot of time and resources, • Medicine is constantly seeking more rapid, but still safe ‘rule-out’ processes.

  14. ASSESSMENT OF CARDIAC CHEST PAIN

  15. GRACE Registry(60,000 patients) • 6 Centre Australasian subset with 4704 patients followed-up. • Six month follow-up death rate • STEMI 4% • NSTEMI 6% • Unstable Angina (UAP) 3%

  16. What do we want when Assessing a Patient with chest pain? = Safe “decisions” Therefore the focus is on both short term prognostic accuracy as well as diagnostic accuracy

  17. Our real aims • Identify those at of short term risk of serious adverse cardiac event • that are now safe for objective cardiac testing for ischaemic heart disease • (Exercise stress test, stress echo etc.)

  18. LECTURE SUMMARY • Background - ED work and overcrowding • Objectives in ED assessment of chest pain • Challenges of ED assessment • ED use of cTn • Integrating cTn into ED diagnostic strategy • ED perspective on HS-cTn

  19. ASSESSMENT OF CARDIAC CHEST PAIN

  20. Bayes Theorem The (post-test) probability of a disease being present after a given test result e.g. positive or negative troponin is dependent on what the probability was before the test was done (pre-test probability)

  21. The true disease status of the patient usually cannot be directly observed.It must be determined from external imperfect clues (clinical assessment). BUT When assessing patients with chest pain the clinical clues are not as reliable as we once thought

  22. Goodacre QJM • Prospective observational study of 972 patients with low risk chest pain. • Excluded if ECG abnormaities, known CAD or clear alternative diagnosis. • Outcome ACS at 30 days (7.9% overall)

  23. Christchurch/Brisbane • 2400 Patients • Similar results

  24. What about risk factors? Family History Cholesterol Age? Gender? Blood Pressure Smoker? Life Style

  25. Cardiac Risk Factors (CRFs) are Poor Diagnostic Predictors Han et. Al. (2007)Annals of Emergency Medicine 49[2]

  26. Diagnostic Predictive Value (DPF) of CRFs decreases with age

  27. Physicians over estimate risk

  28. A structured Calculation (without human bias) Does Better

  29. A Structured Probability Estimate has Much Better Inter-rater Agreement • Geneva PTP score the least variable (most precise) p<0.001 • With empirical judgement, inter-rater variability is related to clinical experience p<0.05 Iles et al. QJM 2003

  30. ASSESSMENT OF CARDIAC CHEST PAIN

  31. RISK !

  32. Audience survey What is AN acceptable rate of missed AMI or major adverse cardiac event in The short term after assessment for chest pain?

  33. Of all the patients seen per year with cardiac chest pain and having Major Cardiac Adverse Events within 30 days death non-fatal AMI emergency revascularization procedure cardiogenic shock ventricular arrhythmia (requiring intervention) high AV block (requiring intervention) Audience survey

  34. Audience survey What is AN acceptable miss rate after a normal diagnostic evaluation? • 1 in 1000 or 0.1% • 1 in 500 or 0.2% • 1 in 200 or 0.5% • 1 in 100 or 1% • 1 in 50 or 2% • 1 in 40 or 2.5% • 1 in 20 or 5%

  35. Acceptable miss -rate of major adverse cardiac events

  36. CARDIAC TROPONIN (cTn) USE BY CLINICIANS • 3 occasionally overlapping categories

  37. 1. Rule-out AMI • Identifying patients at lower risk

  38. 2. Confirm AMI • Confirm myocardial necrosis and diagnosis of AMI in those with normal ECG • Supports planning of future management

  39. 3. Investigation of worrying non-specific symptoms • Symptoms could be due to cardiac ischemia • Hospital admission likely because of concern about symptoms but ACS is part of differential diagnosis

  40. Is there a fourth? • cTn has been ordered without a good reason and the result is positive

  41. 1. Rule-out AMI • Identifying patients at lower risk • Planning further investigations for angina and coronary disease

  42. Usual management for CP patients = prolonged observation Patient with chest pain Time Prolonged observation for additional testing (biomarkers, stress test, etc.)

  43. What timing of blood serial draws should be used to make diagnosis and for triage and therapy decisions?

  44. Timepoint of 2nd Troponin • ACC/AHA guidelines (2007) 8-12 hrs • ACEP (2006) 8-12 hrs • Global Task Force (2007) 6 (-9) hrs • NICE UK guidance (2010) 10-12 hrs

  45. The Impact of Delayed Troponin and Prolonged Observation? HOSPITAL OVERCROWDING

  46. ASSESSMENT OF CARDIAC CHEST PAIN

  47. Usual management for CP patients = prolonged observation Patient with chest pain Time Prolonged observation for additional testing (biomarkers, stress test, etc.)