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Theinvestigation of possible cardiac chest pain MARTIN THAN Director of Emergency Medicine Research C hristchurch Hospital New Zealand. Thank you. For inviting me to speak. An abbreviation. ED = Emergency Department. LEARNING OBJECTIVES.
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Theinvestigation of possible cardiac chest painMARTIN THANDirector of Emergency Medicine ResearchChristchurch Hospital New Zealand
Thank you For inviting me to speak
An abbreviation • ED = Emergency Department
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
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
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
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.
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
Chest pain and Hospital overcrowding • This is a major issue
Overcrowding • Now proven to be associated with poor patient outcomes • Death • Increased adverse events • Delayed treatment • Delayed pain relief
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
Other consequences of prolonged chest pain assessment • Duplication • Risk from multiple handovers • Competing demand for staff time
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.
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%
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
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.)
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
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)
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
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)
Christchurch/Brisbane • 2400 Patients • Similar results
What about risk factors? Family History Cholesterol Age? Gender? Blood Pressure Smoker? Life Style
Cardiac Risk Factors (CRFs) are Poor Diagnostic Predictors Han et. Al. (2007)Annals of Emergency Medicine 49[2]
Diagnostic Predictive Value (DPF) of CRFs decreases with age
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
Audience survey What is AN acceptable rate of missed AMI or major adverse cardiac event in The short term after assessment for chest pain?
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
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%
CARDIAC TROPONIN (cTn) USE BY CLINICIANS • 3 occasionally overlapping categories
1. Rule-out AMI • Identifying patients at lower risk
2. Confirm AMI • Confirm myocardial necrosis and diagnosis of AMI in those with normal ECG • Supports planning of future management
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
Is there a fourth? • cTn has been ordered without a good reason and the result is positive
1. Rule-out AMI • Identifying patients at lower risk • Planning further investigations for angina and coronary disease
Usual management for CP patients = prolonged observation Patient with chest pain Time Prolonged observation for additional testing (biomarkers, stress test, etc.)
What timing of blood serial draws should be used to make diagnosis and for triage and therapy decisions?
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
The Impact of Delayed Troponin and Prolonged Observation? HOSPITAL OVERCROWDING
Usual management for CP patients = prolonged observation Patient with chest pain Time Prolonged observation for additional testing (biomarkers, stress test, etc.)