Chest Pain: New Methods Applied to an Old Problem

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Chest Pain New Methods Applied to an Old
Problem

• Jon W. Wahrenberger, MD
• January 23, 2003

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Chest Pain

• 5 Million emergency department visits
• 2 million hospitalizations annually with cost of
  more than 8 billion
• Cardiac etiology found in less than one third
• 2 of patients with acute MI are unrecognized and
  discharged from the ED

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Chest Pain

• Rapid Dx Tx saved muscle improved outcome
• Largest category of loss from malpractice
  litigation in the emergency department

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Goals

• Rapid recognition of management of true ACS
• Recognition of other life-threatening causes of
  chest pain
• Aortic dissection
• Pulmonary embolism
• Tension pneumothorax
• Minimize cost and hospitalization in patients
  with chest pain of benign etiology.

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Chest Pain Diagnosis

• Clinical diagnosis
• Diagnosis using computer algorithms
• Chest pain centers

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Chest Pain Clinical Diagnosis
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Classic Angina

• Location central chest
• Quality squeezing, heaviness
• Radiation arm(s), neck, jaw
• Associated symptoms dyspnea, diaphoresis,
  nausea
• Eliciting factors exertion
• Relieving factors rest, nitroglycerin

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Differential Diagnosis

• Musculoskeletal
• Gastrointestinal
• Cardiac

• Psychiatric
• Pulmonary
• Other/unknown

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Cardiovascular Chest Pain

• Coronary Heart Disease
• Stable angina pectoris
• Unstable angina
• Myocardial infarction
• Coronary Vasomotor Disease
• Variant angina
• Microvascular angina
• Pericarditis

• Myocarditis
• Valvular Heart Disease
• Aortic stenosis
• Mitral stenosis
• Hypertrophic cardiomyopathy
• Aortic Dissection
• Post-pericardiotomy

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• Cardiac or not?
• If cardiac, how to manage?

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Chest Pain Diagnosis What are we Seeking?

• Pathologic MI or No MI
• Management Based ST Elevation MI or not?
• Prognostic
• Anatomic Correlating with cath findings
• Functional Correlating with ischemia
• Detailed Diagnosis

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Traditional Classification of Pts with CP

• Group 1
• MI with ST elevation or new LBBB
• MI without ST elevation

• Group 2
• Unstable angina-high risk
• Unstable angina low risk
• Non-ischemic chest pain

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Ideal Categorization of Patients with CP
Group 3 Unstable angina low risk
Heparin, admission

• Group 4
• Non-cardiac chest pain
• Discharge
• or
• Treat as condition warrants

• Group 1
• MI with ST elevation
• New LBBB
• Primary PCI
• or
• Thrombolytics

• Group 2
• MI without ST elevation and no LBBB
• Unstable angina high risk
• Heparin,
• GP IIbIIIa inhibitor

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Clinical Evaluation of Chest PainMeta Analysis

• Medline search from 1980-1998
• Inclusion Criteria
• Evaluation of pts thought to have cardiac
  ischemia
• Tool history, PE, ECG
• Outcome assessed MI or no MI
• Sample size 200 patients
• Statistical methods pool studies and determine
  likelihood ratios

Panju, et al. JAMA 1998280141256-1263
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Features Increasing Likelihood of AMI
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Features Decreasing Likelihood of AMI
Panju, et al. JAMA 1998280141256-1263
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ECG Features Increasing Likelihood of MI
Panju, et al. JAMA 1998280141256-1263
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Clinical Symptoms and Angiographic Disease

• Goal determine correlation between clinical
  characteristics and angiographic disease
• Population
• 65 of 1022 patients undergoing angiography and
  with normal coronaries
• 65 consecutive age-matched controls and with
  angiographic CAD ( 70 diameter narrowing)
• Method all patients interviewed within 24 hours
  of angiogram by interviewers blinded to angio
  results

Reference Cook, et al. Heart 199778142-6
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Clinical Symptoms and Angiographic Disease

• Results
• No correlation between site of pain, radiation,
  quality of pain, or relief with NTG and presence
  of disease
• Only four clinical variables separated groups
• a. Reproducibility with exercise (10/10 v.
  1-9/10)
• b. Lack of rest symptoms (0-1/10 v. 2-10/10)
• Duration of 5 minutes or less (5 min. v 5 min)
• Age (

Reference Cook, et al. Heart 199778142-6
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Clinical Symptoms and Angiographic Disease
Reference Cook, et al. Heart 199778142-6
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Clinical Symptoms and MI in Patient with
Non-diagnostic ECG

• Goal measure ability of clinical features to
  predict AMI or ACS in those with non-diagnostic
  ECG
• Study Population 893 pts presenting to large
  teaching hospital in the UK with suspected AMI or
  ACS.
• Study Protocol
• History, PE, ECG CXR
• Baseline CK-MB, Trop T at six hours
• If enzymes negative, stress test and discharge

Reference Goodacre, et al. Acad. Emerg Med
2002920308
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Clinical Symptoms and ACS/MI in Patient with
Non-diagnostic ECG

• Associated symptoms
• Pleuritic Nature
• Response to exercise
• Chest wall tenderness
• Response to NTG

• Pain site
• Radiation
• Nature
• Duration

• Endpoints
• AMI by WHO criteria
• ACS defined by AMI on presentation or w/i 6 mo.

Reference Goodacre, et al. Acad. Emerg Med
2002920308
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Clinical Symptoms and ACS/MI in Patient with
Non-diagnostic ECG
Reference Goodacre, et al. Acad. Emerg Med
2002920308
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Chest Pain Evaluation Based on Prognosis

• Prediction of Risk for Patients with Unstable
  Angina
• Evidence Report/Technology Assessment No. 31
• Agency for Healthcare Research and Quality

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AHRQ Meta Analysis

• MEDLINE search 1966-1998 of studies performing
  multivariate analysis of clinical and/or ECG
  predictors of adverse clinical events in patients
  with suspected or diagnosed unstable angina.
• Separate analysis of predictive value of troponin
  and Chest Pain Units

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AHRQ Meta Analysis

• Clinical Predictors
• Demographics (age, sex, ethnicity)
• Medical history (prior MI, CHF, diabetes, etc)
• Symptom Characteristics
• Initial Exam findings
• Initial ECG features
• Outcomes Cardiac death, MI, other major cardiac
  complications

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AHRQ Meta Analysis

• Demographic features correlating with poor
  prognosis
• Increasing age
• Male gender
• Prior Medical Conditions
• Prior MI
• Diabetes
• (Prior CHF, HTN, smoking)

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AHRQ Meta Analysis

• Symptom characteristics not predictors
• Initial exam features
• Low BP
• CHF
• Cardiogenic shock

1
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Clinical Diagnosis of Chest Pain

• Location, quality of pain generally not
  predictive of cardiac cause
• Response to nitroglycerine not a reliable
  predictor
• While radiation and associated symptoms may be
  predictive, their sensitivity and specificity are
  quite low
• More than a history and physical are needed!

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Chest Pain Diagnosis

• Clinical diagnosis
• Diagnosis using computer algorithms
• Chest pain center

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Computer Guided Chest Pain Diagnosis

• Goldman Chest Pain Protocol
• Acute Coronary Ischemia Time-insensitive
  Predictive instrument (ACI-TIPI)

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Goldman Chest Pain Protocol

• Computer derived decision aid
• Designed to improve triage to CCU
• Initially developed in prospective study of 1379
  patients presenting with acute chest pain
• Recursive partitioning used to divide subjects
  into subgroups correlating with high or low risk
  of MI

Goldman, et al. N Engl J Med 1982307588-96
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Goldman Chest Pain Protocol

Goldman, et al. N Engl J Med 1982307588-96
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Goldman Chest Pain Protocol

• Validated prospectively in second trial of 4770
  patients

Goldman et al. N Engl J Med. 1988318797-803
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Goldman Chest Pain Protocol

• Advantages
• Higher specificity than MD
• Disadvantages
• Predicts only AMI (not USA)
• Never shown to alter
• Hospitalization rate
• Length of stay
• Cost

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ACI-TIPI(Acute coronary ischemia
time-insensitive predictive instrument)

• Predictive protocol incorporated into
  electrocardiogram with automatic results
• Time insensitive so can be used either retro-
  or prospectively

Selker, et al. Ann Intern Med 1998129 845-55
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ACI-TIPI Clinical Variables

• Age
• Sex
• Presence of absence of chest pain or pressure of
  left arm pain
• Chest pain as most important symptom

• ECG Q waves or not
• Presence and degree of ST elevation or depression
• Presence or absence of T-wave elevation or
  inversion

Selker, et al. Ann Intern Med 1998129 845-55
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ACI-TIPI

• Validated in 3 trials
• UCLA Harbor Medical Center N 189
• University of Geneva N605
• ACI-TIPI Trial N 10,689

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ACI-TIPI Trial

• Clinical trial at 10 U.S. hospitals
• ACI-TIPI protocol installed in all ED
  electrocardiograph machines
• Clinical intervention 7 alternating months of
• ACI-TIPI probability of ischemia provided
• ACI-TIPI probability of ischemia not provided
• 10,689 patients enrolled

Selker, et al. Ann Intern Med. 1998129845-55
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ACI-TIPI Trial Results
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ACI-TIPI Trial Results

• No difference in 30 day mortality
• No difference in in-hospital complications
• No difference in re-hospitalization rates

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Chest Pain Diagnosis

• Clinical diagnosis
• Diagnosis using computer algorithms
• Chest pain centers

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Chest Pain in the Emergency Department

• 4.5 million annual ED visits for chest pain
• About one fourth have true ACS
• Treatments for ACS are time sensitive
• About 2-4 of acute MIs are missed in the ED
• Number one cause of ED related malpractice
• Strong bias for admission

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Chest Pain Units

• Goal accurately determine presence or absence
  of acute myocardial ischemia
• Rapid efficient treatment of AMI
• Avoid unnecessary hospitalization (and cost)
• Avoid inappropriate discharge
• Logistics Often associated with and staffed by
  Emergency room and include telemetry and
  resuscitation equipment

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Chest Pain Units

• Heart attack program
• Diagnostic (observational) program to rule out MI
• Educational outreach program

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Diagnostic Strategies in ACS

• Out of hospital ECG
• Continuous/serial ECG
• Exercise stress ECG
• CPK (presentation)
• CPK (serial)
• CK-MB (presentation)
• CK-MB (serial)
• Myoglobin (presentation)
• Myoglobin (serial)
• Troponin I (presentation)
• Troponin I (serial)

• Troponin T (presentation)
• Troponin T (serial)
• Rest echocardiography
• Stress echocardiography
• Sestamibi (rest)
• ACI-TIPI
• Goldman Chest Pain Protocol
• Algorithms/protocols
• Computer based decision aids

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University of Cincinnati Heart ER Strategy
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Randomized Trials of Chest Pain Units
From Agency for Healthcare Research and Quality
Report, 2000
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Randomized Trials of Chest Pain Units
Chest pain evaluation unit versus usual care
From Agency for Healthcare Research and Quality
Report, 2000
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Randomized Trials of Chest Pain Units
From Agency for Healthcare Research and Quality
Report, 2000
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Conclusions

• Clinical characteristics are the least accurate
  predictor of the etiology of chest pain
• Pattern of pain may be most reliable
• Accurate diagnosis and management requires use of
  clinical history, ECG, and other highly specific
  marker of ischemia or infarction
• Computer aided algorithms may improve diagnostic
  accuracy and reduce missed dx

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Conclusions (continued)

• Chest pain units need further study but may be
  useful in
• Reducing unnecessary hospitalization
• Reducing cost