Chest Pain: New Methods Applied to an Old Problem

1. Chest Pain: New Methods Applied to an Old Problem Jon W. Wahrenberger, MD December 2, 2002

2. 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

3. Chest Pain • Rapid Dx &Tx = saved muscle = improved outcome • Largest category of loss from malpractice litigation in the emergency department

4. 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.

5. Audience Question What feature best predicts a cardiac etiology to chest pain? • Location in chest • Character or quality of discomfort • Response to Nitroglycerin • Relationship to exertion

6. Chest Pain Diagnosis • Clinical diagnosis • Diagnosis using computer algorithms • Chest pain centers

7. Chest Pain: Clinical Diagnosis

8. “Classic” Angina • Location: central chest • Quality: squeezing, pressure, heaviness • Radiation: arm(s), neck, jaw • Associated symptoms: dyspnea, diaphoresis, nausea • Eliciting factors: exertion • Relieving factors: rest, nitroglycerin

9. Musculoskeletal Gastrointestinal Cardiac Psychiatric Pulmonary Other/unknown Differential Diagnosis

10. 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 Cardiovascular Chest Pain

11. Immediate Goals • Cardiac or not? • If cardiac, how to manage?

12. 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

13. 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 Traditional Classification of Pts with CP

14. 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 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

15. Clinical Evaluation of Chest Pain:Meta 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 1998;280:14:1256-1263

16. “Likelihood Ratio” • Likelihood ratio expresses the odds that a given level of a diagnostic test result would be expected in a patient with (as opposed to without) the target disorder Sacket, et al. Clinical Epidemiology

19. Features Increasing Likelihood of AMI

20. Features Decreasing Likelihood of AMI Panju, et al. JAMA 1998;280:14:1256-1263

21. ECG Findings Increasing Likelihood of AMI Panju, et al. JAMA 1998;280:14:1256-1263

22. 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 2002;9:20308

23. Pain site Radiation Nature Duration Associated symptoms Pleuritic Nature Response to exercise Chest wall tenderness Response to NTG Clinical Symptoms and ACS/MI in Patient with Non-diagnostic ECG • Endpoints: • AMI by WHO criteria • ACS defined by AMI on presentation or w/i 6 mo. Reference: Goodacre, et al. Acad. Emerg Med 2002;9:20308

24. Clinical Symptoms and ACS/MI in Patient with Non-diagnostic ECG Reference: Goodacre, et al. Acad. Emerg Med 2002;9:20308

26. 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 1997;78:142-6

27. 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 (<55 v. ≥55) Reference: Cook, et al. Heart 1997;78:142-6

28. Clinical Symptoms and Angiographic Disease Reference: Cook, et al. Heart 1997;78:142-6

29. 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

30. 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

31. 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

32. AHRQ Meta Analysis • Demographic features correlating with poor prognosis: • Increasing age • Male gender • Prior Medical Conditions: • Prior MI • Diabetes • (Prior CHF, HTN, smoking) 1

33. AHRQ Meta Analysis • Symptom characteristics: not predictors • Initial exam features: • Low BP • CHF • Cardiogenic shock 1

34. 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!

35. Chest Pain Diagnosis • Clinical diagnosis • Diagnosis using computer algorithms • Chest pain center

36. Computer Guided Chest Pain Diagnosis • Goldman Chest Pain Protocol • Acute Coronary Ischemia Time-insensitive Predictive instrument (ACI-TIPI)

37. 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 1982;307:588-96

38. Goldman Chest Pain Protocol Goldman, et al. N Engl J Med 1982;307:588-96

39. Goldman Chest Pain Protocol • Validated prospectively in second trial of 4770 patients Goldman et al. N Engl J Med. 1988;318:797-803

40. 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

41. 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 1998;129: 845-55

42. 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 ACI-TIPI: Clinical Variables Selker, et al. Ann Intern Med 1998;129: 845-55

44. ACI-TIPI • Validated in 3 trials: • UCLA Harbor Medical Center N= 189 • University of Geneva N=605 • ACI-TIPI Trial N= 10,689

45. 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. 1998;129:845-55

46. ACI-TIPI Trial Results

47. ACI-TIPI Trial Results • No difference in 30 day mortality • No difference in in-hospital complications • No difference in re-hospitalization rates

48. Chest Pain Diagnosis • Clinical diagnosis • Diagnosis using computer algorithms • Chest pain centers

49. Chest Pain in the Emergency Department • 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

50. 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