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Acute Coronary syndromes

Acute Coronary syndromes. Yael Moussadji Aug 21, 2008. Objectives. Diagnosis of ACS in the ED Risk Stratification Cardiac markers ECG Risk Scores Management UA/NSTEMI STEMI Complications. Pathophysiology. Definitions. Case 1.

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Acute Coronary syndromes

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  1. Acute Coronary syndromes Yael Moussadji Aug 21, 2008

  2. Objectives • Diagnosis of ACS in the ED • Risk Stratification • Cardiac markers • ECG • Risk Scores • Management • UA/NSTEMI • STEMI • Complications

  3. Pathophysiology

  4. Definitions

  5. Case 1 • 54 y/o male with 2 hours of exertional retrosternal burning CP • No previous episodes of pain • Feels slightly SOB • VSS, exam normal • ECG non-specific, TnT neg • You ask CCU to see because you are concerned re the possibility of an ACS (UA) • The CCU res asks, does he have any risk factors?

  6. Question 1 Are cardiac risk factors useful in evaluating the risk of ACS?

  7. Post-hoc analysis of 10,806 ED visits for ACS using the i*trACS registry for ED visits for ACS • ACS defined as need for 30-day revascularization (PTCA or CABG), or death or AMI with positive cardiac enzymes at hospitalization • Cardiac RF were diabetes, HTN, dyslipidemia, smoking, + family history of CAD; cardiac RF burden defined as number of RF present • Analysis stratified by age; <40, 40-65, >65

  8. Results

  9. ROC

  10. Conclusions • In patients over 40, cardiac risk factor burden is of limited clinical value in the diagnosis of ACS • In patients under 40, cardiac RF useful if there are none (-LR 0.17) or if there are 4 or more (+LR 7.39)

  11. Case 2 • 61 y/o female with 45 minutes of sharp left sided pleuritic chest pain • Feels nauseated, slightly diaphoretic • Pain is radiating to her left shoulder • No PMHx, no DVT/PE risk factors • Cardiac Risk factors: Who cares? • Vital signs are normal, ECG nonspecific, enzymes pending

  12. Question 2 How useful are clinical features in the diagnosis of acute, undifferentiated chest pain?

  13. Measured the predictive value and diagnostic performance of clinical features used to diagnose ACS in undifferentiated CP • Clinical features were prospectively recorded on a standard form for 893 patients presenting to the ED; 3.8% had an MI and 9.1% had ACS • Six month follow-up for adverse events • Tested the power of each feature to predict AMI (WHO criteria) and ACS (cardiac testing, AMI, death, or revascularization within 6 months

  14. AMI

  15. ACS

  16. Conclusions • Features useful in the diagnosis of AMI were exertional pain (LR 2.35), pain radiating to the shoulder or both arms (LR 4.07), and chest wall tenderness (LR 0.3) • Features useful in the diagnosis of ACS were exertional pain (LR 2.06), pain radiating to the shoulder, left arm, or both arms (LR 1.62) • Location, quality, and presence of N/V or diaphoresis were not predictive

  17. Case 3 • A 57 y/o male with no PMHx presents to the ED with CP • Pain has been intermittent for 2 weeks, and is described as pleuritic and exertional; occational nausea is noted • Physical exam is unremarkable • Patient’s pain resolved spontaneously prior to medical therapy, and he is pain free when you see him

  18. ECG

  19. Case 3 continued • Enzymes were negative • Patient was discharged home with instructions to return if worse, and referral to C-era. • 24 hours later, the patient returns to emerg with ongoing chest discomfort, nausea, and diaphoresis

  20. ECG at 24 hours

  21. Question 3 What is the predictive and prognostic value of the ECG in patients with ACS?

  22. Definitions • Non-specific ST and T wave changes • ST segment depression or elevation of < 1mm with or without an abnormal T wave • T wave may have altered morphology and/or blunted, flattened, or biphasic configuration without inversion or hyperacuity • Normal • Absence of NSSTTW, AV block, intraventricular conduction delay, repolarization changes, and rhythms other than NSR

  23. ECG Findings in ACS • In a study of adult CP patients in the ED, 1% of patients with anormal ECG had a final diagnosis of AMI, and 4% had a final diagnosis of UA • In another study, of patients with classic angina on history and a normal ECG, 3% had a final diagnosis of AMI • 3-4% of patients with AMI and over 20% of patients with an ACS (NSTEMI/UA) have NSSTTW findings • Therefore, of all patients with ACS, one fifth will show a normal or non-specific ECG in the ED

  24. ECG Changes

  25. Causes of ST Elevation

  26. Of 202 chest pain patients presenting to the ED with STE, 15% had an AMI • LVH was the most common cause of STE (25%), followed by LBBB (15%) and AMI (15%) • 12% had BER, 5% had RBBB, and 5% had nonspecific BBB • Other less common diagnoses were LVA, pericarditis, and paced rhythm

  27. Prognostic Value of Admission ECG in ACS • A retrospective analysis of GUSTO-IIb trial • Over 12,000 patients who had ACS confirmed on ECG • 22% had T wave inversion, 28% had STE, 35% had STD, and 15% had a combination of the above • 30 day incidence of death or MI was 5.5% in those with T wave inversions, 9.4% in those with STE, 10.5% in those with STD, and 12.4% in those with a STE + STD • In another study of 205 consecutive patients with UA/NSTEMI, STE of > 0.5mm in aVR was found to be a strong predictor of 30-day mortality, even in patients with low TIMI risk scores

  28. GUSTO 2B: ST DepressionA High Risk Finding ST  P  0.001 ST  T-wave inversion CM Gibson 2002

  29. ECG Pearls • 50% of patients with AMI will have a clearly diagnostic ECG at presentation (STE or STD) • ST segment elevation identifies those who benefit from reperfusion therapy (lytics) • Mortality increases with the number of leads showing STE • Other important predictors of mortality include LBBB and anterior location • Reciprocal changes are seen in 70% of inferior and 30% of anterior MIs, which demonstrates over 90% specificity and PPV for AMI • RV infarcts complicate 40% of inferior AMIs

  30. Question 4 So, if risk factors, clinical features, and ECG’s are not always helpful, how many patient’s with ACS are missed, and what are their characteristics?

  31. Analyzed clinical data from a multicentre prospective trial of over 10,000 patients with chest pain suggestive of ACS • 17% ultimately met the criteria for ACS (8% had AMI and 9% had UA) • 2.1% of those with AMI and 2.3% of those with UA were mistakenly discharged from the ED

  32. Missed diagnosis of ACS • Acute ischemia • Women <55 • Non-white • SOB as chief symptom • Normal or non-diagnostic ECG • AMI • Non-white • Normal or non-diagnostic ECG

  33. Conclusion • Percentage of patients who get discharged home is low, but discharge of these patients may be associated with increased mortality • Failure to make a diagnosis is related to race, gender, and lack of typical features on ECG

  34. Case 4 • 83 y/o male with known renal insufficiency, baseline Cr 150 • Presents with vague intermittent CP of 2 days duration, no associated symptoms • PMhx significant for HTN, previous MI and PCTA 10 years ago • ECG non-diagnostic (no acute changes from baseline) • TnT 0.11 • CCU res says “it’s elevated because of his renal failure”

  35. Question 5 Can you diagnose ACS based on an elevated TnT in a patient with renal failure?

  36. Analyzed outcomes in over 7000 patients enrolled in the GUSTO IV trial • Assessed baseline TnT level (considered abnormal if >0.1 ng/mL) and Cr clearance • Primary end point was death or MI at 30 days • An elevated TnT level was predictive of death of MI, even among patients with a Cr clearance in the lowest quartile • Cardiac troponin is predictive of short term prognosis in patients with ACS regardless of their level of Cr clearance

  37. Cardiac Troponin • Due to near absolute specificity for myocardial tissue and high sensitivity for microscopic zones of myocardial necrosis, cardiac troponins are the preferred biomarker for diagnosing MI • Onset 3-6 hours • Peak 12-18 hours • Elevated for 5-7 days

  38. Examined the TnT, CK-MB, and ECG abnormalities for risk stratification in patients with ACS within 12 hours on onset of symptoms • Use logistic regression to predict outcome • Mortality was significantly higher in the group with Tn >0.1 ng/mL (ARR 8%) • TnT was the variable most strongly related to 30 day mortality, followed by ECG category and the CK-MB level • TnT is a powerful independent predictor of mortality in patients who present with ACS

  39. Prospectively examined 733 patients with acute CP < 12 hours without STE; Tn was measured at least twice on arrival and 4-6 hours later so that one sample was taken at least 6 hours after the onset of pain • TnT was positive in 16% of patients, and 94% of patients who eventually evolved into an AMI • Among patients with UA, TnT was positive in 20% • TnT was a strong independent predictor of cardiac events • The event rate for patients with negative Tn T was 1.1%

  40. Other Causes of Elevated Tn

  41. Risk Stratification • 2 questions • What is the likelihood that the presenting symptoms represent ACS? • What is the likelihood of adverse outcome • Risk stratification process is challenging given then presence of risk factors is an unreliable determinant of ACS, and the ECG and Tn are not very sensitive for UA • 2007 ACC/AHA Update to the guidelings for UA/NSTEMI are helpful

  42. Likelihood of ACS based on signs and symptoms

  43. Predictors of Adverse Outcomes

  44. Use of Risk Stratification Tools • 2002 Guidelines state that tools such as the TIMI Risk Score can be helpful adjuncts • Since 2002, data from a unselected ED chest pain population have validated its utility • Other recommended tools include the GRACE (Global Registry of Acute Coronary Events) Risk Score and the PURSUIT (Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy) risk model • A study comparing the 3 showed good predictive accuracy for death at 1 year and MI • However, these tools were developed using population based models and may not be reliable for individual patients; they do not replace clinical judgement

  45. Two phase 3 international, randomized, double-blinded trials (TIMI 11B, ESSENCE) • A total of 1957 with UA/NSTMEI who were assigned to receive UFH in TIMI 11B(test cohort) • 3 validation cohorts were the UFH group in ESSENCE and both enoxaparin groups (total of over 5000 patients) • Risk score was derived from test cohort using multivariate logistic regression, assinging a value of 1 when risk factor present, and 0 when absent • Outcomes were at least 1 component of the primary end point (mortality, MI, urgent revascularization)

  46. Results • TIMI Risk Score • Age > or = 65 • 3 or more risk factors for CAD • Prior stenosis of 50% or more • ST segment deviation at presentation • At least 2 anginal events in 24 hours • Use of ASA in prior 7 days • Elevated serum cardiac markers

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