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Acute coronary syndromes

Acute coronary syndromes. Jason Smith Consultant in Emergency Medicine Derriford Hospital, Plymouth. The problem. Objectives . To define ACS we all know this bit, but do we apply it in practice? Therapeutic dilemmas Diagnostic dilemmas How do I rule it in? How do I rule it out?

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Acute coronary syndromes

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  1. Acute coronary syndromes Jason Smith Consultant in Emergency Medicine Derriford Hospital, Plymouth College of Emergency Medicine CPD Event, 29 March 2011

  2. The problem

  3. Objectives • To define ACS • we all know this bit, but do we apply it in practice? • Therapeutic dilemmas • Diagnostic dilemmas • How do I rule it in? • How do I rule it out? • Near patient testing • The concept of risk • European and NICE guidelines

  4. What is an acute coronary syndrome? • Coronary Artery Disease is a spectrum • Stable • Unstable • ACS includes • Unstable angina • Non Q wave MI or non STEMI • Q wave MI or STEMI

  5. Angina • Coronary artery plaque • Narrowing • Limitation of exercise tolerance • Exercise tolerance testing

  6. Yeghiazarians, Y et al. Unstable angina pectoris. NEJM 2000; 342: 101-14

  7. ACS definition ACS represent a life-threatening manifestation of atherosclerosis usually precipitated by acute thrombosis, induced by a ruptured or eroded atherosclerotic plaque, with or without concomitant vasoconstriction, causing a sudden and critical reduction in blood flow. European Society of Cardiology definition 2007

  8. Unstable angina • Plaque rupture • 66% of arteries with plaques that rupture causing MI have stenosis of 50% or less • in 97% of patients, stenosis is initially less than 70% Little WC et al. Can coronary angiography predict the site of a subsequent myocardial infarction in patients with mild-to-moderate coronary artery disease? Circulation 1988;78:1157-66

  9. Yeghiazarians, Y et al. Unstable angina pectoris. NEJM 2000; 342: 101-14

  10. UA – NSTEMI - STEMI

  11. STEMI v NSTEMI Savonitto S, et al. Prognostic value of the admission electrocardiogram in acute coronary syndromes. JAMA 1999;281: 707– 713. Volmink JA, et al. Coronary event and case fatality rates in an English population: results of the Oxford myocardial infarction incidence study. Heart 1998;80:40– 44.

  12. A patient • 55 year old male • No PMH • c/o 30 minutes of chest pain at rest, now resolving • Central, tight, heavy • Normal ECG • Treatment?

  13. Treatment • None • Aspirin • Aspirin plus LMW heparin • Aspirin plus LMW heparin plus clopidogrel

  14. Aspirin • Yes, if there’s any chance it’s the heart • 17000 patients in ISIS 2 • 2.4% absolute risk reduction for death following MI [9.4 V 11.8] • ≈20% RRR Randomised trial of intravenous streptokinase, oral aspirin, both, or neither among 17,187 cases of suspected acute myocardial infarction: ISIS-2. Lancet 1988;2(8607):349-60.

  15. Aspirin

  16. Yeghiazarians, Y et al. Unstable angina pectoris. NEJM 2000; 342: 101-14

  17. LMW heparin • If you think it’s the heart • Heparin = 33% reduction in death or MI Eikelboom JW, et al. Unfractionated heparin and low-molecular-weight heparin in acute coronary syndrome without ST elevation: a meta-analysis. Lancet 2000; 355:1936– 1942.

  18. Heparin v placebo

  19. UFH v LMWH

  20. Yeghiazarians, Y et al. Unstable angina pectoris. NEJM 2000; 342: 101-14

  21. Clopidogrel • If they have chest pain and an abnormal ECG • CURE trial – 12 500 patients • Benefit of death or non-fatal MI: 9.3 v 11.4% • Risk of bleeding: 3.7 v 2.7% • Benefits outweigh risks in limited patients with NSTEMI (abnormal ECG or trop rise) Yusuf S, et al. Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation. N Engl J Med 2001;345:494–502.

  22. Summary of treatment strategies

  23. How do we diagnose ACS? • History and exam • ECG analysis • Cardiac enzymes • Exercise ECG testing • CT calcium scoring • Stress echocardiography • Stress nuclear imaging • 64-slice CT coronary angiography • Invasive coronary angiography

  24. A patient • 25 year old female non-smoker • Self presented • Central and right sided chest pain for 2 minutes • Stabbing • Reproducible tenderness over anterior chest wall

  25. ECG

  26. Plan?

  27. Another patient • 55 year old female presents to the ED • Wife of consultant surgeon • No PMH • Presents with chest pain, central, tightness • Lasted 30 minutes after a 20 mile bike ride • Now resolved • Keen to go home • Just came up because husband told her to

  28. ECG

  29. Plan?

  30. Risk • Can we rule out ACS completely? • How we assess risk • Age • Risk factors • History • ECG • Troponin

  31. What is acceptable risk? • 10% • 5%? • 2%? • 1%?

  32. Risk – do we care? • Today? • Tomorrow? • This week? • This month? • This year?

  33. The role of cardiac enzymes • Troponin I or Troponin T • When should we measure? • Newer high sensitivity assays • Does this mean we can discharge sooner?

  34. Troponin • A rise in troponin in NSTEMI is thought to be due to platelet-rich microemboli causing micro-infarction and necrosis that is not picked up on routine analysis of other markers • Surrogate marker of active thrombus formation

  35. Troponin

  36. Troponin - 6 or 12 hours? • Variations in practice across UK • Some do 6, some 12 • Some insist on troponin on arrival and at 6 hours, measuring delta change • Sometimes part of a chest pain observation unit protocol Goodacre S, et al. Randomised controlled trial and economic evaluation of a chest pain observation unit compared with routine care. BMJ doi:10.1136/bmj.37956.664236.EE (published 14 January 2004)

  37. What about near patient testing? • We know PoC testing can safely rule out MI within 90 minutes of arrival in hospital McCord J, Nowak RM, McCullough PA, et al. Ninety-minute exclusion of acute myocardial infarction by use of quantitative point-of-care testing of myoglobin and troponin I. Circulation 2001;104:1483-8 Apple FS, Christensen RH, Valdes R, et al. Simultaneous rapid measurement of whole blood myoglobin, creatininekinase MB and cardiac troponin I by the triage cardiac panel for detection of myocardial infarction. ClinChem 1999;45:199-205 Newby LK, Storrow AB, Gibler WB, et al. Bedside multimarker testing for risk stratification in chest pain units: the CHECKMATE Study. Circulation 2001;103:1832-7 Caragher TE, Fernandez BB, Jacobs FL, et al. Evaluation of quantitative cardiac biomarker point of care testing in the emergency department. J Emerg Med 2002;22:1-7 Ng SM, Krishnaswamy P, Morissey R, et al. Ninety-minute accelerated critical pathway for chest pain evaluation. Am J Cardiol 2001;88:611-17 Hamilton AJ, Swales LA, Neill J, et al. Risk stratification of chest pain patients in the emergency department by a nurse utilizing a point of care protocol. Eur J Emerg Med 2008;15:9-15 Rathore S, Knowles P, Mann APS, et al. Is it safe to discharge patients from accident and emergency using a rapid point of care triple cardiac marker test to rule out acute coronary syndrome in low to intermediate risk patients presenting with chest pain? Eur J Int Med 2008;19:537-40 Straface AL, Myers JH, Kirchick HJ, et al. A rapid point-of-care cardiac marker testing strategy facilitates the rapid diagnosis and management of chest pain patients in the emergency department. Am J ClinPathol 2008;129:788-95

  38. NICE CG95. Chest pain of recent onset: Assessment and diagnosis of recent onset chest pain or discomfort of suspected cardiac origin. NICE 2010.

  39. TIMI 0-7 • Designed for patients with ACS • Age of more than 65 years • Three or more risk factors for atherosclerosis • Known coronary artery disease • Two or more episodes of anginal chest pain in the preceding 24 hours • Aspirin use in the seven days before hospital • ST-segment deviation of 0.05 mV or more • Elevated cardiac markers

  40. TIMI in the ED • Meta-analysis of 10 studies involving 17 265 patients • TIMI score 0 still has 30 day event rate of 1.8% • Death, MI or revascularisation • Sensitivity 97.2%, 95% CI 96.4–97.8 • Specificity 25.0%, 95% CI 24.3–25.7 Hess EP. Diagnostic accuracy of the TIMI risk score in patients with chest pain in the emergency department: a meta-analysis. CMAJ 2010. DOI:10.1503/cmaj.092119 (July 2010)

  41. GRACE • Age • Heart rate • Systolic blood pressure • Serum creatinine • Killip class at admission • Presence of ST-depression • Elevated cardiac biomarkers

  42. GRACE 6 month post discharge mortality

  43. Low risk chest pain • History • Exam • ECG • Troponin • Senior review

  44. The problem

  45. Summary • We have defined ACS • Therapeutic dilemmas • Diagnostic dilemmas • The concept of risk • European and NICE guidelines

  46. Questions jasonesmith@doctors.org.uk

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