Acute coronary syndrome

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In medicine and cardiology, acute coronary syndrome (ACS) is a collection of signs and symptoms due to myocardial ischemia.[1] In common usage, ACS includes myocardial infarction ("heart attack") and angina.

Etiology/causes

Atheroclerotic obstruction

ACS is usually caused by obstruction in an epicardial coronary artery.[2] The obstruction may be due to a thrombus at the site of a ruptured atherosclerotic plaque.[3]

Rupture seems more likely to occur during the morning hours.[4] Rupture may be precipited by inflammation from non-cardiac infections.[5] Rupture may be triggered by vigorous exercise among individuals who do not ordinarily do vigorous exercise.[6]

Coronary vasospasm

Approximately 15% of NSTEMI and 2% of STEMI patients have no obstruction of coronary vessels and in about half of these patients, spasm can be induced of a coronary artery.[2]

Stress-induced (takotsubo) cardiomyopathy

Stress-induced (takotsubo) cardiomyopathy may occur during acute medical illness or after intense emotional or physical stress.[7] It may be caused by catecholamines.

Classification

Classification of acute coronary syndrome[8]
  Electrocardiogram Serum biomarkers Typical appearance of culprit vessel at angioscopy[3]
Unstable angina "ST-segment depression or prominent T-wave inversion"[8] Normal Nonocclusive grayish-white thrombus
(platelet-rich)
Non-ST segment elevation myocardial infarction
(NSTEMI) 		"ST-segment depression or prominent T-wave inversion"[8] Elevated Primary NSTEMI: Nonocclusive grayish-white thrombus
(platelet-rich)

Secondary NSTEMI: no thrombus

ST segment elevation myocardial infarction
(STEMI) 		ST-segment elevation Elevated Occlusive reddish thrombus
(fibrin-rich)
Q-wave myocardial infarction Q-waves Elevated Occlusive reddish thrombus
(fibrin-rich)

Unstable angina

Unstable angina is defined as "precordial pain at rest, which may precede a myocardial infarction".[9]

Myocardial infarction

For more information, see: Myocardial infarction.

A myocardial infarction is defined as "gross necrosis of the myocardium, as a result of interruption of the blood supply to the area".[10] It is usually caused by occlusion of an epicardial coronary artery.[11]

Non-ST segment elevation myocardial infarction (NSTEMI)

NSTEMI is usually caused by a grayish-white thrombus that is platelet-rich.[3]

ST segment elevation myocardial infarction (STEMI)

STEMI is usually caused by a reddish thrombus that is fibrin-rich.[3]

Diagnosis

History and physical examination

A helpful finding is exact reproduction of chest pain upon palpating the chest.[12] In a patient whose other findings also suggest a non-cardiac course of their chest pain, this finding can help rule out coronary disease.[13]

Electrocardiogram

The electrocardiogram is a key part of decision making. For example, the presence of ST changes and Q-waves determines therapy.

A normal electrocardiogram has been reported not to exclude acute coronary syndrome, even when the electrocardiogram is taken during pain.[14] Although this study used defined unstable angina as either a coronary stenosis or positive stress test and so likely includes patients without true acute coronary syndrome as defined by the American Heart Association[8], the study was still not able to show that a normal electrocardiogram helped exclude a NSTEMI.

Isolated abnormalities of T-waves also confers worse prognosis.[15]

Laboratory tests

Clinical practice guidelines jointly written by multiple expert groups anchor the diagnosis on troponin blood assays obtained within 6 hours and again within 8-12 hours of a patient arriving for medical care.[8][16]

In NSTEMI, typical troponin I levels are less than 9 ng/ml with the median values 1.0 to 2.0 nl/ml.[17]

Clinical prediction rules

The Acute Cardiac Ischemia Time-Insensitive Predictive Instrument (ACI-TIPI), a clinical prediction rule, can help diagnose patients with chest pain and has been shown to improve medical care in a randomized controlled trial.[18][19]

The ACI-TIPI was studied up through 1993 before troponin assays were widely available and thus does not incorporate the troponin. However, the ACI-TIPI should retain its ability to use the medical history and the EKG to decide who should be observed for serial troponin levels. It is unclear why this role is not recognized by the ACC/AHA guidelines. One reason may be that the ACI-TIPI is patented.[20][21]

Treatment

Clinical practice guidelines address the treatment of unstable angina and non-ST-elevation myocardial infarction.[8][16]

Patients without contraindication should receive anticoagulation with unfractionated heparin.[22] The risk of bleeding can be estimated with a clinical prediction rule (http://www.crusadebleedingscore.org/).

Unstable angina or NSTEMI

Percutaneous transluminal coronary angioplasty

Among patients with unstable angina or NSTEMI and without ST-segment elevation (but may have other EKG evidence of ischemia such as ST-segment depression of ≥1 mm or transient ST-segment elevation or T-wave inversion of >3 mm) may benefit from early invasive management (percutaneous transluminal coronary angioplasty) if:

Urgent coronary catheterization may occur anytime within the first 24 hours.[26]

Glycoprotein IIb/IIIa inhibitors

Glycoprotein IIb/IIIa inhibitors such as eptifibatide should not be given until after percutaneous transluminal coronary angioplasty.[27]

Myocardial infarction

For more information, see: Myocardial infarction.


Prognosis

Three clinical prediction rules can help prognosticate with similar ability:[28]

These rules can help estimate prognosis and guide decisions.

References

  1. ↑ Anonymous (2024), Acute coronary syndrome (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. ↑ 2.0 2.1 Ong P, Athanasiadis A, Hill S, Vogelsberg H, Voehringer M, Sechtem U (August 2008). "Coronary artery spasm as a frequent cause of acute coronary syndrome: The CASPAR (Coronary Artery Spasm in Patients With Acute Coronary Syndrome) Study". J. Am. Coll. Cardiol. 52 (7): 523–7. DOI:10.1016/j.jacc.2008.04.050. PMID 18687244. Research Blogging.
  3. ↑ 3.0 3.1 3.2 3.3 Mizuno K, Satomura K, Miyamoto A, et al (January 1992). "Angioscopic evaluation of coronary-artery thrombi in acute coronary syndromes". N. Engl. J. Med. 326 (5): 287–91. PMID 1728732. [e]
  4. ↑ Muller JE, Stone PH, Turi ZG, et al (November 1985). "Circadian variation in the frequency of onset of acute myocardial infarction". N. Engl. J. Med. 313 (21): 1315–22. PMID 2865677. [e]
  5. ↑ Harskamp RE, van Ginkel MW (2008). "Acute respiratory tract infections: a potential trigger for the acute coronary syndrome". Ann. Med. 40 (2): 121–8. DOI:10.1080/07853890701753672. PMID 18293142. Research Blogging.
  6. ↑ Siscovick DS, Weiss NS, Fletcher RH, Lasky T (October 1984). "The incidence of primary cardiac arrest during vigorous exercise". N. Engl. J. Med. 311 (14): 874–7. PMID 6472399. [e]
  7. ↑ Kurowski V, Kaiser A, von Hof K, et al (September 2007). "Apical and midventricular transient left ventricular dysfunction syndrome (tako-tsubo cardiomyopathy): frequency, mechanisms, and prognosis". Chest 132 (3): 809–16. DOI:10.1378/chest.07-0608. PMID 17573507. Research Blogging.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Anderson JL, Adams CD, Antman EM, et al (2007). "ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-Elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine". J. Am. Coll. Cardiol. 50 (7): e1–e157. DOI:10.1016/j.jacc.2007.02.013. PMID 17692738. Research Blogging. Executive summary Summary at National Guidelines Clearinghouse Cite error: Invalid <ref> tag; name "pmid17692738" defined multiple times with different content Cite error: Invalid <ref> tag; name "pmid17692738" defined multiple times with different content Cite error: Invalid <ref> tag; name "pmid17692738" defined multiple times with different content
  9. ↑ National Library of Medicine. Unstable angina. Retrieved on 2007-10-28.
  10. ↑ National Library of Medicine. Myocardial infarction. Retrieved on 2007-10-28.
  11. ↑ DeWood MA, Spores J, Notske R, et al (October 1980). "Prevalence of total coronary occlusion during the early hours of transmural myocardial infarction". N. Engl. J. Med. 303 (16): 897–902. PMID 7412821. [e]
  12. ↑ Lee TH, Cook EF, Weisberg M, Sargent RK, Wilson C, Goldman L. Acute chest pain in the emergency room. Identification and examination of low-risk patients. Arch Intern Med. 1985 Jan;145(1):65-9. PMID 3970650
  13. ↑ Bruyninckx R, Aertgeerts B, Bruyninckx P, Buntinx F (February 2008). "Signs and symptoms in diagnosing acute myocardial infarction and acute coronary syndrome: a diagnostic meta-analysis". Br J Gen Pract 58 (547): 105–11. DOI:10.3399/bjgp08X277014. PMID 18307844. Research Blogging.
  14. ↑ Turnipseed, Samuel D.; William S. Trythall, Deborah B. Diercks, Erik G. Laurin, J. Douglas Kirk, David S. Smith, David N. Main, Ezra A. Amsterdam (2009). "Frequency of Acute Coronary Syndrome in Patients with Normal Electrocardiogram Performed during Presence or Absence of Chest Pain". Academic Emergency Medicine 16 (6): 495-499. DOI:10.1111/j.1553-2712.2009.00420.x. Retrieved on 2009-06-13. Research Blogging.
  15. ↑ Lin KB, Shofer FS, McCusker C, Meshberg E, Hollander JE (June 2008). "Predictive value of T-wave abnormalities at the time of emergency department presentation in patients with potential acute coronary syndromes". Acad Emerg Med 15 (6): 537–43. DOI:10.1111/j.1553-2712.2008.00135.x. PMID 18616439. Research Blogging.
  16. ↑ 16.0 16.1 Braunwald E, Antman EM, Beasley JW, et al (2002). "ACC/AHA 2002 guideline update for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction--summary article: a report of the American College of Cardiology/American Heart Association task force on practice guidelines (Committee on the Management of Patients With Unstable Angina)". J. Am. Coll. Cardiol. 40 (7): 1366–74. PMID 12383588. [e]
  17. ↑ http://content.nejm.org/cgi/content/full/335/18/1342
  18. ↑ Selker HP, Beshansky JR, Griffith JL, et al (1998). "Use of the acute cardiac ischemia time-insensitive predictive instrument (ACI-TIPI) to assist with triage of patients with chest pain or other symptoms suggestive of acute cardiac ischemia. A multicenter, controlled clinical trial". Ann. Intern. Med. 129 (11): 845–55. PMID 9867725. [e] Online calculator at InfoRetriever
  19. ↑ Selker HP, Griffith JL, D'Agostino RB (1991). "A tool for judging coronary care unit admission appropriateness, valid for both real-time and retrospective use. A time-insensitive predictive instrument (TIPI) for acute cardiac ischemia: a multicenter study". Med Care 29 (7): 610–27. PMID 2072767. [e]
  20. ↑ Selker HP et al.. Continuous monitoring using a predictive instrument. Retrieved on 2007-11-29.
  21. ↑ Selker HP et al.. Continuous monitoring using a predictive instrument. Retrieved on 2007-11-29.
  22. ↑ Hillis LD, Lange RA (May 2009). "Optimal management of acute coronary syndromes". N. Engl. J. Med. 360 (21): 2237–40. DOI:10.1056/NEJMe0902632. PMID 19458369. Research Blogging.
  23. ↑ Cannon CP, Weintraub WS, Demopoulos LA, et al (2001). "Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with the glycoprotein IIb/IIIa inhibitor tirofiban". N. Engl. J. Med. 344 (25): 1879-87. PMID 11419424. [e]
  24. ↑ Bach RG, Cannon CP, Weintraub WS, et al (2004). "The effect of routine, early invasive management on outcome for elderly patients with non-ST-segment elevation acute coronary syndromes". Ann. Intern. Med. 141 (3): 186-95. PMID 15289215. [e]
  25. ↑ Mehta SR, Granger CB, Boden WE, et al. (May 2009). "Early versus delayed invasive intervention in acute coronary syndromes". N. Engl. J. Med. 360 (21): 2165–75. DOI:10.1056/NEJMoa0807986. PMID 19458363. Research Blogging.
  26. ↑ Montalescot G, Cayla G, Collet JP, Elhadad S, Beygui F, Le Breton H et al. (2009). "Immediate vs delayed intervention for acute coronary syndromes: a randomized clinical trial.". JAMA 302 (9): 947-54. DOI:10.1001/jama.2009.1267. PMID 19724041. Research Blogging.
  27. ↑ Giugliano RP, White JA, Bode C, et al. (May 2009). "Early versus delayed, provisional eptifibatide in acute coronary syndromes". N. Engl. J. Med. 360 (21): 2176–90. DOI:10.1056/NEJMoa0901316. Research Blogging.
  28. ↑ de Araújo Gonçalves P, Ferreira J, Aguiar C, Seabra-Gomes R (May 2005). "TIMI, PURSUIT, and GRACE risk scores: sustained prognostic value and interaction with revascularization in NSTE-ACS". Eur. Heart J. 26 (9): 865–72. DOI:10.1093/eurheartj/ehi187. PMID 15764619. Research Blogging.
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