Myocardial Infarction: Difference between revisions

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[[File:MyocardialInfarction.svg|thumb|right|400px|Myocardial Infarction]]
 
An acute coronary syndrome (ACS) is most commonly caused by rupture or erosion of an atherosclerotic plaque with superimposed thrombus formation. The underlying process is atherosclerosis, a chronic disease in which artery walls thicken by deposition of fatty materials such as cholesterol and inflammatory cells. The accumulation of this material results in the formation of an atherosclerotic plaque, encapsulated by connective tissue, which can narrow the lumen of the arteries significantly and progressively causing symptoms as angina pectoris or lead to an ACS. Depending on the presence of myocardial damage and typical ECG characteristics, ACS can be divided into ST-segment elevation myocardial infarction (STEMI), and non-ST-segment ACS including non-ST-segment elevation MI (NSTEMI) and unstable angina. In the case of STEMI and NSTEMI, there is biochemical evidence of myocardial damage (infarction).  <Cite>REFNAME1</Cite>  
An acute coronary syndrome (ACS) is most commonly caused by rupture or erosion of an atherosclerotic plaque with superimposed thrombus formation. The underlying process is atherosclerosis, a chronic disease in which artery walls thicken by deposition of fatty materials such as cholesterol and inflammatory cells. The accumulation of this material results in the formation of an atherosclerotic plaque, encapsulated by connective tissue, which can narrow the lumen of the arteries significantly and progressively causing symptoms as angina pectoris or lead to an ACS. Depending on the presence of myocardial damage and typical ECG characteristics, ACS can be divided into ST-segment elevation myocardial infarction (STEMI), and non-ST-segment ACS including non-ST-segment elevation MI (NSTEMI) and unstable angina. In the case of STEMI and NSTEMI, there is biochemical evidence of myocardial damage (infarction).  <Cite>REFNAME1</Cite>  
[[File:AMI_scheme.png|thumb|right|200px|A myocardial infarction results from a coronary occlusion (1) with necrosis of myocardial tissue (2) distal to the occlusion]]


==History==
==History==
[[File:chest_pain_to_NSTEMI_STEMI.svg|thunb|Different terminology is used during different phases of the chest pain workup. The ECG classifies into ST elevtion or not. Troponine definitely classifies into myocardial infarction (damage) or not.]]
[[File:chest_pain_to_NSTEMI_STEMI_v2.svg|thumb|400px|right|Different terminology is used during different phases of the chest pain workup. The ECG classifies into ST elevtion or not. Troponine definitely classifies into myocardial infarction (damage) or not.]]
The most typical characteristic of an ACS is acute prolonged chest pain. <Cite>REFNAME2</Cite> The pain does not decrease at rest and is only temporarily relieved with nitroglycerin. Frequent accompanying symptoms include a radiating pain to shoulder, arm, back and/or jaw. <Cite>REFNAME3</Cite> Shortness of breath can occur, as well as sweating, fainting, nausea and vomiting, so called vegetative symptoms. Some patients including elderly and diabetics may present with aspecific symptoms. <Cite>REFNAME4</Cite>, <Cite>REFNAME5</Cite>
The most typical characteristic of an ACS is acute prolonged chest pain. <Cite>REFNAME2</Cite> The pain does not decrease at rest and is only temporarily relieved with nitroglycerin. Frequent accompanying symptoms include a radiating pain to shoulder, arm, back and/or jaw. <Cite>REFNAME3</Cite> Shortness of breath can occur, as well as sweating, fainting, nausea and vomiting, so called vegetative symptoms. Some patients including elderly and diabetics may present with aspecific symptoms. <Cite>REFNAME4</Cite>, <Cite>REFNAME5</Cite>


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*Right ventricle – Leads V3R, V4R, V1
*Right ventricle – Leads V3R, V4R, V1
*Left main coronary artery ischemia – Lead aVR
*Left main coronary artery ischemia – Lead aVR
More information abou the [http://en.ecgpedia.org/wiki/Myocardial_Infarction ECG during myocardial infarction] can be found on ECGpedia.


==Cardiac Markers==
==Cardiac Markers==
[[File:Cardiac_markers.png|thumb|right|Rise and fall of several cardiac markers based on whether the myocardium was reperfused or not]]
Cardiac markers are essential in order to confirm the diagnosis of MI, indicated by elevated Creatine Kinase isoenzyme MB (CK MB) and/or (high-sensitive) troponins. Troponins are more specific and sensitive than CK MB. The cardiac troponin concentration begins to rise around 4 hours after the onset of myocardial cell damage.<Cite>REFNAME12</Cite>
Cardiac markers are essential in order to confirm the diagnosis of MI, indicated by elevated Creatine Kinase isoenzyme MB (CK MB) and/or (high-sensitive) troponins. Troponins are more specific and sensitive than CK MB. The cardiac troponin concentration begins to rise around 4 hours after the onset of myocardial cell damage.<Cite>REFNAME12</Cite>


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===Non-ST-segment elevation Acute Coronary Syndrome===
===Non-ST-segment elevation Acute Coronary Syndrome===
 
[[Image:Non-ST-segment elevation Acute Coronary Syndrome.svg|thumb|right|400px]]
[[Image:Non-ST-segment elevation Acute Coronary Syndrome2.svg|thumb|right|400px]]
[[Image:Swe.jpg|thumb|right|400px|link=http://www.outcomes-umassmed.org/grace/acs_risk/acs_risk_content.html|The [http://www.outcomes-umassmed.org/grace/acs_risk/acs_risk_content.html GRACE risk score model]]]
Comparable to STEMI, revascularization in NSTE-ACS relieves symptoms, shortens hospital
Comparable to STEMI, revascularization in NSTE-ACS relieves symptoms, shortens hospital
stay, and improves prognosis. However, NSTE-ACS patients represent a heterogenous population, and indication and timing of revascularization depend on many factors, including the baseline risk of the patient. According to current guidelines, depending on early risk stratification a choice has to be made between a routine invasive or a selective invasive (or “conservative strategy”) <Cite>REFNAME27</Cite>
stay, and improves prognosis. However, NSTE-ACS patients represent a heterogenous population, and indication and timing of revascularization depend on many factors, including the baseline risk of the patient. According to current guidelines, depending on early risk stratification a choice has to be made between a routine invasive or a selective invasive (or “conservative strategy”) <Cite>REFNAME27</Cite>


Early risk stratification is helpful to identify patients at high risk who might benefit the most from a more aggressive therapeutic approach in order to prevent further ischemic events. <Cite>REFNAME28</Cite>
Early risk stratification is helpful to identify patients at high risk who might benefit the most from a more aggressive therapeutic approach in order to prevent further ischemic events. <Cite>REFNAME28</Cite>
{| class="wikitable" cellpadding="0" cellspacing="0" border="0" width="500px"
|-
|colspan="5" align="center"|'''GRACE risk score'''
|-
!Risk Category
!low
!Intermediate
!High
|-
|NSTEMI Probability of Death In-hospital (%)
|<1
|1-3
|>3
|-
|NSTEMI 6 Month Post-discharge Mortality
|<3
|3-8
|>8
|-
|STEMI In-hospital Mortality (%)
|<2
|2-5
|>5
|-
|STEMI 6 Month Post-discharge Mortality
|<4.4
|4.5-11
|>11
|}


Early risk stratification can be performed using one of the validated risk scores, such as the GRACE risk score. GRACE calculates the probability of death while in hospital. The following characteristics are taken into account:
Early risk stratification can be performed using one of the validated risk scores, such as the GRACE risk score. GRACE calculates the probability of death while in hospital. The following characteristics are taken into account:
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====Cardiac rehabilitation====
====Cardiac rehabilitation====
Cardiac rehabilitation reduces mortality, helps the patient to regain confidence and to resocialise, and helps to reduce risk factors for atherosclerosis. Post-ACS patient should be referred for cardiac rehabilitation.  
Cardiac rehabilitation reduces mortality, helps the patient to regain confidence and to resocialise, and helps to reduce risk factors for atherosclerosis. Post-ACS patient should be referred for cardiac rehabilitation.
 
== References ==
== References ==
<biblio>
<biblio>

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