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Myocardial Infarction: Difference between revisions
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== | == Pathophysiology== | ||
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). | 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). PMID: 11084798 | ||
== | == History == | ||
The most typical characteristic of an ACS is acute prolonged chest pain. PMID 16304077 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. PMID 10099685 Shortness of breath can occur, as well as sweating, fainting, nausea and vomiting, so called vegetative symptoms. Some patient groups like elderly and diabetics might present with aspecific symptoms. PMID 10866870, PMID 10751787 | The most typical characteristic of an ACS is acute prolonged chest pain. PMID 16304077 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. PMID 10099685 Shortness of breath can occur, as well as sweating, fainting, nausea and vomiting, so called vegetative symptoms. Some patient groups like elderly and diabetics might present with aspecific symptoms. PMID 10866870, PMID 10751787 | ||
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== | == Physical Examination == | ||
The focus of the physical examination should be to recognize signs of systemic hypoperfusion such as hypotension, tachycardia, impaired cognition, pale and ashen skin. PMID 15289388 | The focus of the physical examination should be to recognize signs of systemic hypoperfusion such as hypotension, tachycardia, impaired cognition, pale and ashen skin. PMID 15289388 | ||
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In more stable ACS patients, history and physical examination are helpful to exclude other causes of chest pain, such as angina pectoris, aorta dissection, arrhythmias, pulmonary embolism, pneumonia, heartburn, hyperventilation or musculoskeletal problems. PMID 15289388 | In more stable ACS patients, history and physical examination are helpful to exclude other causes of chest pain, such as angina pectoris, aorta dissection, arrhythmias, pulmonary embolism, pneumonia, heartburn, hyperventilation or musculoskeletal problems. PMID 15289388 | ||
== | == Electrocardiogram (ECG) == | ||
An electrocardiogram (ECG) should be made within 10 minutes of arrival in every patient with suspected ACS. PMID 15289388 | An electrocardiogram (ECG) should be made within 10 minutes of arrival in every patient with suspected ACS. PMID 15289388 | ||
The ECG is an important and easy modality which can assist in the diagnosis and prognostication of ACS. | The ECG is an important and easy modality which can assist in the diagnosis and prognostication of ACS. | ||
It can however take 90 minutes after the onset of the symptoms to see abnormalities on the ECG. Furthermore, the ECG does not reflect the dynamic pathophysiology of the ACS. Therefore it is important to make serial ECGs, certainly if a patient has ongoing symptoms. PMID 15289388 | It can however take 90 minutes after the onset of the symptoms to see abnormalities on the ECG. Furthermore, the ECG does not reflect the dynamic pathophysiology of the ACS. Therefore it is important to make serial ECGs, certainly if a patient has ongoing symptoms. PMID 15289388 | ||
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:Left main coronary artery ischemia – Lead aVR | :Left main coronary artery ischemia – Lead aVR | ||
== | == Cardiac Markers == | ||
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. PMID 16556688 | 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. PMID 16556688 | ||
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A pitfall concerning mildly elevated cardiac markers can be patients with renal failure or pulmonary embolism. PMID: 17951284 Although cardiac markers are helpful for confirming the diagnosis, reperfusion should not always wait till the cardiac markers are known if the ECG or symptoms are evident. | A pitfall concerning mildly elevated cardiac markers can be patients with renal failure or pulmonary embolism. PMID: 17951284 Although cardiac markers are helpful for confirming the diagnosis, reperfusion should not always wait till the cardiac markers are known if the ECG or symptoms are evident. | ||
== | == Treatment == | ||
As the formation of an intracoronary thrombus is the most common cause of the ACS and (recurrent) subsequent outcomes, the cornerstone in the treatment of ACS is antithrombotic treatment. All patients diagnosed with ACS should start with aspirin and a P2Y12 receptor blocker (clopidogrel, prasugrel or ticagrelor). PMID | [[File:Figure_2_-_Reperfusion_strategies.png|right|Reperfusion strategies. The thick arrow indicates the preferred strategy.]] | ||
As the formation of an intracoronary thrombus is the most common cause of the ACS and (recurrent) subsequent outcomes, the cornerstone in the treatment of ACS is antithrombotic treatment. All patients diagnosed with ACS should start with aspirin and a P2Y12 receptor blocker (clopidogrel, prasugrel or ticagrelor). PMID 21873419 Aspirin and the P2Y12 receptor blocker are both platelet aggregation inhibitors. The treatment of ACS also focuses on medication to keep the workload of the heart as low as possible. β blockers lower heart rate and blood pressure, to decrease the oxygen demand of the heart. PMID 16735367 Nitrates dilatate the coronary arteries so the heart receives more oxygenated blood. PMID 3925741 | |||
Depending on the (working) diagnosis STEMI or NSTE-ACS, the reperfusion strategy differs. | Depending on the (working) diagnosis STEMI or NSTE-ACS, the reperfusion strategy differs. | ||
=== ST- | === ''ST-Segment Elevation Myocardial Infarction'' === | ||
Initial treatment of STEMI is relief of ischemic pain, stabilize the hemodynamic status and restoration of coronary flow and myocardial tissue perfusion. Reperfusion therapy should be initiated as quickly as possible within 12 hours after symptom onset by preferably primary percutaneous coronary intervention (PCI) or otherwise fibrinolysis. Meanwhile other measures as continuous cardiac monitoring, oxygen and intravenous access are necessary to guarantee the safety of the patient. PMID 15289388 | Initial treatment of STEMI is relief of ischemic pain, stabilize the hemodynamic status and restoration of coronary flow and myocardial tissue perfusion. Reperfusion therapy should be initiated as quickly as possible within 12 hours after symptom onset by preferably primary percutaneous coronary intervention (PCI) or otherwise fibrinolysis. Meanwhile other measures as continuous cardiac monitoring, oxygen and intravenous access are necessary to guarantee the safety of the patient. PMID 15289388 | ||
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There are circumstances in which CABG could be indicated, such as failed fibrinolysis and/or PCI, when the patient develops cardiogenic shock, life threatening ventricular arrhythmias, has three vessel disease, or mechanical complications of the MI. PMID:18191746 | There are circumstances in which CABG could be indicated, such as failed fibrinolysis and/or PCI, when the patient develops cardiogenic shock, life threatening ventricular arrhythmias, has three vessel disease, or mechanical complications of the MI. PMID:18191746 | ||
=== Non-ST- | === ''Non-ST-Segment Elevation Acute Coronary Syndrome'' === | ||
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”) PMID 15289388 | 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”) PMID 15289388 | ||
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invasive approach in the short and long term. One of the most recent meta-analysis has shown a benefit of the routine invasive management that was mainly visisble in intermediate- to high-risk patients. (referentie) | invasive approach in the short and long term. One of the most recent meta-analysis has shown a benefit of the routine invasive management that was mainly visisble in intermediate- to high-risk patients. (referentie) | ||
=== Selective | === Selective Invasive (“or Conservative”) Management === | ||
Patients undergoing a selective invasive (“or conservative”) management are initially stabilized by optimal medication, including aspirin and clopidogrel orally and nitro-glycerine, heparin and a beta blocker intravenously. If the patients becomes unstable or has refractory angina, he/she is referred for coronary angiography. Patients stabilized on medical therapy should undergo ischemia detection test before discharge. Potential advantages of this treatment strategy are a reduction of the number of catherization procedures. A potential disadvantage is a prolonged stay in the hospital. Although meta-analyses suggest the superiority of a routine invasive management, trials in which the selective invasive strategy was characterized by high rates of revascularization show equivalence of the two strategies. | Patients undergoing a selective invasive (“or conservative”) management are initially stabilized by optimal medication, including aspirin and clopidogrel orally and nitro-glycerine, heparin and a beta blocker intravenously. If the patients becomes unstable or has refractory angina, he/she is referred for coronary angiography. Patients stabilized on medical therapy should undergo ischemia detection test before discharge. Potential advantages of this treatment strategy are a reduction of the number of catherization procedures. A potential disadvantage is a prolonged stay in the hospital. Although meta-analyses suggest the superiority of a routine invasive management, trials in which the selective invasive strategy was characterized by high rates of revascularization show equivalence of the two strategies. | ||
=== Routine | === Routine Invasive Management === | ||
The routine invasive strategy consists of routine, early coronary angiography (tijd noemen, ik dacht < 24 uur) and subsequent revascularization by PCI or CABG based on the angiographic findings. | The routine invasive strategy consists of routine, early coronary angiography (tijd noemen, ik dacht < 24 uur) and subsequent revascularization by PCI or CABG based on the angiographic findings. | ||
The optimal timing of coronary angiography with an intended routine invasive management is still a topic for debate. | The optimal timing of coronary angiography with an intended routine invasive management is still a topic for debate. | ||