Myocardial Infarction: Difference between revisions

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>  

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>

Depending on the (working) diagnosis STEMI or NSTE-ACS, the revascularisation strategy varies.

Initial treatment of STEMI is relief of ischemic pain, stabilisation of hemodynamic status and restoration of coronary flow and myocardial tissue perfusion. Reperfusion therapy should be initiated as quickly as possible by preferably primary percutaneous coronary intervention (PCI) or fibrinolysis. Reperfusion is beneficial up to 12 hours after the onset of symptoms. In case of severe hemodynamic compromise, reperfusion therapy may be attempted up to 24 hours after symptom onset. Meanwhile other measures as continuous ECG monitoring, oxygen supply and intravenous access are indicated. <Cite>REFNAME7</Cite>

In rare cases, CABG is indicated, such as failed fibrinolysis with coronary anatomy unsuited for PCI and/or failed PCI, when the patient develops cardiogenic shock, life threatening ventricular arrhythmias, has three vessel disease, or mechanical complications of the MI. <Cite>REFNAME26</Cite>

Comparable to STEMI, revascularization in NSTE-ACS relieves symptoms, shortens hospital

invasive approach in the short and long term. Recent meta-analyse suggest a benefit of the routine invasive management that is mainly visible in intermediate- to high-risk patients. (referentie)

Patients undergoing a selective invasive (“or conservative”) management are initially stabilized by medication only, including aspirin and clopidogrel orally and nitro-glycerin, heparin and a beta blocker intravenously. If the patients is unstable or has refractory angina, he/she is referred for coronary angiography. Patients stabilized on medical therapy should undergo a stress 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.   

The routine invasive strategy consists of routine, early coronary angiography within 24 hours after admission and subsequent revascularization if appropriate by PCI or CABG based on the angiographic findings.  

The optimal timing of coronary angiography with an intended routine invasive management is debated. In patients with high risk features, including hypotension, ventricular arrhythmias or a large myocardial area at risk, should undergo urgent angiography (<2 hours).  

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.