ST-elevation myocardial infarction: Difference between revisions

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<section begin="A&IC" />An '''ST-elevation myocardial infarction''' (STEMI) is a clinical form of [[acute myocardial infarction]] and one form of [[acute coronary syndrome]]. It is defined as the presence of ischaemic symptoms, ST-elevations in a pattern consistent with the blood supply of one coronary artery and a rise and/or fall in [[troponin]] levels. Ischaemic symptoms are classically [[Chest pain|angina]], but may also be dyspnoea, nausea, sweating, anxiety, or non-anginal chest pain. <section end="A&IC" />For initial evaluation, see [[acute coronary syndrome]].
An '''ST-elevation myocardial infarction''' (STEMI) is a clinical form of [[acute myocardial infarction]] and one form of [[acute coronary syndrome]]. It is defined as the presence of ischaemic symptoms, ST-elevations in a pattern consistent with the blood supply of one coronary artery and a rise and/or fall in [[troponin]] levels. Ischaemic symptoms are classically [[Chest pain|angina]], but may also be dyspnoea, nausea, sweating, anxiety, or non-anginal chest pain. For initial evaluation, see [[acute coronary syndrome]].


STEMI must be immediately transferred to a [[Percutaneous intervention|PCI]] centre for treatment.
STEMI must be immediately transferred to a [[Percutaneous intervention|PCI]] centre for treatment.
<section begin="A&IC" />
 
== Diagnosis and evaluation ==
== Diagnosis and evaluation ==
If a patient has typical chest pain and the ECG shows ST-elevations in a pattern consistent with the blood supply of one coronary artery, we do not waste time with a troponin test, as the probability that it is a STEMI is high. However, in many cases a blood test can be performed in the ambulance, thereby not delaying the time to <abbr>PCI</abbr>.
If a patient has typical chest pain and the ECG shows ST-elevations in a pattern consistent with the blood supply of one coronary artery, we do not waste time with a troponin test, as the probability that it is a STEMI is high. However, in many cases a blood test can be performed in the ambulance, thereby not delaying the time to <abbr>PCI</abbr>.
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ST-elevation or depression in the inferior leads (II, III, aVF) suggests inferior wall infarct. In these cases, the right-sided leads V4R, V5R, and V6R should be obtained to assess for a possible right ventricular infarct. In this case, ST-elevation would be present in leads V4R – V6R.
ST-elevation or depression in the inferior leads (II, III, aVF) suggests inferior wall infarct. In these cases, the right-sided leads V4R, V5R, and V6R should be obtained to assess for a possible right ventricular infarct. In this case, ST-elevation would be present in leads V4R – V6R.
<section end="A&IC" />
 
ST-elevations can be present in other conditions which may present similarly, like [[pericarditis]], [[myocarditis]], [[left ventricular hypertrophy]], etc. Care must be used in ambiguous cases, but it’s often better to perform a PCI to be safe.
ST-elevations can be present in other conditions which may present similarly, like [[pericarditis]], [[myocarditis]], [[left ventricular hypertrophy]], etc. Care must be used in ambiguous cases, but it’s often better to perform a PCI to be safe.


== Pathomechanism ==
== Pathomechanism ==
See [[acute myocardial infarction]].
See [[acute myocardial infarction]].
<section begin="A&IC" />
 
== Initial management ==
== Initial management ==
If the expected time to a PCI lab is < 120 minutes, the patient is rushed straight there, with as low time from symptom onset to catheter insertion as possible. If the expected time is > 120 minutes, the patient should receive [[thrombolysis]] and then be rushed to a PCI lab.
If the expected time to a PCI lab is < 120 minutes, the patient is rushed straight there, with as low time from symptom onset to catheter insertion as possible. If the expected time is > 120 minutes, the patient should receive [[thrombolysis]] and then be rushed to a PCI lab.
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[[Nitroglycerine]], either sublingual tablets or sprays, should only be given if the patient has pain. It may be administered to the patient up to three times but does not improve outcome and is therefore not given routinely to all. Nitroglycerine is contraindicated in right ventricular infarction and should therefore not be administered if right ventricular infarction is suspected.
[[Nitroglycerine]], either sublingual tablets or sprays, should only be given if the patient has pain. It may be administered to the patient up to three times but does not improve outcome and is therefore not given routinely to all. Nitroglycerine is contraindicated in right ventricular infarction and should therefore not be administered if right ventricular infarction is suspected.


In the ambulance, [[Aspirin]] (300 mg) should be administered to all patients to be chewed and swallowed in all cases of STEMI. In addition to this, a loading dose of a [[P2Y12 inhibitor]] like clopidogrel (Plavix®) or ticagrelor should be administered. [[Unfractionated heparin]] (<abbr>UFH</abbr>) is administered to all patients unless they’re already anticoagulated.
[[Aspirin]] (300 mg) should be administered to all patients to be chewed and swallowed in all cases of STEMI. In addition to this, a loading dose of a [[P2Y12 inhibitor]] like prasugrel or ticagrelor may be administered.
<section end="A&IC" />
Following entry to the hospital, the following two medications may be considered. They are secondary prophylaxis but can usually be started the same day or the day after:


[[Beta blocker|Beta blocker,]] most often metoprolol, should be administered in all cases where the patient does not have signs of heart failure and is haemodynamically stable.
[[Beta blocker|Beta blocker,]] most often metoprolol, should be administered in all cases where the patient does not have signs of heart failure and is haemodynamically stable.


High intensity statin ([[Atorvastatin]] 40-80 mg or [[rosuvastatin]] 20-40 mg) should be administered to all patients as soon as possible.
[[Atorvastatin]] (80 mg) should be administered to all patients as soon as possible.
<section begin="A&IC" />
 
If the anatomy is unsuitable for PCI and the infarcted myocardial area is large, or there is cardiogenic shock, emergency [[coronary artery bypass surgery]] (<abbr>CABG</abbr>) should be performed.<section end="A&IC" />
[[Unfractionated heparin]] (<abbr>UFH</abbr>) is administered to all patients unless they’re already anticoagulated.
 
If the anatomy is unsuitable for PCI and the infarcted myocardial area is large, or there is cardiogenic shock, emergency [[coronary artery bypass surgery]] (<abbr>CABG</abbr>) should be performed.


Summary:
Summary:


* Aspirin (300 mg loading dose) – in all cases
* Aspirin (300 mg loading dose) – in all cases
* P2Y12 inhibitor loading dose (clopidogrel or ticagrelor) – in all cases
* P2Y12 inhibitor loading dose (prasugrel or ticagrelor) – in all cases
* Atorvastatin – in all cases
* Atorvastatin – in all cases
* Unfractionated heparin – in all cases except with pre-existing anticoagulation
* Unfractionated heparin – in all cases except with pre-existing anticoagulation

Revision as of 12:18, 19 October 2023

An ST-elevation myocardial infarction (STEMI) is a clinical form of acute myocardial infarction and one form of acute coronary syndrome. It is defined as the presence of ischaemic symptoms, ST-elevations in a pattern consistent with the blood supply of one coronary artery and a rise and/or fall in troponin levels. Ischaemic symptoms are classically angina, but may also be dyspnoea, nausea, sweating, anxiety, or non-anginal chest pain. For initial evaluation, see acute coronary syndrome.

STEMI must be immediately transferred to a PCI centre for treatment.

Diagnosis and evaluation

If a patient has typical chest pain and the ECG shows ST-elevations in a pattern consistent with the blood supply of one coronary artery, we do not waste time with a troponin test, as the probability that it is a STEMI is high. However, in many cases a blood test can be performed in the ambulance, thereby not delaying the time to PCI.

These are the ECG leads corresponding to various regions of the heart, and the coronary artery they’re supplied by[1]:

Leads with ST elevations Affected myocardium Supplying coronary artery
V1 – V2 Septal Proximal LAD
V3 – V4 Anterior LAD
V5 – V6 Apical Distal LAD, LCx, or RCA
I, aVL Lateral LCx
II, III, aVF Inferior RCA. LCx in 10% of cases
V7 – V9 (with reciprocal ST depression in V1 – V3) Posterior RCA or LCx

A new-onset LBBB is considered equivalent to ST-elevation in the case of STEMI. Patients with typical chest pain and new-onset LBBB are treated as STEMI patients.

ST-depression in leads V1 – V4 may be reciprocal changes of a posterior wall infarct due to a circumflex (CX) artery occlusion. These cases are considered as equivalent to ST-elevation and is treated like STEMI. Posterior ECG leads (V7 – V9) would show ST-elevation.

ST-elevation or depression in the inferior leads (II, III, aVF) suggests inferior wall infarct. In these cases, the right-sided leads V4R, V5R, and V6R should be obtained to assess for a possible right ventricular infarct. In this case, ST-elevation would be present in leads V4R – V6R.

ST-elevations can be present in other conditions which may present similarly, like pericarditis, myocarditis, left ventricular hypertrophy, etc. Care must be used in ambiguous cases, but it’s often better to perform a PCI to be safe.

Pathomechanism

See acute myocardial infarction.

Initial management

If the expected time to a PCI lab is < 120 minutes, the patient is rushed straight there, with as low time from symptom onset to catheter insertion as possible. If the expected time is > 120 minutes, the patient should receive thrombolysis and then be rushed to a PCI lab.

The “classic” acute management for STEMI used to be “MONA”: Morphine, oxygen, nitroglycerine, aspirin. Nowadays we know that morphine may worsen the outcome of patients with AMI, and it should therefore only be given if the patient has strong pain which does not subside after administration of nitro.

Oxygen should only be given if the oxygen saturation is < 90%, as giving it at normal levels of oxygen saturation has not shown any benefit and may even cause harm.

Nitroglycerine, either sublingual tablets or sprays, should only be given if the patient has pain. It may be administered to the patient up to three times but does not improve outcome and is therefore not given routinely to all. Nitroglycerine is contraindicated in right ventricular infarction and should therefore not be administered if right ventricular infarction is suspected.

Aspirin (300 mg) should be administered to all patients to be chewed and swallowed in all cases of STEMI. In addition to this, a loading dose of a P2Y12 inhibitor like prasugrel or ticagrelor may be administered.

Beta blocker, most often metoprolol, should be administered in all cases where the patient does not have signs of heart failure and is haemodynamically stable.

Atorvastatin (80 mg) should be administered to all patients as soon as possible.

Unfractionated heparin (UFH) is administered to all patients unless they’re already anticoagulated.

If the anatomy is unsuitable for PCI and the infarcted myocardial area is large, or there is cardiogenic shock, emergency coronary artery bypass surgery (CABG) should be performed.

Summary:

  • Aspirin (300 mg loading dose) – in all cases
  • P2Y12 inhibitor loading dose (prasugrel or ticagrelor) – in all cases
  • Atorvastatin – in all cases
  • Unfractionated heparin – in all cases except with pre-existing anticoagulation
  • Metoprolol – in all cases except with heart failure
  • Nitroglycerine – in case of chest pain
  • Morphine – in case of chest pain not responsive to nitro
  • Oxygen – in case of O2 sat < 90%

Secondary prevention

See secondary prevention of ischemic heart disease.

References