STEMI resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]

Definition

ST elevation myocardial infarction (STEMI) is a syndrome defined by symptoms of myocardial ischemia (sudden chest pain and pressure, shortness of breath) associated with persistent ECG ST elevation and subsequent release of cardiac enzymes.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. STEMI is a life-threatening condition and must be treated as such irrespective of the causes.

Risk Factors

• Atherosclerosis
• Hypertension
• Obesity
• Dyslipidemia
• Smoking
• Diabetes

Management

Diagnostic Approach

Shown below is an algorithm summarizing the diagnostic approach to STEMI based on the 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction

Characterize the symptoms: ❑ Chest pain ❑ Sudden onset ❑ Described as a sensation of tightness, pressure, or squeezing ❑ Radiation to the jaw or left arm ❑ No relief with medications or rest ❑ Worse with time ❑ Shortness of breath (Dyspnea) ❑ Diaphoresis ❑ Light-headedness ❑ Nausea and/or vomiting

Obtain a detailed history: ❑ Age ❑ Previous MI ❑ Previous PCI or CABG ❑ Cardiac risk factors: ❑ Hypertension ❑ Diabetes ❑ Hypercholesterolemia ❑ Smoking ❑ Obesity

Examine the patient: ❑ Measure the blood pressure ❑ Measure the heart rate ❑ Auscultate the heart searching for murmurs ❑ Search for signs of CHF ❑ Decreased air entry in the lungs ❑ Edema in the extremities

Rule out life threatening alternative diagnoses: ❑ Aortic dissection ❑ Pulmonary embolism ❑ Cardiac tamponade ❑ Tension pneumothorax ❑ Esophageal rupture

Order labs and tests:

Order EKG ❑ New ST elevation at the J point in at least 2 contiguous leads of 2 mm (0.2 mV) in men or 1.5 mm (0.15 mV) in women in leads V2–V3 and/or of 1 mm (0.1 mV) in other contiguous chest leads or the limb leads ❑ For EKG examples click here

Order Cardiac Enzymes ❑ Troponin I ❑ CK-MB

Other labs: ❑ Creatinine ❑ Glucose ❑ Hemoglobin

❑ Symptoms + increase in Troponin + EKG ST elevation

Start treatment for STEMI

Therapeutic Apporach

Shown below is an algorithm depicting the therapeutic approach to STEMI based on the 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction.

Initial Treatment ❑ Administer 162 - 325 mg of aspirin ❑ Administer oxygen when Sat <90% ❑ Administer beta-blockers (unless contraindicated) ❑ Administer sublingual nitroglycerin (0.4 mg) every 5 minutes for a total of 3 doses ❑ Monitor with a 12-lead EKG all the time ❑ Administer morphine IV (initial dose 2-4 mg with increments of 2-8 mg every 5 to 15 minutes)

Is PCI available?

Yes

No

❑ Send to cath lab for primary PCI

Evaluate for ❑ The time from onset of symptoms ❑ The risk of complications related to STEMI ❑ The risk of bleeding with fibrinolysis ❑ The presence of shock or severe HF ❑ The time required for transfer to a PCI-capable hospital

Adjunctive Antithrombotic Therapy to Support Reperfusion With Primary PCI

❑ Transfer for primary PCI ❑ FMC to device time as soon as possible and ≤ 120 min.

❑ Administer fibrinolytic agent within 30 min of arrival when anticipated FMC to device ≥ 120 min

Antiplatelet Therapy ❑ P2Y12 receptor inhibitors ❑ Clopidogrel (600 mg), or ❑ Ticagrelor (180 mg), or ❑ IV GP IIb/IIIa inhibitors ❑ Abciximab ❑ Loading dose 0.25 mg/kg IV bolus ❑ Maintenance dose 0.125 mg/kg/min, or ❑ Eptifibatide ❑ Loading dose 180 mcg/kg IV bolus followed by another bolus after 10 minutes ❑ Maintenance dose 2 mcg/kg/min, or ❑ Tirofiban ❑ Loading dose 25 mcg/kg ❑ Maintenance dose 0.15 mcg/kg/min

Anticoagulant Therapy ❑ UFH ❑ With GP IIb/IIIa receptor antagonist planned: 50- to 70-U/kg IV bolus to achieve therapeutic ACT of 200-250 s. ❑ With no GP IIb/IIIa receptor antagonist planned: 70- to 100-U/kg bolus to achieve therapeutic ACT of 250-300 s. ❑ Bivalirudin: 0.75-mg/kg IV bolus, then 1.75–mg/kg/h infusion with or without prior treatment with UFH. An additional bolus of 0.3 mg/kg may be given if needed.

FMC: First medical contact; UFH: Unfractionated Heparin; ACT: Activated clothing time

Do´s

• Administer a loading dose followed by a maintenance dose of clopidogrel, ticagrelor or prasugrel (if PCI is planned) as initial treatment instead of aspirin among patients with gastrointestinal intolerance or hypersensitivity reaction to aspirin.

• Administer sublingual nitroglycerin in patients with ischemic chest pain; however, administer IV nitroglycerin among patients with persistent chest pain after three sublingual nitroglycerins.

• Discontinue non-steroidal anti-inflamatory drugs immediately.

Don'ts

• Do not administer IV GP IIb/IIIa inhibitors to patients with low risk of ischemic events or at high risk of bleeding and who are already on aspirin and P2Y12 receptor inhibitors therapy.

• Do not administer prasugrel among patients with prior history of strokes o TIAs.

• Do not administer IV beta-blockers among hemodynamically unstable patients.

• Do not administer a complete dose of prasugrel among patients under 60kg (132lbs) due to high exposure to the active metabolite. They should receive half the dose of prasugrel although there is no evidence that half the dose is as effective as a complete dose.

• Do not administer fibrinolytic therapy to patients with unstable angina.

• Do not administer abciximab for patients nor scheduled for PCI.

References

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