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 associated with persistent ST elevation on ECG and elevated 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 ❑ Sensation of tightness, pressure, or squeezing ❑ Absence of physical exertion ❑ Duration> 20 minutes ❑ Radiation to the jaw or left arm ❑ No relief with medications ❑ No relief with rest ❑ Worse with time ❑ Dyspnea ❑ Nausea ❑ Vomiting ❑ Sweating

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: ❑ EKG ❑ Biomarkers ❑ Troponin I ❑ CK-MB ❑ Creatinine ❑ Glucose ❑ Hemoglobin

Confirm STEMI by the presence of the following: ❑ EKG changes ❑ ST elevation 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 (0.1mV) in other contiguous chest leads or the limb leads ❑ ST depression in at least two precordial leads V1-V4 (suggestive of posterior myocardial infarction) ❑ ST depression in several leads plus ST elevation in lead aVR (suggestive of occlusion of the left main or proximal LAD artery) ❑ New LBBB ❑ Increase in troponin

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 within 90 minutes ❑ Symptoms of ischemia <12 hours (Class I, level of evidence A) ❑ Symptoms of ischemia <12 hours and contraindications to fibrinolytics irrespective of time delay (Class I, level of evidence B) ❑ Cardiogenic shock irrespective of time delay (Class I, level of evidence B) ❑ Heart failure irrespective of time delay (Class I, level of evidence B) ❑ Ongoing ischemia 12-24 hours following onset (Class IIa, level of evidence B)

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 (Class I, level of evidence B)

❑ Administer fibrinolytic agent within 30 min of arrival when anticipated FMC to device ≥ 120 min (Class I, level of evidence B)

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.

Indications for PCI in patients who were managed with fibrinolytic therapy ❑ Cardiogenic shock or acute severe HF ❑ Intermediate- or high-risk findings on predischarge noninvasive ischemia testing ❑Spontaneous or easily provoked myocardial ischemia

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

Discharge Medication

Post-PCI Patient

For all patients

For patients with LVEF< 40%

For patients with AF or Flutter

For patients that where already on ACE inhibitors and Beta-blockers and have LVEF<40% or Diabetes or HF

❑ Give aspirin ❑ 165-325 mg/d for 1 month for BMS: for 3 months for sirolimus-eluting stent; 6 months for paclitaxel-eluting stent ❑ 75-162 mg/d indefinitely ❑ Give clopidogrel ❑ 75 mg/d for at least 12 months for DES ❑ 75 mg/d minimum 1 month up to 12 months for BMS ❑ Give beta-blockers

❑ AddACE inhibitor ❑ Give ARBs if intolerant to ACE inhibitor

❑ Give warfarin to achieve INR of 2.0-3.0 ❑ In patients requiring warfarin, clopidogrel, and aspirin therapy, an INR of 2.0 to 2.5 is recommended with low dose aspirin (75 mg to 81 mg) and a 75 mg dose of clopidogrel. ❑ Monitor closely for bleeding

❑ Use aldosterone blockade

Do's

• Administer reperfusion therapy for all patients presenting with STEMI within 12 hours of the beginning of the symptoms (Class I, level of evidence A).

• 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.

• Rule out any contraindications for fibrinolytic therapy before its administration.

• Initiate therapeutic hypothermia among comatose patients with STEMI (Class I, level of evidence B).

• Perform immediate angiography and PCI among STEMI patients who underwent resuscitation for cardiac arrest (Class I, level of evidence B).

Don'ts

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

• 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 nitroglycerine to patients with systolic BP < 90 mm Hg or ≥ to 30 mm Hg below baseline, severe bradycardia (< 50 bpm), tachycardia (> 100 bpm), or suspected RV infarction.

• Do not delay the time for reperfusion.

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

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

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

• Do not administer fibrinolytic therapy to patients with known cerebral arteriovenous malformation or to patients with suspected aortic dissection.

References

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