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]; Rim Halaby, M.D. [3]

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

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 saturation <90% ❑ 2-4 L/min via nasal cannula ❑ Administer beta-blockers (unless contraindicated) ❑ Metoprolol IV, 5 mg every 5 min, up to 3 doses ❑ Carvedilol IV, 6,25 mg, two times a day (titrate to heart rate) ❑ Administer sublingual nitroglycerin 0.4 mg every 5 minutes for a total of 3 doses ❑ Administer IV morphine if needed ❑ Initial dose 2-4 mg ❑ 2-8 mg every 5 to 15 minutes, as needed ❑ Administer 80 mg atorvastatin ❑ Monitor with a 12-lead EKG all the time

❑ Determine if PCI is available

PCI is available

PCI is not available

Primary PCI within 90 minutes

Fibrinolytic therapy within 30 min FMC to device ≥ 120 min

Transfer for primary PCI FMC to device time ≤ 120 min

Confirm that the patient has one of the following indications: ❑ 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)

❑ Confirm that the patient has one of the following indications: ❑ Symptoms of ischemia <12 hours (Class I, level of evidence A) ❑ Ongoing ischemia 12-24 hours following onset (Class IIa, level of evidence C) ❑ Confirm that the patient has no contraindications for fibrinolytics

Administer ONE of the following antiplatelet agents (before or at the time of PCI): ❑ P2Y12 receptor inhibitors ❑ Clopidogrel 600 mg ❑ Ticagrelor 180 mg ❑ Prasugrel 60 mg ❑ IV GP IIb/IIIa inhibitors ❑ Abciximab ❑ Loading dose 0.25 mg/kg IV bolus ❑ Maintenance dose 0.125 mg/kg/min ❑ Eptifibatide ❑ Loading dose 180 mcg/kg IV bolus ❑ Another 180 mcg/kg IV bolus after 10 minutes ❑ Maintenance dose 2 mcg/kg/min ❑ Decrease infusion by 50% if creatinine clearance <50 mL/min ❑ Avoid in hemodialysis patients ❑ Tirofiban ❑ Loading dose 25 mcg/kg ❑ Maintenance dose 0.15 mcg/kg/min ❑ Decrease infusion by 50% if creatinine clearance <30 mL/min Administer ONE of the following anticoagulant therapy: ❑ UFH ❑ If GP IIb/IIIa receptor antagonist planned: 50- to 70-U/kg IV bolus ❑ If no GP IIb/IIIa receptor antagonist planned: 70- to 100-U/kg bolus ❑ Bivalirudin ❑ 0.75-mg/kg IV bolus, then 1.75–mg/kg/h infusion ❑ Additional bolus of 0.3 mg/kg if needed ❑ Decrease infusion to 1 mg/kg/h when creatinine clearance <30 mL/min

Administer ONE of the following fibrinolytic therapy ❑ Tenecteplase single IV bolus ❑ 30 mg for weight <60 kg ❑ 35 mg for weight 60-69 kg ❑ 40 mg for weight 70-79 kg ❑ 45 mg for weight 80-89 kg ❑ 50 mg for weight ≥60 kg ❑ Reteplase 10 units IV boluses every 30 min ❑ Alteplase ❑ Bolus 15 mg, infusion 0.75 mg/kg for 30 min (maximum 50 mg) ❑ Then 0.5 mg/kg (maximum 35 mg) over the next 60 min ❑ Streptokinase 1.5 million units IV administered over 30-60 min Administer a P12Y2 inhibitor ❑ Clopidogrel If age ≤ 75 years ❑ Loading dose 300 mg ❑ 75 mg daily for at least 14 days, up to one year If age > 75 years ❑ Loading dose 75 mg ❑ 75 mg daily for at least 14 days, up to one year Administer ONE of the following anticoagulant therapy ❑ UFH ❑ IV bolus of 60 units/kg (maximum 4000 units) ❑ Then infusion of 12 units/kg/hour (maximum 1000 units) ❑ Adjust the infusion for a aPTT of 50-70 sec for 48 hours or until revascularization ❑ Enoxaparin (for up to 8 days or until revascularization) If age <75 years ❑ IV bolus 30 mg ❑ Then after 15 minutes, SC 1 mg/kg every 12 hours (maximum 100 mg for the first two doses) If age ≥75 years ❑ SC 0.75 mg/kg every 12 hours (maximum 75 mg for the first two doses) If creatinine clearance <30 mL/min ❑ SC 1 mg/kg every 24 hours ❑ Fondaparinux ❑ Initial dose of 2.5 mg IV ❑ Then, SC 2.5 mg daily (for up to 8 days or until revascularization) ❑ Do not administer if creatinine clearance <30 mL/min

Consider CABG if the coronary anatomy is not amenable to PCI and one of the following: ❑ Ongoing and recurrent ischemia ❑ Cardiogenic shock ❑ Severe heart failure ❑ Other high risk features

Transfer to a PCI-Capable hospital for non primary PCI, if there is: ❑ Cardiogenic shock (Class I, level of evidence B) ❑ Acute severe heart failure (Class I, level of evidence B) ❑ Spontaneous or easily provoked myocardial ischemia (Class I, level of evidence C) ❑ Failed reperfusion after fibrinolytics (Class IIa, level of evidence B) ❑ Reocclusion after fibrinolytics (Class IIa, level of evidence B) ❑ Successful fibrinolytic reperfusion, between 3 and 24 hours (Class IIa, level of evidence B)

FMC: First medical contact; UFH: Unfractionated Heparin

Contraindications to Fibrinolytic Therapy

Shown below is a table summarizing the absolute and relative contraindications for fibrinolytic therapy among STEMI patients.

Absolute contraindications

Relative contraindications

❑ Prior intracranial hemorrhage ❑ Ischemic stroke within the last 3 months (Unless within 4.5 hours) ❑ Structural cerebral vascular lesion ❑ Primary of metastatic intracranial malignancy ❑ Suspicion of aortic dissection ❑ Increased bleeding tendency or actibe bleeding ❑ Severe head or facial trauma within the last 3 months ❑ Intracranial or intraspinal surgery within the last 2 months ❑ Severe hypertension uncontrolled by emergency therapy ❑ Previous treatment with streptokinase within the last 6 months

❑ Oral anticoagulation therapy ❑ Pregnancy ❑ Active puptic ulcer ❑ Previous history of chronic severe hypertension that is poorly controlled ❑ Elevated blood pressure at presentation, such as SBP >180 mmHg or DBP >110mmHg ❑ Previous history of ischemic stroke ❑ Dementia ❑ Intracranial pathology that does not meet the absolute contraindications ❑ CPR that lasted more than 10 min or that is traumatic ❑ Major surgery in the last 3 weeks ❑ Internal bleeding within the last 2-4 weeks ❑ Non compressible vascular punctures

Long Term Management

Administer the following medications for all patients with no contraindications: ❑ Aspirin 81-325 mg (indefinitely) ❑ Beta blockers ❑ Metoprolol tartrate ❑ 25 to 50 mg PO every 6 to 12 hour ❑ Then, metoprolol tartrate twice daily or metoprolol succinate once daily for 2-3 days ❑ Titate to 200 mg daily, OR ❑ Carvedilol ❑ 6.25 mg twice daily ❑ Titrate to 25 mg twice daily, OR ❑ ACE inhibitor ❑ Lisinopril ❑ Begin with 2.5-5 mg ❑ Titrate to 10 mg or higher daily, OR ❑ Captopril ❑ Begin with 6.25-12.5 mg three times daily ❑ Titrate to 25 to 50 mg three times daily, OR ❑ Ramipril ❑ Begin with 2.5 mg twice daily ❑ Titrate to 5 mg twice daily, OR ❑ Trandolapril ❑ Begin with 0.5 mg daily ❑ Titrate to 4 mg daily, OR ❑ Valsartan ❑ Begin with 20 mg twice daily ❑ Titrate to 160 mg twice daily, OR ❑ Atorvastatin 80 mg daily Administer antiplatelet therapy For patients who underwent PCI, for one year ❑ Clopidogrel 75 mg daily, OR ❑ Prasugrel 10 mg daily, OR ❑ Ticagrelor 90 mg twice a day For patients who underwent fibrinolysis, for at least 14 days, up to one year ❑ Clopidogrel 75 mg daily Educate the patient about: ❑ Use of nitroglycerin 0.4 mg, sublingually, up to 3 doses every 5 minutes ❑ Lifestyle modification ❑ Smoking cessation ❑ Physical activity ❑ Dietary changes ❑ Management of comorbidities Manage complications of STEMI ❑ Implantable cardioverter-defibrillator therapy if the patient develops an irreversible non-ischemia related VT/ VF after more than 48 hours following STEMI (Class I, level of evidence B) ❑ Temporary pacing for asymptomatic bradycardia refractory to medical therapy (Class I, level of evidence C) ❑ Aspirin for pericarditis (Class I, level of evidence B)

Do's

• Pre-hospital ECG is recommended. If STEMI is diagnosed the PCI team should be activated while the patient is en route to the hospital.

• 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. If contraindications to fibrinolytics are present, the patient should be transferred to another hospital where PCI is available.

• 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).

• Consider bare-metal stent among STEMI patients with any of the following (Class I, level of evidence C):
  • High bleeding risk
  • Lack of compliance for a one year regimen of dual antiplatelet therapy
  • Surgery or invasive procedure within the next year

• Achieve the following therapeutic activated clotting time when administering UFH:
  • 200 to 250 seconds with the concomitant administration of GPIIbIIIa inhibitor
  • 250 to 300 seconds (HemoTec device) without the concomitant administration of a GPIIbIIIa inhibitor
  • 300 to 350 seconds (Hemochron device) without the concomitant administration of a GPIIbIIIa inhibitor

• Make sure the dose of P2Y12 receptor inhibitors is appropriate among patients undergoing PCI after fibrinolytic therapy:
  • Patients who already received a loading dose of clopidogrel: No loading dose, clopidogrel daily
  • Patients who did not receive a loading dose of clopidogrel and PCI is performed ≤ 24 hours after fibrinolytic therapy: loading dose of 300 mg clopidogrel
  • Patients who did not receive a loading dose of clopidogrel and PCI is performed > 24 hours after fibrinolytic therapy: loading dose of 600 mg clopidogrel
  • Patients who did not receive a loading dose of clopidogrel and PCI is performed >24 hours after therapy with fibrin specific agent, or >48 hours after therapy with a non-fibrin-specific agent: prasugrel 60 mg

• Prepare the patient for urgent CABG when indicated by discontinuing the following:
  • Clopidogrel or ticagrelor at least 24 hours prior to CABG
  • Eptifibatide or tirofiban at least 2 to 4 hours prior to CABG
  • Abciximab 12 hours prior to CABG

• Consider using a mechanical circulatory support among hemodynamically unstable patients with STEMI requiring an urgent CABG (Class IIa, level of evidence C).

• Recommend a long term maintenance dose of 81 mg of aspirin when the patient is administered ticagrelor.

• Include aldosterone antagonist in the discharge medication list among patients who are already on ACE inhibitors and beta-blockers with a left ventricular ejection fraction <40% or diabetes or heart failure.

Don'ts

• Do not administer IV beta-blockers among patients with elevated risk for cardiogenic shock, signs of heart failure, low ouput state, prolonged PR interval more than 0.24 seconds, second or third degree block or asthma (Class I, level of evidence B).

• 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 or TIAs (Class III, Level of evidence B).

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

• Do not withhold aspirin among patients planned to undergo urgent CABG (Class I, level of evidence C).

References

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