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]

Overview

ST elevation myocardial infarction (STEMI) is a syndrome characterized by the presence of symptoms of myocardial ischemia associated with persistent ST elevation on electrocardiogram and elevated cardiac enzymes. The management of STEMI should be initiated without delay and the following timelines should be minimized (the 4 D's):

Door to Data

If a patient presents with chest discomfort, an electrocardiogram must be obtained immediately and no later than 5-10 minutes after arrival. In the patient with chest discomfort, an electrocardiogram should be obtained prior to obtaining insurance / payment information.

Data to Decision

If the electrocardiogram shows ST segment elevation, ST segment depression consistent with posterior MI, or a new left bundle branch block, a decision must be made within 5 to 10 minutes as to whether to administer a fibrinolytic agent or to proceed to primary angioplasty.

Decision to Drug or Device

Once a decision is made to administer a fibrinolytic agent or to proceed to primary angioplasty this should be carried out within 30 minutes.

Causes

Life Threatening Causes

STEMI is a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

• Aortic dissection with propagation to the right coronary artery
• Cocaine
• Plaque rupture
• Takotsubo cardiomyopathy (also known as broken heart syndrome or stress cardiomyopathy)

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.

Abbreviations: CABG: coronary artery bypass graft; ECG: electrocardiogram; LAD: left anterior descending; LBBB: left bundle branch block; MI: myocardial infraction; PCI: percutaneous coronary intervention

Characterize the symptoms: ❑ Chest pain or chest discomfort ❑ Sudden onset ❑ Sensation of heaviness, tightness, pressure, or squeezing ❑ Duration> 20 minutes ❑ Radiation to the left arm, jaw, neck, right arm, back or epigastrium ❑ No relief with medications ❑ No relief with rest ❑ Worse with time ❑ Dyspnea ❑ Weakness ❑ Palpitations ❑ Nausea ❑ Vomiting ❑ Sweating ❑ Loss of consciousness ❑ Fatigue
Obtain a detailed history: ❑ Age ❑ Baseline blood pressure ❑ Previous MI ❑ Previous PCI or CABG ❑ Cardiac risk factors ❑ Hypertension ❑ Diabetes ❑ Hypercholesterolemia ❑ Smoking ❑ Obesity ❑ List of medications Identify possible triggers: ❑ Physical exertion ❑ Psychological stress (anger, anxiety, bereavement, work related stress, natural disasters, wars or sporting events) ❑ Sexual activity ❑ Air pollution or fine particulate matter ❑ Antecedant infection ❑ Heavy meal ❑ Cocaine ❑ Marijuana
Examine the patient: Vital signs ❑ Blood pressure ❑ Blood pressure lower than baseline, suggestive of: ❑ Cardiogenic shock (associated with tachycardia and end organ hypoperfusion), or ❑ Right ventricular MI (associated with increased jugular venous pressure and clear lung fields), or ❑ Bezold-Jarisch reflex (associated with either normal heart rate or bradycardia) ❑ Discrepancy between arms (suggestive or aortic dissection) ❑ Narrow pulse pressure (suggestive of heart failure) ❑ Wide pulse pressure (suggestive of mitral regurgitation or VSD) ❑ Heart rate ❑ Tachycardia (suggestive of heart failure) ❑ Bradycardia (suggestive of heart block) Pulses ❑ Femoral pulse (if a patient is to undergo PCI) ❑ Strength ❑ Bruits Skin ❑ Xanthelasma (suggestive of dyslipidemia) ❑ Xanthoma (suggestive of dyslipidemia) ❑ Edema (suggestive of heart failure) ❑ Cyanotic and cold skin, lips, nail bed (suggestive of cardiogenic shock) Heart ❑ Heart sounds ❑ S3 (suggestive of heart failure) ❑ S4 (associated with conditions that increase the stiffness of the ventricle) ❑ Murmurs ❑ Mitral regurgitation: blowing holosystolic murmur best heard at the apex ❑ VSD: holosystolic murmur along the left and right sternal border ❑ Free wall rupture: holosytolic murmur ❑ Aortic regurgitation: early diastolic high-pitched sound best heard at the left sternal border (suggestive of aortic dissection with propagation to the aortic arch) ❑ Pericardial friction rub (suggestive of pericarditis) Signs of Right Ventricular MI: ❑ Elevated jugular venous pressure (suggestive of right ventricular MI) ❑ Presence of hepatojugular reflux (suggestive of right ventricular MI) Lungs ❑ Rales (suggestive of heart failure)
Rule out life threatening alternative diagnoses: ❑ Aortic dissection (suggestive signs and symptoms: back pain, interscapular pain, aortic regurgitation, pulsus paradoxus, blood pressure discrepancy between the arms) ❑ Pulmonary embolism (suggestive signs and symptoms: acute onset of dyspnea, tachypnea, hemoptysis, previous DVT) ❑ Cardiac tamponade (suggestive signs and symptoms: hypotension, jugular venous distention, muffled heart sounds) ❑ Tension pneumothorax (suggestive signs and symptoms: sudden dyspnea, tachycardia, chest trauma, unilateral absence of breath sounds) ❑ Esophageal rupture (suggestive signs and symptoms: vomiting, subcutaneous emphysema)(
Order labs and tests: ❑ ECG ❑ Biomarkers ❑ Troponin I ❑ CK-MB ❑ Creatinine
❑ Characterize ECG changes consistent with STEMI ❑ 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 ❑ Confirm the diagnosis based on an increase in troponin

Diagnostic Approach to Right Ventricular Myocardial Infarction

Consider right ventricular MI in case of: ❑ Hypotension ❑ Elevated jugular venous pressure ❑ Clear lung fields ❑ ECG changes suggestive of an inferior MI ❑ ST elevation in leads II, III and aVF
Order a right sided ECG in all patients with ST elevation in leads II, III and aVF ❑ Clearly label the ECG as right sided ❑ ST-segment elevation of >1 mm in lead V4R suggests a right ventricular MI
❑ Do not delay the decision and initiation of PCI vs fibrinolytic therapy ❑ Do not administer: ❑ Beta blockers ❑ Nitrates ❑ Diuretics ❑ Increase the right ventricle load by volume expansion with normal saline preferably with invasive monitoring ❑ If central hemodynamic monitoring is available, administer normal saline (40 ml/min, up to total of 2 l, intravenously) until there is an increase in the pulmonary capillary wedge pressure to approximately 15 mmHg ❑ If central hemodynamic monitoring in not available, administer normal saline with a close monitoring of the blood pressure
If hypotension is not corrected with 1-2 L normal saline, administer inotropic agents such as dopamine: ❑ Initial dose 1-5 mcg/kg/min IV ❑ Gradual increase in dose by 1-4 mcg/kg/min every 10 to 30 minutes as needed ❑ Increase the dose up to 20-50 mcg/kg/min

Pre-Hospital Care

Pre-hospital care can begin in the ambulance by Emergency Medical Services (EMS) personnel and it can decrease the delay in the management of STEMI patients. EMS services are staffed by either volunteers, fire fighters, or highly trained paramedics and their services depends on their level of training. Pre-hopital care is different among countries depending on the availability of EMS and highly trained paramedics. In the United States, volunteers and fire fighters are permitted to initiate emergency care prior to the arrival of highly trained paramedics by beginning CPR and if adequately trained, can defibrillate the patient using an automatic external defibrillator. Early access to EMS is promoted by a 9-1-1 system.

Prehospital Care ❑ Check the vital signs ❑ Order 12 lead ECG and transmit it to the receiving hospital ❑ Establish Peripheral IV lines|IV access ❑ Administer Oxygen ❑ Administer medications (depending on the level of training) ❑ Non-enteric coated aspirin ❑ Sublingual nitroglycerin ❑ Clopidogrel ❑ Unfractionated heparin ❑ Glycoprtein IIb IIIa inhibitors ❑ Fibrinolytic therapy (especially in rural areas) ❑ Activate the cardiac cath team in the hospital ❑ Resuscitation in case of cardiac arrest ❑ CPR ❑ Automated defibrillator

Initial Care

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 non enteric aspirin ❑ Orally, crushed or chewed ❑ Intravenously ❑ Administer 2-4 L/min via nasal cannula oxygen when saturation <90% ❑ Caution in COPD patients: maintain an oxygen saturation between 88% and 92% ❑ Administer beta-blockers (unless contraindicated) Contraindicated in heart failure, prolonged or high degree AV block, reactive airway disease, high risk of cardiogenic shock and low cardiac output state ❑ 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 Contraindicated in suspected right ventricular MI, recent use of phosphodiesterase inhibitors, decreased blood pressure 30 mmHg below baseline ❑ 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

First medical contact to device ≥ 120 min

First medical contact to device time ≤ 120 min

❑ Primary PCI within 90 minutes

❑ Fibrinolytic therapy within 30 min

❑ Transfer for primary PCI

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: ❑ Unfractionated heparin ♦ If GP IIb/IIIa receptor antagonist is planned ❑ 50- to 70-U/kg IV bolus ♦ If no GP IIb/IIIa receptor antagonist is 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 ❑ Unfractionated heparin ❑ 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 urgent 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)

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 active 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 peptic 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

Pre-Discharge Care

Administer the following medications in patients without contraindications: ❑ Aspirin 81-325 mg (indefinitely) ❑ Beta blockers Contraindicated in heart failure, prolonged or high degree AV block, reactive airway disease, high risk of cardiogenic shock and low cardiac output state ❑ Metoprolol tartrate ❑ Begin with 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 ❑ Begin with 6.25 mg twice daily ❑ Titrate to 25 mg twice daily ❑ ACE inhibitor in case of anterior MI, ejection fraction ≤ 40% or heart failure Contraindicated in hypotension, renal failure and hyperkalemia ❑ 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 (in case of intolerance to ACE inhibitors) Contraindicated in hypotension, renal failure and hyperkalemia ❑ Begin with 20 mg twice daily ❑ Titrate to 160 mg twice daily ❑ 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 Manage complications of STEMI ❑ Implantable cardioverter-defibrillator at least 40 days following the MI in cases of: ❑ LVEF <30% among patients in NYHA functional Class I (Class I, level of evidence A) ❑ LVEF <35% among patients in NYHA functional Class II or III (Class I, level of evidence A) ❑ LVEF <40% (Class I, level of evidence B) ❑ 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 not administer glucocorticoids or NSAIDs for pericarditis following STEMI (Class III, level of evidence B) Assess the patient for ischemia: ❑ Perform non invasive testing before discharge for the evaluation of ischemia among patients who did not undergo coronary angiography and in whom a coronary angiography is not warranted due to the absence of high risk features (Class I, level of evidence B) ❑ Assess the left ventricular ejection fraction (Class I, level of evidence C)

Long Term Management

❑ Prepare a list of all the home medications and educate the patient about compliance ❑ Aspirin 81-325 mg (indefinitely) ❑ Beta blockers ❑ ACE inhibitors or ARB (in case of anterior MI, ejection fraction ≤ 40% or heart failure) ❑ Atorvastatin 80 mg daily ❑ Antiplatelet therapy ❑ Encourage lifestyle modification ❑ Smoking cessation ❑ Physical activity ❑ Dietary changes ❑ Ensure the initiation of the management of comorbidities ❑ Obesity ❑ Dyslipidemia ❑ Hypertension ❑ Diabetes ❑ Heart failure ❑ Educate the patient about the early recognition of symptoms of MI ❑ Educate the patient about the use of nitroglycerin 0.4 mg, sublingually, up to 3 doses every 5 minutes

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 receptor inhibitor
  • 250 to 300 seconds (HemoTec device) without the concomitant administration of a GPIIbIIIa receptor inhibitor
  • 300 to 350 seconds (Hemochron device) without the concomitant administration of a GPIIbIIIa receptor 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 right ventricular infarction.

• Do not delay the time for reperfusion.

• Do not administer prasugrel among patients with any of the following:
  • Prior history of strokes or TIAs (Class III, Level of evidence B)
  • Active pathological bleeding
  • Age ≥75 years of age, (except in high-risk patients such as diabetes or prior MI, where its use may be considered)
  • Urgent coronary artery bypass graft surgery (CABG) is likely
  • Presence of additional risk factors for bleeding such as body weight <60 kg, propensity to bleed, concomitant use of medications that increase the risk of bleeding

• 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 who are planned to undergo urgent CABG (Class I, level of evidence C).

References

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