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

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% ❑ 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) ❑ Symptoms of ischemia <12 hours (Class I, level of evidence A) ❑ Ongoing ischemia 12-24 hours following onset (Class IIa, level of evidence C)

Antiplatelet Therapy ❑ P2Y12 receptor inhibitors ❑ Clopidogrel ❑ Loading dose 600 mg ❑ Maintenance dose 75 mg daily, or ❑ Ticagrelor ❑ Loading dose 180 mg ❑ Maintenance dose 90 mg daily, or ❑ Prasugrel ❑ Loading dose 60 mg ❑ Maintenance dose 10 mg daily ❑ 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.

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 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

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

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).

• 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

• Reduce infusion of tirofiban by 50% among patients with creatinine clearance inferior to 30 mL/min.

• Reduce infusion of eptifibatide by 50% among patients with creatinine clearance inferior to 50 mL/min.

• Reduce infusion of bivalirudin to 1 mg/kg/hour among patients with creatinine clearance inferior to 30 mL/min.

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

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 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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