Myocardial%20infarction%20w_%20st-segment%20elevation Treatment

• The patient should carry out previous instructions on medications to be taken in case of a possible MI:

Glyceryl Trinitrate (GTN)

• Patients with known coronary heart disease should take one dose of sublingual GTN
• Contraindicated in patients with hypotension and/or who have taken phosphodiesterase 5 inhibitor within 24 hours
• If symptoms do not subside in 10-15 minutes, take a second dose then seek emergency medical treatment in the nearest hospital

Aspirin

• If patient is not on regular Aspirin and is not allergic, it is recommended that he chew and swallow 162-325 mg of Aspirin
• Enteric-coated form should not be used because of its slow onset of action
• If ECG shows STEMI changes, pre-hospital initial therapy should include soluble or chewable Aspirin and Clopidogrel loading dose

• Secure venous access
• Record pulse and blood pressure (BP)

Do pertinent lab exams promptly

• Do 12-lead ECG within 10 minutes
• Draw blood for cardiac biomarkers, full blood count, glucose, electrolytes, renal and lipid profile
  • Anticoagulation studies may be requested for patients on anticoagulant therapy

Administer oxygen (O₂)

• O₂ at 2-4 L/min should be administered (preferably within 6 hours) to all patients and especially to patients who have features of heart failure (HF) or shock, have SaO₂ <90%, or are breathless; maintain O₂ saturation at >90%
  
  • Administer via nasal prongs or face mask

Reassure patient and caregiver 

• Patient will probably have anxiety from the thought of a heart attack and from the pain
• It is helpful to reassure the patient and their caregivers; this may decrease their anxiety

Emergency Department and Acute Care

Relief of Pain

• Tranquilizer may be helpful in anxious patients
• NSAIDs (except Aspirin) and COX-2 inhibitors should be discontinued, if regularly used prior to AMI, due to association with increased cardiovascular risk and prothrombotic effects

Opioid (IV)

• Eg Morphine (analgesic of choice for STEMI-related pain), Diamorphine
• Should be administered selectively for severe pain at the time of diagnosis if patient is unresponsive to nitrates and other anti-ischemic treatments
• Pain is associated with sympathetic activation that results in vasoconstriction and an increase in the workload of the heart
• Avoid MI administration
• Use with caution in inferior wall or posterior wall MI
• Anti-emetics may be given concurrently with opioids to minimize nausea

Antiplatelet Therapy

• DAPT is recommended in patients with STEMI who are undergoing primary PCI and for patients undergoing fibrinolysis and subsequent PCI  
• In the acute phase of STEMI, a loading dose of Aspirin and Clopidogrel, Prasugrel or Ticagrelor may be given for patients undergoing primary PCI; for those receiving fibrinolytic therapy, a loading dose of Aspirin and Clopidogrel may be given

Aspirin

• Should be given promptly and ideally within the 1st 24 hours of suspected MI unless there are contraindications
• When dose >160 mg is given, Aspirin gives rapid clinical antithrombotic action which is caused by near-total and immediate inhibition of thromboxane A₂ production
• Treatment of evolving AMI with Aspirin with or without thrombolytics has shown to reduce mortality

Reperfusion with Thrombolytic Therapy (IV)

• IV thrombolytics should be administered to patients with minimum delay in those with confirmed MI and do not have contraindications
  
  • “Door to needle” time should be within 30 minutes from arrival at the hospital
  • The most benefit is seen when administered <6 hours after onset of symptoms
  • Lesser, but still important benefit is seen when given 6-12 hours after onset of symptoms
  • Should not be given >12 hours after symptom onset except in patients with ongoing ischemia
• Proven to decrease morbidity and mortality when AMI is treated promptly with Aspirin and thrombolytic regimens
• Choice of agent will depend on an individualized assessment of risk and benefit, availability and cost
  
  • Fibrin-nonspecific agents (eg Streptokinase and Anistreplase)
  • Fibrin-specific agents (eg Alteplase [t-PA], Reteplase [r-PA]), Tenecteplase [TNK-tPA])
    • For late-treated patients (>6 hours) or patients with hypotension, LV failure, or cardiac arrest, fibrin-specific agents are preferred
• Monitor ST-segment elevation, cardiac rhythm, clinical symptoms 1-3 hours after thrombolytic therapy

Fibrinolytic Agents

• Alteplase 
  • Fibrin specific and has better reperfusion at 90 minutes
  • Heparin should be given for 48 hours due to high rate of reocclusion
• Streptokinase
  • Not fibrin specific and less efficacious than fibrin-selective agents
  • Antigenic and promotes antibody production
• Tenecteplase
  • 2nd generation fibrin-specific agent that has a slightly lower bleeding risk
  • Given as single or double bolus injections that do not induce production of antibody
  • Heparin or Enoxaparin should be given after completing fibrinolytic therapy and continued for at least 48 hours

Ancillary Therapy

• Patients undergoing reperfusion with thrombolytic therapy should be given anticoagulant therapy for ≥48 hours up to 8 days
  
  • If anticoagulant therapy should be given >48 hours, unfractionated Heparin (UFH) should be used with caution because of the small risk of Heparin-induced thrombocytopenia
  • UFH, Enoxaparin and Fondaparinux have established efficacy as ancillary anticoagulant regimens
• Patients undergoing reperfusion with primary percutaneous coronary intervention (PCI) should be given supportive anticoagulant therapy during the procedure only
  • UFH, Enoxaparin, Bivalirudin are recommended
  • If Fondaparinux is used, anticoagulant with anti-IIa activity (eg UFH, Bivalirudin) should be added

Anticoagulants

• Unfractionated Heparin (UFH) 
  • Important adjunctive therapy after tPA-derived agents (t-PA, r-PA, TNK-tPA, Streptokinase or Anistreplase)
    • Intravenous UFH for 48 hours and continue in patients at high risk of thromboembolism
  • If patient is at high risk of venous thromboembolism (VTE), they should receive intravenous UFH for 48 hours then consider converting to subcutaneous Heparin, Warfarin or Aspirin
    • High-risk patients: Anterior MI, existing HF, previous embolus, atrial fibrillation or left ventricular (LV) thrombus
• Bivalirudin 
  • Useful supportive anticoagulant for primary PCI with or without prior treatment with UFH 
  • Can be considered in STEMI patients who will undergo PCI and are at high risk of bleeding or have a history of heparin-induced thrombocytopenia 
  • Not recommended as an alternative to UFH in patients who received thrombolytic therapy with Streptokinase to avoid excess major bleeding
• Enoxaparin 
  • Can also be used to support rescue PCI
  • No additional anticoagulant needed
  • Use is indicated for patients with creatinine <2.5 mg/dL (190.6 µmol/L) in men and <2.0 mg/dL (152.5 µmol/L) in women
  • Preferred over UFH for anticoagulation extending beyond 48 hours
• Fondaparinux 
  • When used alone to support PCI, there is increased risk for catheter thrombosis, therefore, use of additional anticoagulant with anti-IIa activity is warranted
  • Use is indicated for patients with creatinine <3.0 mg/dL (228.7 mmol/L)

Statin Therapy

• It is recommended to initiate high-intensity statins as early as possible in all patients with STEMI (unless contraindicated) and maintain it long-term 
• Studies show that giving a loading dose of Atorvastatin 80 mg in patients before primary PCI leads to a significant reduction in MI and major adverse cardiovascular events (MACE) 

Further Inpatient Treatment

Antiplatelet Therapy

Dual Antiplatelet Therapy (DAPT)

• Eg Aspirin + Clopidogrel/Prasugrel/Ticagrelor (P2Y₁₂ inhibitors)
• Aspirin should be administered daily and continued indefinitely to all patients without contraindications
• P2Y₁₂ inhibitor therapy is given:
  • Post-fibrinolysis for 1 month to 12 months depending on the ischemic versus bleeding risks  
  • After PCI (BMS or DES) for at least 12 months; after CABG, P2Y₁₂ inhibitor therapy is resumed to complete 12 months of DAPT  
    • In patients at high risk of complications with severe bleeding, consider stopping P2Y₁₂ inhibitors after 6 months
• Continuation of DAPT for >12 months may be reasonable if there is no high risk of bleeding and no significant overt bleeding on DAPT

Aspirin

• Standard 1st-line antiplatelet therapy
• 75-100 mg/day of Aspirin is recommended after stenting, in patients with a prior MI or revascularization, and in those being treated with DAPT 

Clopidogrel

• In combination with Aspirin, Clopidogrel is recommended in STEMI patients receiving thrombolysis and in whom a PCI is planned
• Should be given in STEMI patients up to 75 years of age who are receiving fibrinolysis, Aspirin and Heparin
• If CABG is to be performed, intake of Clopidogrel should be withheld 5 days prior to procedure

Prasugrel

• In combination with Aspirin, Prasugrel is recommended in STEMI patients in whom PCI is planned
• If CABG is to be performed, intake of Prasugrel should be withheld 7 days prior to procedure

Ticagrelor

• In combination with Aspirin, Ticagrelor is recommended in STEMI patients who have undergone PCI or medical management  
• Alternative to Clopidogrel in <75-year-old patients undergoing PCI within 24 hours after fibrinolytic therapy
• Should be withheld 3-5 days prior to CABG

Cangrelor 

• A potent, direct, reversible and short-acting intravenous P2Y₁₂ inhibitor 
• May be used in P2Y₁₂ inhibitor-naive patients undergoing PCI or patients who cannot take oral medications or whose absorption of oral medications is inhibited

Glycoprotein IIb/IIIa Inhibitors

• Adjunctive use of Abciximab, Eptifibatide or Tirofiban at the time of primary PCI can benefit patients with large thrombus burden
• Eptifibatide or Tirofiban should be discontinued at least 2-4 hours and Abciximab at least 12 hours before urgent CABG

Anticoagulants (IV)

• Eg UFH, Enoxaparin, Fondaparinux
• Given to those who received fibrinolytic therapy but did not undergo PCI
• Beneficial in MI with ST elevation
  
  • May also be given to patients treated with fibrin-selective lytic agents, as routine administration after fibrinolysis, and patients with atrial fibrillation or mural thrombus 
• When Fondaparinux is used alone to support PCI, there is increased risk for catheter thrombosis; therefore, use of additional anticoagulant with anti-IIa activity (eg UFH or Bivalirudin) is warranted

ACE Inhibitors

• Start in all patients once the blood pressure is stable and systolic blood pressure remains >100 mmHg unless contraindicated (ideally within the 1st 24 hours and after thrombolytic therapy)
  
  • Greatest benefit has been seen in patients with HF, anterior infarction, LV systolic dysfunction, diabetes
• Associated with small but significant decrease in 30-day mortality with most of the benefit seen in the 1st week after infarction

Angiotensin II Antagonists

• Use in patients who have indications for (eg early-phase HF or LVEF ≤40%) but are intolerant to ACE inhibitors

Beta-Blockers

• Eg Atenolol, Bisoprolol, Carvedilol, Labetalol, Metoprolol, Propranolol 
• Oral beta-blockers should be given within 24 hours of onset of infarction in low-risk patients without contraindications (eg hypotension or evidence of low output state, congestive heart failure [CHF], increased risk for cardiogenic shock, PR interval >0.24 seconds, 2nd- or 3rd-degree heart block, active asthma or reactive airway disease)
• When given during 1st few hours of infarct, beta-blockers may lessen myocardial O₂ demand by decreasing heart rate, systemic arterial pressure and myocardial contractility

Aldosterone Antagonists (Mineralocorticoid Receptor Antagonists)

• Eg Eplerenone, Spironolactone
• When added to beta-blocker and ACE inhibitor, aldosterone antagonist has been shown to reduce mortality and hospitalization rates in post-MI patients with impaired left ventricular function and mild HF

Nitrates

• Nitrate-induced relaxation of the vascular smooth muscle in veins, arteries and arterioles results in vasodilation
  • This reduces right ventricular and left ventricular preload along with afterload reduction which decreases cardiac work and myocardial oxygen demand 
• May be considered in the 1st 24-48 hours if needed in patients with continuing chest pain/ischemia, HF, large anterior infarction or hypertension
  • Intravenous route is usually preferred in early management (1st 48 hours) because of more precise control
• May be used beyond 48 hours if patient has recurrent angina or continued pulmonary congestion

Calcium Antagonists

• Eg Diltiazem or Verapamil
• Should only be considered if beta-blockers and nitrates are ineffective in controlling ischemia or if beta-blockers are contraindicated
• May be used to control rapid ventricular response with atrial fibrillation after AMI
• Have not been shown to reduce mortality after AMI 
• Should not be used in patients with CHF, LV dysfunction or atrioventricular (AV) block

Statins

• High-intensity statins should be given as concomitant pharmacotherapy in the acute treatment of all STEMI patients if without contraindications 

Glucose Control

• Hyperglycemia is managed during the acute phase but hypoglycemic episodes should be avoided

Routine Measures For Acute Myocardial Infarction (AMI) Patients

Bed Rest

• Adequate bed rest as indicated by the clinical status of the patient
• Uncomplicated cases
  • Early ambulation is encouraged
  • Patient may sit out of bed late on the 1st day and be allowed to use commode, perform self-care and self-feeding
  • Ambulation can start the next day (eg walking flat surface up to 200 meters and upstairs within a few days)
• Complicated cases (eg HF, shock or serious arrhythmias)
  • Will need bed rest longer and physical activity should be increased gradually based on extent of myocardial damage and symptoms
  • Consider risk of thrombus formation and appropriate prophylaxis

Monitor Patient

• Vital signs, pulse oximetry and ECG should be continuously monitored

O₂

• Administer O₂ if patient has hypoxemia (SaO₂ <90% or PaO₂ <60 mmHg)
• In uncomplicated cases, O₂ is usually needed only for the 1st day