Myocardial%20infarction%20w_%20st-segment%20elevation Treatment
Patient Instructions
- 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
Emergency Department and Acute Care Measures
- 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
Pharmacotherapy
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
- Important adjunctive therapy after tPA-derived agents (t-PA, r-PA, TNK-tPA, Streptokinase or Anistreplase)
- 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
Non-Pharmacological Therapy
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