Adjunctive treatment to initial therapy in acute coronary syndrome

Summary

Definition

Overview

Recommendations in this article are consistent with the 2021 American Heart Association (AHA) guidelines on chest pain, and 2013 AHA guidelines on STEMI and NSTE-ACS. [1][2][3]

Subtypes of ACS cannot be differentiated based on clinical presentation alone.

Unstable angina is differentiated from MI by the presence of positive troponins, while the type of MI (NSTEMI vs. STEMI) is determined based on ECG findings.

Clinical features

• Classic presentation [5][6]
  • Acute retrosternal chest pain
    • Typical: dull, squeezing pressure and/or tightness
    • Commonly radiates to left chest, arm, shoulder, neck, jaw, and/or epigastrium
    • Precipitated by exertion or stress
    • Symptom relief after administration of nitrates is not a diagnostic criterion for cardiac ischemia. [2]
    • The peak time of occurrence is usually in the morning.
    • See also “Angina.”
  • Dyspnea (especially with exertion)
  • Pallor
  • Nausea, vomiting
  • Diaphoresis, anxiety
  • Dizziness, lightheadedness, syncope
• Other findings
  • Tachycardia, arrhythmias
  • Symptoms of CHF (e.g., orthopnea, pulmonary edema) or cardiogenic shock (e.g., hypotension, tachycardia, cold extremities)
  • New heart murmur on auscultation (e.g., new S4)
• Atypical presentations: more likely in elderly, diabetic individuals, and women ; [2][7]
  • Stabbing, sharp chest pain
  • No or minimal chest pain:
  • Autonomic symptoms (e.g., nausea, diaphoresis)
  • See also “Anginal equivalents.”
• More common in inferior wall infarction
  • Epigastric pain
  • Bradycardia
  • Clinical triad in right ventricular infarction: hypotension, elevated jugular venous pressure, clear lung fields [1]

Classically, it has been taught that STEMI manifests with more severe symptoms than NSTEMI, but this is not always the case.

Management approach

Diagnostics

Consider serial ECGs if the initial ECG is negative or inconclusive, as ECG findings are dynamic and signs of ischemia can appear or disappear within minutes.

Obtain a V7–V9 lead tracing if ST depressions are present in V1–V4, as this may be a sign of a posterior wall STEMI.

In patients with a normal ECG, a single result below the limit of detection using a high-sensitivity troponin assay ≥ 3 hours after symptom onset is considered sufficient to rule out myocardial infarction. [3]

TTE is generally not necessary and should not delay reperfusion therapy. However, it may be a helpful study in patients with atypical symptoms or if the diagnosis is unclear.

Do not delay treatment of ACS for imaging.

Risk stratification

STEMI

Avoid excluding a diagnosis of STEMI based on a single ECG as findings can change over time and with symptom fluctuation.

ECG changes in STEMI

Management

Acute management checklist

For patients < 120 min away from a PCI-capable facility

• Immediate cardiology consult and evaluation for emergency revascularization (code STEMI)
• Transfer to cath lab for angiography.
• Start antiplatelets and anticoagulation (see “Antiplatelet therapy and anticoagulation in STEMI”).
  • Aspirin
  • ADP receptor inhibitor (can also be given at time of PCI)
  • Start anticoagulation with UFH, bivalirudin, or fondaparinux.
  • Consider glycoprotein (GP) IIb/IIIa receptor antagonist.

For patients > 120 min away from a PCI-capable facility and symptom onset < 12 hours

• Immediate cardiology consult (code STEMI), even if no PCI is available
• Check for contraindications to fibrinolysis (see “Contraindications for fibrinolysis in STEMI and STEMI-equivalents”).
• If no absolute contraindications present: Administer fibrinolytic (see “Fibrinolytic therapy in STEMI”).
• Start antiplatelets and anticoagulation (see “Antiplatelet therapy and anticoagulation in STEMI”).
  • Aspirin (as soon as possible)
  • ADP receptor inhibitor: clopidogrel
  • Start anticoagulation with UFH, enoxaparin, or fondaparinux.
• Postfibrinolysis: Evaluate for evidence of reperfusion (i.e., resolution of chest pain and ST-segment elevations).
• Transfer to a PCI-capable facility.

For all patients with STEMI

• Adjunctive medical therapy for ACS
  • Supplemental oxygen as needed: target SpO2 > 90%
  • Nitroglycerin for patients with ongoing chest pain or hypertension
  • Analgesia with morphine only for patients with very strong pain.
  • High-intensity statin
  • Consider a beta blocker if there are no contraindications.
  • Consider an ACE inhibitor if there are no contraindications.
• Order continuous telemetry, serial ECG, and serum troponins every 4–6 hours.
• Consider ICU level of care

NSTEMI/UA

Overview

• Patients with NSTE-ACS are classified based on the presence (NSTEMI) or absence (UA) of significantly elevated cardiac troponin (cTn) levels.
• A key element of management is to assess the necessity for and timing of PCI (fibrinolytics are not indicated in NSTE-ACS).
• Hemodynamically unstable patients and those with intractable angina require immediate PCI (i.e., they are managed like STEMI patients).
• Multiple risk scores (e.g., HEART, TIMI, GRACE) can help to determine an adequate strategy but are no substitute for individual clinical judgment.
• Dual antiplatelet therapy and anticoagulation is indicated initially and the preferred regimens vary based on patient risk factors and timing of revascularization.
• Some low-risk NSTE-ACS patients can be managed conservatively.

ECG changes in NSTEMI/UA

• Findings [2]
  • No ST elevations present
  • Nonspecific signs of ischemia may be present, including:
• Additional considerations
  • Normal ECG may be seen in up to 15% of patients with NSTEMI. [2][29]
  • Be wary of STEMI-equivalent ECG findings (e.g., signs of posterior myocardial infarction) and repeat ECGs if inconclusive.

To identify STEMI or STEMI-equivalent ECG findings, repeat ECGs if the initial one is inconclusive or any changes in symptoms occur.

Management

The following recommendations are generally consistent with the 2014 AHA/ACC guidelines for the management of NSTE-ACS. [2]

Selection of an ischemia-guided strategy via shared decision-making may be appropriate in intermediate-risk patients without serious comorbidities or contraindications. [2]

Fibrinolytic therapy is not indicated in patients with unstable angina or NSTEMI.

Antiplatelet therapy and anticoagulation in NSTE-ACS [2]

Acute management checklist for NSTE-ACS

• Evaluate for very-high risk factors requiring urgent coronary angiography : If present, follow STEMI checklist. [2]
• Start antiplatelet therapy and anticoagulation.
  • Aspirin
  • ADP receptor inhibitor: ticagrelor or clopidogrel
  • Anticoagulation with UFH, enoxaparin, bivalirudin, or fondaparinux
• Calculate TIMI score and GRACE score.
• Cardiology consult for discussion of strategy (see “Risk-dependent timing of revascularization in NSTE-ACS”)
• Adjunctive medical therapy for ACS
  • Supplemental oxygen as needed: target SpO2 > 90%
  • Nitroglycerin for patients with ongoing chest pain or hypertension
  • Analgesia with morphine only for patients with very strong pain
  • High-intensity statin
  • Consider beta blocker if no contraindications.
  • Consider ACE inhibitor if no contraindications.
• Order continuous telemetry, serial ECG, and serum troponins every 3–6 hours.
• Transfer to cardiac telemetry floor or (cardiac) ICU.

Monitoring and adjunctive medical therapy

Adjunct medical therapy in ACS [1][2]

Options for initial MI treatment include “MONA-BASH”: Morphine, Oxygen, Nitroglycerin, Antiplatelet drugs (aspirin + ADP receptor inhibitor), Beta blockers, ACE inhibitors, Statins, and Heparin. The scope of interventions depends on the patient's risk profile (see “Indications”).

Supportive measures

• Oxygen therapy for patients with:
  • Cyanosis
  • Severe dyspnea
  • SpO2 < 90%
• Fluid management: see “Management of acute heart failure.”

Disposition

STEMI [1]

Provide ICU-level care to all patients.

• At PCI-capable site: Consult cardiology immediately and transfer to cath lab as soon as possible for primary PCI.
• < 120 minutes from nearest PCI-capable site: Arrange immediate interfacility transfer for primary PCI at referral center.
• > 120 minutes from nearest PCI-capable site
  • If symptom onset < 12 hours AND no contraindications to fibrinolysis for STEMI: Administer fibrinolytic prior to transfer to PCI-capable site.
  • All other patients: Transfer to PCI-capable site.

NSTEMI and unstable angina [2]

• Cardiology consult
• Hospital admission
  • Continuing angina, hemodynamic instability, uncontrolled arrhythmias, or large-territory MI: Admit to cardiac ICU.
  • All other patients: Admit to step down unit.
• Assess risk-dependent timing of revascularization in NSTEMI and consider the need for transfer to the nearest PCI-capable site.

Negative initial workup for ACS [3]

If the initial evaluation for ACS is negative is inconclusive based on serial ECGs and cardiac troponin but clinical suspicion remains:

• Rule out other potential causes of chest pain.
• Use risk stratification for ACS (e.g., the HEART score) to determine the short-term risk of a MACE.
• Consider the need for observation or admission for further diagnostics based on the risk.

Risk-based management [3]

• High-risk (e.g., HEART score ≥ 7)
  • Inpatient admission
  • Obtain invasive coronary angiography during admission.
• Intermediate-risk (e.g., HEART score 4–6)
  • Noninvasive testing (i.e., cardiac stress test or coronary CT angiography) is usually required prior to discharge.
  • In patients with a recent negative workup for CAD , no further testing is indicated prior to discharge.
• Low-risk (e.g., HEART score ≤ 3)
  • No further testing is indicated prior to discharge from the ED.
  • Ensure outpatient follow-up.
  • Outpatient coronary artery calcium scoring may be considered for ASCVD risk evaluation.

Differential diagnoses

Related One-Minute Telegram

Interested in the newest medical research, distilled down to just one minute? Sign up for the One-Minute Telegram in “Tips and links” below.

References

What is an adjunctive treatment in ACS?

What is the initial treatment for acute coronary syndrome?

What is the initial drug therapy for ACS Aha?

What treatment is indicated in the first 12 hours of myocardial infarction?