Pulmonary Embolism Classification

D-Dimer Testing

• Not recommended if clinical suspicion is high, as a normal result does not exclude PE in patients with high predicted probability, even with high-sensitivity assays
• Positive result: perform diagnostic imaging
• Negative result: do not perform diagnostic imaging (PE may be excluded)

Diagnosis

• McConnell's sign: a distinct echocardiographic feature of acute massive PE, characterized by RV free wall akinesis with sparing of the apex
• Hampton hump sign: a dome-shaped area of opacification in the periphery of the left lower lobe, indicating PE
• CT angiogram: demonstrates multiple pulmonary artery filling defects, consistent with pulmonary emboli

Risk Stratification

• Assess all patients with acute PE for severity and risk of early death to determine management strategy
• Initially stratify patients by presence of hemodynamic instability to identify those at high risk of early death
• Hemodynamic instability definitions include:
  • Cardiac arrest: need for CPR
  • Obstructive shock: SBP < 90 mm Hg or vasopressors required to achieve blood pressure ≥ 90 mm Hg despite adequate filling status, with end-organ hypoperfusion

Management

• Catheter-directed thrombolysis: suggested in patients with acute hypotensive PE in case of high bleeding risk, failed systemic thrombolysis, and/or shock likely to result in death before systemic thrombolysis takes effect
• Surgical pulmonary embolectomy: suggested as an alternative to systemic thrombolysis if contraindicated or failed

High-Risk (Massive PE) Management

• Clot-specific lyrics and dosing regimens:
  • Alteplase: 100 mg over 2 hours (FDA-approved)
  • Urokinase: 4,400 units/kg over 10 minutes (FDA-approved)
  • Streptokinase (no longer on market in US): 250,000 units loading dose over 30 minutes (FDA-approved)
• Absolute contraindications:
  • Structural intracranial disease
  • Previous intracranial hemorrhage
  • Previous hemorrhagic stroke or stroke of unknown origin
  • Ischemic stroke within 3 months
  • Active bleeding or diathesis
  • Recent intracranial or spinal surgery
  • Recent lumbar puncture
  • Major trauma, surgery, or head injury within 3 weeks
  • Known malignant intracranial neoplasm
  • Suspected aortic dissection
• Relative contraindications:
  • Refractory HTN
  • History of chronic, severe, and poorly controlled HTN
  • Recent extracranial or internal bleeding
  • Recent major surgery
  • Recent invasive procedure
  • Ischemic stroke > 3 months prior
  • Current anticoagulation therapy
  • Traumatic cardiopulmonary resuscitation
  • Pericarditis or pericardial fluid
  • Diabetic retinopathy
  • Pregnancy
  • Noncompressible vascular puncture site
  • Dementia
  • Age > 75 years old, low body weight, female, black race
  • Active peptic ulcer, advanced hepatic disease, infective endocarditis

Submassive PE

• Defined as acute PE without systemic hypotension but with either RV dysfunction or myocardial necrosis
• RV dysfunction:
  • RV dilation or RV systolic dysfunction on echocardiography
  • Brain natriuretic peptide (BNP) > 90 pg/mL
  • N-terminal pro-BNP > 500 pg/mL
  • ECG changes
• Myocardial necrosis:
  • Troponin I > 0.4 ng/mL or troponin T > 0.1 ng/mL

Low-Risk PE

• Defined as acute PE without clinical markers of adverse prognosis that define massive or submassive PE

Risk Factors

• In surgical inpatients:
  • Pregnancy or postpartum
  • Recent sepsis
  • Malignancy
  • Prior VTE
  • Central venous access
• In hospitalized patients:
  • Prior VTE
  • Thrombophilia
  • Surgery
  • Cancer
  • Pregnancy
  • Immobilization
  • Trauma
  • Central venous access
• Medical illnesses:
  • Cancer
  • Prior VTE
  • Inflammatory disease
  • Infections
  • Autoimmune disorders (IBD, SLE, and RA)
• Medications:
  • Hormonal contraceptives
  • Hormonal replacement therapy (HRT)
  • Antipsychotics
  • Fibrates