What is the diagnosis, signs, symptoms, and treatment of pulmonary embolism (PE) in the Cardiovascular Intensive Care Unit (CVICU)?

Pulmonary Embolism in the CVICU: Diagnosis, Signs, Symptoms, and Management

Pulmonary embolism (PE) in the Cardiovascular Intensive Care Unit (CVICU) is a life-threatening condition requiring immediate risk stratification, diagnosis, and treatment based on hemodynamic stability to reduce mortality and morbidity.

Definition and Pathophysiology

• PE occurs when a blood clot (thrombus) travels through the venous system and occludes a pulmonary artery, typically originating from deep vein thrombosis (DVT) in the lower limbs 1, 2
• In the CVICU, PE may present as a primary admission diagnosis or develop as a complication in patients admitted for other cardiovascular conditions 3, 4

Clinical Presentation

• Symptoms and signs of PE are highly non-specific and may include chest pain, dyspnoea, syncope, haemoptysis, cardiac arrest, or a combination of these 1
• PE can present atypically, mimicking other cardiovascular conditions such as acute pericarditis, making diagnosis challenging 5
• The most frequent ECG signs are limited to sinus tachycardia or atrial fibrillation 1
• In more severe cases, ECG may show signs of right ventricular overload: inversion of T waves in leads V1–V4, QR pattern in V1, S1Q3 pattern, and incomplete or complete right bundle-branch block 1

Risk Stratification

• Initial risk stratification is essential and should be based on hemodynamic status to distinguish between high-risk and non-high-risk PE 1, 6
• PE is classified into three categories 6:
  • High-risk (massive): Patients with shock or hypotension (systolic BP <90 mmHg or a drop of ≥40 mmHg for >15 min) 1
  • Intermediate-risk (submassive): Hemodynamically stable with evidence of right ventricular dysfunction and/or myocardial injury 1, 6
  • Low-risk: Hemodynamically stable without evidence of RV dysfunction or myocardial injury 1, 6

Diagnostic Approach

• The use of clinical prediction scores to determine the likelihood of PE is highly recommended 1
• Definitive diagnosis requires pulmonary perfusion imaging, typically CT pulmonary angiography 1, 2
• In hemodynamically unstable patients where immediate CT is not feasible:
  • Bedside transthoracic echocardiography (TTE) should be performed immediately 7
  • Unequivocal signs of RV overload or dysfunction on TTE may justify emergency reperfusion treatment without further testing 1, 7
  • TTE can also help identify other causes of shock (tamponade, acute valvular dysfunction, LV dysfunction, aortic dissection) 1, 7
• Compression ultrasonography (CUS) can detect DVT in 30-50% of patients with PE 1
  • Finding a proximal DVT in patients suspected of having PE is sufficient to warrant anticoagulant treatment 1
  • In hemodynamically unstable patients, combining venous ultrasound with cardiac ultrasound increases diagnostic specificity 1

Key Echocardiographic Findings in PE

• RV dilatation (RV/LV diameter ratio ≥1.0) 7
• RV hypokinesia 7
• Abnormal motion of the interventricular septum 7
• Tricuspid regurgitation with elevated peak systolic gradient 7
• Decreased tricuspid annular plane systolic excursion (TAPSE <16 mm) 7
• Right heart thrombi (detected in up to 4% of unselected PE patients and up to 18% in ICU settings) 1, 7

Treatment Approach

High-Risk PE (with shock/hypotension)

• Immediate systemic thrombolytic therapy is recommended for patients with cardiogenic shock and/or persistent hypotension 6, 2
• If thrombolysis is contraindicated or has failed, consider surgical embolectomy or catheter-directed treatment 6
• Supportive measures include:
  • Intravenous access, continuous ECG, and oxygen saturation monitoring 1
  • Vascular expansion and inotropes as needed 1
  • Oxygen supplementation for hypoxemia 1

Intermediate-Risk PE

• Anticoagulation is the primary treatment 6
• Consider thrombolysis in selected patients who show clinical deterioration (new hemodynamic instability, worsening respiratory failure, severe RV dysfunction) 6
• Close monitoring in the CVICU is essential 7, 3

Low-Risk PE

• Anticoagulation is the mainstay of treatment 6, 2

Anticoagulation Therapy

• Anticoagulation should be initiated immediately while completing diagnostic workup, unless absolutely contraindicated 6
• For hemodynamically stable patients, direct oral anticoagulants (DOACs) like apixaban, rivaroxaban, edoxaban, or dabigatran are preferred over vitamin K antagonists 6, 2
• Heparin is indicated for prophylaxis and treatment of venous thrombosis and PE 8
• Anticoagulation should be continued for at least 3 months for all patients with PE 6

Special Considerations in CVICU

• PE patients in the CVICU often have comorbidities that complicate management 3, 4
• Mechanical ventilation and immobilization increase the risk of thromboembolic disease in CVICU patients 4
• In patients with cancer, edoxaban or rivaroxaban should be considered as alternatives to low molecular weight heparin, except in those with gastrointestinal cancer 6
• For patients with antiphospholipid syndrome, indefinite treatment with vitamin K antagonists is recommended 6

Monitoring and Follow-up

• Continuous monitoring of vital signs, oxygen saturation, and hemodynamic parameters is essential in the CVICU 1, 3
• Serial echocardiographic assessments may be valuable to monitor RV function and response to treatment 7
• Extended anticoagulation should be considered for patients without identifiable risk factors for the initial PE event 6