When to repeat Computed Tomography Angiography (CTA) in a patient with massive pulmonary embolism (PE) currently on anticoagulants?

From the Guidelines

For patients with massive pulmonary embolism on anticoagulation therapy, a follow-up CT angiography (CTA) scan is typically recommended after 3-6 months of treatment, as this timing allows for assessment of clot resolution and evaluation for chronic thromboembolic pulmonary hypertension (CTEPH) 1. The decision to rescan should be individualized based on the patient's clinical status and response to anticoagulation.

• Key factors to consider when deciding on the timing of a follow-up CTA scan include the patient's symptoms, hemodynamic stability, and the presence of any new or worsening symptoms such as increased shortness of breath, chest pain, or hemodynamic instability.
• The European Society of Cardiology guidelines suggest that the optimal time point for transitioning from parenteral to oral anticoagulation has not been determined by existing evidence, but should instead be based on clinical judgement 1.
• For patients receiving standard anticoagulation therapy, the 3-6 month timeframe allows sufficient time for clot resolution while providing information to guide treatment duration decisions.
• If the scan shows complete resolution, anticoagulation may be discontinued after completing the planned treatment course, whereas if residual thrombi are present, extended anticoagulation may be warranted.
• The rationale for this timing is that most clot resolution occurs within the first few months of treatment, and earlier scanning may not provide meaningful information about long-term outcomes or the need for extended therapy. Some patients may require earlier rescanning, such as those with new or worsening symptoms, and the decision to rescan should be made on a case-by-case basis, taking into account the individual patient's clinical status and response to anticoagulation 1.

From the Research

Rescan with CTA in Massive Pulmonary Embolism

• The decision to rescan with computed tomography angiography (CTA) in a patient with massive pulmonary embolism (PE) now on anticoagulants depends on several factors, including the patient's clinical stability and the presence of any new or worsening symptoms 2, 3.
• In patients with massive PE, the primary goal is to stabilize the patient and prevent further clot formation, rather than to immediately rescan with CTA 3, 4.
• However, if the patient's condition worsens or if there are concerns about the effectiveness of anticoagulation therapy, a repeat CTA scan may be necessary to assess the extent of the clot and guide further treatment 5, 6.
• The use of CTA scans in patients with massive PE is generally reserved for those who are clinically stable and can tolerate the scan, as well as those who have a high risk of complications or recurrence 2, 3.

Timing of Rescan

• The optimal timing of a rescan with CTA in patients with massive PE is not well established, but it is generally recommended to wait until the patient is clinically stable and any acute symptoms have resolved 3, 4.
• In some cases, a repeat CTA scan may be necessary within 24-48 hours of the initial scan to assess the effectiveness of treatment and guide further management 5, 6.
• However, the decision to rescan should be individualized based on the patient's clinical condition and the presence of any new or worsening symptoms 2, 3.

Considerations for Rescan

• Before rescanning with CTA, it is essential to consider the patient's renal function, as contrast agents used in CTA scans can be nephrotoxic 2, 3.
• Additionally, patients with a history of allergy to contrast agents or those with severe kidney disease may require alternative imaging modalities, such as magnetic resonance angiography (MRA) or ventilation-perfusion scanning 4, 5.
• The use of CTA scans in patients with massive PE should be guided by a multidisciplinary team, including radiologists, cardiologists, and pulmonologists, to ensure that the benefits of the scan outweigh the risks 6.