Massive pulmonary embolism usually requires being treated immediately to avoid loss of life. However, in patients with Submassive PE that is not characterized by hemodynamic instability, there is quite a huge debate regarding what treatment options to use. This article will review the existing risk assessment research on the topic. It will also discuss why it is imperative to have it treated.
Thrombolysis is the therapy used in dealing with massive pulmonary embolism. However, there is a bit of controversy on the use of this therapy to treat Submassive PE. However, there are many other types of PE treatment that can be used, including EKOS catheter treatment. Patients with Submassive PE are at an intermediate level between massive and low-risk PE. In general, patients with massive PE will be given the treatment immediately it is recognized. Over 600,000 suffer from a level of PE in the US annually. Of this, about 50,000 to 200,000 will die from it. Let us discuss the topic of PE and the different levels.
The Three Levels of Risk
PE can be classified as low risk, which affects about 70% of patients, massive, which affects about 5% of patients, and Submassive, which affects around 25% of all patients.
This type of PE is characterized by the absence of dysfunction in the right ventricle. There is also no observable myocardial necrosis. In this type of PE, the death rate is about 1%. The management of this condition is using parenteral anticoagulation and the initiation of long-term anticoagulation therapy.
This condition is characterized by high hemodynamic instability such as sustained hypertension.
The main symptoms are:
- Systolic blood pressure <90 mm hg for over 15 minutes
- absolute fall in systolic blood pressure of ≥ 40 mm hg
- the patient requires inotropic support
- cardiac arrest
- heart rate of <40 beats a minute (bradycardia)
This condition has a death rate of over 30% in patients that have shock. It can be as high as 70% in those that suffer cardiac arrest. It is thus agreed upon widely that for inpatients with this condition, aggressive treatment is needed. Inpatients that have a low risk of bleeding, thrombolytic therapy is recommended.
This level of PE is characterized by dysfunction in the right ventricle but with normal blood pressure. The American College of Chest Physicians (ACCP) recommends that thrombolytic therapy is considered when the patient has a low risk of bleeding but at risk of developing hypotension.
Diagnosing Submissive PE
In managing PE, it is important to recognize when the patient is at high risk of deterioration. Some of the symptoms of a pulmonary embolism are analyzed here:
1. Blood Pressure
Systolic blood pressure helps to show whether the patient has hypotension, which helps to classify the risk level of the PE. When the patient has a decrease in systolic BP of 40 mm Hg or more, there is a high chance of the worst outcomes.
2. Dysfunction of the Right Ventricle
The occlusion of the pulmonary arteries can cause right ventricular dysfunction.
3. Echocardiographic Analysis
Signs of dysfunction can be deduced by checking the following:
- Dilation of the Right Ventricle
- Free wall hypokinesis of the right ventricle with apical sparing
- New onset akinesis or hypokinesis
- An increase in the systolic pressure of the right ventricle
- Paradoxical movement of the interventricular septum
- Tricuspid regurgitation jet velocity > 2.8 m/s in the pulmonary artery
4. PESI Score
The European Society of Cardiology developed the score in 2014.
The risk is assessed according to a patients score on the PE Severity index (PESI). According to the scale, patients can be in classes ranging from I to V. Those in classes III or IV are considered to be at intermediate risk. The PESI scoring system is based on a wide range of symptoms that include heart failure history, cancer history, sex, age, history of lung disease, respiratory rate, altered mental status, and temperature.
The main option for PE is aggressive thrombolysis therapy. At some experienced centers, use of embolectomy for patients exhibiting hemodynamic stability with major RV dysfunction is common. They cite the high bleeding risk of systemic thrombolysis as the main reason.
This will entail taking medication that reduces the risk of blood clot formation. It is a recommended treatment for all patients no matter the risk level.
Catheter Directed Therapy
The other common option for PE treatment is the use of EKOS catheter to deal with PE. This pharmacomechanical thrombolytic therapy will entail the use of a catheter system that utilizes a high frequency, low-powered ultrasound. The ultrasound cannot dissolve a thrombus, but it aids fibrinolysis. It does this by causing the disaggregation of uncrosslinked fibrin fibers. It thus leads to better permeability for the drug used in thrombolytic treatment. The pressure waves also aid in the penetration of the thrombolytic drug.
Why Submassive PE should be treated
In patients that have been treated for Submassive PE, the following has been observed:
- In treated patients, there is a lower risk of combined adverse events with studies showing only 5.4% percent suffer adverse events compared to 45.7% of those that were untreated.
- In treatment with the use of tenecteplase, 37% of patients on placebos had adverse outcomes compared to only 15% of those on tenecteplase.
- Studies have found that those undergoing thrombolytic therapy see clots dissolve fast, with about 35% reduction in the total perfusion defect within 24 hours.
- Patients undergoing treatment die less often and experience reduced hemodynamic instability
- Patients undergoing treatment resolve any physical symptoms much faster
- The MOPPET trial showed that patients undergoing treatment have less long-term pulmonary hypertension
- A study showed that the patients undergoing treatment have a decreased recurrence of PE90