A pulmonary embolism (PE) is a serious medical event caused by a blockage in one of the pulmonary arteries in the lungs. This blockage is usually a blood clot that has traveled from a deep vein in the leg, a condition known as deep vein thrombosis. While PE is life-threatening, survival is overwhelmingly likely if diagnosis and treatment are initiated quickly. If left untreated, the mortality rate for an acute PE can be as high as 30%, but timely intervention reduces this rate significantly to approximately 8%.
Factors Determining Survival and Prognosis
Survival from a pulmonary embolism depends on the severity of the blockage and the patient’s existing health profile. Medical professionals classify PE severity based on the clot’s impact on the heart to determine prognosis. Severity is categorized into three risk groups: low-risk (non-massive), intermediate-risk (submassive), and high-risk (massive) pulmonary embolism.
High-Risk PE
A high-risk, or massive, PE is characterized by hemodynamic instability, meaning the patient has dangerously low blood pressure or is in shock. This indicates the blockage is large enough to cause acute right ventricular failure, as the heart struggles to pump blood past the obstruction. High-risk PE carries the highest short-term mortality rate, reaching 58% without aggressive intervention.
Intermediate and Low-Risk PE
Patients with an intermediate-risk PE are hemodynamically stable but show signs of strain on the right side of the heart, detectable through imaging or blood markers. The 90-day mortality rate for this group is around 15%, requiring close monitoring and possible advanced therapy. A low-risk PE involves a smaller clot that does not cause heart strain or instability, leading to a better prognosis with a 90-day mortality rate less than 2%. Advanced age, chronic cardiopulmonary diseases, and underlying conditions like cancer significantly worsen the outcome by reducing the body’s capacity to cope with the sudden strain.
Recognizing the Signs and Initial Medical Response
Recognizing the symptoms of a PE and acting immediately is the first step toward survival. Common symptoms include the sudden onset of shortness of breath, a sharp chest pain that worsens with deep breathing, and a rapid heart rate (tachycardia). Less common signs include coughing, sometimes with blood, or lightheadedness and fainting. These symptoms should prompt an immediate call for emergency medical services.
The initial medical response focuses on rapid diagnosis and stabilization once a patient arrives at the hospital. Stabilization begins with administering supplemental oxygen to counteract low blood oxygen levels and closely monitoring the patient’s heart rate and blood pressure. Diagnosis is often achieved through a computed tomography pulmonary angiography (CTPA), which uses an injected dye to visualize blood flow in the pulmonary arteries. A D-dimer blood test, which measures a protein fragment from clot breakdown, is also used to help rule out the condition in low-risk patients. If clinical suspicion is high, treatment with blood thinners may be started before imaging results are confirmed to stabilize the patient and prevent the clot from growing.
Treatment Options to Resolve the Clot
Survival is achieved by quickly stopping the clot from growing and, in severe cases, actively dissolving or removing it. Anticoagulation is the standard treatment for the majority of PE cases. These medicines, often called blood thinners, include injectable heparin followed by oral medications such as warfarin or newer direct oral anticoagulants (DOACs). Anticoagulants prevent new clots from forming and stop the existing one from enlarging, allowing the body’s natural processes to gradually break down the blockage.
For patients with a high-risk, massive PE and hemodynamic instability, a more aggressive approach is necessary to quickly restore blood flow. Thrombolysis involves administering potent “clot-busting” drugs like tissue plasminogen activator (TPA) intravenously to rapidly dissolve the clot. This therapy is reserved for the most severe cases because it carries a significant risk of severe bleeding, including internal hemorrhage.
When thrombolysis is contraindicated due to high bleeding risk, or when the patient is critically unstable, interventional or surgical procedures are necessary. Catheter-directed treatments involve threading a thin tube to the pulmonary artery, where the clot can be broken up, sometimes using a low dose of thrombolytic drug delivered directly to the site. In rare, life-threatening instances, a surgical pulmonary embolectomy is performed to physically remove the clot. If anticoagulation is impossible, an inferior vena cava (IVC) filter may be temporarily placed to catch clots before they reach the lungs.
Long-Term Recovery and Preventing Recurrence
Long-Term Anticoagulation
Recovery centers on preventing recurrence and extends well beyond the initial hospital stay. Patients typically experience fatigue and reduced exercise tolerance for weeks or months, which gradually improves with activity. Long-term anticoagulation therapy is prescribed for at least three to six months. If the PE was unprovoked—meaning there was no clear temporary risk factor—blood thinner use may be extended indefinitely to minimize recurrence risk.
Monitoring and Complications
Regular follow-up appointments monitor for recurrence and check for side effects. Lifestyle adjustments are advised, including remaining active, maintaining a healthy weight, and discussing risk factors like long-distance travel or estrogen-containing contraceptives with a healthcare provider. A small percentage of patients may develop chronic thromboembolic pulmonary hypertension (CTEPH), where the clot does not fully dissolve, requiring specialized treatment.