Surreal illustration linking fainting to pulmonary embolism, showing interconnected blood vessels forming a lung.

Syncope and Pulmonary Embolism: What You Need to Know About This Risky Combination

Theo Raines in Health & Wellness December 2025 • 4 min read.

"New research reveals the surprising link between fainting spells and dangerous blood clots, highlighting who's most at risk and how to protect yourself."

That dizzy spell, the sudden blackout—syncope, or fainting, is something most people experience at least once. Usually, it’s harmless, maybe a sign of dehydration or low blood sugar. But what if that faint was a warning sign of something far more serious, like a pulmonary embolism (PE), a life-threatening blood clot in the lungs? It sounds scary, and it is, but understanding the connection is the first step to protecting yourself and your loved ones.

Pulmonary embolism is a serious condition where blood clots block the arteries in your lungs. It can cause shortness of breath, chest pain, and even death. Syncope has long been recognized as a potential symptom of PE, but the relationship isn't always clear. Is syncope simply a sign of a more severe PE, or does it independently increase the risk? Recent research is shedding light on this complex issue, providing vital information that could save lives.

This article breaks down the latest findings, translating complex medical research into easy-to-understand language. We'll explore the link between syncope and PE, who is most at risk, and what steps you can take to stay informed and advocate for your health. It's about empowering you with knowledge so you can recognize the warning signs and seek help when it matters most.

The Syncope-PE Connection: Unpacking the Risks

Surreal illustration linking fainting to pulmonary embolism, showing interconnected blood vessels forming a lung.

A recent study published in the European Heart Journal delved into this very question. Researchers conducted a meta-analysis, pooling data from 29 studies involving nearly 22,000 patients with pulmonary embolism. Their goal was to determine if syncope was associated with worse outcomes in PE patients.

The results revealed a concerning trend: patients with PE who experienced syncope were more likely to have:

Hemodynamic Instability: This means problems with blood pressure and blood flow, indicating a more severe PE.
Right Ventricular Dysfunction: The right ventricle is a chamber of the heart that pumps blood to the lungs. PE can strain this chamber, leading to dysfunction.
Higher Risk of Early Death: Syncope was linked to an increased risk of death within the first 30 days of the PE diagnosis.

But before you panic, there's more to the story. The researchers discovered that the increased risk associated with syncope was most pronounced in patients who were already hemodynamically unstable. In other words, syncope might be a marker of a more severe PE presentation rather than an independent risk factor. This highlights the importance of assessing overall hemodynamic status in PE patients.

What Does This Mean for You? Taking Control of Your Health

The key takeaway is that syncope in the context of pulmonary embolism shouldn't be ignored. If you experience syncope along with symptoms like shortness of breath or chest pain, seek immediate medical attention. It's also crucial to inform your doctor about any history of syncope, as this information can help them assess your risk and make informed decisions about your care. While more research is always needed, understanding the potential link between syncope and PE empowers you to be a more informed and proactive advocate for your own health.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1093/eurheartj/ehy631, Alternate LINK

Title: Differential Impact Of Syncope On The Prognosis Of Patients With Acute Pulmonary Embolism: A Systematic Review And Meta-Analysis

Subject: Cardiology and Cardiovascular Medicine

Journal: European Heart Journal

Publisher: Oxford University Press (OUP)

Authors: Stefano Barco, Yvonne M Ende-Verhaar, Cecilia Becattini, David Jimenez, Mareike Lankeit, Menno V Huisman, Stavros V Konstantinides, Frederikus A Klok

Published: 2018-10-17

Everything You Need To Know

What is the connection between syncope and pulmonary embolism, and why is it important to understand?

Syncope, commonly known as fainting, can be a warning sign of pulmonary embolism (PE), a life-threatening condition involving blood clots in the lungs. While syncope is often harmless, its occurrence alongside symptoms like shortness of breath or chest pain can indicate a more severe PE. Understanding this connection is crucial for early detection and timely intervention, potentially saving lives. Recognizing syncope as a possible indicator empowers individuals to seek prompt medical attention and inform healthcare providers about their medical history, enabling informed decisions about their care.

Who is most at risk when experiencing syncope in relation to pulmonary embolism, and what factors contribute to this risk?

Individuals already experiencing hemodynamic instability, which involves issues with blood pressure and blood flow, are at a higher risk when syncope occurs in conjunction with pulmonary embolism. These patients are more likely to have a severe presentation of PE. Syncope in such cases might serve as a marker of the PE's severity rather than being an independent risk factor. Recognizing this nuanced relationship emphasizes the importance of assessing a patient’s overall hemodynamic status when PE is suspected.

What does 'hemodynamic instability' mean in the context of pulmonary embolism and syncope, and why is it a concern?

Hemodynamic instability refers to problems with blood pressure and blood flow. In the context of pulmonary embolism and syncope, it indicates a more severe case of PE. When a patient is hemodynamically unstable, it means that the pulmonary embolism is significantly affecting their heart's ability to pump blood effectively, leading to reduced oxygen delivery to vital organs. This instability can result in right ventricular dysfunction, where the right ventricle of the heart struggles to pump blood to the lungs due to the blockage caused by the PE, and ultimately increases the risk of early death.

If someone experiences syncope along with shortness of breath or chest pain, what immediate actions should they take?

If you experience syncope along with symptoms like shortness of breath or chest pain, it's crucial to seek immediate medical attention. These symptoms could indicate a pulmonary embolism (PE), a serious condition requiring prompt diagnosis and treatment. Inform your doctor about your history of syncope, as this information can help them assess your risk and make informed decisions about your care. Acting quickly can significantly improve outcomes in cases of PE.

How did the European Heart Journal study contribute to our understanding of the relationship between syncope and pulmonary embolism?

The study published in the *European Heart Journal* conducted a meta-analysis of 29 studies involving nearly 22,000 patients with pulmonary embolism. The researchers found that patients with PE who experienced syncope were more likely to have hemodynamic instability, right ventricular dysfunction, and a higher risk of early death. However, the increased risk associated with syncope was most pronounced in patients who were already hemodynamically unstable, suggesting that syncope might be a marker of a more severe PE presentation rather than an independent risk factor. This highlights the importance of assessing overall hemodynamic status in PE patients.