What Is the Survival Rate of a Saddle Pulmonary Embolism?

A meta-analysis pooling data from 17 observational studies found an overall mortality rate of roughly 8 percent for saddle pulmonary embolism, meaning about 92 percent of patients diagnosed with one survive.¹ That number, though, masks enormous variation depending on whether the patient’s heart is holding up under the strain and how quickly treatment begins. The location of the clot at the fork of the main pulmonary artery sounds catastrophic, and it can be, but survival hinges less on where the clot sits than on what it does to blood flow and the right side of the heart.

What a Saddle Pulmonary Embolism Actually Is

A saddle pulmonary embolism is a blood clot that lodges at the bifurcation of the main pulmonary artery, the point where that vessel splits into its left and right branches. The name comes from the clot’s shape on imaging: it straddles the fork like a saddle. Because of its position, a saddle PE partially blocks blood flow into both lungs at once, which is why clinicians treat the diagnosis as a potential emergency.² Saddle PEs account for about 10 percent of all pulmonary embolism cases.¹

Why Clot Location Alone Does Not Determine Survival

You might assume that a clot sitting at the main crossroads of the pulmonary circulation would always be more dangerous than one lodged farther out in a smaller branch. The data do not clearly bear that out. One study of nearly 300 patients with non-high-risk pulmonary embolism found that the one-month mortality rate for saddle PE was 18.5 percent compared with 11.9 percent for non-saddle PE, but that difference was not statistically significant.³ A post hoc analysis of a randomized trial in intermediate-high-risk PE patients found that having a saddle embolus was not associated with worse short-term outcomes compared with having a non-saddle embolus.⁴

This is one of the more counterintuitive findings in the field: a large, dramatic-looking clot at the bifurcation does not automatically translate into a worse prognosis than a smaller clot that lands in a more distal branch but happens to cause more hemodynamic damage. The reason is that what kills people with PE is not the clot itself but the downstream cardiovascular collapse it can trigger. A saddle PE that only partially occludes the fork may leave enough flow to keep the right ventricle functioning, while a smaller clot wedged deep in one lung’s vessels can sometimes provoke a disproportionate hemodynamic crisis in a patient with limited cardiac reserve.

How a Saddle PE Can Kill

The mechanism is a chain reaction that starts with the right ventricle. The right ventricle is built for a low-pressure job: pumping blood through the normally compliant lung circulation. When a large clot blocks the pulmonary arteries, the resistance the right ventricle has to pump against spikes dramatically.⁵ The clot itself raises resistance, and oxygen deprivation triggers spasm in surrounding pulmonary vessels, making the blockage functionally worse than the physical size of the clot would suggest.⁶

Under this sudden pressure overload, the right ventricle stretches and begins to fail. As the right side’s output drops, less blood reaches the left side of the heart, and the left ventricle’s filling drops with it. To make matters worse, the ballooning right ventricle pushes the wall between the two chambers (the septum) toward the left, physically crowding the left ventricle and reducing its ability to fill even further. The combined effect is a steep fall in the blood pressure and cardiac output that sustains the rest of the body’s organs. When this cascade spirals fast enough, it becomes fatal.

What Actually Predicts Whether You Survive

Because clot location is a poor standalone predictor, clinicians rely on markers of how the heart is responding. Two measurements stand out in the research. The first is the ratio of right ventricle to left ventricle size on a CT scan. A ratio greater than 1.0, meaning the right ventricle has dilated larger than the left, predicts adverse outcomes. Conversely, a ratio below 1.0 is reassuring.⁷ The second is troponin, a protein released by damaged heart muscle. In patients with saddle PE, both the right-ventricle-to-left-ventricle ratio and troponin levels were independently associated with death within one month.⁸

In practical terms, a saddle PE with stable blood pressure, normal troponin, and a right-ventricle-to-left-ventricle ratio under 1.0 carries a much better prognosis than a saddle PE with elevated troponin and a dilated right ventricle. The same imaging that finds the clot at the bifurcation already captures the heart’s dimensions, so clinicians can risk-stratify a patient within minutes of the diagnostic scan.

One study of 120 saddle PE patients reported an in-hospital mortality of about 9 percent, with only around 4 percent presenting with vital signs consistent with massive PE.² That means most saddle PE patients were hemodynamically stable at the time of diagnosis. Another 8.6 percent of the cohort died within six months of discharge, though, suggesting that the risk does not end when the patient leaves the hospital.

How Treatment Choices Shape Survival

Treatment for saddle PE falls along a spectrum that ranges from anticoagulation alone to open-chest surgical removal of the clot, with several options in between. The choice depends almost entirely on the patient’s hemodynamic status and the degree of right heart strain.

Anticoagulation

For hemodynamically stable patients with minimal right heart dysfunction, blood thinners alone remain the standard first-line treatment. Anticoagulation does not dissolve the existing clot; it prevents new clot formation and lets the body’s own fibrinolytic system break down the blockage over time. Most saddle PE patients fall into this category and are treated with anticoagulants, sometimes alongside careful monitoring in an ICU.

Catheter-Based Interventions

When right heart strain is present but the patient is not in full cardiovascular collapse, catheter-directed therapies have become increasingly common. These involve threading a catheter through the veins into the pulmonary arteries and either delivering clot-dissolving medication directly at the clot, mechanically fragmenting it, or physically suctioning it out. A study of 12 saddle PE patients who underwent catheter-guided thrombolysis and fragmentation showed significant hemodynamic improvement in all patients.⁹ Aspiration thrombectomy, a technique that uses suction to pull clot material out, has also shown favorable results. The large FLASH registry of aspiration thrombectomy enrolled over 700 patients and reported an all-cause mortality rate below 1 percent, with low bleeding rates.¹⁰

Surgical Embolectomy

In the most critical scenario, when a patient with a saddle PE goes into shock, surgical embolectomy (open-heart surgery to physically remove the clot) can be lifesaving. A large database study of saddle PE patients with hemodynamic shock found that embolectomy was associated with substantially lower odds of death compared with standard treatment. Catheter-directed therapies also showed reduced mortality in these patients. Interestingly, systemic thrombolytics, the intravenous clot-dissolving drugs that are sometimes given in emergencies, were not associated with a survival benefit in this population.¹¹ The number needed to treat was about 5, meaning that for roughly every 5 patients in shock who underwent embolectomy or catheter-directed therapy instead of standard treatment, one additional life was saved.

ECMO as a Bridge

Extracorporeal membrane oxygenation, which takes over the work of the heart and lungs using an external circuit, is sometimes deployed when a patient is too unstable for any other intervention. The evidence here is mixed and sobering. One case series of 10 patients with massive or submassive PE requiring ECMO (70 percent of whom had a saddle PE) found that all patients survived to ECMO removal, but only 60 percent survived to hospital discharge.¹² A larger study reported 90-day survival of just 47 percent for patients with massive PE rescued by ECMO.¹³ In the database study already mentioned, ECMO use was actually associated with increased odds of death, probably reflecting the fact that it is reserved for the sickest patients and carries significant complications of its own.¹¹

Major Adverse Events Beyond Death

Survival alone does not capture the full picture. Saddle PE patients who do not die can still experience serious complications. In the study of non-high-risk PE patients, those with a saddle embolus had significantly more major adverse events than those with non-saddle PE (about 59 percent versus 26 percent), and they were far more likely to need thrombolytic therapy (about 30 percent versus 8 percent).³ The meta-analysis similarly reported a late decompensation rate of about 9.5 percent and a PE recurrence rate of roughly 4.5 percent among saddle PE patients.¹ So even when survival statistics look encouraging, the road to full recovery is often complicated by setbacks.

The Speed Problem

A recurring theme in the PE literature is that faster diagnosis and treatment improve outcomes. A study looking specifically at how long it takes to reach diagnostic certainty in saddle PE patients found that roughly a quarter of patients who had PE present on admission waited more than 6 hours for a confirmed diagnosis, and about 16 percent experienced treatment delays beyond 6 hours.¹⁴ These delays matter. A study of multidisciplinary pulmonary embolism response teams (PERTs) found that the risk of death dropped by about 5 percent for each hour earlier that the diagnosis was made.¹⁵

Why does diagnosis take so long when the clot is large enough to see clearly on a CT? Part of the answer is that saddle PE does not always present with the classic sudden collapse. Many patients arrive with vague symptoms like shortness of breath, chest discomfort, or lightheadedness that overlap with dozens of other conditions. Without high clinical suspicion and rapid imaging, hours can slip by.

How Response Teams Are Changing Outcomes

Pulmonary embolism response teams, or PERTs, bring together specialists from cardiology, pulmonology, interventional radiology, vascular surgery, and cardiac surgery to rapidly evaluate and treat complex PE cases. These teams were specifically designed for situations like saddle PE, where the right treatment approach is not always obvious and the decision needs to be made fast. One institution reported that implementing a PERT was associated with a reduction in 6-month mortality from 24 percent to 14 percent for high-risk PE patients.¹⁵ Saddle and main pulmonary artery embolisms were among the strongest triggers for PERT activation, and patients evaluated by a PERT were more likely to undergo catheter-directed interventions and less likely to receive unnecessary inferior vena cava filters.¹⁶ PERT consultation also halved the median number of ICU days.

The PERT model has spread rapidly across major hospitals. If you or someone close to you is diagnosed with a saddle PE, asking whether the hospital has a pulmonary embolism response team is a reasonable question. Not every facility has one, and transfer to a center with more advanced PE capabilities can sometimes make a meaningful difference in outcomes.

Cancer and Saddle PE

Cancer patients deserve separate mention because they face a double disadvantage. Active malignancy increases the risk of clotting in the first place, and it also raises the mortality when PE occurs. In a study of over 10,600 cancer patients admitted with acute PE, about 4.5 percent had a saddle PE, and in-hospital mortality across the cohort was about 6 percent. After adjusting for age and sex, saddle PE in cancer patients was associated with roughly 50 percent higher odds of dying in the hospital compared with non-saddle PE.¹⁷ The challenge in these patients is compounded by the fact that many have low platelet counts or other clotting abnormalities that make standard anticoagulation or thrombolysis riskier.¹⁸

Recovery and Quality of Life After Treatment

For those who survive the acute event, the question shifts to how fully they can recover. Post-PE syndrome, which includes persistent shortness of breath, exercise limitation, and reduced quality of life, is common after any significant PE and is an active area of research. Data from a registry studying patients who underwent vacuum-based clot removal showed that functional capacity and quality of life improved sharply within the first 90 days and continued to improve over the following year. Walking distance increased, breathlessness at rest resolved for most patients, and quality-of-life scores reflected less daily-life impact from PE over time. Heart function classification generally returned to pre-PE levels by 90 days.¹⁹

That said, these results come from patients who received advanced catheter-based treatment, often at specialized centers. Recovery for the broader population of saddle PE survivors, many of whom are treated with anticoagulation alone, is less well studied. Persistent right heart dysfunction, chronic thromboembolic pulmonary hypertension (a condition in which old clot material scars the pulmonary arteries and permanently raises pulmonary pressure), and deconditioning from prolonged hospitalization are all real possibilities. Follow-up imaging and cardiopulmonary testing in the months after a saddle PE help clinicians catch these problems early.

Why the Numbers Are Hard to Pin Down

If you search for a single definitive survival rate for saddle PE, you will find numbers that range from around 80 percent to over 95 percent depending on the study, the patient population, and the time frame. Several factors explain the spread. First, studies define their populations differently. Some include only hemodynamically stable patients, which selects for a less sick group and inflates survival estimates. Others include patients in cardiogenic shock, which drags survival down. Second, saddle PE is identified by imaging, and not every patient with chest symptoms gets a CT scan. There is an inherent selection bias: the patients who are imaged and diagnosed may not represent all patients who have saddle PEs. Third, treatment has evolved rapidly. Studies from 10 or 15 years ago, when catheter-based interventions were uncommon and PERTs did not exist, may report worse outcomes than what you would expect today at a well-equipped center.

The meta-analytic estimate of about 8 percent mortality is probably the most balanced single number currently available, drawing on multiple institutions and study designs. But your own risk, if you are a patient reading this, would be higher or lower depending on whether your heart is tolerating the clot, how quickly you were diagnosed, what comorbidities you have, and what treatments are available where you are being treated. A hemodynamically stable patient without cancer or major cardiac compromise who receives timely treatment at a hospital with catheter-based capabilities and a response team has a very different outlook from an elderly cancer patient who presents in shock.

1
PubMed. Optimal management, prevalence, and clinical behavior of saddle pulmonary embolism: A systematic review and meta-analysis
2
PubMed Central. Saddle Pulmonary Embolism: Demographics, Clinical Presentation, and Outcomes
3
PubMed Central. The impact of saddle embolism on the major adverse event rate of patients with non-high-risk pulmonary embolism
4
Research and Practice in Thrombosis and Haemostasis. Saddle embolus and short-term outcomes in patients with intermediate-high-risk pulmonary embolism: a post hoc analysis of a randomized trial
5
PubMed Central. Pathophysiology of right ventricular failure in acute pulmonary embolism and chronic thromboembolic pulmonary hypertension: a pictorial essay for the interventional radiologist
6
PubMed Central. Saddle pulmonary embolism with normal right ventricular function: a treatment enigma
7
PubMed Central. The role of computed tomography in the diagnosis of acute and chronic pulmonary embolism
8
PubMed. Saddle Pulmonary Embolism: Laboratory and Computed Tomographic Pulmonary Angiographic Findings to Predict Short-term Mortality
9
SpringerLink / Intern Emerg Med. Saddle pulmonary embolism: results of a series of patients undergoing pharmaco-mechanical thrombolysis
10
PubMed Central. Saddle Pulmonary Embolus Treated With Bilateral Emergent Aspiration Pulmonary Thrombectomy
11
The Annals of Thoracic Surgery. Modern Treatment Trends and Outcomes of Pulmonary Embolism With and Without Hemodynamic Significance
12
PubMed Central. Extracorporeal membrane oxygenation for large pulmonary emboli
13
PubMed Central. Life-threatening massive pulmonary embolism rescued by venoarterial-extracorporeal membrane oxygenation
14
Biomolecules and Biomedicine. Time to diagnostic certainty for saddle pulmonary embolism in hospitalized patients
15
PubMed Central. Effect of a Multidisciplinary Pulmonary Embolism Response Team on Patient Mortality
16
PubMed. Effect of a pulmonary embolism response team on the management and outcomes of patients with acute pulmonary embolism
17
PubMed. Saddle pulmonary embolism and in-hospital mortality in patients with cancer
18
PubMed Central. Saddle pulmonary embolism in a cancer patient with thrombocytopenia: a treatment dilemma
19
European Heart Journal: Acute Cardiovascular Care. STRIKE-PE interim analysis: one-year functional outcomes and quality of life after treatment of pulmonary embolism with computer assisted vacuum thrombectomy