A new guideline from the American Heart Association and American College of Cardiology is changing how doctors diagnose and treat pulmonary embolism, a blood clot that can travel to the lungs and become life-threatening. The updated recommendations, published in the journal Circulation, provide a roadmap for clinicians to quickly assess severity and determine the most appropriate care for each patient. About 470,000 people are hospitalized for pulmonary embolism in the U.S. each year, and in 2023, it was the primary cause of nearly 8,800 deaths and a contributing factor in more than 46,000 more .

What Exactly Is Pulmonary Embolism and How Does It Develop?

Pulmonary embolism, often abbreviated as PE, typically begins as a deep vein thrombosis (DVT), a blood clot that forms in the veins of the legs or pelvis. When pieces of that clot break free, they travel through the bloodstream to the heart and then into the arteries of the lungs, where they can block blood flow. This blockage is what doctors call an embolism. The condition can develop suddenly and without warning, making it particularly dangerous .

One patient's story illustrates how quickly PE can escalate. Sherrell Clark, an Army veteran, noticed she was short of breath while climbing stairs in September 2015. She initially thought it was bronchitis or simply being out of shape. By November, she experienced chest pain severe enough to send her to the emergency room. After tests and scans revealed her left lung was blocked by blood clots, a nurse told her that waiting any longer could have been fatal .

What Are the Main Risk Factors for Developing Pulmonary Embolism?

The new guideline identifies numerous risk factors that increase the likelihood of developing PE. Understanding these can help you recognize whether you or a loved one might be at higher risk and warrant medical evaluation if symptoms appear .

• Surgery and Trauma: Major trauma or surgery, particularly orthopedic procedures like hip or knee replacement, significantly increase PE risk
• Immobility: Prolonged hospitalization or extended bed rest creates conditions where blood clots are more likely to form
• Pregnancy and Hormonal Factors: Pregnancy itself increases clot risk, as do oral contraceptives like birth control pills
• Active Cancer: People undergoing cancer treatment face elevated PE risk
• Genetic Predisposition: Some people inherit a tendency toward blood clotting disorders
• Travel and Lifestyle: Long-haul flights and obesity both contribute to PE risk
• Age and Existing Heart Disease: Risk increases with age, and people with atherosclerotic conditions like coronary artery disease face unexplained increased risk

Interestingly, sometimes doctors never identify an underlying cause. Clark's clots were initially attributed to her birth control pills, but she later learned she had additional risk factors as well .

How to Recognize Pulmonary Embolism Symptoms

Recognizing PE symptoms is critical because the condition requires immediate emergency care. The classic warning signs include sharp chest pain that worsens when you breathe, and sudden shortness of breath that may occur at rest or during activities you previously tolerated without difficulty. Other symptoms include a rapid heart rate, coughing up blood, or fainting .

The challenge is that PE symptoms can mimic other serious conditions like a heart attack, which is why any combination of these symptoms warrants calling 911 rather than driving yourself to the hospital. Ignoring PE symptoms can lead to severe disability or death. Complicating diagnosis further, some people have no symptoms at all. Doctors sometimes discover PE incidentally when patients undergo CT scans for other reasons, such as during cancer treatment .

How the New Guidelines Help Doctors Provide Better Care

The most impactful part of the new guideline is its categorization system, which helps doctors determine how aggressively to treat each patient. The guideline places patients into five main severity categories, allowing clinicians to match treatment intensity to actual risk .

"That is the newest and one of the more impactful parts of this guideline," explained Dr. Mark Creager, a professor of medicine and surgery at the Geisel School of Medicine at Dartmouth and the committee chair who led the guideline development.

Dr. Mark Creager, Professor of Medicine and Surgery at Geisel School of Medicine at Dartmouth

Category A includes patients with no symptoms whose PE was discovered by chance. Categories B and C involve patients with mild to moderate symptoms and signs of PE. Category D includes patients showing signs of shock, meaning their organs aren't receiving adequate blood flow. Category E represents cardiac arrest. This categorization system allows doctors to see exactly what treatment approach is recommended for their particular patient's situation .

"We use these categorizations to help guide us as to how aggressive we should be in managing these patients to increase their likelihood of survival," stated Dr. Creager.

Dr. Mark Creager, Professor of Medicine and Surgery at Geisel School of Medicine at Dartmouth

What Treatment Options Are Available for Pulmonary Embolism?

Nearly all PE patients require anticoagulants, medications that prevent blood clots from forming or growing. However, not all patients need hospitalization. Someone in Category A, for example, typically wouldn't require hospital admission for PE treatment. The guideline also helps doctors determine who needs advanced therapies, which can include catheter-based procedures that physically remove the clot from the lungs .

Clark spent four days in the hospital receiving powerful clot-busting medications while being closely monitored. Before discharge, she learned to inject medications herself at home. Though the injections were challenging initially, they didn't continue long-term. Today, she takes only a low dose of aspirin. The good news, according to Dr. Creager, is that PE "is a condition that is easily diagnosed and treatable in most patients" .

Dr. Creager

How Doctors Diagnose Pulmonary Embolism Efficiently

The guideline offers recommendations to streamline diagnosis. A blood test can measure D-dimer, a clotting marker that rises when blood clots are present. If that level is elevated, a CT scan can confirm whether PE is the cause. This two-step approach helps doctors avoid unnecessary imaging while ensuring they don't miss cases. Notably, less than 10% of patients evaluated for PE symptoms actually have the condition, so efficient diagnostic protocols are important .

Clark's own diagnostic experience followed this pattern. After arriving at the emergency room, her doctor asked detailed questions, ordered a D-dimer test, and then a CT scan. When the results came back, her doctor delivered the sobering news: "Ms. Clark, um, you're not going home tonight" .

The new American Heart Association and American College of Cardiology guideline represents a significant step forward in PE care. By providing clear categorization of severity and evidence-based treatment recommendations, it helps ensure that patients receive appropriate care quickly. For someone like Sherrell Clark, whose early symptoms were easy to dismiss, awareness of PE risk factors and symptoms, combined with these improved diagnostic and treatment guidelines, could mean the difference between recovery and tragedy.