Evidence-based risk stratification of patients with acute pulmonary embolism: communication from the ISTH SSC Subcommittee on Predictive and Diagnostic Variables in Thrombotic Disease

Background: Acute pulmonary embolism (PE) includes clinical presentations with a wide spectrum of severity, making risk stratification essential to guide the decision-making process in daily practice. However, international guidelines differ in their definition of risk classes and consequent treatment recommendations. Objectives: To summarize high-quality evidence supporting 4 key management decisions in acute PE: hospitalization, intensive care unit admission, reperfusion therapy, and discharge. Methods: A multidisciplinary International Society on Thrombosis and Haemostasis task force, composed of international experts, conducted a literature review of randomized controlled trials and prospective management studies reporting hard clinical outcomes and assessed as having a low risk of bias, focusing on any of the 4 management decisions detailed above. Results: Available evidence supports the use of either the Hestia criteria or the (simplified) PE Severity Index, combined with clinical judgment, to select PE patients for outpatient treatment. In contrast, no PE-specific evidence exists to guide intensive care unit admission. Reperfusion therapy in hemodynamically unstable patients is supported by 1 small randomized trial, while currently available high-quality evidence does not support routine reperfusion therapy in hemodynamically stable patients; therefore, hemodynamic instability remains the only established indication for reperfusion therapy to date. The decision to discharge a PE patient may be supported by the use of the (simplified) PE Severity Index, combined with clinical assessment of stability. Conclusion: Overall, substantial evidence gaps persist, underscoring the need for further research to inform clinical practice and future guidelines.