Although pulmonary embolism (PE) occasionally presents with syncope, patients with syncope are infrequently assessed for PE. This prospective study from Italy studied 560 elderly adults (mean age, 76) who were hospitalized for syncope. Those excluded from the study included patients taking anticoagulants.
Each hospitalized patient underwent D-dimer testing and Wells score calculation as well as a standard syncope work-up. Those patients with a positive D-dimer OR a high pretest probability based on the Wells score underwent a CT pulmonary angiogram or a ventilation-perfusion lung scan. Forty one percent of patients had either an elevated D-dimer or a high-probability Wells scores. Ninety seven of these patients (17% of the study population) had a PE. PE was diagnosed in 25% of patients with unexplained syncope but also in 13% of patients with other potential explanations. A high thrombotic burden was not universal in patients with PE and syncope. One third of patients with a PE had a subsegmental PE, which was not likely to be the cause of syncope. This study demonstrated that 1 in 7 of these elderly patients hospitalized for syncope had a pulmonary embolus (PE); although many of these pulmonary emboli were unlikely to be the cause of syncope.