Saddle pulmonary embolism and knee jerk alarm

Here's an interesting paper linked at Hospital Medicine Virtual Journal Club. From the abstract:

Saddle pulmonary embolism (PE) is defined as the presence of a visible thromboembolus that straddles the bifurcation of the main pulmonary artery. It occurs in about 2-5% of all PE cases [1]. Visualization of saddle PE on a Computed Tomography (CT) scan causes alarm among physicians due to the possibility of a large clot burden and impending hemodynamic collapse. However, recent studies have challenged this reflexive assumption, along with the assumption that clot burden predicts outcomes [2].

Not that saddle PE isn't serious, but all too often the appearance of a “saddle” trumps further thinking about parameters that mean more such as the shock index, biomarkers and echocardiographic assessment of RV function.