Role of helical CT pulmonary angiography in risk stratification for patients with pulmonary embolism

Initial risk stratification for patients with pulmonary embolism (PE) is based on clinical assessment and rapidly separates those who are hemodynamically stable from those who are unstable. Unstable patients have a high short-term mortality and are candidates for thrombolysis. A subset of stable patients will have right ventricular dysfunction placing them at increased risk for PE-related mortality. Further risk stratification that can reliably distinguish this subset of patients from those who will have an uneventful course may justify expanding the indication for thrombolysis to include this high-risk group. Current risk stratification methods focus on comorbid conditions, ECG, blood gas analysis, serum biomarkers, and echocardiography. Computed tomography (CT) pulmonary angiography (CTPA) is principally used for the diagnosis of PE, but because CTPA is obtained very early in the evaluation of patients with suspected PE, there is interest in its potential role as a risk stratification tool. CT findings of right ventricular dysfunction and CT scores quantifying the degree of pulmonary arterial obstruction have been studied as possible risk stratification parameters. This study briefly reviews clinical risk stratification schemes before undertaking a more in-depth review of the research regarding the potential role of CTPA as a risk stratification tool for patients with PE.