Are clinical parameters and biomarkers predictive of severity of acute pulmonary emboli on CTPA?

BACKGROUND: Previous studies have shown that findings of computed tomography pulmonary angiography (CTPA) relate to outcome in pulmonary embolus (PE). These include clot burden as quantified using an obstruction index and markers of pressure overload such as right ventricle to left ventricle size ratio (RV/LV ratio). Little data exists correlating these findings with clinical presentation and biomarkers. AIM: To explore the link between clinical presentation and biomarkers with CTPA findings.
METHODS: Retrospective case note analysis of consecutive cases presenting to a large teaching hospital. An independent radiologist reviewed CTPAs and clot burden quantified using an obstruction index.
RESULTS: One hundred and seventy cases were identified and notes retrieved in 137 cases. (i) CLINICAL
PRESENTATION: correlation was seen between clot burden and systolic blood pressure (BP) (r = -0.299, P = 0.0006) and heart rate (r = 0.240, P = 0.0056). Median obstruction index was significantly higher in those with a presenting BP <90 mmHg [41.25% (95% CI 30-50) vs. 15% (95% CI 12.5-25), (P = 0.0004)]. Clot burden was significantly higher in patients with temperature of >37.5 degrees C [30% (95% CI 25.0-42.5) vs. 15% (95% CI 12.5-28.3), P = 0.02)] and (ii)Biomarkers: significant correlation between clot burden and D-dimer was seen (r = 0.36, P = 0.0001). Location of thrombus was associated with significant differences in D-dimer level. A subgroup of patients had cardiac biomarkers measured (n = 24). There was a statistically significant correlation between troponin I and clot burden (r = 0.412, P = 0.048) and RV/LV ratio (r = 0.699, P = 0.0013). DISCUSSION: These findings suggest that clinical parameters and biomarkers have a role in predicting the radiological severity of PE. These data support the need for further studies of risk stratification in patients presenting with acute PE.