Lung Infarction Following Pulmonary Embolism: A Comparative Study on Clinical Conditions and CT Findings to Identify Predisposing Factors

PURPOSE: The aim of this study was to identify factors predisposing to lung infarction in patients with pulmonary embolism (PE).

MATERIALS AND METHODS: We performed a retrospective analysis on 154 patients with the final diagnosis of PE being examined between January 2009 and December 2012 by means of a Toshiba Aquilion 64 CT scanner. The severity of clinical symptoms was defined by means of a clinical index with 4 classes. The pulmonary clot load was quantified using a modified severity index of PE as proposed by Miller. We correlated several potential predictors of pulmonary infarction such as demographic data, pulmonary clot burden, distance of total vascular obstruction and pleura, the presence of cardiac congestion, signs of chronic bronchitis or emphysema with the occurrence of pulmonary infarction.

RESULTS: Computed tomography revealed 78 areas of pulmonary infarction in 45/154 (29.2 %) patients. The presence of infarction was significantly higher in the right lung than in the left lung (p < 0.001). We found no correlation between pulmonary infarction and the presence of accompanying malignant diseases (r = -0.069), signs of chronic bronchitis (r = -0.109), cardiac congestion (r = -0.076), the quantified clot burden score (r = 0.176), and the severity of symptoms (r = -0.024). Only a very weak negative correlation between the presence of infarction and age (r = -0.199) was seen. However, we could demonstrate a moderate negative correlation between the distance of total vascular occlusion and the occurrence of infarction (r = -0.504).

CONCLUSION: Neither cardiac congestion nor the degree of pulmonary vascular obstruction are main factors predisposing to pulmonary infarction in patients with PE. It seems that a peripheral total vascular obstruction more often results in infarction than even massive central clot burden.