Regular ArticleClinical relevance of pulmonary infarction in patients with pulmonary embolism
Introduction
Pulmonary embolism (PE) has diverse clinical spectrum, ranging from an asymptomatic event in a previously healthy person to sudden death [1]. Pulmonary infarction (PI) may or may not occur in association with PE [2]. Pathologically, PE can lead to a pulmonary hemorrhage in an area distal to the embolic obstruction; pulmonary hemorrhages that are not resorbed will consequently progress to PI [2]. Multi-detector row computed tomography (MDCT) scan has recently been employed as an acceptable, although not accurate, diagnostic modality for PI [3], [4], [5].
The lung receives blood from two separate vascular systems: the pulmonary and bronchial arteries [6], and the pulmonary parenchyma receives oxygen from the airways [7]. Only approximately 10% of pulmonary emboli cause PI, due to multiple oxygen sources for the lung [8]. The size of an occluded pulmonary artery and underlying medical conditions are the two most important factors associated with development of PI. Occurrence of PI is more common in peripheral PE than in central PE [2]. Dalen et al. [2] suggested correlation between the size of the occluded pulmonary artery and development of an infarct; in addition, they reported that occurrence of PI was not common when central arteries were obstructed by emboli, but PI frequently occurred when distal arteries were involved. More specifically, PI was found to be more commonly associated with occlusion of pulmonary arteries of 3 mm or less in diameter, compared to larger ones [9]. Second, occurrence of PI is more common in patients with underlying conditions such as heart disease, particularly congestive heart failure, chronic lung disease, and malignancy, compared to patients without these comorbidities [1], [2], [9]
Data regarding the role of PI as a prognostic factor in patients with PE is limited. Some researchers have suggested that PE patients with the clinical syndrome of PI characterized by pleuritic chest pain or hemoptysis may be less severe and the mortality rate for those patients may be lower, compared to those without PI [10], [11], [12]. However, those studies were based on patients’ symptoms rather than on detection of a “true” infarct. Thus, the prognostic implication of PI in patients with PE remains unclear. This study was conducted in order to investigate the prevalence, clinical features, and clinical course and outcome of PE patients with PI, thereby elucidating whether PI may have prognostic significance for patients with PE.
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Study Population
For this retrospective study, we searched the computer-based database for patients ≥ 18 years of age who underwent CT pulmonary angiography with or without indirect CT venography and who were diagnosed with a PE between September 2003 and December 2010 at the Kyungpook National University Hospital (KNUH), a tertiary referral center in Daegu, South Korea. The study population included 509 patients with PE. This study was approved by the Institutional Review Board of the KNUH, and written informed
Clinical Characteristics
PI was identified in 45 (8.8%) of 509 total PE patients. With regard to the presence of PI, the inter-observer agreement between the two radiologists was very good with a kappa value of 0.801. All patients were divided into the infarction group with PI (n = 45) and the non-infarction group without PI (n = 464) (Table 1). No significant differences in age, gender, BMI, and smoking history were noted between the infarction and non-infarction groups. Of the presenting manifestations, incidentally
Discussion
The prevalence of PI in patients with PE who participated in the current study was approximately 9%. As expected, PE pleuritic chest pain and hemoptysis were more commonly observed in PE patients with PI, compared to those without PI. However, the presence of underlying heart and lung diseases did not differ significantly between PE patients with PI and those without. In addition, no significant difference in in-hospital mortality, particularly PE-related deaths, was noted between the two
Conflict of Interest Statement
None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.
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