[Clinical characteristics of pulmonary embolism without definitive predisposing factors].

Patients with pulmonary embolism may have no definitive predisposing factors for thrombi. The clinical entity of chronic pulmonary embolism is also uncertain. This study clarified the clinical characteristics of pulmonary embolism without definitive predisposing factors. During the last 10 years, 36 consecutive patients were diagnosed as having pulmonary embolism (mean age 61 years, female 75%). Twenty-four patients (67%) had definitive predisposing factors ("definitive" group). Patients without definitive predisposing factors had the following characteristics. The onset of symptoms was out-hospital and insidious. The main symptom was exertional dyspnea without acute episode compatible with an embolism. In four patients (33%) there was a delay of over 2 years form the onset of symptoms to the diagnosis. Three patients had been treated for depression. Thrombolytic therapy caused an inadequate fall in mean pulmonary artery pressure from 41 +/- 11 to 24 +/- 8 mmHg and in three patients it remained over 30 mmHg. Deep vein thrombosis were found in four of nine patients in whom venography were performed 10 days after thrombolytic therapy, but only one patient showed thrombus in the "definitive" group. During the convalescent stage, all patients were treated with prophylactic warfarin. Home oxygen therapy was indicated in three patients and an inferior vena caval filter was implanted in two patients. One third of patients with pulmonary embolism in our institute had no definitive predisposing factors. In these patients, even with thrombolytic therapy, recovery of pulmonary hypertension was often insufficient and deep vein thrombosis persisted. Clinicians should be aware of this disease to avoid undue delay in its diagnosis.