Systematic study of occult pulmonary thromboembolism in patients with deepvenous thrombosis

Purpose: This study was carried out to evaluate the prevalence and extensio n of pulmonary thromboembolism (PTE) in symptom-free patients with symptoma tic deep venous thrombosis (DVT) of lower limbs and to evaluate their possi ble implication in the adequate treatment of thromboembolic disease. Material and Methods: We prospectively studied, using noninvasive examinati on (pulmonary spiral computed tomography [CT] angiography), 159 consecutive patients with acute DVT confirmed by duplex scanning without symptoms of P TE. CT was repeated at 30 days to study evolution of these clinically occul t PTE. Results: We observed silent PTE in 65 patients (41%) in all levels of lower limb venous thrombosis. Prevalence of PTE showed significant association w ith male sex (P = .001) and previously diagnosed heart disease (P = .023). There was no significant association between the level of DVT and the prese nce of PTE nor the DVT side and thromboembolic pulmonary localization. Of t he 65 patients with positive CT exploration results for PTE, 52 had charact eristics of acute PTE, 10 had chronic PTE, and 3 patients had both. Chronic PTE was found more frequently in patients with previous episodes of DVT (P = .024). A total of 165 pulmonary artery-affected segments were found at s everal locations: 5 main, 35 lobar, 58 interlobar and 67 segmental. Multipl e segments were affected in 59% of patients. Repeat CT examinations were pe rformed at 30 days in 53 of 65 patients with positive CT scanning results. In 48 cases (90.6%) PTE had completely disappeared. Conclusions: Silent PTE occurred frequently in association with clots of lo wer limbs. The CT scan had a good availability and cost-effectiveness to de tect clinically underestimated PTE. The incorporation of this exploration i n the systematic diagnostic strategy of most patients with DVT to establish the extension of thromboembolic disease at diagnosis may be useful in the evaluation of added pulmonary artery symptoms and treatment strategies.