Noninvasive Diagnosis of Suspected Severe Pulmonary Embolism: Transesophageal Echocardiography vs Spiral CT

Abstract

Patients with pulmonary embolism (PE) and echocardiographic signs of right ventricular overload have worse prognosis and may require aggressive therapy. Unequivocal confirmation of PE is required before thrombolysis or embolectomy. This study compares the value of transesophageal echocardiography (TEE) and spiral CT (sCT) in direct visualization of pulmonary artery thromboemboli in patients with suspected PE and echocardiographic signs of right ventricular overload. Forty-nine consecutive patients (29 men and 20 women), aged 52.2+/-18.3 years, with clinical suspicion of acute (23) or chronic (26) PE and otherwise unexplained right ventricular overload at transthoracic echocardiography underwent TEE and sCT. Main and lobar (central) pulmonary arteries were searched for emboli with both TEE and sCT, while segmental and subsegmental (distal) pulmonary arteries were searched only with sCT. Of 40 patients with PE confirmed by high-probability lung scan (27) or angiography (13), central pulmonary arterial emboli were found at TEE and sCT in 32 (80%) and 36 (90%) patients, respectively. Neither method reported false central PE (specificity, 100%). When distal pulmonary arteries were analyzed, sensitivity of sCT increased to 97.5%, but three patients with primary pulmonary hypertension according to standard tests were misclassified as having distal PE (specificity, 90.1%). Most patients had bilateral PE according to sCT (34/36) and standard tests (40/40) but not TEE (15/32), probably due to its topographic limitations. Because of high prevalence of bilateral central pulmonary thromboemboli in patients with hemodynamically significant PE, both sCT and TEE allow its definitive confirmation in most cases. Thrombi reported by sCT distally to lobar arteries should be interpreted with caution.