The cell blood count, electrolytes, coagulation parameters, urinalysis, and chest radiography were noncontributory. The ECG demonstrated first-degree atrioventricular block with no evidence of ischemia. As the possibility of a cardiac etiology for syncope was entertained, the patient was admitted to the hospital for continuous telemetry and serial cardiac enzymes, the results of both of which were negative. The patient underwent two-dimensional echocardiography that confirmed moderate-to-severe tricuspid regurgitation, with an estimated pulmonary systolic pressure of 90 to 99 mm Hg. Bilateral compression ultrasound of the legs revealed no evidence of deep venous thrombosis. The patient subsequently underwent an infused spiral CT of the chest, which demonstrated bilateral chronic pulmonary emboli in the main pulmonary arteries with acute pulmonary embolism in the left segment (Fig 1
). The patient was later identified as heterozygous for the factor V Leiden mutation. The patient received anticoagulation with unfractionated heparin, and warfarin therapy was initiated for life.