Clinical and transthoracic echocardiographic findings in 92 patients w
ho had atrial mass lesions identified by transesophageal echocardiogra
phy were retrospectively analyzed. Transthoracic echocardiography fail
ed to diagnose or misdiagnosed 16 patients with small (< 3 cm) atrial
thrombi, patients with thrombi localized to the appendage, or patients
with technically difficult studies. The 3 patients with atrial myxoma
who were not detected or were misdiagnosed by transthoracic echocardi
ography had small tumors (< 3 cm) or origin from the free wall of the
atrium away from the atrial septum. Transthoracic study also failed to
diagnose or misdiagnosed normal anatomic variants in 17 of 32 patient
s. In conclusion, transesophageal echocardiography is superior to the
transthoracic study in evaluating the etiology and significance of atr
ial mass lesions.