Prevalence of Thrombus, Spontaneous Echo Contrast, and Atrial Stunning in Patients Undergoing Cardioversion of Atrial Flutter

BACKGROUND: Several studies have shown that patients undergoing cardioversion of atrial fibrillation have a high prevalence of of atrial thrombus and spontaneous echo contrast and frequently develop atrial stunning after restoration of sinus rhythm. These findings are strongly associated with increased risk of embolism in these patients. However, little is known about the prevalence of these markers of thromboembolism in patients undergoing cardioversion of atrial flutter. METHODS AND RESULTS: We performed transesophageal echocardiography in 47 consecutive, nonanticoagulated patients scheduled for elective cardioversion of atrial flutter. In patients who underwent successful cardioversion, mitral inflow velocity was recorded by transthoracic pulsed Doppler examination immediately after restoration of sinus rhythm. All patients were men (mean age, 65 +/- 10 years). Mean duration of flutter was 4 +/- 9 weeks. Atrial thrombus and/or spontaneous echo contrast were found in 16 patients (34%). Left atrial thrombus was seen in 5 patients (11%), either with (n = 4) or without spontaneous contrast. Of 40 patients with successful cardioversion, atrial mechanical activity was absent in 28% immediately after restoration of sinus rhythm. CONCLUSIONS: Our findings suggest that contrary to traditional teaching, atrial thrombus and spontaneous contrast are not uncommon in patients with atrial flutter and cardioversion may be associated with increased risk of thromboembolism.