Transesophageal echocardiographic detection of atrial thrombi in patients with nonfibrillation atrial tachyarrhythmias and congenital heart disease

OBJECTIVES: We hypothesized an association between atrial thrombi and nonfibrillation atrial tachyarrhythmias in patients with congenital heart disease. BACKGROUND: We observed a fatal thromboembolus after direct current cardioversion in an adolescent with atrial flutter and repaired tetralogy of Fallot. METHODS: Using transesophageal echocardiography, we prospectively studied 19 consecutive patients with congenital heart disease with nonfibrillation atrial tachyarrhythmia (atrial flutter in 18, primary atrial tachycardia in 1) undergoing electrophysiologic procedures (median age 19.6 years, range 7.0 to 53.8; 11 male, 8 female). Transthoracic echocardiograms were available for 17 patients. RESULTS: All transesophageal examinations were performed without incident. No atrial thrombi were detected in 11 patients who subsequently had uncomplicated direct current cardioversion. Eight solitary atrial thrombi were detected (incidence 42%). Six thrombi were located in the right atrium (Fontan repair in four patients, Ebstein's malformation repair in two), and two were noted in the left atrium (congenital hypertrophic cardiomyopathy and atrial septal defect repair in one patient each). Transthoracic echocardiograms were available in seven of eight patients with thrombus detected by transesophageal echocardiography, with only one study conclusive for an atrial thrombus. Cardioversion was deferred in six of eight patients with thrombus, and anticoagulation therapy was initiated. Uncomplicated electrophysiologic procedures were conducted in two patients at the time of detection of right atrial thrombus (atrioventricular node ablation in one patient, direct current cardioversion in the other). CONCLUSIONS: Prothrombin conditions exist in patients with congenital heart disease with nonfibrillation atrial tachyarrhythmias, as indicated by a significant incidence of transesophageally detected atrial thrombi. The need for prophylactic anticoagulation and the safety of pharmacologic or direct current cardioversion are issues that remain unresolved.