Left ventricular outflow tract obstruction in patients with Ebstein anomaly

Objective: In this study, we investigated the clinical characteristics of patients with Ebstein anomaly and left ventricular outflow tract (LVOT) obstruction as well as possible mechanisms of obstruction as assessed by 2-dimensional echocardiography. Methods: We queried our institutional echocardiography and surgical databases for patients with the diagnosis of Ebstein anomaly seen from 1985 through 2022. Fourteen patients had the additional diagnosis of LVOT obstruction identified from transthoracic echocardiography. Results: The mean age of the 14 patients at the time that LVOT obstruction was identified was 51.9 ± 9.9 years, and 11 (78%) were female. LVOT obstruction (mean gradient 61.0 ± 25.7 mm Hg) was documented at the time of initial diagnosis of Ebstein anomaly for 8, and in the remaining, was recognized on follow-up imaging. Dynamic LVOT obstruction with systolic anterior motion (SAM) was the most common mechanism and was mostly accompanied by leftward septal movement and septal hypertrophy. Seven of the 9 patients with SAM had the diagnosis of hypertrophic cardiomyopathy. Leftward bowing of the septum appeared to be the sole cause of LVOT obstruction in 3 and a contributing factor to SAM in 4. Among the 13 patients who underwent an operation for Ebstein anomaly, 7 had concomitant septal myectomy and 3 had a subsequent procedure. Conclusions: There are multiple mechanisms of LVOT obstruction in patients with Ebstein anomaly, including SAM and leftward bowing of the interventricular septum, which may exist alone or in combination. Septal myectomy at the time of tricuspid valvuloplasty is safe and effectively reduces gradients in the outflow tract and may prevent the need for subsequent reintervention.