BACKGROUND Refractory pulmonary edema is an infrequent but serious complication in patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) for myocardial failure. Left atrial (LA) decompression in this setting is important. Although a few methods have been reported, the experience is mostly limited to children. We aimed to evaluate the feasibility of Inoue balloon catheter in percutaneous trans-septal LA decompression in adult cardiogenic patients.Methods and Results:We retrospectively analyzed 16 procedures of trans-septal LA decompression by Inoue balloon catheter in 15 VA-ECMO patients (aged 22-65 years, 6 men) with refractory pulmonary edema from May 2012 to December 2014. Mean left ventricular ejection fraction was 15%. The cause of cardiogenic shock included 7 cases of ischemic heart disease, 1 of dilated cardiomyopathy, 5 of myocarditis, and 2 of fatal ventricular arrhythmia.The procedures were performed 4.3 days after ECMO. Inoue balloon size was 24-27 mm. LA septostomy were successfully created in 14 patients. Procedure time on average was 36.8 min (range, 15-85 min). There were no procedure-related complications.Radiography on the next day showed rapid resolution of pulmonary edema. CONCLUSIONS Trans-septal LA decompression by Inoue balloon catheter is a feasible alternative method for adult patients with refractory pulmonary edema under ECMO.