Patient presentation: An 84-year-old male was referred for transcatheter edge-to-edge repair (TEER) of the mitral valve. The patient had a history of recurrent admissions for acute heart failure in a peripheral hospital, where severe secondary mitral valve regurgitation was diagnosed. The patient was already turned down for surgical repair due to advanced age and EUROSCORE II of  8.5%. Upon transfer, the patient was stable, but showed clear signs of decompensated heart failure. He was complaining of shortness of breath on minimal activity and peripheral edema resistant to diuretics. Initial Work-up: Transthoracic echocardiography was performed, which showed abnormal anatomy (Fig.1). Also, both atrio-ventricular (AV) valves had significant regurgitation, either moderate to severe, or severe. Correct probe positioning was confirmed and a sternal scar ruled out. Transesophageal echocardiography (Fig.1) showed regurgitation of both atrio-ventricular valves, with unusual depth between annular plane and cardiac apex. The texture of both ventricles equally stood out, with increased trabeculation of the left ventricle and hypertrophic free right ventricular wall. Furthermore, the great vessels seemed to have a parallel course. The left-sided AV valve showed functional moderate regurgitation with a typical central jet, under high sedation dose. The right-sided valve suffered from severe eccentric regurgitation due to leaflet prolapse. Cardiac MRI confirmed these morphological features. Diagnosis and Management: A diagnosis of congenitally corrected transposition of the great arteries (ccTGA) was made. Typical features were the apical displacement of the left-sided AV-valve, parallel course of the great arteries, and morphological characteristics of the right ventricle in systemic position. All these pointed to the favorable double discordance, both atrioventricular and ventriculoarterial. The valve that the patient was referred for was not the mitral valve, but in fact the tricuspid valve, and represented the systemic AV-valve. The mitral valve was the right-sided non-systemic AV-valve and showed severe primary regurgitation due to prolapse of the anterior leaflet. The Heart Team discussed the case again and recommended percutaneous treatment. Thus, a decision was made to first repair the systemic valve, which showed moderate to severe regurgitation. Follow-up: The patient underwent TEER of the systemic atrioventricular (tricuspid) valve (Fig.2). After implantation of one Clip, regurgitation was reduced to mild. There were no complications, and the patient was discharged 2 days later. After 2 months, he reported a significant improvement in shortness of breath, with residual peripheral edema. Echocardiography confirmed both the excellent result after interventional repair, and the remaining severe regurgitation of the non-systemic (mitral) valve. The heart team recommended again TEER for the true mitral valve, which was successful in reducing the degree of regurgitation to mild to moderate (Fig.2). Currently, 3 months after the second procedure, the patient has considerably less dyspnea, with trace peripheral edema. Conclusions: ccTGA manifests itself only in adulthood and affects both ventricles and atrio-ventricular valves. A thorough cardiac imaging work-up is needed, in order to understand morphology. Transcatheter treatment of atrio-ventricular valves is a valuable therapeutic option in these often-inoperable patients.