Patients were operated in 30° right supine position as described previously [22 (link)]. From 2017 onwards, all patients underwent preoperative computer tomography (CT) scan to exclude severe atherosclerosis or kinking of the femoro-iliac vessels and the aorta as well as major mitral annular calcifications. Cardiopulmonary bypass was installed via femoro-femoral cannulation. Femoral cannulation is performed in our centre routinely via a surgical approach. An additional distal leg perfusion was used in a standardized fashion since 2013 to avoid ischaemic complications of the leg. An additional venous cannula was inserted in the right jugular vein in case of right heart surgery or patients with increased body surface area to allow total cardiopulmonary bypass and optimal drainage. A periareolar or a 4- to 5-cm-long skin-cut lateral to the nipple or a similar incision in the submammary fold in female patients was made to allow access to the 4th intercostal space. The 3rd intercostal space on the anterior axillary line was used for the endoscope and the transthoracic clamp. A 30° 2D scope was used until 2014 and a 3D scope (Einstein-Vision, Aesculap, Tuttlingen, Germany) was introduced thereafter. Since 2015 a typical procedure has been performed by 3D endoscopy and a soft tissue retractor (Alexis Wound-protector, Applied Medical, Santa Margarita, CA) without the use of a rib retractor. After pericardial incision, the cardioplegia line was inserted in the ascending aorta and externalized in the 3rd intercostal space. The same incision was used for the atrial retractor (Geister, Tuttlingen, Germany). Common mitral repair techniques including chordal replacement (single PTFE chords, secondary chord transfer or pre-fabricated PTFE loops), leaflet resection, sliding plasty or indentation closure were applied. A semi-rigid complete annuloplasty ring was used in all procedures. When indicated, concomitant left atrial or bi-atrial ablation was performed for atrial fibrillation in addition to closure of the left atrial appendage. Older patients with long persistent atrial fibrillation and enlarged left atria were not deemed to be good candidates for rhythm correction therapy. All patients with an indication for left atrial appendage (LAA) closure receive external atrial clipping in our current practice. The LAA was closed by a double layer of endocardial suture or atrial clipping, according to the surgeons’ preference. Moreover, a tricuspid valve repair was performed in all patients with severe tricuspid valve regurgitation or annular dilatation above 21 mm/m2 BSA. The types of procedures performed are shown in Table 2. Six main surgeons performed the procedures which in the frame of a university hospital also included many teaching cases. The main reasons for non-eligibility for MIMVS were either concomitant coronary/other valve disease or calcifications of the iliac artery/abdominal aorta precluding retrograde perfusion as described previously [22 (link)]. The allocation of the patient to conventional or MIMVS was dictated by institutional protocols. During the program development (2001–2006), patients with complex mitral pathology, concomitant tricuspid disease, need for left atrial ablation, pulmonary hypertension > moderate, impaired left ventricular or renal function and older age (>80) were not deemed as candidates for MIMVS. This decision was made to keep the risk of the procedure predictable and to minimize the risk of technical failures due to the limited experience.