The transaxillary approach is widely used for atrial-level defects, particularly atrial septal defect (ASD) closure, with outcomes comparable to sternotomy. We sought to describe procedural efficacy and expansion toward more complex lesions in a single-center cohort.

All patients < 18 years undergoing transaxillary MICS (minimally invasive cardiac surgery) between 2018 and 2025 were retrospectively included. We recorded demographics, procedure type, cardiopulmonary bypass (CPB) and aortic cross-clamp times, conversions, and early outcomes. Temporal trends and procedural efficiency were assessed across the study period. Postoperative outcomes included complications, conversion, mortality, and hospital length of stay (LOS).

A total of 348 MICS patients were included (median age 5.63 years [4.01–9.48]). Twenty-nine (8.4%) were below 1 year of age. Procedures comprised ASD closure (n = 168, 48.3%), partial anomalous pulmonary venous connection repair (n = 72, 20.6%), ventricular septal defect closure (n = 36, 10.3%), atrioventricular septal defect repair (partial: n = 45, 12.9%; complete: n = 9, 2.6%), atrioventricular valve repair (n = 12, 3.4%), and cavopulmonary connection (n = 6, 1.7%). Over time, the proportion of non-ASD procedures increased from 23.8% in the early period (2018–2019) to 54.8% in the late period (2024–2025) ( Fig. 1 ). When assessed by lesion, median CPB and cross-clamp times decreased over time ( p < 0.05). Median LOS was 2.8 days [1.4–4.0]. The overall complication rate was 8%, and conversion to sternotomy was 0.5%. No death occurred.

Vertical transaxillary MICS can be performed safely for a broad spectrum of congenital lesions. With experience, procedural efficiency improved and indications extended to higher-complexity repairs. This approach is associated with low morbidity, short hospital stays, and favorable early outcomes, and may also allow postoperative recovery without CCU admission in selected patients.