Minithoracotomy Approach for Redo Mitral Valve Surgery: Feasibility, Operative Outcomes and Comparative Analysis of Myocardial Protection Techniques

Objective Redo mitral valve surgery (MVS) poses technical challenges and high operative risks due to adhesions and sternal re-entry. Right minithoracotomy has emerged as an alternative to repeat sternotomy. This study evaluated feasibility and perioperative outcomes of redo MVS through right minithoracotomy and compared three different myocardial protection strategies: cardioplegia, ventricular fibrillation (VF) and beating-heart. Methods All patients undergoing redo MVS via right minithoracotomy between 2015 and 2023 were identified from the Mini-Mitral International Registry . The primary endpoint was in-hospital mortality. Secondary endpoints included stroke, low cardiac output (LCO), bleeding requiring revision, conversion to sternotomy, and major complications. Moreover, three myocardial protection strategies were analyzed: cardioplegic arrest (n=373), VF (n=105), and beating-heart (n=24). Results A total of 502 patients were included (median age 68 years). Overall in-hospital mortality was 7.6% (4.1% in elective and 24.4% in urgent cases). Conversion to sternotomy occurred in 3%. Stroke rate was 2.8% and reoperation for bleedingrequiring revision 8.8%. After adjustment, VF was independently associated with a higher risk of LCO (adjusted OR 3.5, p=0.004). Beating-heart surgery was associated with increased in-hospital mortality (adjusted OR 6.6, p=0.02). No significant association was observed between myocardial protection strategy and stroke or major complications. Conclusions Redo MVS via right minithoracotomy is feasible and safe in experienced centers. Cardioplegic arrest was associated with more favorable early outcomes and should be considered the default myocardial protection strategy whenever feasible. No-clamp techniques remain valuable in selected high-risk scenarios but are associated with trade-offs that warrant careful patient selection.