eComment. The effect of conversion rate on the cost-effectiveness of minimal access mitral valve repair

We read with great interest the best evidence topic by Santana et al. [1]. The Authors conclude that minimally invasive mitral valve repair (MIMVS) is safe and significantly more cost-effective than median sternotomy. Cost-effectiveness is influenced by factors relating to the technique, the length of stay and the presence of postoperative complications. Owing to severe intraoperative difficulties, conversion to full sternotomy is also a serious complication of MIMVS that has not been mentioned in this article. Conversion to median sternotomy is a risk that raises the cost of MIMVS. Occasionally, conversion to a full sternotomy is required during minimally invasive mitral valve surgery for reasons that have not yet been well investigated. The main reason for conversion reported in the literature is major bleeding. Other causes are severe pulmonary adhesions and aortic dissection type A. In all such converted cases, the operative course is significantly prolonged. Furthermore, Vollroth et al. [2] revealed that conversion to full sternotomy leads to severe perioperative morbidities and causes very high 30-day mortality i.e. above 23%. In recent, large series, however, the incidence of conversion to a full sternotomy was 1% [3], in contrast to previously reported studies where the conversion rate was between 2.4% and 2.6% [4]. Despite the fact that conversion from right lateral thoracotomy to full sternotomy occurs infrequently during minimally invasive mitral valve surgery, it still represents a rare but fatal complication and should be considered when assessing operative costs. Identification of potential risk factors and contraindications for the minimally invasive approach is essential to achieve excellent postoperative results. Conflict of interest: none declared.