Minithoracotomy versus sternotomy in mitral valve surgery: meta-analysis from recent matched and randomized studies.

Background: There is still ongoing debate about the benefits of mini-thoracotomy (MTH) approach in mitral valve surgery in comparison with complete sternotomy (STER). This study aims to update the current evidence with mortality as primary end point.

Methods: The MEDLINE and EMBASE databases were searched through June 2022. Two randomized studies and 16 propensity score matched studies published from 2011 to 2022 were included with a total of 12,997 patients operated on from 2005 (MTH: 6467, STER: 6530). Data regarding early mortality, stroke, reoperation for bleeding, new renal failure, new onset of atrial fibrillation, need of blood transfusion, prolonged ventilation, wound infection, time-related outcomes (cross clamp time, cardiopulmonary bypass time, ventilation time, length of intensive care unit stay, length of hospital stay), midterm mortality and reoperation, and costs were extracted and submitted to a meta-analysis using weighted random effects modeling.

Results: The incidence of early mortality, stroke, reoperation for bleeding and prolonged ventilation were similar, all in the absence of heterogeneity. However, the sub-group analysis showed a significant OR in favor of MTH when robotic enhancement was used. New renal failure (OR 1.67, 95% CI 1.06-2.62, p = 0.03), new onset of atrial fibrillation (OR 1.31, 95% CI 1.15-1.51, p = 0.001) and the need of blood transfusion (OR 1.77, 95% CI 1.39-2.27, p = 0.001) were significantly lower in MTH group. Regarding time-related outcomes, there was evidence for important heterogeneity of treatment effect among the studies. Operative times were longer in MTH: differences in means were 20.7 min for cross clamp time (95% CI 14.9-26.4, p = 0.001), 36.8 min for CPB time (95% CI 29.8-43.9, p = 0.001) and 37.7 min for total operative time (95% CI 19.6-55.8, p < 0.001). There was no significant difference in ventilation duration; however, the differences in means showed significantly shorter ICU stay and hospital stay after MTH compared to STER: - 0.6 days (95% CI - 1.1/- 0.21, p = 0.001) and - 1.88 days (95% CI - 2.72/- 1.05, p = 0.001) respectively, leading to a significant lower hospital cost after MTH compared to STER with difference in means - 4528 US$ (95% CI - 8725/- 326, p = 0.03). The mid-term mortality was significantly higher after STER compared to MTH: OR = 1.50, 1.09-2.308 (95% CI), p = 0.01; the rate of mid-term reoperation was reported similar in MTH and STER: OR = 0.76, 0.50-1.15 (95% CI), p = 0.19.

Conclusions: The present meta-analysis confirms that the MTH approach for mitral valve disease remains associated with prolonged operative times, but it is beneficial in terms of reduced postoperative complications (renal failure, atrial fibrillation, blood transfusion, wound infection), length of stay in ICU and in hospitalization, with finally a reduction in global cost. MTH approach appears associated with a significant reduction of postoperative mortality that must be confirmed by large randomized study.