Redo mitral valve surgery requires careful planning around adhesions, prior grafts, vascular access, and myocardial protection. A study from the Mini-Mitral International Registry examines outcomes after right minithoracotomy and compares cardioplegic arrest, ventricular fibrillation, and beating-heart techniques in this challenging setting.
Giovanni Domenico Cresce and colleagues report a retrospective analysis of 502 patients treated between 2015 and 2023 at 17 international centres. The findings support the feasibility of the approach in selected patients at experienced centres, while raising important questions about the choice of myocardial protection.
Study Design and Patient Selection
The primary endpoint was in-hospital mortality. Secondary outcomes included stroke, low cardiac output, bleeding requiring revision, major complications, and conversion to sternotomy. The median patient age was 68 years. Cardioplegia was used in 373 patients, ventricular fibrillation in 105, and a beating-heart approach in 24.
These were not interchangeable patient groups. Median EuroSCORE II was 5.91 with cardioplegia, 7.51 with ventricular fibrillation, and 10.13 with beating-heart surgery. Previous coronary bypass surgery was present in 21.2%, 46.7%, and 62.5%, respectively. Ventricular function, concomitant procedures, and other characteristics also differed.
The investigators used mixed-effects regression with a centre-level random intercept and adjustment for clinical covariates. Missing observations were handled by complete-case analysis. Statistical adjustment improves the comparison but cannot remove all effects of patient selection or unmeasured procedural complexity.
Overall Operative Outcomes
| Outcome | Reported result |
|---|---|
| Patients | 502 |
| In-hospital mortality | 38 patients (7.6%) |
| Elective versus urgent mortality | 4.1% versus 24.4% |
| Conversion to sternotomy | 15 patients (3%) |
| Stroke | 14 patients (2.8%) |
| Bleeding requiring revision | 44 patients (8.8%) |
| Low cardiac output | 46 patients (9.2%) |
| Median CPB time | 155 minutes |
| Median hospital stay | 9 days |
The large difference between elective and urgent mortality emphasises the importance of clinical status when interpreting the aggregate result. This study did not include a concurrent repeat-sternotomy comparator, so it cannot establish that minithoracotomy itself reduces mortality or complications relative to sternotomy.
Myocardial Protection Comparisons
Cardioplegia and Ventricular Fibrillation
Unadjusted in-hospital mortality was 7.0% with cardioplegia, 8.6% with ventricular fibrillation, and 12.5% with beating-heart surgery; the overall unadjusted comparison was not statistically significant. Low cardiac output occurred in 7.0%, 16.2%, and 12.5%, respectively.
After adjustment, ventricular fibrillation was associated with greater odds of low cardiac output than cardioplegia: odds ratio 3.5, 95% confidence interval 1.5–8.0, P=.004. Its association with mortality did not reach conventional statistical significance: adjusted odds ratio 3.5, 95% confidence interval 0.9–12.9, P=.07.
The Beating-Heart Finding Requires Particular Caution
Beating-heart surgery was associated with higher adjusted odds of in-hospital mortality than cardioplegia: odds ratio 6.6, 95% confidence interval 1.2–34.1, P=.02. However, this subgroup contained only 24 patients and three deaths. The very wide confidence interval signals substantial uncertainty, and the authors identify the result as exploratory.
No significant adjusted association was found between myocardial-protection strategy and stroke or the composite of major complications. Absence of statistical significance does not establish equivalent safety, particularly with small subgroups and uncommon events.
Perfusion and Operative Context
Femoral arterial cannulation was used in 89.6% of cases. Venous drainage was predominantly femoral alone or femoral with jugular cannulation. Median bypass time was 150 minutes with cardioplegia, 174 minutes with ventricular fibrillation, and 168.5 minutes with beating-heart surgery.
In the methods, the authors describe ventricular fibrillation under moderate hypothermia and beating-heart surgery on full CPB support without planned aortic crossclamping. Cardioplegia cases used either external clamping or endoaortic balloon occlusion. The operative data nevertheless record some clamping and cardioplegia in patients classified in other groups, indicating that the categories were not completely uniform procedural exposures.
For perfusion teams, the practical message is to integrate the protection strategy with the patient’s prior operations, ventricular function, graft anatomy, expected dissection, and surgical exposure. The study reports associations between strategies and outcomes; it does not establish that changing the strategy alone would reproduce those differences.
Limitations and Clinical Interpretation
The registry design introduces selection and reporting bias, and surgical and perfusion practices varied by centre. Detailed management of patent internal mammary artery grafts was not systematically available. The small beating-heart group, limited event counts, and complete-case analysis further constrain interpretation. Long-term survival and valve durability were not assessed.
Some subgroup counts and percentages in the published tables are also difficult to reconcile, including urgency-related entries. The overall findings and adjusted estimates are therefore more useful for this summary than reconstructing detailed subgroup risks from those tables.
The authors favour cardioplegia whenever feasible and retain no-clamp techniques for selected situations in which clamping is problematic. The data support that preference as an observational finding, not proof of causal superiority. Right minithoracotomy remains an option for carefully selected redo cases in experienced centres, with clinical urgency and patient complexity central to risk assessment.
Original IPA educational summary of Cresce and colleagues’ registry analysis. The source article is published under the Creative Commons Attribution–NonCommercial–NoDerivatives licence; the linked PDF is the original article uploaded to IPA.
Original Article
Cresce GD, Berretta P, Wilbring M, et al. Minithoracotomy approach for redo mitral valve surgery: Feasibility, operative outcomes, and comparative analysis of myocardial protection techniques. JTCVS Techniques. 2026;39:102509. doi:10.1016/j.xjtc.2026.102509.
