Sparing the mitral valve in aortic root endocarditis involving the intervalvular fibrosa: appealing and intuitively right

Reconstruction of the intervalvular fibrosa (IVF) in infective endocarditis (IE)—with or without mitral valve replacement—requires experienced and flexible operative judgement. Marin-Cuartas and the Leipzig team report their early experience on a valuable mitral-sparing option for limited anterior leaflet destruction at the time of IVF reconstruction [1]. An early survival of 86%, in patients that would have faced a dismal prognosis, calls for an applause to the authors.

The theoretical benefits of this technique include decreased risk of recurrent endocarditis, less thromboembolic events and preservation of the subvalvular apparatus impacting systolic function. This contribution, with 22 patients, adds to the available reports from the Cleveland Clinic [2, 3] and the Dutch colleagues [4]. The alternative option to the presented technique would be either double valve replacement (Commando) or a full root replacement (Root-Commando), both implying prosthetic mitral valve replacement [3, 5].

The challenging Commando procedure remains seldomly performed by most surgeons. Arguably, the less experienced surgeon may find in a mitral replacement option a more reliable and reproducible solution. Most early experiences of IVF reconstruction have utilized non-sparing mitral variants before advancing into more creative reconstructions [3, 5–8]. Avoidance of repeat aortic cross-clamp and residual regurgitant lesions remains the primary goal to grant survival. Such vulnerable patients may not tolerate residual lesions and early reoperations. However, it is relatively frequent to encounter full destruction of the IVF and the basal segments of the anterior mitral leaflet while the remaining valve is unaffected. When the surgeon has developed proficiency in mitral repair and IVF reconstruction instinct pushes to this type of repair.

Potentially, more judgement and artistic work is required to nail the size of the mitral/new IVF patch and use of prosthetic mitral annuloplasty in the reported technique. Hence, the risk mitral valve distortion leading to regurgitation exists. Although not reported in here, the induction of systolic anterior motion of the mitral valve due to manipulation of its relationships with the left ventricular outflow tract needs to be considered. In this regard, the presence of closed mitral and aortic angles and hypertrophied basal septum call for prudence when considering this mitral-sparing approach. Hence, as in any mitral valve repair exercise, preoperative image interpretation and understanding is key.

Little is known on the mechanical behaviour of the preserved mitral valve and replaced IVF. The possibility of IVF-mitral pericardial patch rigidity and calcification over time exists, resulting in progressive mitral stenosis. For better anatomic understanding, it would be useful to gather data on the residual length of the anterior mitral leaflet (suture line with pericardium to anterior mitral free edge). Intuitively, the longest the remaining mitral leaflet tissue the lower the risk of functional anterior leaflet stiffness. Such data may help us define to which level of mitral destruction can we push this variant of the Commando without compromising long-term function. Improving the follow-up of this series is mandatory to judge its appropriateness. Our impression is that provided that enough flexible native mitral tissue participates in valve function stability of repair will follow. We are more sceptical of such reconstructions when the pericardial patch reaches the distal third of the anterior leaflet close to the free edge. This contribution by Marin-Cuartas et al. [1] is well received as it adds some data for better understanding in this complex scenario. Of course, there are some issues that may be fixed over time such as the limited duration (median 12 months) and completeness (77% at 1 year) of follow-up, which may eventually affect outcome analysis. This is to be kept in mind, too. The 12-month echocardiographic data would have been also of value but are not confirmed by the authors.

The surgical community shall be prepared for iterations of the Commando operation that will need to be adapted for patients previously treated with TAVI, sutureless prostheses and aortic valve replacements with annular enlargement. For that, this communication is also relevant beyond the endocarditis field.

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