Mitral valve repair has been increasingly utilized for the surgical treatment of active infective endocarditis because of its low early mortality rate and long-term outcomes exceeding those of mitral valve replacement . However, mitral valve replacement is sometimes required for profoundly extensive and destructive active infective endocarditis of the mitral valve, for which mitral valve reconstruction is extremely challenging. Especially in young patients, mechanical mitral valve replacement is usually the standard procedure, after which lifelong anticoagulation with warfarin is mandatory to avoid stroke and systemic embolization. Some authors have reported extensive reconstruction of the mitral valve leaflets and chordae using autologous or bovine pericardium with or without chordal reconstruction for such devastating cases. These reports described only the short- or mid-term results; the long-term outcomes remain unclear because the durability of the pericardial leaflet is still controversial [2–5]. Furthermore, these reports included repair for chronic endocarditis, whereas repair for active endocarditis may be more challenging. Therefore, in this study, we aimed to clarify the long-term results of extensive mitral valve leaflet reconstruction with autologous pericardium focusing only on active infective endocarditis. Ito et al.  described 25 patients who underwent seamless reconstruction of the mitral leaflet and chordae with one piece of pericardium and demonstrated good short- and mid-term outcomes. In their observational study, only 6 of 25 patients had active endocarditis. The repaired lesion was the posterior leaflet together with its chordae (n = 3) and the commissural leaflet (n = 3). Miura, et al.  analyzed the relation of the localization and durability of the mitral valve repair in the 83 patients diagnosed with infective endocarditis. However, their study also included healed infective endocarditis (n = 17) and simple mitral valve repair (n = 66) without artificial chordae nor pericardium, and it was unclear about detail range of autologous pericardium patch repair whether the scallop was reconstructed with/without artificial chordae or not.
Therefore, there has been no study about the long-term result about only the extensive mitral valve scallop reconstruction with autologous pericardium for active infective endocarditis. In our study, all five patients had active endocarditis. The anterior leaflet was included with the repaired leaflet in three patients in whom large autologous pericardium and several artificial chordae were placed. Mitral regurgitation recurred in one of our five patients and similarly in one of six patients with active endocarditis in the study by Ito et al.  and Miura et al.  for the same reason (detachment of the pericardial suture line).
Another crucial issue is the durability of the autologous pericardium when implanted as part of the valve leaflet and whether the autologous pericardium should be treated by glutaraldehyde. Shomura et al.  reported good results with a mean follow-up of 4.5 years after mitral valve repair with glutaraldehyde-treated autologous pericardium in 139 patients, including 32 with active infective endocarditis (the 10-year rate of freedom from reoperation was 82%). Although the results for patients with only active infective endocarditis and the details of the surgical procedures (e.g., major or partial leaflet reconstruction and with or without chordal implantation) were not clear, this report demonstrated that the mid-term durability of glutaraldehyde-treated autologous pericardium might be favorable. Glutaraldehyde treatment may reportedly improve the durability of the reconstructed pericardium leaflet, providing a lower rate of calcification, shrinkage, or disruption than fresh autologous pericardium [9, 10]. In contrast, however, some reports have indicated that glutaraldehyde treatment might be associated with pericardial calcification [11, 12]. Excellent long-term outcomes of mitral valve leaflet repair using fresh autologous pericardium were recently reported (89% per 10 years of freedom from reoperation) . This report demonstrated that glutaraldehyde treatment of the pericardium might be associated with late calcification and mitral valve stenosis due to leaflet thickening and loss of pliability. A conclusion has not yet been reached about the durability of the pericardium and how to manage the pericardium to obtain a good long-term result; however, minimum use of the pericardium should be desired. We believe that the chordae should be reconstructed not by using pericardium as described by Ito et al.  but by using artificial chordae (polytetrafluoroethylene sutures) to decrease the use of pericardium as much as possible. Furthermore, implantation of artificial chordae is a widespread and familiar technique for many cardiac surgeons. Instead of immediate mitral valve replacement, our technique of mitral valve repair is worth trying especially in young patients with profoundly extended and destructed active infective endocarditis.