BACKGROUND: This study aimed to evaluate the efficacy of preoperative computed tomography for safe robotic mitral annuloplasty.METHODS From July 2018 to August 2023, we performed robotic mitral valve repair with loop technique and ring annuloplasty using a semi-rigid ring in 100 patients. Preoperative anatomical assessment of the mitral annulus by 3-dimensional computed tomography was done to evaluate the distance between mitral annulus and left circumflex artery, trigon-to-trigon distance, and posterior annular length. The ring size was selected based on the perioperative trigon-to-trigon distance or anterior leaflet area. All annuloplasty procedures were performed using the continuous wrapping suture technique. We placed an interrupted suture at the bilateral fibrous trigons using CV4 polytetrafluoroethylene (PTFE). The threads were sutured continuously at the mitral annulus from the bilateral trigone, as if the ring was wrapped. The ring was inserted into a continuous suture without passing through it.RESULTS: The mean trigon-to-trigon length, posterior mitral annular length, and minimum distance between the left circumflex artery and mitral annulus values were 31, 109, and 3.8 mm, respectively. No postoperative left circumflex artery injury or ring detachment were recorded. The mean plication rate (length of posterior side of the prosthetic ring / posterior mitral annular length) was 0.68, which did not differ among each prosthetic ring size. Posterior plication rate duplicate ring size of 19.4 was a factor influencing the post-operative transmitral mean pressure gradient of 5 mmHg or higher. Freedom from moderate or severe mitral regurgitation was not different between the two groups above and below the posterior plication rate × ring size of 19.4 (p = 0.73), with an event-free rate of 97% versus 96% in three years, respectively.CONCLUSIONS: Preoperative evaluation of the mitral annular anatomy is useful for safe ring annuloplasty. Determining ring size by focusing on the posterior annular plication rate may be a new method for ring size selection.
