Cardiac Computed Tomography Assessment of the Variation of Papillary Muscle Morphology before Mitral Valve Surgery

Background. The morphology of the papillary muscles of the left ventricle is highly variable. Few studies have investigated papillary muscle morphology using imaging. Objective. This study aimed to assess papillary muscle morphology with primary mitral regurgitation (MR) using cardiac computed tomography (CT). Methods. We examined 116 patients who underwent robotic mitral valve repair for primary MR using preoperative cardiac CT. Papillary muscle morphology was assessed using CT images and compared with operative findings. Results. CT images of papillary muscles were consistent with the operative findings during robotic mitral valve repair in all cases. Both the anterolateral papillary muscle (APM) and posteromedial papillary muscle (PPM) groups were identified in all cases, and the middle papillary muscle (MPM) group was identified in 24.1% of cases. The PPM group had a higher proportion of complex morphologies with more heads and bases than the APM group (head: p<0.001 and base: p<0.001). The PPM group had smaller papillary muscle sizes than the APM group. The MPM group in most patients had one base and one head (78.6%). Papillary muscle sizes were significantly smaller in the order of the APM, PPM, and MPM groups (p<0.001). Conclusions. Cardiac CT allowed clear visualization and accurate assessment of papillary muscle morphology in the left ventricle. It may be useful to obtain the papillary muscle variations preoperatively using CT imaging in procedures involving the papillary muscles such as mitral valve repair.