Strengths, Limitations and Future Studies
The strength of this study is the relatively large number of patients (n=200) who underwent surgical intervention in a single timeframe at a single center dedicated to the care of complex, degenerative MV disease. Further, the TEE examinations were performed on the same subset of patients included in the internally validated and published surgical score study by Anyanwu et al. Additionally, the examinations were rated by two independent, board-certified cardiac anesthesiologists with a subset of examinations evaluated by both clinicians.
The retrospective nature of our study is one of its limitations. This study used a surgical scoring system published previously by Anyanwu et al. as the standard of comparison for MV repair complexity stratification. The scoring system in that study was extrapolated retrospectively from surgical notes, rather than generated in real-time based on intraoperative anatomic inspection. Also, the echocardiographic scores included in this cohort are from this older study and were also generated from retrospective review of previously performed echocardiography examinations. However, we chose to use the previously studied and published cohort to allow for better comparison with the same patients.
Importantly, the echocardiographic studies in the current report were performed using TEE imaging technology that has since been updated. Contemporary images obtained using newer echocardiography machines and updated software packages are of better quality, with greater temporal and spatial resolution, better three-dimensional capacity and improved post-processing capabilities. Accordingly, better image quality is likely to further improve the agreement between surgical and echocardiographic scores. Indeed, a prior investigation of echo-guided mitral valve repair by Drake et al. demonstrated that 3D echo images of the mitral valve were more highly concordant with intraoperative surgical findings, further supporting that improved echo technology (which in recent years has seen more noticeable improvements in 3D than 2D imaging), will further improve agreement between surgical and echocardiographic scores.
Training, education, and dissemination of a standardized scoring system is also likely to improve the agreement between TEE and surgical scores, demonstrated by the higher level of agreement between surgical scores and the scores given by the more experienced rater. Though further analysis is required to assess inter-clinician reliability on a larger scale, targeted training and education can standardize image acquisition and reduce variability amongst echocardiographers. Additionally, the current study used a retrospective analysis consisting of images acquired by one clinician then interpreted by another. Future studies applying the scoring system can intentionally focus on acquiring specific images for subsequent interpretation. Importantly, prospective studies are needed to validate the use of TEE in predicting intra-operative surgical complexity scores. Once validated, assessment of the clinical impact of the scoring system can be carried out, ultimately in terms of its ability to improve clinical outcomes, patient education and patient satisfaction.