Our study showed the feasibility of utilising CORKNOT® in both aortic and mitral valve surgeries. The incidence of paravalvular leak, transvalvular regurgitation and post-operative follow-up ejection fraction were comparable between both groups with comparable incidence with other studies. Similar conclusions regarding re-intervention, cardiac mortality and all-cause mortality both groups can be made. The difference in exposure and location of valves have proven to have minimal effect on valvular complications. The incidence of new-onset atrial fibrillation was observed to be higher in single mitral valve surgeries. However, atrial fibrillation is an expected complication of mitral valve surgeries due to the nature of valvular exposure compared to aortic valve surgery.
In this study, we observed a longer operative time compared to other studies. Grapow T.R. et al.2 reported a mean operation time of 203.9 minutes (SD, 31.02), a shorter duration in comparison to our study. Various concomitant procedures were performed in 50% of our patients in the study; the complexity of concomitant operations may account for the difference in operative time. Our inclusion of patients with multiple comorbidities may prompt additional intra-operative considerations to ensure optimal post-operative recovery. Variability of surgical technique and level of experience of using CORKNOT® in our setting may contribute to this outcome.
Moderate to severe paravalvular leak was reported to be present in the range of 3-6% in studies done by O’Rourke et. al8, Smolka, G.9 and Kliger, C.10. Hwang H.Y. et. al.11 reported an incidence of 4.5% of post-operative paravalvular leak. These studies were comparable to our incidence of post-operative paravalvular leak. Consistent use of CORKNOT® may allow surgeons to progress through the learning curve at a quicker pace and achieve superior valvular replacement or repair outcomes.
Pinheiro C.P. et. al.12 and Hwang H.Y. et. al.11 reported institutional in-hospital mortality rates of 6.1% and 4.5% respectively, both which showed poorer outcomes in comparison to our study. Postoperative complications reported by Beute T.J. et. al.3 included 1 incident of stroke (1.9%), 2 incidents (3.8%) of renal failure, 17 incidents (33.0%) of new-onset atrial fibrillation, 3 incidents (5.7%) of permanent pacemaker insertions and 11 incidents (21.2%) of post-operative transfusion of blood products. Except for renal failure and permanent pacemaker insertions, all reported incidences of post-operative complications were higher or comparable to our study.
Beute T.J. et. al. 3 reported a mean post-operative follow-up ejection fraction of 57.7% (SD, 12.2) in the automated titanium suture fasteners group, which was higher than the ejection fraction measured during follow-up in our study. In the same study, the mean pre-operative ejection fraction of the same group was 62%. The decline in ejection fraction in the study was 4.3%, comparable to the 4.0% reported in our study. The decline in ejection fraction from baseline to follow-up is therefore an expected outcome. Most reported trivial or mild paravalvular leaks were resolved during the follow-up, suggesting spontaneous resolution of paravalvular leak. However, 4 patients developed paravalvular leak between post-operative and follow-up.
The incidence of valvular regurgitation6, leaflet perforation13,14,15, paravalvular leakage 6,16 and embolization7 have not been reflected in clinical trials or larger scale studies. Similarly, our study reported nil incidence of leaflet perforation with bioprosthesis or repaired heart valves. Larger-scale comparative studies will be required to elicit the true complication profile of CORKNOT®.
This is a single-centre retrospective database analysis which has relatively low case volume. Our analysis is limited to single valve comparisons between commonly operated aortic and mitral valves. Analysis of multiple valves and less commonly operated valves such as pulmonary and tricuspid valves would be less feasible in our institution. Another limitation of our study is the paucity in current literature on complications arising from the use of automated titanium suture fasteners, with most being case reports or comments.