Replacing the root, a burden on mid to long term outcomes?
Yang B and colleagues 5 reported a set of contrasting results from their single center study, compared to various other articles as seen in Table A. From a cohort of 94 patients (10 patients had no root procedure), the 4 year Kaplan-Meier survival for the small sample size of 45 patients undergoing root repair was 91%. The patients in the root replacement group underwent either the Bentall (n=24), or the VSRR David procedure (n=15). The Bentall group was independently compared with the conservative repair group, and the reported 4 year survival was significantly lower at 39% (p = 0.03). The authors suggest that previous studies which may have caused higher mortality in the root repair groups were caused by the use of surgical glue which was not used in this study.5 Following adjustments made for; “age, sex, coronary artery disease, pre-operative severe aortic insufficiency, previous cardiac surgery, and cardiac tamponade” 5, it was then stated in this study that the mortality risk was comparable (p=0.24). In addition, no statistically significant difference was reported between root repair and VSRR David procedure (p=0.25).5 The retrospective nature and short follow up period (mean of 22 months), as well as the fact that the study is based on a single surgeons experience, adds significant limitations to the conclusions being drawn.
The study published by Hysi I and colleagues (2015)7have reported outcomes showing improved long term survival for complete aortic root replacement, contrasting the results to Yang B and colleagues.5 This study had a far longer mean follow up period of 9.1 years (109.2 months), compared to the study by Yang B and colleagues discussed above which had a mean follow up time of 22 months only. In addition to this, Hysi I and colleagues reported their long term survival outcomes at 5, 10 and 15 years showing continuously at multiple time points that the group of 82 patients that underwent the Bentall (n=77) or Tirone David (n=5) procedure, showed far favourable results (p=0.03)7 compared to the group that underwent supracomissural repair. This is in contrast to the aforementioned study, where the authors had only reported outcomes for a single point in their follow up time for a 4 years survival result.5 However it is again important to appreciate that as the aortic root replacement group was reported to be more recent in the study7compared to conservative repairs, the study does acknowledge this may have been a source of bias as a consequence of surgical strategy evolution.
Similarly to the discussed short term outcomes, various different studies4, 19, 20 have reported no statistically significant long term results when comparing these mentioned approaches for aortic root management. It is important to appreciate, however, the very significant indications and requirements for a radical root replacement method to be implemented at all. Patients that underwent a more extensive approach of root replacement were generally younger, and with fewer co-morbidities, as well as more likely to have had a more extensive dissection. The presentation of poor morphology and physiology of the root, as well as the presence of connective tissue diseases, were strong indicators for root replacement across the studies in this review. Furthermore, the highly limiting retrospective and single-center characteristics are vital for consideration when reviewing the data of articles in Table A.