Response to Letter Regarding Article, “Retrograde Ascending Aortic Dissection During or After Thoracic Aortic Stent Graft Placement: Insight from the European Registry on Endovascular Aortic Repair Complications”
To the Editor:
We thank Canaud et al for their interest in our article1 and for raising some concerns. They suggested that the findings of our study should be interpreted with caution, particularly with respect to factors that may be predisposing toward the occurrence of retrograde ascending aortic dissection (rAAD) after thoracic endovascular aortic repair (TEVAR). We fully agree with Canaud and coworkers that it is difficult to draw conclusions from a retrospective registry. We have clearly acknowledged the lack of a control group of patients who did not develop rAAD as the major limitation of our study. Therefore, our findings should be considered as hypothesis generating, as we have stated in the limitations section of our article.
We agree with Canaud et al that the relatively high use of stent grafts with proximal bare springs among patients with rAAD (83%) could indeed simply reflect the higher market share of proximal bare spring stent grafts in Europe at the time of the analysis. Interestingly, however, 93% of patients in whom the rAAD was considered by the operator to be stent graft induced received a stent graft with proximal bare springs, whereas in patients in whom rAAD was considered to be caused by progression of aortic disease but not by the stent graft prosthesis, such stent grafts were used less frequently (57%). Nevertheless, the retrospective design of our registry makes it impossible to draw definitive conclusions about the device-specific nature of rAAD. As such, we have concluded “that it is the semirigid stent graft design rather than the proximal bare spring that may be responsible for the tear in the aorta.”
rAAD has been anecdotally associated with excessive stent graft oversizing, but this was not observed in our analysis. On average, there was only 6% oversizing of the stent graft in relation to the aorta in our series, rendering oversizing less likely as a contributing factor.
We thank Canaud et al for their statement that rAAD is not specific to endovascular repair, which corroborates the findings of our study. Our analysis revealed that, although the majority was still associated with the stent graft itself or the TEVAR procedure (eg, wire manipulation), rAAD also occurred spontaneously as a result of progression of the aortic disease.
Our study is the first attempt to address unusual evolving complications of TEVAR from a larger, multicenter perspective and has provided important insights into this rare complication of rAAD after TEVAR. Thus far, there are only a few multicenter studies on TEVAR, and the somewhat low number of centers ultimately participating in the registry (28 of 72 contacted centers) underscores the difficulty in organizing multicenter studies in TEVAR. This may be due to the fact that TEVAR is performed by experts from different medical specialties (eg, cardiologists, vascular surgeons, cardiothoracic surgeons, and radiologists). Communication and cooperation should be improved to allow large multicenter, prospective trials in TEVAR in the future.
Eggebrecht H, Thompson M, Rousseau H, Czerny M, Lönn L, Mehta RH, Erbel R; on behalf of the European Registry on Endovascular Aortic Repair Complications. Retrograde ascending aortic dissection during or after thoracic aortic stent graft placement: insight from the European Registry on Endovascular Aortic Repair Complications. Circulation. 2009; 120: S276–S281.