We thank Dr. Donas and Dr. Wisselink for their comments on our article and do appreciate Dr. Donas' efforts to defend the chimney technique. It would be wrong to go into a battle over details regarding inclusion of articles in reviews, statistics, or even their last article. Reviews are always prone to several inclusion biases, mainly to avoid double inclusion of patients. In their own latest pooled analysis, they included two of our studies with some overlapping patient cohorts. With regard to the statistical analysis, one could find support in the literature for every single method. Other authors as well have previously used the Fisher exact test for a similar type of comparison. Far more important to the reader is to remain critical about any new technique before adopting it in a large proportion of patients. In an expert center such as Munster, there is no doubt that all treatment options (open surgery, fenestrated stent-graft, and chimney technique) are carefully balanced before choosing the most appropriate option for each individual patient. It is the ethical task of each expert center, however, to underline in every presentation and publication that patients treated with chimneys were carefully selected or that no other treatment options seemed more suited. We congratulate Donas et al. for their recent series demonstrating durability of Ch-EVAR at 24-month follow-up. We would like to point out, however, that Munster uses the fenestrated technique for more complex cases (i.e., more than 1 to 2 chimneys required) and that the 40 patients studied in the aforementioned article represented only 32% of the total patients treated in the 3-year observation period. As elaborated by Dr. Wisselink in his invited comment, the longer-term outcome of "gutter" type I endoleaks, especially in cases where progression of aneurysmal disease (i.e., shortening of the neck) may occur, are unknown and a cause for concern. Two recent systematic reviews demonstrated a high percentage of proximal type I endoleak rates (13% and 14%) after Ch-EVAR. It is far too early to be reassured about so-called disappearing early type I gutter endoleaks, as they may still pressurize the sac or reappear after years. Recently, presumed low-flow gutter-associated endoleaks after single renal chimney grafts became larger during follow-up and led to aneurysm rupture and death.
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