DISCUSSION
AEF is a relatively rare condition that is often life-threatening.
Despite significant refinement in surgical techniques, the operative
mortality of open repair ranges from 25% to 100%.1-3There are several etiologies of primary AEF including thoracic aortic
aneurysm, foreign body ingestion, esophageal malignancy, and prolonged
gastric intubation.6,7 There are several etiologies of
secondary AEF resulting from surgery in the posterior mediastinum such
as aortic arch replacement, TEVAR to descending aorta, and esophageal
surgery. 4,8 The number of secondary AEF is increasing
due to increase in the number of TEVAR being performed. Treatment of
secondary AEF can be more challenging than that of primary AEF due to
the presence of adhesion in the pleural space and the poor general
status of patients. In the patients in this study who underwent combined
repair, reconstruction of the aorta and esophagus could not be completed
due to severe adhesions caused by previous TEVAR. There have been few
studies comparing the degree of adhesion between post-TEVAR cases and
post-graft replacement cases. Moreover, there have been few studies
regarding outcomes between post-TEVAR and post-graft replacement in
secondary AEF cases. Further studies are warranted, however, according
to the present study, secondary AEF after TEVAR can be more critical
than secondary AEF after graft replacement.
The exact mechanism of secondary AEF after TEVAR remains unknown.
Eggebrecht et al. reported that the incidence of AEF was 1.9% and
occurred 1–16 months following intervention in a series of 268 patients
who underwent TEVAR.5 Some reports suggested that its
pathogenesis was related to inflammation of the aneurysmal
wall.9,10 They also suggested that the pathogenesis
was related to esophageal ischemia secondary to elevated pressure in the
posterior mediastinum, inflammation due to the resorbed hematoma, and
mechanical compression by a large aneurysm following
TEVAR.9,10 In post-TEVAR cases, fistulas were
reportedly caused by endoleaks into the residual aneurysmal sac, erosion
of the stent-graft through the aorta, and ischemic necrosis of the
esophageal wall due to compression of its feeding arteries by the
stent-graft.4,5 In accordance with these reports,
severe adhesion between the descending aorta and esophagus might occur
more frequently in secondary AEF after TEVAR than after graft
replacement. In aortic rupture cases, endovascular stenting does not
remove the hematoma or the thrombosis, and thoracic compartment syndrome
is likely to occur. Therefore, emergency TEVAR is associated with an
increased risk of AEF occurrence.4,5,11 In the present
study, in three (75%) patients who had undergone TEVAR previously, AEF
developed after emergency TEVAR.
It has been previously reported that aggressive treatment for patients
with AEF was associated with good outcomes5,10,12 and
reduced short-term mortality. In the present study, although patients
who received open surgical repair were hospitalized for a longer period,
they were discharged without complications. However, the patients who
underwent TEVAR alone were also discharged without complications. The
treatment strategy should be carefully decided especially in patients
with secondary AEF. In severely deteriorated cases, palliative treatment
can be considered as an alternative.
Although TEVAR was proposed as an alternative surgical management
strategy for open surgery,13 secondary AEF after TEVAR
can have severe consequences when left untreated.4,5With the increasing numbers of TEVAR procedures being performed and the
longer follow-up periods, late complications of TEVAR are becoming
increasingly evident.4,5 The treatment strategy for
secondary AEF after TEVAR should be carefully designed considering the
presence of severe adhesions between the aorta and esophagus. Moreover,
the patient’s frailty should be considered in the decision of treatment.
Further studies on surgical treatment for secondary AEF cases,
especially regarding patient inclusion and exclusion criteria are
warranted.
This study had several limitations. First, a small number of patients
was included owing to the rarity of secondary AEF. Therefore, accurate
evaluation might be difficult because combined surgery was performed on
severely ill patients. Second, it was a retrospective study and the data
were obtained from a single institution. Therefore, the study results
may not reflect the general features of patients with AEF. Third,
endovascular treatment strategy has evolved during the time period of
this study.