5.1. TEVAR risks and risk mitigation
TEVAR remains an imperfect procedure. Early survival in unTBAD patients
receiving OMT is ± 90% (34, 35) which is appreciably lower than
patients managed with TEVAR (36-40). Nonetheless, 30-40% (36, 41, 42)
of surviving patients will experience aneurysmal dilatation or
dissection progression despite being under cautious clinical
surveillance which could mandate downstream TEVAR intervention. TEVAR is
associated with moderate risk of ischemic stroke and spinal cord
ischemia (SCI) / paraplegia even when preventative actions (e.g., CSF
drainage) are taken (43, 44). A recent multicentre study found an
incidence of SCI post-TEVAR is ± 3.6% with ± 60% being permanent (45).
In addition to CSF drainage (46), other potentially more effective
strategies to reduce paraplegia risk include permissive hypertension and
left subclavian revascularization (47). Further trials using these
strategies to characterise TEVAR outcomes are warranted. Accordingly, a
list of significant SCI-predicting factors (45) is shown inTable 1 .
The aetiology and management of TEVAR-related stroke is still not fully
understood and further evidence can add value to the management
approach. The MOTHER registry reports a higher incidence of
TEVAR-related strokes in procedures where endovascular stent extends to
cover the left subclavian artery (LSA), which usually manifests as
posterior territory strokes and may cause left upper limb ischemia (48,
49). However, other aetiologies may be present due to the increased
embolic load during the procedure which usually leads to middle cerebral
artery territory strokes (50). Nonetheless, a recent observational study
showed non-significant association between LSA revascularization and SCI
(p = 0.58) or stroke (p = 0.37) incidence in patients undergoing TEVAR
(51).
Other less commonly reported post-procedural complications include acute
myocardial infarction, left upper limb ischemia, acute kidney injury,
malperfusion, access-related pseudoaneurysm, or groin hematoma (38, 51).
Aorta-specific TEVAR-related complications including
retrograde type A aortic
dissection (RTAD) and stent graft-induced new entry (SINE) are serious
TEVAR-related complications. RTAD has an incidence of 2.5% and a
mortality rate of up to 37.1%. (52). The incidence of RTAD is higher in
patients undergoing acute procedures, whereas SINE occurs with higher
incidence in chronic procedures. Incidence of these TEVAR-related
complications and associated mortality can be reduced with using more
appropriately sized stents and better developed aortic facilities (53,
54). Other aorta specific post-TEVAR complications include rupture,
endoleaks, or stent failure, which are usually managed by
reinterventions (55). Therefore, pre-procedural risk identification,
interventional expertise, choice of appropriate stents, and the
availability of well-developed aortic centres are necessary factors when
offering early TEVAR for patients with unTBAD to achieve optimal
outcomes.
Table 1 . Predictor of increased risk for spinal cord ischemia
for TEVAR procedures reported by Mousa et. al (45).