Title:
Current evidence is insufficient to define an optimal threshold for intervention in isolated type II endoleak after endovascular aneurysm repair.

Abstract:
To report a systematic review and meta-regression of the association between the threshold for intervention in patients with isolated type II endoleak after endovascular aneurysm repair (EVAR) and the fate of the aneurysm sac.
Medline, trial registries, conference proceedings, and article reference lists were searched to identify case series reporting sac outcomes following a specific treatment threshold for isolated type II endoleak. Articles were classified by the threshold for intervention as conservative, selective (intervention for >5-mm sac expansion or persistent type II endoleak >6 months), or aggressive (any type II endoleak or persistent for >3 months) and sac outcomes were extracted for review. Standard meta-regression to estimate the pooled odds ratios (OR), presented with the 95% confidence interval (CI), was performed to identify whether an aggressive, selective, or conservative threshold for intervention was associated with sac expansion or sac regression.
Ten series were analyzed that reported the outcomes of isolated type II endoleak in 231 patients; of these, 56 patients were treated at an aggressive threshold, 104 at a selective threshold, and 71 at a conservative threshold. The majority (194/231, 84.0%) demonstrated either stable or shrinking sacs during follow-up. No ruptures occurred. Meta-regression demonstrated no evidence that any strategy, compared to using a conservative approach, reduced sac expansion (aggressive estimated OR 0.70, 95% CI 0.15 to 3.31, p = 0.60; selective estimated OR 1.72, 95% CI 0.49 to 6.00, p = 0.34) or improved sac regression (aggressive estimated OR 0.55, 95% CI 0.02 to 16.94, p = 0.69; selective estimated OR 5.54, 95% CI 0.39 to 79.21, p = 0.17).
There is inadequate information to support any one threshold for intervention. The rarity of rupture and sac expansion confirms the predominantly benign nature of isolated type II endoleak. In the absence of statistical support for a uniform approach to this problem, patient and physician preference remain key. Prospective data are still needed to investigate whether an optimum management algorithm can be devised.