Increasing Disparity between SVS Guidelines for AAA Repair and Real World Practice; Are the Guidelines still relevant?
Ioannis Kontopidis, MD, Stuart Blackwood, MD, Emilia Krol, MD, Alan Dietzek, MD, RPVI, FACS.
Danbury Hospital, Danbury, CT, USA.
Objective: Current SVS guidelines, based upon randomized controlled trials published more than a decade ago, recommend a minimum threshold diameter of 5.5cm for infrarenal abdominal aortic aneurysm (iAAA) repair. It is unknown whether practice patterns with respect to size of repair have changed since the publication of these guidelines. We aimed to evaluate the real world practice of vascular surgeons in our region with respect to iAAA size at the time of repair, whether this has changed over the past 12 years and if any changes were associated with the repair type, open vs endovascular.
Methods: The Vascular Study Group of New England (VSGNE) database was used to identify all patients receiving iAAA repair between 2003 and 2015. Primary endpoint was to quantify the annual percentage of iAAAs repaired in different size categories (>5.5cm; <5.5cm but >5.0cm; <5.0cm) over the study time period and by type of repair. Secondary endpoints were morbidity and mortality in these groups. We excluded non-elective cases (ruptured or symptomatic), patients with co-existing iliac artery aneurysms and those missing critical data.
Results: 5314 patients with iAAA repairs (1538 open; 3776 endovascular) were identified in the VSGNE database during the study period. In 40% (2110/5314) of patients, repair was performed for aneurysms <5.5cm, with EVAR comprising 75% (1581/2110) and open 25% (529/2110) respectively. More EVARs were performed <5.5cm in 2015 (46%) compared to 2003 (33%) (P < 0.05, n-1 Chi Square) with an average increase of 1.1%/yr. There was also a non-statistically significant increase in open repair of small aneurysms (0.7%/yr; P=0.759). Overall 30 day mortality was 1.11% in the EVAR group (0.54% in <5.0cm, 0.91% in >5.0 but <5.5cm, and 1.55% in >5.5cm), compared to 3% in the open group (2.88%, 1.79% and 3.77% respectively) with no significant change in mortality in either group over time.
Conclusions: Despite SVS guidelines suggesting surveillance rather than repair of iAAA <5.5cm, an increasing proportion of repairs in the VSGNE database were performed below that threshold. The reasons for this are likely multifactorial and might include a lesser complexity and lower operative mortality for smaller aneurysms and markedly improved third and fourth generation stent graft technology with possibly better long term survival. As such, it may be time to re-examine current guidelines for iAAA repair.
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