A Cochrane Review (Joshi et al. 2014) assessed the effectiveness of an endovascular stent graft versus conventional open surgery for the treatment of asymptomatic PAA on primary and assisted patency rates, hospital stay, length of the procedure and local complications. Due to the limitations of the current evidence from one small underpowered study, this review was unable to determine the effectiveness of endovascular stent graft versus conventional open surgery for the treatment of asymptomatic PAAs. However, it seemed reasonable to suggest that endovascular repair should be considered as a viable alternative to open repair of PAA on a case by case basis.

In a systematic review of data published between 1994 and 2009, Cina (2010) came to the same conclusion. In his paper, the pooled estimate of patency rate for ER of PAA showed that primary and secondary patency rates at 1 year were 83% and 86%; and at 3 years 74% and 85%, respectively. These results were comparable with that obtainable with open surgery: pooled estimates of 5-year patency for OR was 72%. From this, Cina concluded that ER in the presence of a suitable anatomy and with good tibial run-off is not only feasible, but also safe and with midterm results that are clinically acceptable and probably not different from open repair.

More recently, a further metaanalysis including five studies with a total of 652 PAA repairs (236 ER, 416 OR) in 597 patients with a mean age of 71 years has been published (von Stumm et al. 2015). They, too, found no statistically significant differences between open and endovascular treatment in the categories of patient survival, limb loss, and primary patency when calculated as the hazard ratios (HR) in a random model. The conclusion was that midterm primary patency rates did not differ between ER and OR, but 30-day reintervention and thrombosis following ER was more frequent than after OR. Yet the evidence of this conclusion was low.

The treatment of PAA is not standardised. A considerable variability exists in terms of the incidence of procedures, the operative indicators and the choice of operative procedure. This is shown by the data from the multinational VASCUNET Collaboration (Björck et al. 2014). The incidence of procedures in the 8 participating countries ranged from 3.4 (Hungary) to 17.6 (Sweden) per 1 million inhabitants per year. Selective procedures made up, depending on the country, 26.2 to 86.2% of all procedures. Of all aneurysms, 34.7% in Australia and 29.5% in Sweden were treated through endovascular repair, compared with 0% in Switzerland and Finland. The choice of operative technique depended more on surgical tradition than on the original diagnosis. The large variance in information provided and the variable involvement in compiling the register mean that, at present, it is not possible to assess the efficacy of ER and OR. As the authors themselves emphasise, this will first be possible when longer-term post-operative examination results are analysed. Nonetheless, the averaged values of the registry do provide insight into the present state of PAA-treatment and are therefore given in Table 11.1.

Galiñanes et al. (2013) analysed data from Medicare and Medicaid services’ inpatient claims from 2005 to 2007. During this period, a total of 2962 patients with PAA were registered, from which initially 11.7%, and subsequently 23.6% were treated with endovascular repair. The total rate of complications was 11.3% (OR) vs. 9.3% (ER). The 30-day and 90-day mortality did not differ between the two techniques. The re-intervention rate following ER was higher as compared to OR (after 30 days 4.6% vs. 2.1%; after 90 days 11.8% vs. 7.4%). The length of stay and charges were greater for OR than for ER. However, as a result of the high reintervention rate, there was no financial advantage for the endovascular procedure. Despite a significant increase in the utilization of endovascular repair of PAA, ER was associated with greater reinterventions over time and did not offer a mortality or cost benefit.

In the Swedish vascular registry, Swedvasc, 592 interventions for PAA (499 patients) were registered between May 2008 and May 2012 (Cervin et al. 2015). Of the 592 PAA, 187 (31.6%) were treated emergently and 405 (68.4%) electively. The indication for treatment was: rupture 2.2%, acute ischaemia 29.4%, elective symptomatic 17.7%, and asymptomatic 50.7%. In symptomatic patients, the amputation free survival at 1 year was 73/83 (88%) with OR and 9/9 (100%) with ER. In asymptomatic patients it was 216/221 (97.8%) with OR and 48/52 (92.3%) with ER (p < 0.048). In patients with acute ischemia, significantly poorer results were obtained with ER as compared to OR, the amputation free survival after 1 year was 19/25 (76.0%) with ER vs. 109/122 (89.3%) with OR. These results favor OR for treatment of PAA, in particular among those treated for acute ischemia and put the use of ER for PAA outside trials in question.

Dorweiler et al. (2014) have reported on OR of 206 PAA with an average diameter of 3 cm, in a total of 154 patients. One hundred sixty-one PAA were treated electively, and 45 were treated under emergency conditions. Vein grafts were predominantly used (82%) and a medial approach was chosen in 92%. Hospital mortality was 2% for elective procedures and 3% for emergencies. The late results in this study showed a median follow-up of 137 months with an overall survival rate of 63.5% at 5 years and 40.8% at 10 years and no significant difference between elective and emergent surgeries. Primary, assisted primary, and secondary patency rates were 88.1% (73.5%), 92.1% (84.3%), and 96.5% (89.8%) at 5 (at 10) years, respectively, with no significant difference between elective and emergent surgeries. Limb salvage rate, however, was significantly reduced in the emergent group vs the elective group with 91.1% vs 98.6% at 5 and 10 years. Freedom from any necessary reintervention was 84.3% after 5 and 69.8% after 10 years. The long-term results of this study were excellent and can be considered a standard, against which the ER of PAA can be compared and measured.

From January 1981 to December 2013, Dorigo et al. (2015) performed 234 open surgical interventions for PAA in 196 patients. The PAA was asymptomatic in 97 limbs, intermittent claudication was present in 68, and limb-threatening ischemia was present in 62 limbs. The intervention consisted of aneurysmal ligation and bypass grafting in 122 interventions, aneurysmectomy with graft interposition was used in 108, and four patients underwent aneurysmectomy with an end-to-end anastomosis. An autologous vein was used in 49 interventions, and a prosthetic graft was used in 181. In 71 interventions a posterior approach was used, and in the remaining 163, a medial approach was preferred. There were two perioperative deaths, with a cumulative mortality rate of 1%. Perioperative thrombosis occurred after 18 interventions (7.7%). The cumulative rate of amputations at 30 days was 3.8% (9 of 234 limbs). Mean duration of follow-up was 62 months. The estimated 13-year survival rate was 50.8%; during the same interval, primary patency, secondary patency, and limb preservation rates were 55.1%, 68%, and 86%.

Long-term results of the posterior approach (PA) for the treatment of popliteal artery aneurysms, compared with those operated on through a standard medial approach (MA) were reported by Mazzacarro et al. (2015). A total of 77 aneurysms were treated in 65 patients (64 men). Thirty-six aneurysms were asymptomatic (47%). A PA was used in 43 PAAs (55%) and a MA in 34. All PA repairs consisted of aneurysmectomy with an interposition graft with end-to-end anastomoses; among MA repairs, 22 interposition grafts and 12 bypasses were performed. A polytetrafluoroethylene graft was used in 54 cases. No perioperative deaths or early amputations occurred. The median in-hospital stay was longer for MA (10 days) than for PA (7 days; P = .02). Median follow-up was 58.8 months. The differences between the two groups were small and not statistically significant. The 5-year primary and secondary patency rates were 59.6% ± 8.6% and 96.5% ± 3.4%, respectively, for PA, and 65.1% ± 11.1% and 79.4% ± 9.7%, respectively, for MA. Limb salvage was 100% at 5 years and 93.3% ± 6.4% at 10 years for PA and 91.1% ± 6.3% at both times for MA (P = .28).

Long-term outcomes after ER of PAA (46 procedures on 42 patients) were presented by Piazza et al. (2014). In 93% of cases (n = 43) the procedure was elective. Technical success was 98%. Mean duration of follow-up was 56 ± 21 months. Primary patency at 1, 3, and 5 years was 82%, 79%, and 76%, while secondary patency was 90%, 85%, and 82% respectively; at 5 years there was 98% limb salvage and an 84% survival rate. During follow-up, 11 limbs had stent graft failure: six required conversions, one underwent amputation, and four continued with mild claudication. Of those with graft failure, 63% (7/11) occurred within the first year of follow-up. Segment coverage >20 cm was a negative predictor for patency (HR 2.76). The mean aneurysm sac volume shrinkage between preoperative and 5-year post-procedure measurement was significant (45.5 ± 3.5 mL vs. 23.0 ± 5.0 mL). In addition, Piazza et al. (2016) evaluated in a randomized study outcomes of intraoperative aneurysm sac embolization during endovascular aneurysm repair (EVAR) in patients considered at risk for type II endoleak (EII), using a sac volume-dependent dose of fibrin glue and coils. One hundred twenty-six patients underwent EVAR. One hundred seven patients (85%) were defined as at risk for EII and assigned to randomization for standard EVAR (group A; n = 55) or EVAR with intraoperative sac embolization (group B; n = 52). Freedom from EII was significantly lower for group A compared with group B at 3 months (58% vs 80%), 6 months (68% vs 85%), and 12 months (70% vs 87%), but not statistically significant at 24 months (85% vs 87%). Freedom from EII-related reintervention at 24 months was significantly lower for group A compared with group B (82% vs 96%). Patients in group B showed a significantly overall mean difference in aneurysm sac volume shrinkage compared with group A at 6 months (−11 ± 17 cm³ vs −2 ± 14 cm³ ), 12 months, and 24 months (−27 ± 25 cm³ vs −5 ± 26 cm³ ). In this study, sac embolization during EVAR was a valid method to significantly reduce EII and its complications during early and midterm follow-up in patients considered at risk.

Saunders et al. (2014) identified 34 PAAs in 26 patients, of which 32% presented with acute symptoms. PAA were repaired with either Hemobahn(®) or Viabahn(®) endografts, using an entirely percutaneous approach. At 1, 3, and 5 years follow-up, the primary graft patency was 88, 82, and 82%, respectively, and secondary patency was 90, 86, and 86%. Amputation-free survival at 1, 3, and 5 years was 97, 94, and 94%, respectively. Technical success was achieved in 100%. The authors concluded that the primary and secondary patency rates of endovascular repair of PAA are equivalent to the reported outcome of open repair.