William P. Robinson

Predictors of Abdominal Aortic Aneurysm Sac Enlargement After Endovascular Repair

Background— The majority of infrarenal abdominal aortic aneurysm (AAA) repairs in the United States are performed with endovascular methods. Baseline aortoiliac arterial anatomic characteristics are fundamental criteria for appropriate patient selection for endovascular aortic repair (EVAR) and key determinants of long-term success. We evaluated compliance with anatomic guidelines for EVAR and the relationship between baseline aortoiliac arterial anatomy and post-EVAR AAA sac enlargement. Methods and Results— Patients with pre-EVAR and at least 1 post-EVAR computed tomography scan were identified from the M2S, Inc. imaging database (1999 to 2008). Preoperative baseline aortoiliac anatomic characteristics were reviewed for each patient. Data relating to the specific AAA endovascular device implanted were not available. Therefore, morphological measurements were compared with the most liberal and the most conservative published anatomic guidelines as stated in each manufacturers instructions for use. The primary study outcome was post-EVAR AAA sac enlargement (>5-mm diameter increase). In 10 228 patients undergoing EVAR, 59% had a maximum AAA diameter below the 55-mm threshold at which intervention is recommended over surveillance. Only 42% of patients had anatomy that met the most conservative definition of device instructions for use; 69% met the most liberal definition of device instructions for use. The 5-year post-EVAR rate of AAA sac enlargement was 41%. Independent predictors of AAA sac enlargement included endoleak, age ≥80 years, aortic neck diameter ≥28 mm, aortic neck angle >60°, and common iliac artery diameter >20 mm. Conclusion— In this multicenter observational study, compliance with EVAR device guidelines was low and post-EVAR aneurysm sac enlargement was high, raising concern for long-term risk of aneurysm rupture.

Surgeon case volume, not institution case volume, is the primary determinant of in-hospital mortality after elective open abdominal aortic aneurysm repair

OBJECTIVE Studies analyzing the effects of volume on outcomes after abdominal aortic aneurysm (AAA) repair have primarily centered on institutional volume and not on individual surgeon volume. We sought to determine the relative effects of both surgeon and institution volume on mortality after open and endovascular aneurysm repair (EVAR) for intact AAAs. METHODS The Nationwide Inpatient Sample (2003-2007) was queried to identify all patients undergoing open repair and EVAR for nonruptured AAAs. To calculate surgeon and institution volume, 11 participating states that record a unique physician identifier for each procedure were included. Surgeon and institution volume were defined as low (first quintile), medium (second, third, or fourth quintile), and high (fifth quintile). Stratification by institution volume and then by surgeon volume was performed to analyze the primary endpoint: in-hospital mortality. Multivariable models were used to evaluate the association of institution and surgeon volume with mortality for open repair and EVAR, controlling for potential confounders. RESULTS During the study period, 5972 open repairs and 8121 EVARs were performed. For open AAA repair, a significant mortality reduction was associated with both annual institution volume (low <7, medium 7-30, and high >30) and surgeon volume (low ≤ 2, medium 3-9, and high >9). High surgeon volume conferred a greater mortality reduction than did high institution volume. When low and medium volume institutions were stratified by surgeon volume, mortality after open AAA repair was inversely proportional to surgeon volume (8.7%, 3.6%, and 0%; P < .0001, for low, medium, and high-volume surgeons at low-volume institutions; and 6.7%, 4.8%, and 3.3%; P = .02, for low, medium, and high-volume surgeons at medium-volume institutions). High-volume institutions stratified by surgeon volume demonstrated the same trend (5.1%, 3.4%, and 2.8%), but this finding was not statistically significant (P = .57). Multivariable analysis was confirmatory: low surgeon volume independently predicted mortality (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.3-3.1; P < .001); low institution volume did not (P = .1). For EVAR, neither institution volume nor surgeon volume influenced mortality (univariate or multivariable). CONCLUSION The primary factor driving the mortality reduction associated with case volume after open AAA repair is surgeon volume, not institution volume. Regionalization of AAAs should focus on open repair, as EVAR outcomes are equivalent across volume levels. Payers may need to re-evaluate strategies that encourage open AAA repair at high-volume institutions if specific surgeon volume is not considered.

Inferior outcomes of autogenous infrainguinal bypass in Hispanics: an analysis of ethnicity, graft function, and limb salvage.

INTRODUCTION Recent evidence suggests disparities exist among racial groups with peripheral arterial disease (PAD). Hispanics (HI) are the fastest growing demographic in the United States, but little outcome data is available for this population. Therefore, we undertook this study to compare the results of autogenous infrainguinal bypass grafting in HI to Caucasians (CA) and African Americans (AA). METHODS This was a comparative cohort study of prospectively collected registry data of infrainguinal bypass performed at a tertiary center. Patient demographics and comorbidities, operative indications, bypass graft characteristics, and postoperative courses were analyzed. Cumulative patency rates, limb salvage, mortality, and factors associated with these outcomes were determined using Kaplan-Meier analysis and Cox proportional hazards models. RESULTS From January 1, 1985, through December 31, 2007, 1646 consecutive patients (1408 CA, 57 HI, and 181 AA) underwent 1646 autogenous infrainguinal reconstructions. HI and AA were younger and more often diabetic than CA but HI had less chronic renal insufficiency (CRI) and dialysis-dependence than AA. AA, but not HI, more commonly underwent bypass for critical limb ischemia (CLI) in comparison to CA (AA 90% vs CA 80%, P < .0001; HI 86%). HI and AA bypass grafts had inflow and outflow distal to that in CA. Perioperative mortality (2.3%) and morbidity were similar between groups. Five-year primary patency (+/- standard error [SE]) was significantly lower in HI compared to CA and similar to that in AA (HI 54% +/- 7% vs CA 69% +/- 1%, P = .02; AA 58% +/- 4%). Cox proportional hazard modeling showed high-risk conduit, age <65, CLI, female gender, and AA race were risk factors for failure of primary patency. Secondary patency of HI grafts, unlike AA, was not different than that in CA. Five-year limb salvage (+/- SE) was significantly lower in HI compared to CA and similar to that in AA (HI 80% +/- 6% vs CA 91% +/- 1%, P = .004; AA 83% +/- 3%). Hispanic ethnicity, CLI, high-risk conduit, age <65, CRI, female gender, and diabetes were significant predictors of limb loss. CONCLUSION Autogenous infrainguinal bypass surgery in HI is associated with primary patency and limb salvage inferior to that of CA and similar to that of AA, despite HI rates of CLI equivalent to CA and HI comorbidities less severe than AA. HI ethnicity was an independent predictor of limb loss. Our data provides evidence of outcome disparities in HI treated aggressively for their PAD. Further investigation with regard to biologic and social factors is required to delineate the reasons for these inferior outcomes in HI patients.

Acute Limb Ischemia Due to Popliteal Artery Aneurysm: A Continuing Surgical Challenge

Up to 50% of all popliteal artery aneurysms (PAA) present with acute limb ischemia (ALI). ALI due to PAA is a difficult surgical problem, with a 20% to 60% incidence of limb loss and up to 12% mortality reported in the literature in the last three decades. Imminent limb threat requires emergency infrainguinal reconstruction, preferably with autogenous conduit. ALI due to PAA is limb-threatening, often due to obliteration of the tibial vessels in addition to thrombosis of the PAA itself. Arteriography is needed to define inflow vessel and outflow vessel anatomy followed by thrombectomy of the run-off vasculature to establish an appropriate target for bypass. Patients without evidence of neurologic deficit are best served by formal arteriography. Intraarterial thrombolysis is used to establish an outflow vessel for bypass if no runoff vessels are visible. In general, emergency operations are associated with inferior patency and limb salvage compared to elective procedures. Endovascular exclusion of PAA with covered stent graft is used increasingly in the elective setting and has been reported in patients presenting with limb ischemia. The following discussion outlines our algorithm in managing ALI from PAA and reviews management decisions and results of treatment.

Optimal selection of patients for elective abdominal aortic aneurysm repair based on life expectancy

OBJECTIVE Elective abdominal aortic aneurysm (AAA) repair is beneficial when rupture is likely during a patients expected lifetime. The purpose of this study was to identify predictors of long-term mortality after elective AAA repair for moderately sized AAAs (<6.5-cm diameter) to identify patients unlikely to benefit from surgery. METHODS We analyzed 2367 elective infrarenal AAA (<6.5 cm) repairs across 21 centers in New England from 2003 to 2011. Our main outcome measure was 5-year life-table survival. Cox proportional hazards analysis was used to describe associations between patient characteristics and 5-year survival. RESULTS During the study period, 1653 endovascular AAA repairs and 714 open AAA repairs were performed. Overall, 5-year survival rates were similar by procedure type (75% endovascular repair, 80% open repair; P = .14). Advanced age ≥75 years (hazard ratio [HR], 2.0; P < .01) and age >80 years (HR, 2.6; P < .01), coronary artery disease (HR, 1.4; P < .04), unstable angina or recent myocardial infarction (HR, 4.6; P < .01), oxygen-dependent chronic obstructive pulmonary disease (HR, 2.7; P < .01), and estimated glomerular filtration rate <30 mL/min/1.73 m(2) (HR, 2.8; P < .01) were associated with poor survival. Aspirin (HR, 0.8; P < .03) and statin (HR, 0.7; P < .01) use were associated with improved survival. We used these risk factors to develop risk strata for low-risk, medium-risk, and high-risk groups with survival, respectively, of 85%, 69%, and 43% at 5 years (P < .001). CONCLUSIONS More than 75% of patients with moderately sized AAAs who underwent elective repair in our region survived 5 years, but 4% were at high risk for 5-year mortality. Patients with multiple risk factors, especially age >80 years, unstable angina, oxygen-dependent chronic obstructive pulmonary disease, and estimated glomerular filtration rate <30 mL/min/1.73 m(2), are unlikely to achieve sufficient long-term survival to benefit from surgery, unless their AAA rupture risk is very high.

Performance of the Aorfix endograft in severely angulated proximal necks in the PYTHAGORAS United States clinical trial.

OBJECTIVE This study compared the performance of the Aorfix endograft (Lombard Medical, Oxfordshire, United Kingdom) in standard (<60°), highly angled (60°-90°), and severely angled (>90°) aortic necks in the PYTHAGORAS study and evaluated changes in neck morphology over time. METHODS PYTHAGORAS is a prospective nonrandomized clinical trial of the Aorfix endograft. We divided the endovascular aneurysm repair (EVAR) cohort into groups by standard, high, and severe neck angle. The primary control group was patients concurrently undergoing open repair. Mortality at 30 days, 1 year, and 2 years and 30-day freedom from Society for Vascular Surgery major adverse events for the EVAR groups was compared with the open control. Aneurysm sac change, type I and III endoleaks, graft migration, and the reintervention rate at 1 and 2 years was compared between the standard, highly, and severely angled populations. The relative risk of graft complications with a neck diameter increase >10% was also calculated. At predetermined anatomic points, the effect of oversizing on aortic diameter was evaluated by calculating oversize percentage ([1 - outer aortic diameter measured at a given time/stent graft diameter] × 100%) preoperatively and at 3 years. In addition, the average oversizing percentage at 30 days and annually at 1 to 5 years was compared with the preoperative oversizing percentage. Finally, complication rates with ≥30% vs <30% planned oversizing were compared. RESULTS The adverse event rate was lower for every EVAR group than the open control. In addition, the mortality rates at 30 days, 1 year, and 2 years were similar between the standard-angle (1.5%, 3.0%, 4.5%), high-angle (0.9%, 7.3%, 13.8%), and severe-angle (4.8%, 9.5%, 14.3%) EVAR groups and the open control groups (1.3, 6.6%, 10.5%). At 1 and 2 years, there was no difference in graft complications among the EVAR groups. However, with neck dilatation of >10% at 5 mm above the proximal renal and 1 mm below the distal renal, there was an increased risk of graft migration (relative risk, 4.38 [P = .01] and 4.33 [P = .002], respectively). For all predetermined anatomic points, the oversizing percentage decreased over time. The rate of oversize percentage decrease was faster at more distal aortic locations, reaching <10% at 30 days 15 mm below the renal, at 2 years 7 mm below the renal, and at 5 years 1 mm below the renal (P < .001 for all). Half the oversize percentage achieved at the index procedure remained at 3 years (Pearson correlation coefficient = 0.5). However, there was no difference in complications between the ≥30% and <30% planned oversize groups. CONCLUSIONS The Aorfix endograft has performed well in excluding aneurysms with standard and highly angled aortic neck anatomy.

In patients stratified by preoperative risk, endovascular repair of ruptured abdominal aortic aneurysms has a lower in-hospital mortality and morbidity than open repair

OBJECTIVE Previous studies have reported that endovascular repair (EVAR) of ruptured abdominal aortic aneurysms (RAAAs) has lower postoperative mortality than open repair (OR). However, comparisons involved heterogeneous populations that lacked adjustment for preoperative risk. We hypothesize that for RAAA patients stratified by a validated measure of preoperative mortality risk, EVAR has a lower in-hospital mortality and morbidity than does OR. METHODS In-hospital mortality and morbidity after EVAR and OR of RAAA were compared in patients from the Vascular Quality Initiative (2003-2013) stratified by the validated Vascular Study Group of New England RAAA risk score into low-risk (score 0-1), medium-risk (score 2-3), and high-risk (score 4-6) groups. RESULTS Among 514 patients who underwent EVAR and 651 patients who underwent OR of RAAA, EVAR had lower in-hospital mortality (25% vs 33%, P = .001). In risk-stratified patients, EVAR trended toward a lower mortality in the low-risk group (n = 626; EVAR, 10% vs OR, 15%; P = .07), had a significantly lower mortality in the medium-risk group (n = 457; EVAR, 37% vs OR, 48%; P = .02), and no advantage in the high-risk group (n = 82; EVAR, 95% vs OR, 79%; P = .17). Across all risk groups, cardiac complications (EVAR, 29% vs OR, 38%; P = .001), respiratory complications (EVAR, 28% vs OR, 46%; P < .0001), renal insufficiency (EVAR, 24% vs OR, 38%; P < .0001), lower extremity ischemia (EVAR, 2.7% vs OR, 8.1%; P < .0001), and bowel ischemia (EVAR, 3.9% vs OR, 10%; P < .0001) were significantly lower after EVAR than after OR. Across all risk groups, median (interquartile range) intensive care unit length of stay (EVAR, 2 [1-5] days vs OR, 6 [3-13] days; P < .0001) and hospital length of stay (EVAR, 6 [4-12] days vs OR, 13 [8-22] days; P < .0001) were lower after EVAR. CONCLUSIONS This novel risk-stratified comparison using a national clinical database showed that EVAR of RAAA has a lower mortality and morbidity compared with OR in low-risk and medium-risk patients and that EVAR should be used to treat these patients when anatomically feasible. For RAAA patients at the highest preoperative risk, there is no benefit to using EVAR compared with OR.

Follow-up compliance after endovascular abdominal aortic aneurysm repair in Medicare beneficiaries

OBJECTIVE Lifelong imaging follow-up is essential to the safe and appropriate management of patients who undergo endovascular abdominal aortic aneurysm repair (EVAR). We sought to evaluate the rate of compliance with imaging follow-up after EVAR and to identify factors associated with being lost to imaging follow-up. METHODS We identified a 20% sample of continuously enrolled Medicare beneficiaries who underwent EVAR between 2001 and 2008. Using data through 2010 from Medicare Inpatient, Outpatient, and Carrier files, we identified all abdominal imaging studies that may have been performed for EVAR follow-up. Patients were considered lost to annual imaging follow-up if they did not undergo any abdominal imaging study within their last 2 years of follow-up. Multivariable models were constructed to identify independent factors associated with being lost to annual imaging follow-up. RESULTS Among 19,962 patients who underwent EVAR, the incidence of loss to annual imaging follow-up at 5 years after EVAR was 50%. Primary factors associated with being lost to annual imaging follow-up were advanced age (age 65-69 years, reference; age 75-79 years: hazard ratio [HR], 1.23; 95% confidence interval [CI], 1.15-1.32; age 80-85 years: HR, 1.45; 95% CI, 1.35-1.55; age >85 years: HR, 2.03; 95% CI, 1.88-2.20) and presentation with an urgent/emergent intact aneurysm (HR, 1.27; 95% CI, 1.20-1.35) or ruptured aneurysm (HR, 1.84; 95% CI, 1.63-2.08). Additional independent factors included several previously diagnosed chronic diseases and South and West regions of the United States. CONCLUSIONS Annual imaging follow-up compliance after EVAR in the United States is significantly below recommended levels. Quality improvement efforts to encourage improved compliance with imaging follow-up, especially in older patients with multiple comorbidities and in those who underwent EVAR urgently or for rupture, are necessary.

Results of second-time angioplasty and stenting for femoropopliteal occlusive disease and factors affecting outcomes

OBJECTIVE Repeat percutaneous endoluminal interventions for femoropopliteal occlusive disease are common, but the outcomes are poorly understood. We sought to determine the results of second-time femoropopliteal percutaneous transluminal angioplasty/stenting (SPTAS) and identify factors associated with success or failure of a continued endoluminal revascularization strategy. METHODS A retrospective review of patients undergoing multiple percutaneous endoluminal lower extremity interventions at a single institution from 2002 and 2009 identified 70 SPTAS in 70 limbs. Patient comorbidities, anatomic severity of disease, and procedural characteristics were analyzed with respect to outcomes with descriptive statistics, Kaplan-Meier curves, and Cox proportional hazards modeling. Patency rates were determined from the time of SPTAS. RESULTS Patients included 37 men (63%) and 22 women (27%) at a mean age of 70 ± 10 years. Indications for SPTAS included claudication in 54 limbs (77%) and critical limb ischemia (CLI) in 16 (23%). Median time from the initial endoluminal intervention to SPTAS was 330 days. Lesion TransAtlantic InterSociety Consensus II (TASCII) classification was A in 18 (25.7%), B in 18 (25.7%), C in 25 (35.7%), and D in 9 (12.9%). Technical success was achieved in 68 (97%) with low rates of intraprocedural (10%) and postprocedural (4%) complications as well as initial clinical improvement in 61 (87%) patients. Over a median follow-up of 22.9 months following SPTAS, 2-year primary patency, secondary patency, limb salvage (in patients with CLI), and survival were 33% ± 7%, 63% ± 7%, 87% ± 9%, and 88% ± 5%, respectively. Cox proportional hazard modeling showed that SPTAS within 180 days of the initial endovascular intervention was the only significant predictor of failure of primary patency (hazard ratio, 2.65; 95% confidence interval, 1.4-5.2) and secondary patency (hazard ratio, 3.1; 95% confidence interval, 1.4-7.1) of SPTAS. CONCLUSIONS Second-time femoropopliteal angioplasty/stenting has excellent technical success but limited midterm primary and secondary patency. Early failure of the initial endovascular intervention strongly predicts poor outcome following SPTAS and in this cohort was more significant than comorbidities, anatomic factors, or procedural characteristics. These data suggest that after early endovascular failure, alternatives to a continued endoluminal strategy should be adopted.

Designation as “Unfit for Open Repair” Is Associated With Poor Outcomes After Endovascular Aortic Aneurysm Repair

BACKGROUND Endovascular aortic aneurysm repair (EVAR) is often offered to patients with abdominal aortic aneurysms (AAAs) considered preoperatively to be unfit for open AAA repair (oAAA). This study describes the short- and long-term outcomes of patients undergoing EVAR with AAAs <6.5 cm who are considered unfit for oAAA. METHODS AND RESULTS We analyzed elective EVARs for AAAs <6.5 cm diameter in the Vascular Study Group of New England (2003-2011). Patients were designated as fit or unfit for oAAA by the treating surgeon. End points included in-hospital major adverse events and long-term mortality. We identified patient characteristics associated with being unfit for open repair and predictors of survival using multivariable analyses. Of 1653 EVARs, 309 (18.7%) patients were deemed unfit for oAAA. These patients were more likely to have advanced age, cardiac disease, chronic obstructive pulmonary disease, and larger aneurysms at the time of repair (54 versus 56 mm, P=0.001). Patients unfit for oAAA had higher rates of cardiac (7.8% versus 3.1%, P<0.01) and pulmonary (3.6 versus 1.6, P<0.01) complications and worse survival rates at 5 years (61% versus 80%; log rank P<0.01) compared with those deemed fit for oAAA. Finally, patients designated as unfit for oAAA had worse survival, even adjusting for patient characteristics and aneurysm size (hazard ratio, 1.6; 95% confidence interval, 1.2-2.2; P<0.01). CONCLUSIONS In patients with AAAs <6.5 cm, designation by the operating surgeon as unfit for oAAA provides insight into both short- and long-term efficacy of EVAR. Patients unable to tolerate oAAA may not benefit from EVAR unless their risk of AAA rupture is very high.