Annals of Vascular Surgery
Volume 22, Issue 2 , Pages 195-199, March 2008

Increased Endovascular Interventions Decrease the Rate of Lower Limb Artery Bypass Operations without an Increase in Major Amputation Rate

Surgical Health Care Group, Veterans Affairs Medical Center, Long Beach, CA & the Department of Surgery, University of California, Irvine

Article Outline

Progression of peripheral vascular disease may lead to major amputations. We sought to understand whether more frequent endovascular angioplasty and stenting in patients with limb-threatening ischemia would affect the number of major amputations. We retrospectively reviewed the effects of implementing more frequent endovascular intervention for the 4 years 2003-2006 at the Veterans Affairs Medical Center in Long Beach, California. During this interval angioplasty became the preferred method for the treatment of infrainguinal vascular disease. Open bypass procedures were performed for patients with limb-threatening ischemia and extensive lesions that could not be treated by angioplasty. Patients were on average 68 ± 1 years, and 96% were male. The patients were 45% active smokers, with 43% diabetics. There was 0% 30-day mortality for both groups over the 4 years. the number of below-the-knee, above-the-knee, and transmetatarsal amputations for fiscal years 2003, 2004, 2005, and 2006 were, 42, 50, 62, and 41, respectively. Concurrently, there has been a reduction in open femoral to popliteal or trifurcation vessel bypasses with 37, 43, 28, and 14 procedures for 2003, 2004, 2005, and 2006. Angioplasty and stenting increased from 12, 12, 24, to 59 over the same period. Patients who had a femoral to distal bypass were more likely to have an amputation than those undergoing angioplasty (odds ratio = 4.2, 95% confidence interval 1.6-11.5) for those with at least 1 year of follow-up, likely due to these patients having more severe disease. Increasing the frequency of angioplasty for infrainguinal vascular lesions did not increase the number of major lower extremity amputations in our stable patient population.

 

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Introduction 

Two recent randomized trials comparing open femoral bypass to percutaneous transluminal angioplasty (PTA) and stenting (S) have shown equivalency between the methods in terms of patency as well as major amputations.1, 2 The Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial randomized patients with critical limb ischemia to open bypass or angioplasty and did not show significant differences in amputation after 5.5 years of follow-up. For patients with severe limb ischemia due to infrainguinal disease, bypass surgery and PTA were associated with similar outcomes in terms of amputation-free survival. However, they found surgery to be more expensive than angioplasty. Other trials comparing surgery and PTA have failed to show a distinction between the interventions. A randomized trial comparing percutaneous stent grafts versus prosthetic femoral-popliteal bypass showed similar patency over 12 months of follow-up. Van der Zaag et al.3 in Amsterdam showed bypass to be superior to PTA, with occlusion occurring more frequently in the PTA group, although the study was underpowered due to the difficulty of recruiting patients to the separate arms of the trial. The similarity in outcome between the two interventions led us to retrospectively analyze our own experience with open femoral bypass procedures and PTA/S of infrainguinal occlusive disease in order to determine if the number of amputations has been affected by our trend of performing PTA/S as the primary intervention. We hypothesized that, as with prior randomized trials comparing the techniques, there would be no change in amputations. We examined all interventions performed over the last 4 years to determine if patients had undergone amputation during the study period.

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Methods 

Study Design 

We conducted a retrospective cohort study using the Veterans Affairs Medical Center in Long Beach, California, computer database Computerized Patient Record System (CPRS). Records of interventions for lower extremity arterial occlusive disease and discharge records were evaluated to assess the frequency of the intervention and outcome of patients undergoing PTA/S and femoral bypass.

Data Source 

Patient records were obtained from CPRS. These data contain records of clinic visits, inpatient consults, operative reports, admission history and physicals, progress notes, and discharge summaries. The database also contains demographic variables and International Classification of Diseases, ninth revision (ICD-9), codes for procedure and diagnosis.

Subjects 

We reviewed records of patients who had been evaluated and treated by the vascular surgery service. Patients were referred to vascular surgery through outpatient clinic visits, inpatient surgery consults, or emergency department visits with severe occlusive disease. Patients were over 18 years old. From fiscal year (FY) 2003 to 2006 we identified 39,466, 40,061, 40,813, and 40,854 unique social security numbers of veterans who received care at our institution. Approximately 1,960 patients were seen annually between 2003 and 2006 in the vascular outpatient clinics.

Analysis 

Amputation codes were identified by ICD-9 codes 27590, 28800, 28805, 27880, 27886, 27884, 27881, 28810, and 27596, which are codes for transmetatarsal, below-the-knee, and above-the-knee amputations. Patients undergoing evaluation had diagnosis by codes for peripheral artery disease, ulceration, claudication, and rest pain. Only patients who had amputations for dysvascular extremities were included; we did not include patients who had amputation for diabetic foot infection without arterial occlusive disease. We excluded PTA/S of the renal and carotid arteries. All vascular procedures were performed by four vascular surgeons, who participated throughout the study period. Radiologists did not perform PTA/S for peripheral vascular disease during the study period. Patient characteristics include sex, age, tobacco use, and diabetic status. Outcomes assessed include length of follow-up, need for reintervention, amputation following intervention, and 30-day mortality. Reinterventions include PTA/S, bypass operations, or amputations. The 30-day mortality was defined as all-cause death within 30 days of the intervention. Patient populations were compared using a Pearson χ2 test and analysis of variance. Statistical analysis was performed using Systat 12 (Systat, San Jose, CA).

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Results 

Our patient population has remained stable over this time, with 40,300 (±300) unique social security numbers each year. Patient characteristics remained unchanged over the 4 years of the study and are typical for vascular surgery patients in the Veterans Affairs Medical Center population: 96% male, 40% current smokers, with 43% having diabetes (Table I). PTA/S for femoral artery occlusive disease became more frequent over the 4 years of our study. PTA/S of the iliac or femoral arteries increased from 12 procedures in FY2003 to 59 in FY2006 (Table II). In contrast, the number of femoral to distal arterial bypass operations decreased from a high of 43 in FY2004 to 14 in FY2006. Other arterial bypass operations, including aortobifemoral, femoral to femoral, and axillary to femoral bypass as well as femoral artery endarterectomy operations, remain largely unchanged. Thirty-day mortality was 0 for both groups over the study period. Average length of follow-up was 710 days ±20 days.

Table I. Characteristics of patients undergoing PTA/S or femoral bypass operations in 2003-2006
Total number of patients170
Total number of procedures228
Age (years)68 ± 1
Male96%
Smokers
Current45%
Nonsmoker20%
Past smoker35%
Diabetics43%
Indication for intervention
PTA/S
Claudication89%
Limb salvage11%
Femoral bypass
Claudication51%
Limb salvage49%
Table II. Angioplasty and stenting procedures compared to femoral to distal arterial bypasses for fiscal year 2003-2006
FY2003FY2004FY2005FY2006
Femoral to distal arterial bypass operations37432814
Revision of femoral to distal arterial bypass operations6741
Diagnostic angiogram1213257
Angioplasty or stent of iliac arteries45618
Angioplasty of femoral arteries871841
Femoral artery endarterectomy3655
Aorta-bifemoral arterial bypass operations2914
Axillary to femoral-femoral arterial bypass operations1413
Femoral-femoral arterial bypass operations1662
Total741009495

Despite increasing numbers of angioplasties and decreasing numbers of femoral bypasses, the number of amputations remained unchanged (Table III). The numbers of major amputations (above-the-knee, below-the-knee, and transmetatarsal) for FY2003, 2004, 2005, and 2006 were 42, 50, 62, and 41, respectively. Patients who had a femoral to distal bypass were more likely to have an amputation than those undergoing angioplasty (odds ratio [OR] = 4.2, 95% confidence interval [CI] 1.6-11.5) for those with at least 1 year of follow-up. Patients with multiple procedures were excluded from the analysis. Diagnostic angiograms varied over the time period but showed a decline in FY2006 to 7 (Table IV). In contrast, computed tomographic (CT) angiograms increased steadily over the period FY2003-2006 from 41 to 101.

Table III. Amputations performed for ischemia for fiscal year 2003 through 2006
AmputationsFY2003FY2004FY 2005FY 2006
Above-the-knee9162111
Below-the-knee21263219
Transmetatarsal128911
Total42506241
Table IV. Diagnostic angiograms and CTA for peripheral vascular disease 2003-2006
AngiogramFY2003FY2004FY2005FY2006
Diagnostic1213257
CTA416385101

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Discussion 

We sought to understand the outcome of our policy of using PTA/S as the first-line treatment for patients with occlusive disease of the arteries of the leg. Patients who had failed conservative management of intermittent claudication caused by superficial femoral artery occlusive disease would be preferentially treated with angioplasty or stenting of these arteries. We counseled patients that angioplasty may not be successful, particularly if the artery had a long complete occlusion or was heavily calcified. The indication for intervention did not change with this new policy. We continue to recommend intervention for patients with limb threat as manifested by lack of demonstrable blood flow to the extremity, rest pain, or ulceration. Intervention for claudication was left to the discretion of the operating surgeon, although each patient was reviewed by the vascular group conference and a joint recommendation was made. In general, we performed PTA/S after patients failed to improve after a trial of medical management and had marked limitations to activities of daily living associated with an ankle-brachial index < 0.6. Our end point was major amputation. Over the 4 years of the study, PTA/S became a more common intervention for all patients with peripheral arterial disease. Femoral to distal bypass remained a common operation, but it was performed in only 30% of patients (14/43) in its peak year of 2004. We attribute the change to several factors. In 2004 the operating rooms at the hospital were reconstructed to include an angiogram suite in the vascular operating room. Vascular surgeons in our department have also become more adept at using angioplasty to treat occlusive disease of the peripheral arteries. Despite the increase in PTA/S and decrease in bypass operations, amputation for patients with peripheral vascular disease has not increased. Other vascular departments have reported similar outcomes with preferential angioplasty with a similar limb salvage of 87% at 2 years.4

Open femoral bypass was associated with more frequent amputations (OR = 4.2, 95% CI 1.6-11.5). We attribute this increase to patient selection as patients undergoing bypass were more likely to have severe ischemia rather than claudication (Table I). Also, femoral bypass operations were common at the early period of our study, and these patients had a longer follow-up with more opportunity for progression of their vascular disease. With our retrospective analysis, we can only describe an association between open bypass and amputation rather than a direct causal relationship. The trend to perform more frequent endovascular interventions in the later years of our study limited the follow-up of patients who received angioplasty. As patient follow-up increases, we may find that PTA/S subsequently affects amputation.

In the past, PTA/S had technical limitations that limited its application to extensive arterial occlusive disease. Open bypass operations were used to treat those patients who were PTA/S technical failures. However, vascular surgeons have many recent published series showing improved outcomes with PTA/S for severe infrainguinal occlusive disease. We have previously reported patencies following transluminal stenting of femoropopliteal occlusions using contrast angiograms. Secondary patency was 89% and 55% at 12 and 36 months, respectively.5 PTA/S as primary therapy of femoropopliteal occlusive disease has been recently reported with favorable patency.6, 7 Reports that include patients who have rest pain/gangrene show 58% 1-year patency.8 Long lesions of stenosis or complete occlusions can be traversed using a subintimal approach in which the wire is not advanced through the true lumen of the vessel but rather in the subintimal wall of the vessel.9 Long lesions (>20 cm) represent a technical challenge, although reports of successful treatment have been published.10 Lenti et al.11 report treating longer lesions of the superficial femoral artery with polytetrafluoroethlene-covered stents with 59% 2-year patency. Factors that affect patency of the subintimal angioplasty include the number of patent run-off crural vessels and the length of the occlusion.12 Patency of long segment disease treated by subintimal PTA/S at 3 years ranges 18-57%.13, 14 Popliteal arteries represent a unique challenge as they require flexible stents adjacent to the knee joint. Stent fractures have been reported.15 Recently published patency for 54 patients who had angioplasty of the popliteal artery was considered satisfactory.16

The increase in PTA/S is likely due to more aggressive treatment of claudication. Trans-Atlantic InterSociety Consensus (TASC) treatment guidelines for PTA/S depend on the location and severity of the stenosis, as well as patient symptoms. Because patency is good for both PTA/S and bypass, PTA/S for critical limb ischemia manifested by ulcer or rest pain can be effective, with a limb salvage rate of 89% at 5 years.17 Tefera et al.18 also reported a series of patients who were poor surgical candidates as demonstrated by absent distal target vessels or severe comorbid conditions, and they were able to achieve limb salvage of 84% at 3 years. Vogel et al.19 described a dramatic increase of PTA for claudication over the past 8 years, with PTA use nearly doubling between 1997 and 2004 for the entire population of Washington State residents. Unadjusted outcomes show readmission (30-day) of 10% for claudicants and 23% for other diagnoses, which is higher than that of the BASIL trial's 7% reintervention rate. Vogel et al. describe claudication as the primary diagnosis for patients undergoing PTA, who were also younger and healthier than patients undergoing femoral to distal bypass. Recent published series show claudication as a common indication for angioplasty, ranging 44-66% of patients undergoing PTA/S.20, 21 The minimally invasive nature of angioplasty and its relatively minimal morbidity may lead interventionalists to more frequently apply it to earlier claudication, despite the recommendations of medicine and exercise as the primary therapy.22, 23, 24 Aggressive treatment for claudication with open bypass is not endorsed by the TASC, although Berglund et al.,25 using the Swedish Vascular Registry, reported that claudication was the indication for 44% of open bypass procedures.

Diagnostic angiograms for peripheral vascular occlusive disease decreased during our study interval from a high of 25 in 2005 to 7 in 2006. The change in our practice is due to our early favorable experience with CT angiography (CTA) for arterial disease and the acquisition of a 64 detector CT scanner in 2003. The scanner has sufficient resolution to develop three-dimensional images of the extremity arteries. We have found that CTA is adequate to plan operative intervention with the advantages of noninvasive access and the ability to assess three-dimensional structure via reconstructed images. In contrast to a catheter angiogram, CTA employs a single contrast bolus and brief scan that subject the patient to less contrast and radiation exposure.26 It is also less expensive.27 The 64-channel CT identifies submillimeter vessels through the plantar arch.28 The increased heat capacity of scanners allows acquisition of 16 slices with one gantry rotation in 500 ms.29 A single contrast bolus can be sufficient to capture images from diaphragm to the ankles. Slice thickness is typically 1 mm. Contrast dye continues to pose a risk for renal injury. However, the shorter scan times permit smaller doses of contrast. Eighty to 150 mL of non-ionic iodinated contrast are typically administered via an upper extremity intravenous catheter.30 Our current practice is to use CTA as the operative “map” after an initial patient visit with history, physical, and abnormal ankle-brachial indices and reserve catheter angiography for intraoperative imaging during endovascular procedures.

In conclusion, increasing the frequency of angioplasty for infrainguinal vascular lesions did not increase the number of major lower extremity amputations in our stable patient population.

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References 

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PII: S0890-5096(08)00003-4

doi:10.1016/j.avsg.2007.12.002

Annals of Vascular Surgery
Volume 22, Issue 2 , Pages 195-199, March 2008

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