Abstract
Background:
There is currently no positive opinion regarding infrapopliteal revascularization for intermittent claudication (IC) in any guidelines. The aim of this study was to analyze the outcomes of infragenicular bypass and verify the adequacy of tibial artery bypass for IC.
Methods and Results:
Over a 21-year period, 58 below-knee popliteal artery (BKPOP) bypasses and 35 tibial artery bypasses were performed for IC caused by arteriosclerosis obliterans. Graft patency and major amputation (MA) were examined as primary endpoints and the predictor of each outcome was estimated by multivariate analysis. The primary patency (PP), secondary patency (SP), and freedom from MA (ffMA) rates of a prosthetic/vein graft in all cases at 5 years were 19/68%, 22/86%, and 78/100% (P<0.01 in all). Limited to vein graft cases, PP and SP rates of popliteal/tibial bypass at 5 years were 73/62% (P=0.32) and 92/80% (P=0.22), respectively. In tibial artery bypass with a vein graft, the PP and SP rates of a single saphenous vein/spliced vein graft at 5 years were 71/46% (P=0.11) and 89/61% (P=0.03). A prosthetic graft was a common negative predictor for graft patency and MA by multivariate analysis.
Conclusions:
Tibial artery bypass is an acceptable treatment option for IC when a single saphenous vein can be harvested as a graft conduit.
In recent clinical settings, the development and evolution of catheter-based technology has made recanalization possible in almost all cases of peripheral artery disease and, as a result, endovascular therapy (EVT) is widely performed regardless of the lesion classification. Several guidelines have described recommendations regarding the role of EVT and surgical bypass according to the lesion characteristics and runoff quality, and the comorbidity and life expectancy of the patient.1–4
Although infrapopliteal revascularization by either method is recommended for critical limb ischemia (CLI),1–3
there is no clear-cut guideline for intermittent claudication (IC).
The Society for Vascular Surgery (SVS) practice guidelines for IC4
recently applied the recommendation of Grade 1 to surgical bypass as an initial revascularization strategy for patients with complicated femoropopliteal (FP) disease if the patient has favorable anatomy for bypass, such as a popliteal artery target with good runoff. Although EVT is not recommended for isolated infrapopliteal disease,4
there is no recommendation with respect to surgical revascularization for IC caused by infrapopliteal disease with or without continuity to FP disease. If the result of bypass with a tibial artery target is equivalent to that of a popliteal artery target, then there is no hesitation for surgical bypass to the tibial arteries. Only 2 reports have demonstrated the long-term results of tibial artery bypass for IC.5,6
The aim of this study, the first English report regarding tibial artery bypass for IC in Japan, is to review the results of infragenicular bypasses targeting the below-knee popliteal (BKPOP) and tibial artery and consider the reasonable indications for tibial artery bypass as a strategy for IC.
Methods
Patients
The first author (S.M.) experienced 115 infragenicular bypasses (BKPOP in 64, tibial artery in 51) as the operator or an assistant from April 1994 to March 2015 at 2 institutions (85 bypasses: April 1994–March 2007; April 2011–March 2015 in Steel Memorial Yawata Hospital; 30 bypasses: April 2007–March 2011 in Kokura Memorial Hospital, Kitakyushu-city). The clinical records of patients were prospectively collected in a database and retrospectively analyzed.
The following data were selected as predictors from the database: age, sex, pre- and postoperative ankle-brachial pressure index (ABI), etiology of chronic arterial occlusion, preoperative complications or past history such as previous revascularization (EVT or surgical bypass) in the ipsilateral infrainguinal artery, hypertension (HT), diabetes mellitus (DM), coronary artery disease (CAD), chronic obstructive pulmonary disease (COPD), stroke, endstage renal disease (ESRD), dyslipidemia, self-reported previous smoking history, malignancy, graft material, inflow artery, distal target artery, and postoperative prescription at discharge.
Endpoints
Graft patency and major amputation (MA) were primary endpoints and major adverse limb events (MALE) and early postoperative complications were secondary endpoints.
Patients with chronic arterial occlusion because of arteriosclerosis obliterans (ASO) were selected for analysis. The numbers of limbs and grafts for analysis were 90 and 93, respectively. The graft patency rate was estimated for 93 bypass grafts and freedom from MA (ffMA) and freedom from MALE (ffMALE) were calculated for 90 limbs. Three patients underwent infragenicular bypass twice in 1 limb because of occlusion of the first bypass graft. The data for these 3 limbs with a second bypass were omitted from the analysis of the limbs.
Long-Term Outcomes
With all cases as subjects, graft patency, ffMA, and ffMALE were calculated for a prosthetic graft vs. a vein graft. With vein grafts as subjects, graft patency and ffMALE were calculated for BKPOP vs. tibial artery bypass. With tibial artery bypasses using a vein graft as subjects, graft patency and ffMALE were calculated for a single saphenous vein vs. a spliced vein graft (Figure 1).
Risk Factor Assessment
The relative risk of the predictors, except for etiology, was calculated. Age and ABI were calculated as continuous variables; the hazard ratio of age and ABI was measured per 10 years and 0.1, respectively. Graft material was divided into 3 groups: a single saphenous vein vs. a spliced vein vs. a prosthetic graft including a composite graft and a sequential bypass graft using a prosthetic graft and a vein. The inflow artery was divided into 2 groups: external iliac or common femoral artery vs. superficial or deep femoral or popliteal artery. The distal target artery was divided into 2 groups: BKPOP vs. tibial artery. Postoperative prescriptions included cilostazol, aspirin, clopidogrel or ticlopidine, sarpogrelate, eicosapentaenoic acid (EPA), beraprost or limaprost, warfarin, statin, calcium-channel blocker, β-blocker, and angiotensin-II receptor blocker (ARB) or angiotensin-converting enzyme inhibitor (ACEI).
Strategy for IC
The initial strategy for IC caused by infrainguinal disease was surgical treatment if the patient suffered from lifestyle-limiting claudication even after 3–6 months of conservative therapy with medication and exercise and then desired improvement of IC by sequential potential treatment. Cases of short lesions suitable for EVT, without an available vein as an arterial conduit or an adequate target artery for bypass, were excluded. As the target, the tibial artery with best runoff to the foot was selected, and if the condition of runoff was equivalent, then the posterior tibial artery was selected. Until March 1998, a prosthetic graft was frequently used in patients with BKPOP target according to the policy of the then chief vascular surgeon. During that period, externally supported knitted Dacron (EXS) grafts were used in 13 of 16 BKPOP bypasses. Thereafter, the use of a prosthetic graft was restricted to patients without an available vein. The ipsilateral great saphenous vein was initially harvested, but if not possible, then the contralateral great saphenous vein or bilateral lesser saphenous vein was used. Although the criterion of vein diameter for use was ≥3.5 mm for BKPOP bypass and ≥3 mm for tibial artery bypass, the final decision of vein availability was made by the attending doctor who became the operator. The deep vein or arm vein was not used for IC. Direct bypass to the tibial artery using a prosthetic graft was not performed. When the length of an available vein was not adequate, sequential FP-tibial bypass was performed using a composite of a prosthetic graft in the FP artery section and a vein in the popliteal-tibial artery section.
Postoperative medication with antithrombotic or anticoagulant agents was determined by each attending doctor and continued permanently unless side effects were observed.
Surveillance
The patients were followed at regular intervals of 1–3 months until 2 years after discharge and at regular intervals of 3–6 months thereafter. Until March 2007, pulsation of the arteries in the lower leg and ABI were examined. Angiography was recommended if the ABI became lower than the previous data by more than 0.15, without recovery at reexamination after 1 month, or pulsation on the graft was felt to be remarkably weaker. Since April 2007, evaluation using duplex ultrasonography was added as long as the bypass graft was working. Graft patency was objectively determined by pulsation of the graft itself or with duplex ultrasonography by clinical vascular technicians who were blinded to the patient information except with regard to the bypass site. Patients who could not visit the institution were interviewed on the phone, at least annually, to confirm the situation. When obvious stenosis with a peak systolic velocity >300–350 cm/s or velocity ratio >3.0–3.5 was detected by duplex ultrasonography, revision surgery was actively recommended. Percutaneous transluminal angioplasty with a cutting balloon was selected as the first strategy for revision. Redo surgery was performed when recurrence of the ischemic symptoms after graft failure made the patient so uncomfortable that sequential revascularization was requested.
A final review was conducted from January to February 2016 and the data up to 5 years were analyzed.
Definitions
HT was defined as systolic blood pressure >140 mmHg or diastolic blood pressure >90 mmHg, both, or ongoing therapy for HT. DM was defined as fasting blood glucose >105 mg/dl or ongoing therapy for DM with an oral hypoglycemic agent or insulin injection. CAD was defined as a history of angina pectoris, myocardial infarction, percutaneous coronary intervention, or coronary artery bypass grafting. Stroke was defined as a history of transient ischemic attack, cerebral infarction, or cerebral bleeding. COPD was defined as the percent of forced expiratory volume in 1 s <70%. ESRD was defined as hemodialysis or peritoneal dialysis. Dyslipidemia was defined as fasting total cholesterol >220 mg/dl, triglycerides >207 mg/dl in males or >137 mg/dl in females or both with or without ongoing therapy for dyslipidemia. Malignancy was defined as a history of any treatment for cancer. Early graft failure was defined as loss of primary patency (PP) within 30 days after surgical bypass. PP was defined as uninterrupted duration of patency without any intervention, assisted PP was defined as duration of patency with any intervention to protect patency before graft occlusion, and secondary patency (SP) was defined as duration of patency with any intervention to protect patency before or after graft occlusion.7
MA was defined as loss of the leg above the ankle. MALE was defined as MA or major reintervention including a new bypass graft, jump/interposition graft revision, or thrombectomy/thrombolysis related to the target lesion.
Statistical Analysis
Comparisons of the categorical and continuous variables were performed using Fisher’s exact test and Student’s t-test, respectively. Survival curves were calculated by Kaplan-Meier method and evaluated by the log-rank test. To determine the relative risk of each variable, a multivariate analysis was performed with variables that reached P<0.1 in a univariate analysis by Cox proportional hazard analysis. P<0.05 was considered to be significant. All statistical analyses were performed using JMP version 11.2 software program for Mac (SAS Institute, Cary, NC, USA).
Results
Etiology
The etiology of chronic arterial occlusion requiring bypasses to the BKPOP and tibial artery was ASO in 58 bypasses of 56 limbs and 35 bypasses of 34 limbs (which were the subjects for analysis in this study), Buerger’s disease in 1 and 2, occluded popliteal artery aneurysm in 4 and 4, and unknown disease showing no typical findings of arteriosclerosis on angiography or an enhanced CT scan without any definite cause of chronic arterial occlusion in 1 and 6, respectively. In addition, the etiology of tibial artery bypass included a chronic state of acute arterial occlusion, vascular injury, collagen disease, or occlusion of residual sciatic artery in 1 case each.
Baseline Characteristics
The preoperative properties, operative information, and postoperative medications of 93 bypass graft patients, who were divided into 2 groups with BKPOP target or tibial artery target, are summarized in
Table 1. The proportion of males was significantly higher in the tibial artery bypass group than in the BKPOP bypass group (P<0.01). The preoperative complication rate of HT (P<0.01) and DM (P=0.01), use of a prosthetic graft (P<0.01), and external iliac or common femoral artery as the inflow artery (P<0.01) were significantly higher in the BKPOP bypass group than in the tibial artery bypass group. There was no significant difference in any other properties.
Table 1.
Demographic and Clinical Characteristics of the Study Patients With Intermittent Claudication
| |
Tibial artery (n=35) |
BKPOP (n=58) |
P value |
| Age (years) |
72.0±8.3 (55–88) |
71.8±7.4 (50–86) |
NS |
| Sex, male |
32 (91%) |
39 (67%) |
<0.01 |
| De novo revascularization |
23 (66%) |
37 (64%) |
NS |
| Redo bypass |
8 (23%) |
15 (26%) |
NS |
| Preoperative ABPI* |
0.46±0.25 (0–1.02) |
0.38±0.27 (0–0.86) |
NS |
| HT |
19 (54%) |
47 (81%) |
<0.01 |
| DM |
12 (34%) |
35 (60%) |
0.01 |
| CAD |
15 (43%) |
29 (50%) |
NS |
| COPD |
6 (17%) |
7 (12%) |
NS |
| Stroke |
5 (14%) |
14 (24%) |
NS |
| ESRD |
4 (11%) |
10 (17%) |
NS |
| Malignancy |
2 (6%) |
8 (14%) |
NS |
| Dyslipidemia |
8 (23%) |
19 (33%) |
NS |
| History of smoker |
22 (63%) |
35 (60%) |
NS |
| Postoperative ABPI** |
1.03±0.40 (0.61–1.92) |
0.94±0.30 (0.44–1.38) |
NS |
| Operation |
| Graft |
| Vein |
33 (94%) |
38 (66%) |
<0.01 |
| Single saphenous vein |
22 (63%) |
30 (52%) |
|
| In situ |
1 |
7 |
|
| Non-reversed |
6 |
14 |
|
| Reversed |
15 |
9 |
|
| Spliced vein |
11 (31%) |
8 (14%) |
|
| Prosthesis |
2 (6%) |
20 (34%) |
|
| Prosthetic graft |
0 |
20 |
|
| EXS |
0 |
13 |
|
| ePTFE+ |
0 |
6 |
|
| Composite graft++ |
2 |
1 |
|
| Proximal anastomosis |
| External iliac artery |
0 (51%) |
2 (88%) |
<0.01 |
| Common femoral artery |
18 |
51 |
|
| Deep femoral artery |
0 |
0 |
|
| Superficial femoral artery |
8 |
5 |
|
| Above-knee popliteal artery |
6 |
0 |
|
| Below-knee popliteal artery |
3 |
0 |
|
| Distal anastomosis |
| Below-knee popliteal artery |
|
58 |
|
| Tibioperoneal trunk |
4 |
|
|
| Anterior tibial artery |
6 |
|
|
| Posterior tibial artery |
20 |
|
|
| Peroneal artery |
5 |
|
|
| Postoperative medication |
| Cilostazol |
17 (49%) |
18 (31%) |
NS |
| Aspirin |
8 (23%) |
18 (31%) |
NS |
| Ticlopidine/clopidogrel |
9 (26%) |
14 (24%) |
NS |
| Sarpogrelate |
4 (11%) |
9 (16%) |
NS |
| EPA |
8 (23%) |
22 (38%) |
NS |
| Beraprost/limaprost |
8 (22%) |
9 (16%) |
NS |
| Warfarin |
18 (51%) |
26 (45%) |
NS |
| Statin |
4 (11%) |
13 (22%) |
NS |
| Calcium-channel blocker |
11 (31%) |
16 (28%) |
NS |
| β-blocker |
2 (6%) |
5 (7%) |
NS |
| ARB/ACEI |
10 (29%) |
16 (28%) |
NS |
*Preoperative ABPI was measured in 29 of tibial artery and 55 of BKPOP cases. **Postoperative ABPI was measured in 29 of tibial artery and 51 of BKPOP cases. +Linton patch in 2, Miller cuff in 1 at distal anastomosis. ++Femoro-BKPOP bypass with ePTFE and BKPOP-peroneal artery or BKPOP-posterior tibial artery with a vein in 1 each in tibial artery bypass, femoro-BKPOP bypass with ePTFE and a vein in BKPOP. ABPI, ankle-brachial pressure index; ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin-II receptor blocker; BKPOP, below-knee popliteal artery; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; EPA, eicosapentaenoic acid; ePTFE, expanded polytetrafluoroethylene; ESRD, endstage renal disease; EXS, externally supported knitted Dacron graft; HT, hypertension.
Prosthetic Graft vs. Vein Graft in All Cases
The 1- and 5-year PP, assisted PP, and SP rates of a prosthetic graft were 62.2% and 19.4%, 62.2% and 19.4%, and 71.6% and 21.8%, respectively, and those of a vein graft were 73.6% and 67.7%, 87.9% and 83.5%, 89.6% and 85.7%, respectively. (Figures 2A–C) The 1- and 5-year ffMA rates in a prosthetic graft were 89.5% and 77.5%, respectively, and no MA was performed in a vein graft. In 3 patients with BKPOP bypass and 1 with tibial artery bypass, a below-knee amputation was performed. The respective rates of ffMALE in a prosthetic graft and a vein graft were 79.2% and 94.3% at 1 year and 44.8% and 92.2% at 5 years (Table 2). There were significant differences in all outcomes between prosthetic and vein grafts.
Table 2.
Rates of ffMA and MALE in Patients With Intermittent Claudication by Kaplan-Meier Method
| |
1 year |
2 years |
3 years |
4 years |
5 years |
P value |
| Freedom from MA |
|
|
|
|
|
<0.01 |
| Prosthesis (n=20) |
89.5±7.0% (n=17) |
89.5±7.0% (n=16) |
77.5±10.0% (n=12) |
77.5±10.0% (n=11) |
77.5±10.0% (n=10) |
|
| Vein (n=70) |
100±0% (n=62) |
100±0% (n=57) |
100±0% (n=47) |
100±0% (n=38) |
100±0% (n=33) |
|
| Freedom from MALE |
| All grafts |
|
|
|
|
|
<0.01 |
| Prosthesis (n=20) |
79.2±9.3% (n=16) |
58.1±11.3% (n=12) |
52.3±11.6% (n=9) |
52.3±11.6% (n=8) |
44.8±12.1% (n=6) |
|
| Vein (n=70) |
94.3±5.7% (n=59) |
94.3±5.7% (n=54) |
92.2±7.8% (n=43) |
92.2±7.8% (n=36) |
92.2±7.8% (n=30) |
|
| Vein grafts |
|
|
|
|
|
0.78 |
| BKPOP (n=38) |
94.7±3.6% (n=32) |
94.7±3.6% (n=29) |
90.6±5.3% (n=22) |
90.6±5.3% (n=17) |
90.6±5.3% (n=12) |
|
| Tibial artery (n=32) |
93.8±4.3% (n=28) |
93.8±4.3% (n=26) |
93.8±4.3% (n=22) |
93.8±4.3% (n=20) |
93.8±4.3% (n=18) |
|
| Tibial artery bypass with vein graft |
|
|
|
|
|
0.047 |
| Single (n=21) |
100±0% (n=20) |
100±0% (n=19) |
100±0% (n=16) |
100±0% (n=16) |
100±0% (n=14) |
|
| Spliced (n=11) |
81.8±11.6% (n=9) |
81.8±11.6% (n=8) |
81.8±11.6% (n=7) |
81.8±11.6% (n=5) |
81.8±11.6% (n=4) |
|
ffMA, freedom from major amputation; MALE, major adverse limb event.
Tibial Artery Target vs. BKPOP Target in Cases of Vein Graft
The 1- and 5-year PP, assisted PP, and SP rates of tibial artery bypass were 65.8% and 62.0%, 80.7% and 76.2%, and 84.0% and 79.8%, respectively, and those of BKPOP bypass were 80.8% and 73.1%, 94.7% and 90.9%, 94.6% and 91.2%, respectively (Figures 3A–C). The respective rates of ffMALE of the tibial artery and BKPOP bypass were 93.8% and 94.7% at 1 year and 93.8% and 90.6% at 5 years (Table 2). There was no significant difference in any long-term outcomes between tibial artery and BKPOP bypass.
Single Saphenous Vein vs. Spliced Vein Graft in Tibial Artery Bypass
The 1- and 5-year PP, assisted PP, and SP rates of a single saphenous vein graft were 76.6% and 70.7%, 95.0% and 88.2%, and 95.2% and 88.9%, respectively. In a spliced vein graft, the 1–5-year PP, assisted PP, and SP rates were 45.5%, 52.0%, and 60.6%, respectively. There was no significant difference in the PP rate, whereas there was a significant difference in the assisted PP and SP rates (Figures 4A–C). The respective rates of ffMALE of a single saphenous vein graft and spliced vein graft were 100% and 81.8% at 1 and 5years, which was significantly different (Table 2).
Morbidity and Mortality
An 82-year-old patient, who underwent femoro-anterior tibial artery bypass with a spliced vein graft, died of multiple organ failure (MOF) on postoperative day 18 following acute coronary syndrome, and another patient, aged 78 years, with BKPOP target died of sepsis following infection of the prosthetic graft on postoperative day 140. The rates of operative death within 30 days after surgery were 3% and 0% and that of in-hospital death were 3% and 2% in tibial artery bypass and BKPOP bypass, respectively. A total of 8 (23%) tibial artery bypasses had local complications (arteriovenous shunt, lymphorrhea, wound infection, hematoma, and neuropathy in 1 case each) in 5 procedures and general complications (MOF in 1, delirium in 2) in 2 procedures, including 2 early graft failures. In 20 (34%) BKPOP bypasses there were 11 local complications (lymphorrhea, skin necrosis in 3 each; peroneal nerve paralysis, bone fracture, arteriovenous shunt, graft infection, and hematoma in 1 each) in 11 procedures, or general complications (gastrointestinal tract in 3, lung or delirium in 2 each, heart or kidney in 1 each) in 9 procedures, including 4 early graft failures. One patient with BKPOP bypass underwent early redo bypass for graft occlusion and 5 patients (2 tibial artery bypasses, 3 BKPOP bypasses) underwent revision surgery to maintain graft patency. There was no significant difference in the mortality or morbidity between the tibial artery and BKPOP bypass groups.
Relative Risk of Perioperative Properties for Each Outcome
A prosthetic graft was a significant independent risk factor for all long-term outcomes (P<0.01 for a saphenous vein graft in all outcomes, P=0.02 for a spliced vein graft in ffMA, P<0.01 for a spliced vein graft in ffMALE). Malignancy was another significant predictor of secondary graft patency (P=0.02). For MA, the preoperative ABI (P=0.03) and history of smoking (P<0.01) were positive predictors whereas dyslipidemia (P<0.01) and ARB/ACEI (P=0.04) were negative predictors (Table 3).
Table 3.
Predictors of Graft Patency and ffMA and MALE in Patients With Intermittent Claudication
| Variable |
Univariate |
Multivariate |
| HR |
95% CI |
P value |
HR |
95% CI |
P value |
| Primary patency |
| Redo bypass |
1.93 |
0.95–3.74 |
0.07 |
0.96 |
0.32–3.23 |
0.94 |
| Previous revasc. |
1.87 |
0.97–3.58 |
0.06 |
1.78 |
0.55–4.90 |
0.32 |
| Malignancy |
2.51 |
0.85–5.98 |
0.09 |
2.72 |
0.90–6.76 |
0.07 |
| Bypass graft |
| Pro. vs. saph. |
3.48 |
1.67–7.39 |
0.01 |
3.77 |
1.74–8.44 |
<0.01 |
| Pro. vs. spli. |
2.06 |
0.90–5.10 |
0.09 |
2.11 |
0.91–5.32 |
0.08 |
| Spli. vs. saph. |
1.69 |
0.69–4.01 |
0.26 |
1.79 |
0.70–4.30 |
0.21 |
| Assisted primary patency |
| Redo bypass |
2.21 |
0.97–4.81 |
0.06 |
1.90 |
0.77–4.49 |
0.16 |
| Malignancy |
3.06 |
0.88–8.18 |
0.07 |
4.12 |
1.11–12.6 |
0.36 |
| Bypass graft |
| Pro. vs. saph. |
9.90 |
3.86–30.4 |
<0.01 |
8.66 |
2.61–34.2 |
<0.01 |
| Pro. vs. spli. |
3.31 |
1.29–10.2 |
<0.01 |
2.07 |
0.70–7.16 |
0.19 |
| Spli. vs. saph. |
2.99 |
0.83–10.8 |
0.29 |
4.19 |
1.11–15.9 |
0.04 |
| Inflow (EIA/CFA) |
3.01 |
1.04–12.7 |
0.04 |
1.16 |
0.22–4.94 |
0.84 |
| Warfarin |
2.05 |
0.93–4.82 |
0.07 |
1.03 |
0.41–2.64 |
0.96 |
| β-blocker |
1.8e−9 |
0.86–0.86 |
0.04 |
1.6e−9 |
2.0e−308–1.57 |
0.10 |
| ARB/ACEI |
0.31 |
0.07–0.89 |
0.03 |
0.51 |
0.12–1.69 |
0.31 |
| Secondary patency |
| Malignancy |
2.81 |
0.81–7.56 |
0.095 |
5.15 |
1.33–17.1 |
0.02 |
| Bypass graft |
| Pro. vs. saph. |
9.60 |
3.70–29.7 |
<0.01 |
9.25 |
2.63–38.8 |
<0.01 |
| Pro. vs. spli. |
4.18 |
1.50–14.8 |
<0.01 |
2.43 |
0.79–9.50 |
0.13 |
| Spli. vs. saph. |
12.3 |
0.57–8.68 |
0.23 |
3.80 |
0.89–15.3 |
0.07 |
| Inflow (EIA/CFA) |
2.67 |
0.92–11.3 |
0.07 |
1.19 |
0.22–5.24 |
0.82 |
| Warfarin |
2.30 |
1.01–5.68 |
0.047 |
1.25 |
0.51–3.32 |
0.64 |
| β-blocker |
1.9e−9 |
0.87–0.87 |
0.04 |
1.8e−9 |
0–2.24 |
0.16 |
| ARB/ACEI |
0.21 |
0.03–0.71 |
<0.01 |
0.39 |
0.06–1.41 |
0.17 |
| Freedom from MA |
| Pre. ABPI (/0.1) |
0.66 |
0.36–1.00 |
0.05 |
0.46 |
0.00–0.94 |
0.03 |
| Dyslipidemia |
1.2e−9 |
1.45–1.45 |
0.09 |
9.6e−12 |
0–0.32 |
<0.01 |
| Smoking history |
1.1e+9 |
1.06–1.06 |
0.04 |
1.1e+11 |
4.28– |
<0.01 |
| Bypass graft |
| Pro. vs. saph. |
7.6e+9 |
4.32–13.6 |
<0.01 |
1.2e+12 |
6.95– |
<0.01 |
| Pro. vs. spli. |
7.6e+9 |
1.68–4.49 |
0.02 |
3.5e+11 |
1.62– |
0.02 |
| Spli. vs. saph. |
1.00 |
0– |
1.00 |
3.51 |
0– |
1.00 |
| Inflow (EIA/CFA) |
2.67 |
0.92–11.3 |
0.07 |
4.5e+8 |
0.28– |
1.00 |
| ARB/ACEI |
1.2e−9 |
1.45–1.45 |
0.09 |
|
|
0.04 |
| Freedom from MALE |
| Post. ABPI (/0.1) |
0.67 |
0.46–0.94 |
0.02 |
0.70 |
0.44–1.03 |
0.07 |
| Redo bypass |
3.31 |
1.20–8.62 |
0.02 |
1.47 |
0.40–5.11 |
0.53 |
| Bypass graft |
| Pro. vs. saph. |
14.4 |
3.80–94.1 |
<0.01 |
12.5 |
2.48–128 |
<0.01 |
| Pro. vs. spli. |
3.52 |
1.01–15.8 |
0.04 |
10.4 |
1.81–199 |
<0.01 |
| Spli. vs. saph. |
4.10 |
0.67–31.2 |
0.12 |
1.20 |
0.05–13.9 |
0.89 |
| Inflow (EIA/CFA) |
5.39 |
1.08–97.7 |
0.04 |
1.88 |
0.08–23.0 |
0.64 |
CFA, common femoral artery; CI, confidence interval; EIA, external iliac artery; HR, hazard ratio; MA, major amputation; post., postoperative; pre., preoperative; pro., prosthetic graft; saph., saphenous vein graft; spli., spliced vein graft. Other abbreviations as in Tables 1,2.
Discussion
No significant difference between tibial artery and BKPOP bypass was demonstrated for early and long-term outcomes, and the strong negative predictor for all long-term outcomes was a prosthetic graft. No patients with infragenicular bypass using a vein graft lost the limb even after graft occlusion. It is well known that the long-term patency of a prosthetic graft to BKPOP is poor,8,9
which was reconfirmed in this study. These results suggested that a prosthetic graft should not be readily used as an arterial conduit for infragenicular bypass in patients with IC.
In contrast, the long-term patency of FP bypass with a vein graft has been reported as acceptable, regardless of above- or below-knee popliteal artery target.5,10,11
However, with respect to tibial artery bypass for IC, there are only 2 reports of the long-term results.5,6
Byrne et al reported 5-year patency rates of 79% for primary and 83% for SP after surgical bypass with a vein graft5
and Conte et al reported 5-year patency rates of 81% for PP and 86% for SP after surgical bypass.6
No operative death or MA was described in either report. The long-term patency of tibial artery bypass in those reports5,6
was equivalent to those of bypass with a more proximal artery taget.12
The PP and SP rates of a vein graft in the present study were 62% and 80%, respectively, at 5 years, which was markedly inferior to the previous reports. In the subanalysis of tibial artery bypass, the patency of the spliced vein graft was much lower than that of the single saphenous vein graft, which has been previously reported.13,14
In the present study, one-third of tibial artery bypasses with a vein graft cases were performed using a spliced vein graft, which greatly decreased the patency rate of the vein graft. The percentage of composite grafts with a vein in the report of Conte et al was 2.7%,6
and Byrne et al5
reported that 70% in-situ vein grafts and 30% excised vein grafts were used in their study. The primary and SP rates of a single saphenous vein graft in the present study were 71% and 89%, respectively at 5 years. Although a policy of early revision for a failing graft decreases the PP rate, it maintains a higher SP rate. Together with these results, the present study might provide insight into the indications for tibial artery bypass for IC.
The goal of IC treatment is extension of the claudication distance followed by an improvement in the patient’s quality of life (QOL). Exercise training, especially supervised exercise training, is recommended for patients with IC caused by chronic peripheral arterial occlusive disease with Level of Evidence A.15
However, in the real-world clinical settings in Japan, supervised exercise training is difficult to continue and self-exercise training with pharmacotherapy is encouraged in most cases. If such medical therapy fails to improve IC, then patients require another strategy with a more apparent effect. Revascularization of the occluded artery certainly ameliorates limb ischemia leading to elongation of IC. Because the natural history of a patient or a limb with IC is much better than with that of CLI,16
durability of the revascularized vessel is essential to achieve the goal of IC treatment.
EVT is typically performed even for complicated lesions such as TASC II C or D in the FP artery. Aihara et al reported that surgical bypass is superior to EVT regarding PP and is equivalent in SP,17
and Soga et al also demonstrated the superiority of surgical bypass in reintervention, MALE, and restenosis except for reocclusion,18
which was equivalent to EVT. EVT is often repeated to maintain patency and, in some cases, multiple revision procedures are required and finally lead to CLI.19
This vicious cycle can degrade the patient’s QOL and might result in limb loss with an otherwise good prognosis. Accordingly, it is important to maintain patency without multiple revision procedures and stabilize ischemia even after a failure of revascularization. Although a variety of newly developed devices, such as interwoven stents, drug-eluting stents (DES), covered stents, bioabsorbable stents, and drug-coated balloons, are currently available for FP disease,20
the estimated effectiveness of these devices for IC is premature because the observation terms has been too short. When focusing on infrapopliteal disease, there are very few reports regarding EVT for IC. Krankenberg et al reported a 1-year PP rate of 66% following balloon angioplasty to the infrapopliteal artery for IC.21
Rastan et al,22
in a prospective randomized trial of a DES vs. a bare-metal stent (BMS) for the treatment of infrapopliteal disease, demonstrated the superior results of the DSE at 1 year (PP: 85% in DES vs. 55% in BMS, target lesion revascularization: 6% in DES vs. 20% in BMS). The PP rates, except for the DES, were far from satisfactory, and the duration of observation was too short to be conclusive. The fact that over 70% of patients with IC have a life expectancy of 5 years16
should not be overlooked in the analysis of patients with IC. The root of the problem is the clinical significance of EVT for infrapopliteal disease, because isolated infrapopliteal disease does not present with symptoms of IC in most cases.
Surgical bypass occasionally causes postoperative complications especially in the operative wound, which extends hospitalization. In the present study, local complications, including wound complications, were encountered in 14% of tibial artery bypass procedures. One of the primary reasons to avoid open surgery is longer hospitalization. However, for patients with IC who need revascularization, durability is more important than less invasiveness at operation. The SVS guideline showed that EVT for infrapopliteal disease for IC is possibly harmful with an unproven benefit,4
and Gasper et al insisted that it may be a contraindication.23
Therefore, it must be stressed that tibial artery bypass is an important strategy, especially for patients with lifestyle-limiting IC. It is unnecessary to avoid surgical bypass to preserve the saphenous vein for CLI in the future because IC rarely progresses to CLI.24
This study also showed the various etiologies of diseases causing occlusion of the popliteal to tibial artery. Our results suggested that a definite diagnosis should be made with MRI or CT scan before angiography and that EVT should not be readily performed for occlusive lesions in this area because EVT cannot guarantee a long-term outcome.
Study Limitations
This study was retrospective, the sample size was small, the term of the study was long, the strategy of treatment (including revision surgery) was operator-dependent, and the method of follow-up examination was changed in the middle of the study. In addition, in the evaluation of claudication or QOL, graft patency was used as a surrogate marker and questionnaires were not utilized.
Conclusions
Tibial artery bypass is a strong strategy for patients with the following conditions: (1) persistent lifestyle-limiting claudication even after pharmacotherapy with exercise, (2) presence of a target artery with good runoff to the foot, (3) availability of a great saphenous vein as a single graft, (4) no severe comorbidity precluding the ability to undergo operation or anesthesia, and (5) an intense desire to walk.
Disclosure Statements
The authors have neither financial nor other potential conflicts to declare.
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