Multivariate Cox regression analysis of covariates for patency rates after femorodistal vein bypass grafting

Integrative approach for classifying male tumors based on DNA methylation 450K data

Malignancies such as bladder urothelial carcinoma, colon adenocarcinoma, liver hepatocellular carcinoma, lung adenocarcinoma and prostate adenocarcinoma significantly impact men's well-being. Accurate cancer classification is vital in determining treatment strategies and improving patient prognosis. This study introduced an innovative method that utilizes gene selection from high-dimensional datasets to enhance the performance of the male tumor classification algorithm. The method assesses the reliability of DNA methylation data to distinguish the five most prevalent types of male cancers from normal tissues by employing DNA methylation 450K data obtained from The Cancer Genome Atlas (TCGA) database. First, the chi-square test is used for dimensionality reduction and second, L1 penalized logistic regression is used for feature selection. Furthermore, the stacking ensemble learning technique was employed to integrate seven common multiclassification models. Experimental results demonstrated that the ensemble learning model utilizing multiple classification models outperformed any base classification model. The proposed ensemble model achieved an astonishing overall accuracy (ACC) of 99.2% in independent testing data. Moreover, it may present novel ideas and pathways for the early detection and treatment of future diseases.

Infrainguinal Atherectomy Using the Transluminal Endarterectomy Catheter: Patency Rates and Clinical Success for 144 Procedures

Purpose:

To determine if atherectomy using the transluminal endarterectomy catheter (TEC) is an effective endoluminal therapy for infrainguinal occlusive disease.

Methods:

Three surgeons used the TEC for 144 infrainguinal atherectomy procedures in 133 patients. The indications were severe claudication in 83, critical ischemia in 56, and graft stenosis in 5 limbs. The pathology was stenosis in 36 and occlusion in 105 limbs. Balloon dilation was also performed in 109 and stenting in 17 limbs.

Results:

There was initial technical and anatomic success in 124 (86%) procedures. There were 67 technically successful procedures at mean follow-up of 19 months, although 3 of these limbs with gangrene and extensive distal disease required major amputation. There were 26 failures due to stenosis leading to further intervention and 51 due to occlusion. Twenty of these cases were managed conservatively, 21 were treated with repeat endovascular intervention, 31 with bypass grafting, and 5 with amputation. Repeat intervention in 52 limbs resulted in 36 with patent arteries, 10that are occluded, and 6that required amputation. Thirteen of the 14 amputations were for limbs with critical ischemia, but 1 was in a patient with claudication. Life-table analysis showed that the primary patency rate was 51%, the assisted primary patency rate was 61%, and the secondary patency rate was 75% at 15 months. The clinical success rate was 49%, and the salvage rate for limbs with critical ischemia was 78% at 12 months. Univariate log-rank testing showed no significant differences according to the clinical presentation or pathology, but results were worse for lesions > 5 cm long due to more frequent immediate failures. However, multivariate Cox regression analysis showed that results were significantly worse for critical ischemia than for claudication, stenosis compared to occlusions, for limbs with poor runoff, for operations performed by percutaneous rather than an open approach, and for those performed more recently.

Conclusions:

TEC atherectomy may have a place in selected patients, but the optimal circumstances for its use and long-term efficacy require further study.

The Giacomini vein as an autologous conduit in infrainguinal arterial reconstruction

The standard conduit in infrainguinal arterial bypass grafting, the great saphenous vein, is often unavailable. Arm and small saphenous veins are used as alternative conduits; yet both are deficient in length to accommodate femorocrural bypasses as a single conduit. In light of its high prevalence, the Giacomini vein harvested in continuity with the small saphenous vein may offer the latter extra length, promoting their combination into a single conduit able to meet the needs of infrainguinal reconstruction, particularly in lengthy infrainguinal bypass grafting. The Giacomini vein merits consideration when arterial reconstruction is performed in proximity to its anatomic course.

Limb salvage after infrainguinal bypass graft failure

OBJECTIVE

The purpose of this study was to examine the outcome of patients in whom an infrainguinal bypass graft failed.

METHODS

This was a retrospective analysis of consecutive patients undergoing infrainguinal bypass grafting in a single institution over 8 years.

RESULTS

Six hundred thirty-one infrainguinal bypass grafts were placed in 578 limbs in 503 patients during the study period. The indication for surgery was limb-threatening ischemia in 533 patients (85%); nonautologous conduits were used in 259 patients (41%), and 144 (23%) were repeat operations. After a mean follow-up of 28 +/- 1 months (median, 23 months; range, 0-99 months), 167 grafts (26%) had failed secondarily. The rate of limb salvage in patients with graft failure was poor, only 50% +/- 5% at 2 years after failure. The 2-year limb salvage rate depended on the initial indication for bypass grafting: 100% in patients with claudication (n = 16), 55% +/- 8% in patients with rest pain (n = 49), and 34% +/- 6% in patients with tissue loss (n = 73; P <.001). The prospect for limb salvage also depended on the duration that the graft remained patent. Early graft failure (<30 days; n = 25) carried a poor prognosis, with 2-year limb salvage of only 25% +/- 10%; limb salvage was 53% +/- 5% after intermediate graft failure (<2 years, n = 110) and 79% +/- 10% after late failure (>2 years, n = 15; P =.04). Multivariate analysis revealed shorter patency interval before failure (P =.006), use of warfarin sodium (Coumadin) postoperatively (P =.006), and infrapopliteal distal anastomosis (P =.01) as significant predictors for ultimate limb loss.

CONCLUSION

The overall prognosis for limb salvage in patients with failed infrainguinal bypass grafts is poor, particularly in patients with grafts placed because of tissue loss and those with early graft failure.

Postoperative and amputation-free survival outcomes after femorodistal bypass grafting surgery: findings from the Department of Veterans Affairs National Surgical Quality Improvement Program

PURPOSE

A noncardiac surgery risk model was used as a means of analyzing variations in postoperative mortality and amputation-free survival for older veterans undergoing femorodistal bypass grafting surgery.

METHODS

A prospective cohort study was undertaken in 105 Veterans Affairs (VA) hospitals at the time of index operation from 1991 to 1995. Each patient was linked to subsequent hospitalizations, major amputation surgery, and survival through 1999. Logistic regression and proportional hazards models were used as a means of developing risk indices on the basis of risk factors from the VA National Surgical Quality Improvement Program. A total of 4288 male veterans 40 years or older underwent artificial, vein, or in situ bypass grafting surgery at the femoral to tibial level. The main outcome measures were 30-day postoperative mortality and amputation-free survival.

RESULTS

Approximately half of all patients had undergone an earlier revascularization or amputation at any level for vascular disease. The 30-day postoperative mortality rate was 2.1% and varied greatly between mortality risk index quartiles (0.6%-5.2%). In a median 44.3 months of follow-up, surviving patients had 17,694 subsequent VA hospitalizations, 1147 patients (26.7%) underwent subsequent major amputation, and 1913 patients (44.6%) died. The overall survival probability was 88% at 1 year and 63% at 5 years; 1- and 5-year (any sided) limb salvage rates were 87% and 74%, respectively, for patients who underwent a femoropopliteal bypass grafting procedure, compared with 77% and 63%, respectively, for patients who underwent a tibial bypass grafting procedure. When amputation and death were combined as end points, amputation-free survival probability rates at 1, 3, and 7.5 years were 74%, 56%, and 29%, respectively. Patients with the best 20% survival risk scores had observed mean survival probability rates 30% higher than patients in the poorest 20% of survival risk.

CONCLUSION

Risk indices derived from the preoperative workup may be of use to clinicians in assessing and communicating risk and prognosis. Risk-adjustment of outcomes is critical for evaluating future disease management initiatives for patients with advanced peripheral arterial disease.

Measures of success and health-related quality of life in lower-extremity vascular surgery

Lower-extremity vascular surgery is most often indicated for patients with critical leg ischemia but has increasingly been used for patients with disabling intermittent claudication. This article reviews indications, follow-up protocols, and procedure-related outcomes including perioperative and late mortality, complications, and long-term patency rates, which vary with patient risk factors, vascular disease severity, and hospital volume. Population-based studies have yet to establish whether rates of limb-preserving bypass surgery are related to overall amputation rates, partly because of the continued high rate of primary amputation. The functional benefits of vascular surgery have been traditionally assessed by treadmill protocols and batteries of physical tests. Claudication treatment is increasingly being measured by both generic and disease-specific functional and health-related quality-of-life questionnaires. Patient self-reported measures of physical functioning and walking ability are reviewed. Finally, conclusions are presented about trends in lower-extremity bypass surgery rates.

Infrainguinal revascularisation in the era of vein-graft surveillance--do clinical factors influence long-term outcome?

OBJECTIVES

To investigate the variables affecting the long-term outcome of infrainguinal vein bypass grafts that have undergone postoperative surveillance.

DESIGN

A retrospective analysis.

PATIENTS AND METHODS

Details of 299 consecutive infrainguinal vein grafts performed in 275 patients from a single university hospital were collected and analysed. All grafts underwent postoperative duplex surveillance. Factors affecting patency, limb salvage and survival rates were examined. These factors were gender, diabetes, hypertension, aspirin, warfarin, ischaemic heart disease, run-off, graft type, early thrombectomy, level of anastomoses and indication for surgery.

RESULTS

The 6-year primary, primary assisted and secondary patency rates were 23, 47, and 57%, respectively. Six-year limb salvage and patient survival were 68 and 45%, respectively. Primary patency was adversely influenced by the use of composite vein grafts. Early thrombectomy was the only factor that significantly influenced secondary patency. Limb salvage was worse in diabetic limbs, limbs with poor run-off and in grafts that required early thrombectomy. Postoperative survival was better in males, claudicants and in patients who took aspirin.

CONCLUSIONS

Although co-morbid factors did not influence graft patency rates, diabetes did adversely effect limb salvage. This study, like others before it, confirms that aspirin significantly reduces long-term mortality in patients undergoing infrainguinal revascularisation.

Outcome and influence of age after infrainguinal revascularisation in critical limb ischaemia. The Swedish Vascular Registry

OBJECTIVES

To evaluate whether revascularisation has any influence on the mortality rate, and the impact of old age in patients with critical limb ischaemia (CLI).

DESIGN

Analysis of Swedish Vascular Registry (Swedvasc) data.

PATIENTS AND METHODS

During 1987-1995, 3730 surgical and 1199 endovascular (PTA) procedures below the groin due to CLI were reported. At 1 year three groups were defined: "occluded, amputated"; "occluded, not amputated" and "patent". Survival was also calculated. Clinical outcome at 1 month and at 1 year was defined as: patient "alive, improved", "alive, not improved", "alive, amputated" and "dead". Two age groups < or = 75 years or and > or = 76 years were compared.

RESULTS

The mortality rate for the whole group was 5.3% at 1 month and 22.9% at 1 year, with no difference between the Surgery and PTA groups. Significantly more patients were alive and improved after surgery than after PTA at 1 month (82.3% vs. 77.7%) and at 1 year (49.6% vs. 44.3%). The amputation rate was 5.6% at 1 month and 14.4% at 1 year; 17% for diabetics. After surgery, the cumulative mortality rate did not differ between patients with a salvaged limb, irrespectively of patency of the re-construction, but was significantly higher after amputation. After PTA, only a reconstruction reported as patent was linked to the most favourable survival rate. The older patient group had a mortality rate of 6.4% at 1 month and 26.4% at 1 year, significantly higher than the younger group (3.8% and 17.6%, respectively). The amputation rate did not differ according to age. Significantly more patients were alive but not improved in the older group.

CONCLUSIONS

The outcome of surgery vs. PTA was similar regarding survival and amputation, but surgery resulted in a greater improvement although this might be due to selection. Older patients and those with an amputation had higher mortality rates.

Patient recovery after infrainguinal bypass grafting for limb salvage

PURPOSE

The outcome of infrainguinal bypass surgery for limb salvage has traditionally been assessed by graft patency rates, limb salvage rates, and patient survival rates. Recently, functional outcome of limb salvage surgery has been assessed by patient ambulatory status and independent living status. These assessments fail to consider the adverse long-term patient effects of delayed wound healing, episodes of recurrent ischemia, and need for repeat operations. An ideal result of infrainguinal bypass surgery for limb salvage includes an uncomplicated operation, elimination of ischemia, prompt wound healing, and rapid return to premorbid functional status without recurrence or repeat surgery. The present study was performed to determine how often this ideal result is actually achieved.

METHODS

The records of 112 consecutive patients who underwent initial infrainguinal bypass surgery for limb salvage 5 to 7 years before the study were reviewed for operative complications, graft patency, limb salvage, survival, patient functional status, time to achieve wound healing, need for repeat operations, and recurrence of ischemia.

RESULTS

The mean patient age was 66 years. The mean postoperative follow-up was 42 months (range, 0 to 100.1 months). After operation 99 patients (88%) lived independently at home and 103 (92%) were ambulatory. There were seven perioperative deaths (6.3%), and wound complications occurred in 27 patients (24%). By life table, the assisted primary graft patency and limb salvage rates of the index extremity 5 years after operation were 77% and 87%, respectively, and the patient survival rate was 49%. At last follow-up or death, 73% of the patients (72 of 99) who lived independently at home before the operation were still living independently at home, and 70% (72 of 103) of those who were ambulatory before the operation remained ambulatory. Wound (operative and ischemic) healing required a mean of 4.2 months (range, 0.4 to 48 months), and 25 patients (22%) had not achieved complete wound healing at the time of last follow-up or death. Repeat operations to maintain graft patency, treat wound complications, or treat recurrent or contralateral ischemia were required in 61 patients (54%; mean, 1.6 reoperations/patient), and 26 patients (23.2%) ultimately required major limb amputation of the index or contralateral extremity. Only 16 of 112 patients (14.3%) achieved the ideal surgical result of an uncomplicated operation with long-term symptom relief, maintenance of functional status, and no recurrence or repeat operations.

CONCLUSIONS

Most patients who undergo infrainguinal bypass surgery for limb salvage require ongoing treatment and have persistent or recurrent symptoms until their death. A significant minority have major tissue loss despite successful initial surgery. Clinically important palliation is frequently achieved by bypass surgery, but ideal results are distinctly infrequent.

Use of arm and lesser saphenous vein compared with prosthetic grafts for infrapopliteal arterial bypass: are they worth the effort?

PURPOSE

Arm and lesser saphenous veins (ALSVs) are generally considered to be the best alternative for infrapopliteal arterial bypass grafts when greater saphenous vein is not available. The need for additional incisions and repositioning of the patient, along with occasional use of general anesthesia for arm vein harvesting, led to our perception that the use of ALSVs increased operative time and possibly patient discomfort. Therefore, we compared the outcome of ALSVs with that of prosthetic infrapopliteal arterial bypass procedures performed at our hospital.

METHODS

Between July 1, 1991, and Dec. 31, 1996, we performed 96 infrapopliteal arterial bypass procedures using 45 ALSVs (28 arm vein, 17 lesser saphenous) and 51 polytetrafluoroethylene (PTFE) grafts. Seventy grafts were single-length ALSV or PTFE bypass grafts, and 26 grafts were placed as the distal segment of a sequential or composite bypass graft. Every attempt was made to use ALSV and avoid the use of PTFE, even if a short segment of the vein graft measured less than 4.0 mm in diameter. There were no significant differences between patients with ALSV compared with PTFE grafts in terms of age, sex, indication for surgery, or number of previous revascularization procedures (2.1 vs 1.7), respectively (p > 0.05). However, ALSV grafts had more factors associated with an expected worse outcome: they were more commonly anastomosed to pedal arteries (17% [8 of 45] vs 0%; p = 0.0009), less commonly single-segment grafts (62% [28 of 45] vs 82% [42 of 51]; p = 0.03), had higher average runoff resistance values (2.3 vs 1.5; p = 0.001), and were less frequently treated with lifelong warfarin (65% [29 of 45] vs 95% [48 of 51]; p = 0.0001).

RESULTS

The hospital mortality rate was 3.1% (3 of 96; 3 PTFE). All deaths were cardiac-related. Despite the potential factors associated with worse patency rates for ALSVs, 2-year assisted primary patency rates tended to be higher for arm veins (46%) than for lesser saphenous veins (23%) and PTFE grafts (26%), although this difference was not statistically significant. Limb salvage rates were similar between ALSV and PTFE grafts (76% vs 71%, respectively). The average operative time was significantly longer for ALSV bypass procedures (mean, 6.2 hours) than for PTFE bypass procedures (mean, 4.9 hours; p = 0.003), and for single-length conduits when revision of previously placed grafts was not attempted, the operative time was 4.0 hours for ALSV grafts and 2.5 hours for PTFE grafts.

CONCLUSION

In our experience ALSV bypass grafts to infrapopliteal arteries do not function as well as reported by some others. In spite of the extra effort involved, arm vein grafts are preferred over PTFE grafts for their likely higher assisted primary patency rates and equivalent, if not better, limb salvage rates.

Validation of a new and specific intraoperative measurement of vein graft resistance

PURPOSE

Clinical studies have revealed that the most important predictor of successful bypass grafting is the origin and quality of the bypass conduit. Attempts at intraoperative evaluation of the hemodynamic properties of the conduit, including assessment of blood flow (Q), pressure gradients (delta P), and resistance (R), have not been useful. This is because each of these parameters measures the characteristics of the graft plus the outflow bed. To date, no specific measurement of the resistive properties of the conduit only is available. The purpose of this investigation was to evaluate longitudinal impedance (ZL) as a measure of conduit-specific resistance and to evaluate its potential in predicting the outcome of infrainguinal vascular reconstructions.

METHODS

ZL was measured during surgery in 73 infrainguinal autologous vein reconstructions performed in 68 patients in two separate institutions over a 21-month period. Vein graft ultrasonic transit time Q and delta P (from proximal to distal anastomosis) were measured at baseline and after maximal peripheral vasodilatation with an intraarterial injection of papaverine 30 mg. Waveforms were recorded for 10 seconds at 200 Hz using a digital acquisition system. R was calculated as proximal mean pressure divided by mean blood flow (Q). After Fourier transformation, ZL was calculated as delta P/Q at each harmonic and total ZL (integral of ZL) was defined as the integral of moduli from 0 to 4 Hz.

RESULTS

All hemodynamic variables were significantly affected by papaverine vasodilatation (delta P, 3.9 +/- 0.5 vs 6.3 +/- 0.8 mm Hg; Q, 78.2 +/- 7.0 vs 126 +/- 11 ml/min; R, 134 +/- 17 vs 72.7 +/- 6.2 x 10(3) dyne.sec.cm-5; p < 0.0001), except integral of ZL, which remained constant (31.1 +/- 2.8 vs 30.8 +/- 2.8 x 10(3) dyne.cm-5; p = NS). After follow-up of 1 week to 17 months (median, 5 months), the 1-year primary, primary-assisted, and secondary patency rates were 72% +/- 7%, 77% +/- 6%, and 81% +/- 6%, respectively. Using Cox analysis, primary patency was significantly associated with decreased integral of ZL (p = 0.0001), but not with baseline or papaverine-stimulated delta P, Q, delta P/Q, or R integral of ZL > 47 x 10(3) dyne.cm-5 predicted primary failure with 90% positive and negative predictive value.

CONCLUSIONS

Intraoperative measurement of integral of ZL in infrainguinal vein grafts is independent of outflow conditions (that is, does not change with papaverine), and hence describes the resistive properties of the conduit only. In addition, these preliminary data suggest that integral of ZL is predictive of short-term primary patency. integral of ZL is the first available hemodynamic measurement that is conduit-specific and may therefore be a better predictor of graft patency than currently available methods.

Measurement of vascular input impedance in infrainguinal vein grafts

The purpose of this investigation was to measure vascular input impedance in infrainguinal vein grafts and assess the importance of clinical and hemodynamic parameters in predicting graft patency. Fifty-seven patients undergoing infrainguinal vein bypass grafting for limb salvage (n = 40) or claudication (n = 17) were prospectively studied. At the time of revascularization, simultaneously acquired intraluminal pressure and blood flow waveforms were digitized at 200 Hz and subjected to Fourier transformation in near real-time. Input impedance was calculated at baseline (immediately after unclamping) and after stimulation with either papaverine or completion arteriography. Resistance (Rin) was calculated as mean pressure divided by mean blood flow (Q). Characteristic impedance (Z0) was calculated as the mean of harmonics 3-10. Intraoperative data acquisition required approximately 5 min, utilized the completion angiography cannula already in place, and was uncomplicated in all patients. Stimulation with either papaverine or arteriography resulted in increased Q (72 +/- 7 to 146 +/- 11 ml/min, p < 0.001), decreased Rin (126 +/- 13 to 52 +/- 4 x 10(3) dyne.s.cm-5, p < 0.001), and slightly decreased Z0 (18 +/- 2 to 15 +/- 1, p = 0.002). After a mean follow-up of 20 months, the 2-year primary patency, secondary patency, limb salvage, and survival rates were 61 +/- 8%, 74 +/- 7%, 76 +/- 6%, and 86 +/- 6%, respectively. Primary patency was not associated with any of the clinical variables studied including age, sex, smoking history, history of previous vascular surgery, hypertension, coronary artery disease, diabetes mellitus, creatinine, indication for revascularization (claudication versus limb salvage), anesthesia (general versus regional), or level of distal anastomosis (popliteal versus infrapopliteal). Furthermore, there was no association between primary patency and baseline Q, baseline Rin, or stimulated Z0. However, using univariate analysis, patency was positively associated with decreased stimulated Rin (p = 0.002), elevated stimulated Q (p = 0.006), and decreased baseline Z0 (p = 0.02). Multiple regression analysis identified stimulated Rin as the only independent predictor of primary patency (p = 0.002). Stimulated Rin > or = 50 x 10(3) dyne.s.cm-5 was 71% sensitive and 65% specific for graft failure. It is concluded that 1) vascular input impedance can be simply and reliably measured in the operating room, and 2) elevated stimulated Rin is an independent predictor of primary patency.

Infrainguinal atherectomy using the transluminal endarterectomy catheter: patency rates and clinical success for 144 procedures

PURPOSE

To determine if atherectomy using the transluminal endarterectomy catheter (TEC) is an effective endoluminal therapy for infrainguinal occlusive disease.

METHODS

Three surgeons used the TEC for 144 infrainguinal atherectomy procedures in 133 patients. The indications were severe claudication in 83, critical ischemia in 56, and graft stenosis in 5 limbs. The pathology was stenosis in 36 and occlusion in 105 limbs. Balloon dilation was also performed in 109 and stenting in 17 limbs.

RESULTS

There was initial technical and anatomic success in 124 (86%) procedures. There were 67 technically successful procedures at mean follow-up of 19 months, although 3 of these limbs with gangrene and extensive distal disease required major amputation. There were 26 failures due to stenosis leading to further intervention and 51 due to occlusion. Twenty of these cases were managed conservatively, 21 were treated with repeat endovascular intervention, 31 with bypass grafting, and 5 with amputation. Repeat intervention in 52 limbs resulted in 36 with patent arteries, 10 that are occluded, and 6 that required amputation. Thirteen of the 14 amputations were for limbs with critical ischemia, but 1 was in a patient with claudication. Life-table analysis showed that the primary patency rate was 51%, the assisted primary patency rate was 61%, and the secondary patency rate was 75% at 15 months. The clinical success rate was 49%, and the salvage rate for limbs with critical ischemia was 78% at 12 months. Univariate log-rank testing showing no significant differences according to the clinical presentation of pathology, but results were worse for lesions > 5 cm long due to more frequent immediate failures. However, multivariate Cox regression analysis showed that results were significantly worse for critical ischemia than for claudication, stenosis compared to occlusions, for limbs with poor runoff, for operations performed by percutaneous rather than an open approach, and for those performed more recently.

CONCLUSIONS

TEC atherectomy may have a place in selected patients, but the optimal circumstances for its use and long-term efficacy require further study.