Failure of thrombolytic therapy to improve long-term vascular patency

A History of Thrombolytic Therapy

Thrombolytic therapy has been available for the last 5 decades, but the modern era of thrombolysis began in the early 1990s, with the execution of 3 multicenter trials designed to compare this potentially less invasive therapy to the then standard of care for acute limb ischemia, open surgical revascularization. Even with the development of several bioengineered lytic agents, the major risk of thrombolytic therapy continues to be bleeding complications. Nevertheless, data exist to suggest that thrombolysis should be considered as an adjunct to open surgery, percutaneous interventions, or, occasionally, as sole therapy for acute vascular occlusion. This review summarizes the developmental milestones in the history of thrombolysis and reviews data supporting its use in acute arterial occlusions.

Jetstream® atherectomy for subacutely or chronically occluded femoro-popliteal prosthetic bypass grafts: a report of three cases

A failed infrainguinal bypass is associated with poor prognosis for the limb in question, particularly if the graft was initially placed for limb salvage. Revascularization of occluded grafts is an important but challenging issue. We present three patients with occluded femoro-popliteal graft in whom the Jetstream(®) system was used successfully to perform thromboatherectomy. The Jetstream(®) system is minimally invasive and avoids use of thrombolytic therapy and its associated costs and complications. The device seems to be highly effective in removing thrombus beyond the acute setting.

The role of thrombolysis in acute infrainguinal bypass occlusion: a prospective nonrandomized controlled study

Current treatment of acute infrainguinal bypass occlusion consists of either surgical revascularization or catheter-guided intra-arterial thrombolysis with adjunctive correction of the underlying flow-limiting lesion. In maintaining long-term patency, improving the number of outflow vessels could be of utmost importance. To compare the efficiency of both thrombolysis and primary surgical revascularization and to study the effect of thrombolysis on the number of patent outflow vessels, a prospective nonrandomized study was performed. Between February 2002 and August 2003, 54 patients with 56 occluded bypasses were included. Thirty bypasses were treated with thrombolysis, 26 primarily with surgery. Thrombolysis was successful in 80% of cases, with restoration of patency of the bypass but also with doubling of the amount of patent outflow vessels; surgery was successful in 85.71% of cases. However, in only 60% of the successfully lysed bypasses no adjunctive major surgery was needed. Amputation-free survival was 87.5% 1 year after surgery and 82.6% 1 year after thrombolysis. One year after thrombolysis without adjunctive major surgery, the amputation-free survival was only 39.7%. Therefore, a strategy could be to start with thrombolysis to improve outflow followed by a new bypass, whatever the underlying causative lesions are.

Thrombolysis as Initial Treatment of Peripheral Native Artery and Bypass Graft Occlusions in a General Community Hospital

Large series with long-term follow-up of thrombolytic therapy in the treatment of lower limb arterial occlusion from a single, general, non-university hospital are absent. We studied retrospectively the results of 129 consecutive patients who underwent thrombolysis with intraarterial urokinase as initial treatment for lower limb native artery or bypass graft occlusions. The mean age of patients was 71 years; 55% of the patients were male, and preexisting peripheral arterial disease was present in 47%. Presenting symptoms were disabling claudication (31%) and limb-threatening ischemia (69%). Forty-two percent of the patients presented with acute symptoms (<1 week duration). The mean follow-up of patients still alive at the time of analysis was 36 months (range 1-120 months). Thrombolytic treatment was successful in 93 patients (72%). In 53% of the patients acute surgical intervention could be avoided: 28 patients (22%) did not need any additional procedure and 40 (31%) underwent a concomitant angioplasty. When thrombolysis failed, 6 patients (5%) underwent successful surgical revascularization and 11 patients (8%) eventually underwent major amputation during their hospital stay. Amputation-free survival at 6 months and at last follow-up was 88% and 83%, respectively. The mortality rates were 4% at 30 days, 5% at 6 months, and 30% at last follow-up. Thrombolysis was significantly less successful when patients had diabetes (62% vs. 81%, p = 0.019) or preexisting peripheral arterial disease (61% vs. 80%, p= 0.018). Successful radiological treatment (thrombolysis+/-angioplasty) could less often be performed in patients with preexisting peripheral arterial disease (41% vs. 59%, p = 0.011) and in patients with occluded bypass grafts (33% vs. 62%, p= 0.002). Duration of symptoms and Fontaine stage at presentation did not predict thrombolysis outcomes. Thrombolytic-related complications occurred in 17 patients (13%), with significant bleeding from the puncture site in 3 patients (2%). Thrombolysis can safely and effectively be performed in a general community hospital with results comparable to those reported from specialized university centers and large randomized trials.

Surgical Thrombectomy and Transluminal Balloon Angioplasty for Failed Above-knee Femoropopliteal Polytetrafluoroethylene Bypass Grafts

Endovascular therapy offers an alternative to redo bypass or surgical graft revision for failed above-knee femoropopliteal PTFE bypass grafts. We evaluated the outcome of surgical thrombectomy and balloon angioplasty for the treatment of thrombosed bypass grafts. Thirty selected patients with thrombosed above-knee femoropopliteal PTFE bypass grafts were treated. Under local anesthesia, a surgical thrombectomy followed by bypass graft angiography and balloon angioplasty of perianastomotic stenoses was performed. Stents were used selectively for suboptimal angioplasty results. Patients underwent duplex scanning of the bypass graft postoperatively and at 6-month intervals. Life-table analysis and log-rank (Mantel-Cox) comparisons were performed. Patients were categorized into two groups on the basis of time elapsed from initial bypass graft construction to graft failure. Group 1 included 21 patients with a mean time to graft failure of 10 months (range, 0-20). Surgical thrombectomy was successful in 20 grafts (95%) and 17 patients had a stent placed after angioplasty. Rethrombosis occurred within 30 days in seven grafts (33%) in group 1 and major amputations were performed in six patients (28%). Group 2 included nine patients with a mean time to initial bypass graft failure of 48 months (range, 29-96). All patients in group 2 had a successful surgical thrombectomy and all received a stent. None of the grafts treated in group 2 reoccluded within 30 days of intervention and one patient (11%) went on to require a major amputation. By life-table analysis, the 6- and 12-month patency for group 1 was 15.3% and 5.1%, compared to 58.3% and 38.9% for group 2 (p = 0.027). Surgical thrombectomy along with balloon angioplasty has an unacceptably high rate of failure and limb loss in patients treated for early (<2 years) femoropopliteal PTFE bypass graft thrombosis. Surgical graft revision or redo bypass is recommended to achieve successful revascularization in these patients. Treatment with surgical thrombectomy and balloon angioplasty achieves significantly greater short-term patency results in patients with late (>2 years) bypass graft failure and may be a reasonable alternative for patients who cannot tolerate reoperation or lack autogenous conduit.

Endovascular techniques in the treatment of acute limb ischemia: thrombolytic agents, trials, and percutaneous mechanical thrombectomy techniques

Acute peripheral arterial occlusion is associated with great risk to the patient's limb and life. Failure to restore adequate arterial flow in a timely fashion can result in the development of irreversible tissue infarction and the opportunity for limb salvage is lost. On the other hand, patients with acute limb ischemia are often elderly and frail, and early invasive open surgical procedures without adequate preoperative stabilization and preparation result in an unacceptably high risk of perioperative cardiopulmonary complications and death. Percutaneous methods designed to remove the intraluminal thrombus offer an alternative to immediate open surgical revascularization. These less invasive techniques constitute an option that is better tolerated in medically compromised patients. The causative lesion can be precisely identified and the patency of outflow vessels can be restored. The lesion can then be addressed on an elective basis in a well-prepared patient, using percutaneous or open surgical techniques to effect a durable long-term solution. The treatment options include primary surgical revascularization, thrombolytic therapy, percutaneous mechanical thrombectomy, or a combination of any of the three. Clinicians who themselves have the skills to perform a wide assortment of interventions ranging from percutaneous therapies through open surgical revascularization are best able to arrive at the most rational option for treating a specific clinical scenario. This article is directed at providing the practicing surgeon with a basic fund of knowledge on the diagnostic and therapeutic strategies useful in treating patients with peripheral arterial occlusion. Only in this manner can we expect to reduce the high rate of morbidity and mortality that remains associated with these events.

Long-term results of catheter-directed thrombolysis to treat infrainguinal bypass graft occlusion: the urokinase era

PURPOSE

This study was undertaken to review the long-term results of catheter-directed thrombolysis in treatment of infrainguinal bypass graft occlusion.

METHODS

From January 1987 to December 1998, 67 patients with 69 acutely occluded infrainguinal arterial bypass grafts (48 vein grafts, 21 prosthetic grafts) underwent treatment with catheter-directed thrombolysis with urokinase. Long-term results were assessed with Kaplan-Meier life-table analysis, and factors predictive of success were determined with multivariate analysis.

RESULTS

Thrombolysis was aborted in 7 patients (10%) because of major complications or technical failure and was unsuccessful in restoring graft patency (</=90% lysis) in 13 patients (19%). Successful lysis was achieved in 49 patients (71%). A causative lesion was identified and treated with percutaneous transluminal angioplasty (PTA) or limited operative revision in 33 patients. Diffuse vein graft intimal hyperplasia or poor runoff was identified in the remaining 9 patients, who were offered no further intervention. Cumulative patency at 60 months was 65% +/- 8% for successfully lysed vein grafts; however, only 3 of 16 successfully lysed prosthetic grafts were patent at 9 months. Although univariate analysis identified several factors associated with successful long-term vein graft function, only white race was significant at multivariate regression analysis.

CONCLUSIONS

Coupled with identification and aggressive treatment of underlying causative lesions, catheter-directed thrombolysis can salvage many thrombosed vein grafts, with expectation of long-term patency similar to that with repeat bypass grafting. Poor short-term results of thrombolysis of occluded prosthetic grafts support repeat operation with a completely new bypass graft as a more appropriate option.

Current status of thrombolysis for peripheral arterial occlusive disease

Acute peripheral arterial occlusion occurs as a result of thrombosis or embolism. A reduction in the prevalence of rheumatic heart disease accounts for a shift in the frequency of embolic to thrombotic occlusions. Also, a dramatic increase in the number of lower extremity arterial bypass graft procedures explains the predominance of graft occlusions in most recent series of patients with acute limb ischemia. While open surgical procedures remain the gold standard in the treatment of peripheral arterial occlusion, thrombolytic agents have been employed as an alternative to primary surgical revascularization in patients with acute limb ischemia. Systemic administration of thrombolytic agents, while effective for small coronary artery clots, fails to achieve dissolution of the large peripheral arterial thrombi. Catheter-directed administration of the agents directly into the occlusive thrombus is the only means of effecting early recanalization. Prior to 1999, urokinase was the sole agent used in North America for peripheral arterial indications, but the loss of the agent from the marketplace forced clinicians to turn to alternate agents, specifically alteplase and reteplase. Interest in the use of platelet glycoprotein inhibitors and mechanical thrombectomy devices also rose, coincident with the loss of urokinase from the marketplace. Most clinicians welcome the predicted return of urokinase to the marketplace. New investigative trials should be organized and executed to answer some of the remaining questions related to thrombolytic treatment of peripheral arterial disease. Foremost in this regard remains the question of which patients are best treated with percutaneous thrombolytic techniques and which are best treated with primary operative intervention. Ultimately, however, the thrombolytic agents are but one tool in the armamentarium of the vascular practitioner. This review is directed at providing the practicing clinician with the basic fund of knowledge necessary when determining the most appropriate intervention in a particular patient with peripheral arterial occlusion, be it thrombolytic therapy, percutaneous mechanical thrombectomy, primary surgical revascularization, or a combination of the three.

Lysis/balloon angioplasty versus thrombectomy/ open patch angioplasty of failed femoropopliteal polytetrafluoroethylene bypass grafts

PURPOSE

Several studies have reported on the outcome of lysis/percutaneous transluminal balloon angioplasty (PTA) of failed or failing femoropopliteal bypass grafts (FPGs) with mixed results. None of these studies have compared the results of lysis/PTA versus thrombectomy/open patch repair for failed above-knee polytetrafluoroethylene (PTFE) FPGs.

METHODS

Patients with failed (thrombosed) above-knee FPGs (PTFE, Goretex) during a 10-year period were given the option to choose between thrombectomy/open patch repair for localized anastomotic short stenosis (less-than-or-equal2 cm; group A, 31 patients) and lysis/PTA or thrombectomy/balloon angioplasty when lysis failed or was contraindicated (group B, 26 patients). The cumulative patency rates were compared by using a Kaplan-Meier life table analysis. All patients underwent routine color duplex ultrasound scanning/ankle brachial index measurements at 30 days, 6 months, and every 6 months thereafter.

RESULTS

Demographic and clinical characteristics and indications for intervention were comparable in both groups. The mean follow-up period was 54.1 and 46.2 months in group A and group B, respectively. There were four perioperative complications in group A (13%) and seven perioperative complications in group B (27%). Initial technical success and 30-day secondary graft patency rates were 100% in both groups. Overall, 17 of 31 patients (55%) had open grafts, with no further revisions in group A and six of 26 patients (23%) in group B requiring further revisions (P =.012). Nine of 31 grafts (29%) failed in group A versus 15 of 26 grafts (58%) in group B (P =.027). The rate of limb loss was comparable in both groups (6% vs 12%). The overall cumulative secondary patency rates at 6 months and 1, 2, 3, 4, and 5 years were 100%, 93%, 85%, 72%, 67%, and 62% for group A and 100%, 96%, 88%, 76%, 63%, and 45% for group B (P =.035). Thirty-five further interventions were needed to maintain graft patency in group B (mean, 1.35; range, 0-3) versus five further interventions in group A (mean, 0.16; range, 0-1; P <.05).

CONCLUSION

Thrombectomy/open surgical repair is superior to lysis/PTA (or thrombectomy/balloon angioplasty) for the treatment of failed above-knee PTFE FPGs with anastomotic stenoses. Therefore, balloon angioplasty should be reserved for patients who are at high risk for surgery.

Indications for directed thrombolysis or new bypass in treatment of occlusion of lower extremity arterial bypass reconstruction

The long-term results after directed thrombolytic therapy for thrombosis of infrainguinal arterial bypass reconstructions are disappointing if broad indications are applied. This work presents criteria for determining the indications for thrombolysis or the insertion of a new bypass. In a retrospective study we compared the secondary cumulative patency after bypass thrombolysis (n = 82) and after replacement bypass (n = 143). Using multivariate analysis, the influence of prognostic factors on secondary long-term patency was investigated. Our results showed that brief occlusions (< or = 3 days) in older bypasses (> or = 11 months) should be treated by thrombolysis. In all other cases, efforts should be made to replace the bypass with autologous vein. In the absence of autologous vein, we found umbilical vein to be a suitable material for vessel replacement.

Transcatheter interventions for the treatment of peripheral atherosclerotic lesions: part I

Transcatheter endovascular procedures are increasingly used to treat symptomatic peripheral atherosclerosis. This two-part review identifies the existing evidence supportive of the application of transcatheter treatments for peripheral atherosclerotic lesions. The first part addresses the treatment of obstructive lesions that cause limb claudication and critical ischemia, renovascular hypertension and azotemia, and mesenteric ischemia. Studies were identified via a search of MEDLINE (January 1993 through April 1999) and reference lists of identified articles. When multicenter prospective randomized trials or other high-quality studies were unavailable, a preference was given to studies with at least 50 patients per treated group and a minimum mean follow-up duration of 6 months. Data presented in tables are proportionally weighted averages from included studies. For each application, the authors assessed the quality of evidence (QOE; efficacy, safety, and, where available, cost-effectiveness) and made recommendations with appropriate caveats. There is higher QOE supporting the more established treatments such as lower limb percutaneous transluminal angioplasty (PTA) with stent placement and thrombolysis. Treatments such as renal artery PTA and stent placement and mesenteric and brachiocephalic PTA are in wide use, but high QOE supporting general application is lacking. Blanket recommendations based on established efficacy and cost-effectiveness cannot be made. However, the use of transcatheter therapies can be supported in specific circumstances based on an expected reduction in procedure-related morbidity and/or mortality rates. It is hoped that the identification of deficiencies in the literature will inform and inspire critically needed research in this area.

Thrombolysis for native arterial occlusions of the lower extremities: clinical outcome and cost

INTRODUCTION

Intra-arterial thrombolysis is commonly used as the initial treatment of acute or subacute lower extremity ischemia.

METHODS

To evaluate the efficacy and cost of thrombolysis, we retrospectively analyzed 100 consecutive cases (87 patients) in which intra-arterial lysis (urokinase) was used as the initial treatment for native arterial lower extremity occlusive disease. The mean age of patients was 67 years, 57% of the patients were male, and preexisting peripheral vascular disease was present in 74%. Presenting symptoms were limb-threatening ischemia (53%) and claudication (47%). Acute symptoms (< 2 weeks' duration) were present in 48%.

RESULTS

The 30-day morbidity rate was 31%, and four patients died. Complications were significant bleeding (23%), ischemic stroke (1%), and renal failure with (2%) and without (2%) dialysis. Concomitant angioplasty was performed in 63%. Complete or significant lysis as demonstrated with angiography was achieved in 75% of iliac, 58% of femoropopliteal, and 41% of crural vessels (P <.001). Within 30 days of lysis, 9% of patients underwent major amputation and 20% surgical revascularization (in 3 patients the extent of revascularization was lessened by the lytic therapy). Amputation-free survival was 83% and 75% at 6 months and 2 years, respectively. Relief of ischemia (defined as relief of claudication or limb salvage without major surgical intervention) was achieved in only 70% and 43% of patients at 30 days and 2 years, respectively (Kaplan-Meier analysis; mean follow-up, 31 months). Patients with aortoiliac disease had significantly better outcomes than those with infrainguinal disease (P =.03). Duration or type of presenting symptoms did not predict outcome. The cost of the initial hospitalization per patient for thrombolysis was $18,490.

CONCLUSION

Thrombolysis can be as or more costly than surgery and is associated with a suboptimal outcome in a significant number of patients. These data lead us to caution against a uniform policy of initial thrombolysis for patients who present with lower extremity ischemia.

Two-year follow-up after acute thromboembolic limb ischaemia: the importance of anticoagulation

BACKGROUND

evidence on the effectiveness and usage of long-term anticoagulant therapy after acute thromboembolic limb ischaemia is very sparse. This study correlated medical events with administration of warfarin.

METHOD

during a three-month audit in 1996, 287 patients with embolism or thrombosisin situ survived for 30 days, and 214 (75%) were reviewed by questionnaires returned from clinicians throughout the United Kingdom. Minimum follow-up was two years.

RESULTS

thirty-five per cent had died. Recurrent acute limb ischaemia was reported in 11%, arterial intervention in 11%, and major amputation in 12%. Warfarin was given initially to 57% patients, but at follow-up only 43% were still taking warfarin (p<0. 05); reasons for stopping anticoagulation were often unknown. Recurrent limb ischaemia was less common in patients given warfarin initially (7% versus 17%) and still taking warfarin (3% versus 19%) -p;<0.05. Amputation was also less common in patients given warfarin initially (5% versus 21%) and still on warfarin (3% versus 21%) -p;<0.05.

CONCLUSION

long-term oral anticoagulation was associated with reduced risk of recurrent limb ischaemia and amputation, but more research is needed to define the benefits and risks, especially for thrombosisin situ. Clinicians should give clear advice about anticoagulation when patients are discharged from hospital.

Shredding embolectomy thrombectomy catheter for treatment of acute lower-limb ischemia

We undertook a prospective evaluation to prove a new mechanical thrombectomy device, the shredding embolectomy thrombectomy catheter (S.E.T. catheter), for the treatment of patients with acute lower-limb ischemia. The study evaluated the success, patency, mortality, limb salvage, and complication rates for 51 patients treated from January 1994 through June 1996, with this device, which was an 8-F three-lumen catheter. The onset of symptoms was 8.6 +/- 9 days. Thrombus length was 18 +/- 9 cm situated in 44 native vessels and in 7 bypasses, 42 limbs were graded as threatened. Hydromechanical thrombectomy with the S.E.T. catheter proved to be a quick and safe adjunct for therapy of acute femoropopliteal thromboembolic occlusions with a high initial success rate and an acceptable mid-term patency rate.

Thrombolysis of occluded infrainguinal vein grafts: predictors of outcome

PURPOSE

The purpose of this study was to identify factors that influence graft patency and limb salvage rates after thrombolysis of occluded infrainguinal vein grafts.

METHODS

The records of patients who underwent percutaneous catheter-directed thrombolysis of occluded infrainguinal vein bypass grafts at our institution between 1985 and 1995 were reviewed. Life table analysis was used to determine survival and patency differences. Univariate and multivariate analyses were used to identify the patient-specific factors that affected outcomes.

RESULTS

Forty-four patients with 44 thrombosed infrainguinal vein grafts underwent thrombolysis with urokinase. The thrombolysis-related mortality rate was 2%, and nonfatal complications occurred in 16%. Thrombolysis was unable to restore graft patency in 25% of grafts (11 of 44). Of the remaining 33 successfully lysed grafts, 88% required adjunctive surgery or percutaneous transluminal angioplasty after thrombolysis. Overall, the primary graft patency rate was 25% at 1 year and 19% at 2 years after thrombolysis. Considering only successfully lysed grafts, the primary patency rate improved to 34% at 1 year and 25% at 2 years. Multivariate analysis revealed that the graft patency rate was substantially better in patients without diabetes and in vein grafts that had been in place for longer than 12 months (p < 0.01). The limb salvage rate was significantly improved by successful thrombolysis (63% at 2 years vs 31% if lysis failed; p < 0.01). The patient survival rate was high-89% 2 years after thrombolysis.

CONCLUSIONS

Even with adjunctive therapy, vein graft thrombolysis is unlikely to yield durable patency overall. However, successful thrombolysis improves limb salvage rates and may be beneficial in patients without diabetes who have mature vein grafts but who do not have options for other autogenous revascularization procedures.

Surgical revascularization versus thrombolysis for nonembolic lower extremity native artery occlusions: results of a prospective randomized trial. The STILE Investigators. Surgery versus Thrombolysis for Ischemia of the Lower Extremity

PURPOSE

Early results of a prospective study that compared surgical revascularization and thrombolysis for lower extremity arterial and graft occlusions have been published. This report details the final results in patients who have native artery occlusions.

METHODS

Two hundred thirty-seven patients who had lower extremity ischemia as a result of iliac-common femoral (IF; 69 patients) or superficial femoral-popliteal (FP; 168 patients) occlusion, and had symptomatically deteriorated within the past 6 months were randomized to catheter-directed thrombolysis (150 patients) or surgical revascularization (87 patients). After diagnostic arteriographic examination but before randomization, the optimal surgical procedure was determined. Lytic patients were randomized to recombinant tissue plasminogen activator (rt-PA; 84 patients) or urokinase (UK; 66 patients). Recurrent ischemia, morbidity, amputation, and death rates were determined at 30 days, 6 months, and 1 year, and were analyzed on an intent-to-treat basis.

RESULTS

For patients randomized to lysis, a catheter was properly positioned and the lytic agent delivered in 78%. This provided a reduction in the predetermined surgical procedure in 58% of patients who had an FP occlusion and 51% of those who had an IF occlusion. rt-PA and UK were equally effective and safe, but lysis time was shorter with rt-PA (8 vs 24 hr; p < 0.05). At 1 year, the incidence of recurrent ischemia (64% vs 35%; p < 0.0001) and major amputation (10% vs 0%; p = 0.0024) was increased in patients who were randomized to lysis. Factors associated with a poor lytic outcome included FP occlusion, diabetes, and critical ischemia. No differences in mortality rates were observed at 1 year between the lysis and surgical groups.

CONCLUSION

Surgical revascularization for lower extremity native artery occlusions is more effective and durable than thrombolysis. Thrombolysis used initially provides a reduction in the surgical procedure for a majority of patients; however, long-term outcome is inferior, particularly for patients who have an FP occlusion, diabetes, or critical ischemia.

Results of a prospective, randomized trial of surgery versus thrombolysis for occluded lower extremity bypass grafts

PURPOSE

The purpose of this study was to prospectively evaluate the treatment of patients with occluded lower extremity bypass grafts, comparing surgical revascularization with catheter-directed thrombolysis.

MATERIALS AND METHODS

One hundred twenty-four patients (68% male and 32% female) with lower limb bypass graft occlusion (46 autogenous and 78 prosthetic) were prospectively randomized to surgery (n = 46) or intra-arterial catheter-directed thrombolysis (n = 78) with recombinant tissue plasminogen activator (rt-PA) 0.1 mg/kg/h modified to 0.05 mg/kg/h for up to 12 hours, or urokinase (UK) 250,000 U bolus followed by 4,000 U/min for 4 hours, then 2,000 U/min for up to 36 hours. A composite clinical outcome including death, amputation, ongoing/recurrent ischemia, and major morbidity was analyzed on an intent-to-treat basis at 30 days and 1 year.

RESULTS

The average duration of graft occlusion was 34.0 days, with 58 (48%) presenting with acute ischemia (0 to 14 days) and 64 (52%) with chronic ischemia (> 14 days). Thirty-nine percent randomized to lysis failed catheter placement and required surgical revascularization. Overall, there was a better composite clinical outcome at 30 days (P = 0.023) and 1 year (P = 0.04) in the surgical group compared with lysis, due predominately to a reduction in ongoing/recurrent ischemia, most notable in autogenous grafts. However, following successful catheter placement, patency was restored by lysis in 84%, and 42% had a major reduction in their planned operation. One-year results of successful lysis compared favorably with the best surgical procedure, which was new graft placement. Acutely ischemic patients (0 to 14 days) randomized to lysis demonstrated a trend toward a lower major amputation rate at 30 days (P = 0.074) and significantly at 1 year (P = 0.026) compared with surgical patients, while those with > 14 days ischemia showed no difference in limb salvage but higher ongoing/recurrent ischemia in lytic patients (P < 0.001). Patients with occluded prosthetic grafts had greater major morbidity than did those with occluded autogenous grafts (P < 0.02).

CONCLUSIONS

Proper catheter positioning currently limits the potential of catheter-directed thrombolysis for lower extremity bypass graft occlusion. Patients with graft occlusion > 14 days have a significantly better outcome when treated surgically, with a new bypass being the best surgical option. However, in patients with acute limb ischemia (< 14 days) successful thrombolysis of occluded lower extremity bypass grafts improves limb salvage and reduces the magnitude of the planned surgical procedure. Patients with occluded prosthetic grafts suffer more major morbid events compared with occluded autogenous grafts.

Assessment of peripheral intraarterial thrombolysis versus surgical revascularization in acute lower-limb ischemia: a review of limb-salvage and mortality statistics

PURPOSE

To review the risks and benefits of using peripheral intraarterial thrombolysis (PIAT) versus surgical revascularization (SR) as the initial treatment of acute lower-limb ischemia (ALLI).

MATERIALS AND METHODS

Two prospective, randomized trials that compared PIAT with SR in the treatment of ALLI were analyzed along with recent large, retrospective studies. Overall, 1,051 SR cases and 895 PIAT cases were included; when possible, the ischemic events were further categorized as acute, chronic, embolic, or thrombotic. Limb salvage and mortality at 30-day and 6-12-month follow-up were assessed. Combined percentages were derived by proportionally weighing each study.

RESULTS

When all studies were combined, limb salvage rates were 93% for PIAT and 85.5% for SR at 30 days and 89% versus 73%, respectively, at 6-12-month follow-up. Mortalities were 4% versus 15%, respectively, at 30 days and 8% versus 29%, respectively, at 6-12-month follow-up.

CONCLUSION

PIAT is associated with a substantially better limb-salvage rate and mortality than SR in the treatment of ALLI.

Surgery versus thrombolytic therapy in the management of peripheral arterial occlusions

Thrombolytic therapy has been used as an alternative to surgery in the treatment of peripheral arterial occlusion. Only recently has data from controlled clinical trials become available to allow comparison of the results of both treatment modalities. This article reviews surgical results in the treatment of peripheral arterial occlusions, the history of and techniques for thrombolysis in peripheral arterial occlusion, and the results of studies comparing the two treatments.

Drug variables in thrombolytic therapy

Fibrinolytic therapy has become an accepted treatment modality for recent peripheral arterial and bypass graft occlusions and, in some cases, for chronic arterial occlusions. Streptokinase, urokinase, and tissue plasminogen activator have all been used for intraarterial infusion with varying protocols and results. This review focuses on dosing variables and clinical results for the various thrombolytic agents in peripheral arterial and bypass graft occlusions. Also discussed are new thrombolytic agents and the effects of concomitant use of other drugs as part of the treatment regimen.

Occluded infrainguinal grafts: when to choose lytic therapy versus a new bypass graft

BACKGROUND

The published results of thrombolysis for occluded bypass grafts, including a prospective multicenter trial, have been disappointing, prompting many investigators to proceed directly to a new bypass rather than attempt graft salvage. Our series of 61 occluded grafts treated with lytic therapy, however, identified a subgroup that justified attempted graft salvage.

METHOD

The grafts consisted of saphenous vein 59% (36/61), other vein (arm or composite vein) 21% (13/61), and polytetrafluoroethylene (PTFE) 29% (13/61). The data analysis was designed to identify the graft subgroup that would benefit from lytic therapy by using cumulative survival analysis techniques with the Wilcoxon (Gehan) test for univariate analysis and Cox proportional hazards model for multivariate analysis. Specific variables examined by univariate analysis were graft age (defined as the interval from initial bypass to graft lysis), graft material, graft type (femoropopliteal versus femorotibial), diabetes, symptoms (claudication versus salvage) and duration of occlusion prior to lysis.

RESULTS

Complete lysis was achieved in 72% (44/61) of the grafts, and 86% (38/44) had an underlying stenosis that was treated by percutaneous balloon angioplasty (28/38) or surgery (7/38). Three stenotic outflow lesions were not treated. Cumulative 5-year patency for all 61 grafts was 23% +/- 0.075 (SE). Only graft age < 10 versus > 10 months was significant (P < 0.004) by univariate analysis, and it was also the only significant variable found by multivariate analysis; it indicated a 1.58 increase in relative risk of occlusion for the younger grafts. The combination of a saphenous vein graft that was also > 10 months old resulted in a 45% 5-year patency, compared to 21% for < 10-month-old saphenous vein grafts (P < 0.008). A review of 161 bypass grafts performed at our institution over the past 10 years revealed a 52% 5-year secondary patency in previously bypassed limbs, which varied with graft material (67% saphenous, 50% alternative vein, 31% prosthetic). Lysed graft patency was comparable to that of a second bypass using other veins or PTFE conduit.

CONCLUSIONS

In the absence of an intact saphenous vein for a second bypass, thrombolytic therapy is an alternative to surgery.

Lysis-assisted angioplasty in the treatment of lower-limb arterial thrombosis

This study examined the results in 30 patients treated with lysis-assisted angioplasty and compared them with the results of 30 patients with simple stenotic disease treated by angioplasty alone. One patient died on the day of treatment with lysis-assisted angioplasty from arterial perforation and haemorrhage. Of the remaining 29 patients 16 (55 per cent) were symptomatically improved and 13 had early reocclusion. Six patients developed major complications (two deaths, two major haemorrhage, two cerebrovascular accident). The late results were comparable to those for patients undergoing angioplasty alone. The best outcome was obtained in patients with proximal disease (P < 0.01); poor run-off or critical ischaemia did not preclude a good outcome.

Lower limb intra-arterial thrombolysis

In the UK, approximately 5000 patients present annually with acute lower limb ischaemia. The aetiology is usually thromboembolic disease, other causes include aortic dissection and arterial trauma. Over the past two decades thrombosis has replaced embolism as the principal cause of acute ischaemia, and now accounts for approximately 59% of cases. As a consequence, intra-arterial thrombolysis is being increasingly used as first-line treatment for this condition.

Results of a prospective randomized trial evaluating surgery versus thrombolysis for ischemia of the lower extremity. The STILE trial

PURPOSE

This study was designed to evaluate intra-arterial thrombolytic therapy as part of a treatment strategy for patients requiring revascularization for lower limb ischemia caused by nonembolic arterial and graft occlusion.

MATERIALS AND METHODS

Patients with native arterial or bypass graft occlusion were randomized prospectively to either optimal surgical procedure or intra-arterial, catheter-directed thrombolysis with recombinant tissue plasminogen activator (rt-PA) or urokinase (UK). Thrombolysis patients required successful catheter placement into the occlusion before infusion of either rt-PA at 0.05 mg/kg/hr for up to 12 hours or UK of 250,000 units bolus followed by 4000 units/min x 4 hours, then 2000 units/min for up to 36 hours. A composite clinical outcome of death, ongoing/recurrent ischemia, major amputation, and major morbidity was the primary endpoint. Additional endpoints were reduction in surgical procedure, clinical outcome classification, length of hospitalization, and outcome by duration of ischemia.

RESULTS

Randomization was terminated at 393 patients because a significant primary endpoint occurred by the first interim analysis. Failure of catheter placement occurred in 28% of patients who were randomized to lysis, and thus, were considered treatment failures. Thirty-day outcomes demonstrated significant benefit to surgical therapy compared with thrombolysis (p < 0.001), primarily because of a reduction in ongoing/recurrent ischemia (p < 0.001). However, clinical outcome classification at 30 days was similar. Stratification by duration of ischemia indicated that patients with ischemic deterioration of 0 to 14 days had lower amputation rates with thrombolysis (p = 0.052) and shorter hospital stays (p < 0.04). Patients with ischemic deterioration of > 14 days who who were treated surgically had less ongoing/recurrent ischemia (p < 0.001) and trends toward lower morbidity (p = 0.1). At 6-month follow-up, there was improved amputation-free survival in acutely ischemic patients treated with thrombolysis (p = 0.01); however, chronically ischemic patients who were treated surgically had significantly lower major amputations rates (p = 0.01). More than half of thrombolysis patients (55.8%) had a reduction in magnitude of their surgical procedure (p < 0.001). There was no difference in efficacy or safety between rt-PA and UK; however, in the thrombolysis group as a whole, fibrinogen depletion predicted hemorrhagic complications (p < 0.01).

CONCLUSIONS

Surgical revascularization of patients with < 6 months of ischemia is more effective and safer than catheter-directed thrombolysis. Although ongoing/recurrent ischemia is greater in the patients undergoing thrombolysis, 30-day clinical outcomes are similar, probably because of cross-over treatment to surgery. There is no difference in efficacy or safety between rt-PA and UK, although bleeding occurs in patients with greater fibrinogen depletion. A significant reduction in planned surgical procedure is observed after thrombolysis. Patients with acute ischemia (0-14 days) who were treated with thrombolysis had improved amputation-free survival and shorter hospital stays. However, for patients with chronic ischemia (> 14 days), surgical revascularization was more effective and safer than thrombolysis. Combining a treatment strategy of catheter-directed thrombolysis for acute limb ischemia with surgical revascularization for chronic limb ischemia offers the best overall results.