When is Thrombolysis for Acute Lower Limb Ischemia Worthwhile?

Infusion techniques for peripheral arterial thrombolysis

BACKGROUND

Acute limb ischaemia usually is caused by a blood clot blocking an artery or a bypass graft. Severe acute ischaemia will lead to irreversible damage to muscles and nerves if blood flow is not restored in a few hours. Once irreversible damage occurs, amputation will be necessary and the condition can be life-threatening. Infusion of clot-busting drugs (thrombolysis) is a useful tool in the management of acute limb ischaemia. Fibrinolytic drugs are used to disperse blood clots (thrombi) to clear arterial occlusion and restore blood flow. Thrombolysis is less invasive than surgery. A variety of techniques are used to deliver fibrinolytic agents. This is an update of a review first published in 2004.

OBJECTIVES

To compare the effects of infusion techniques during peripheral arterial thrombolysis for treatment of patients with acute limb ischaemia.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registries to 20 October 2020. We undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing infusion techniques for fibrinolytic agents in the treatment of acute limb ischaemia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as recommended by Cochrane. We assessed the risk of bias in included trials using the Cochrane 'Risk of bias' tool. We evaluated certainty of evidence using GRADE. For dichotomous outcomes, we calculated the odds ratio (OR) with the corresponding 95% confidence interval (CI). We were not able to carry out meta-analyses due to clinical heterogeneity, so we have reported the results and performed the comparisons narratively. The main outcomes of interest were amputation-free survival or limb salvage, amputation, mortality, vessel patency, duration of thrombolysis, and complications such as cerebrovascular accident and major and minor bleeding.

MAIN RESULTS

Nine studies with a total of 671 participants are included in this update. Trials covered a variety of infusion techniques, dosage regimens, and adjunctive agents. We grouped trials according to types of techniques assessed (e.g. intravenous and intra-arterial delivery of the agent, 'high-' and 'low-dose' regimens of the agent, continuous infusion and 'forced infusion' of the agent, use of adjunctive antiplatelet agents). We assessed the certainty of evidence as very low to low due to the limited power of individual studies to deliver clinically relevant results, small and heterogeneous study populations, use of different inclusion criteria by each study in terms of severity and duration of ischaemia, considerably different outcome measures between trials, and use of different fibrinolytic agents. This heterogeneity prevented pooling of data in meta-analyses. No regimen has been shown to confer benefit in terms of amputation-free survival (at 30 days), amputation, or death. For vessel patency, complete success was more likely with intra-arterial (IA) than with intravenous (IV) infusion (odds ratio (OR) 13.22, 95% confidence interval (CI) 2.79 to 62.67; 1 study, 40 participants; low-certainty evidence); radiological failure may be more likely with IV infusion (OR 0.02, 95% CI 0.00 to 0.38; 1 study, 40 participants; low-certainty evidence). Due to the small numbers involved in each arm and design differences between arms, it is not possible to conclude whether any technique offered any advantage over another. None of the treatment strategies clearly affected complications such as cerebrovascular accident or major bleeding requiring surgery or blood transfusion. Minor bleeding complications were more frequent in systemic (intravenous) therapy compared to intra-arterial infusion (OR 0.03, 95% CI 0.00 to 0.56; 1 study, 40 participants), and in high-dose compared to low-dose therapy (OR 0.11, 95% CI 0.01 to 0.96; 1 study, 63 participants). Limited evidence from individual trials appears to indicate that high-dose and forced-infusion regimens reduce the duration of thrombolysis. In one trial, the median duration of infusion was 4 hours (range 0.25 to 46) for the high-dose group and 20 hours (range 2 to 46) for the low-dose group. In a second trial, treatment using pulse spray was continued for a median of 120 minutes (range 40 to 310) compared with low-dose infusion for a median of 25 hours (range 2 to 60). In a third trial, the median duration of therapy was reduced with pulse spray at 195 minutes (range 90 to 1260 minutes) compared to continuous infusion at 1390 minutes (range 300 to 2400 minutes). However, none of the studies individually showed improvement in limb salvage at 30 days nor benefit for the amputation rate related to the technique of drug delivery. Similarly, no studies reported a clear difference in occurrence of cerebrovascular accident or major bleeding. Although 'high-dose' and 'forced-infusion' techniques achieved vessel patency in less time than 'low-dose' infusion, more minor bleeding complications may be associated (OR 0.11, 95% CI 0.01 to 0.96; 1 study, 72 participants; and OR 0.48, 95% CI 0.17 to 1.32; 1 study, 121 participants, respectively). Use of adjunctive platelet glycoprotein IIb/IIIa antagonists did not improve outcomes, and results were limited by inclusion of participants with non-limb-threatening ischaemia.

AUTHORS' CONCLUSIONS

There is insufficient evidence to show that any thrombolytic regimen provides a benefit over any other in terms of amputation-free survival, amputation, or 30-day mortality. The rate of CVA or major bleeding requiring surgery or blood transfusion did not clearly differ between regimens but may occur more frequently in high dose and IV regimens. This evidence was limited and of very low certainty. Minor bleeding may be more common with high-dose and IV regimens. In this context, thrombolysis may be an acceptable therapy for patients with marginally threatened limbs (Rutherford grade IIa) compared with surgery. Caution is advised for patients who do not have limb-threatening ischaemia (Rutherford grade I) because of risks of major haemorrhage, cerebrovascular accident, and death from thrombolysis.

Mid-Term Outcomes of Thrombolysis for Acute Lower Extremity Ischemia at a Tertiary Care Center

BACKGROUND

Acute limb ischemia (ALI) is challenging to treat because of high morbidity and mortality. Endovascular-first options beginning with thrombolysis are technically feasible with similar results to open surgery. We examined our experience with thrombolysis to identify patients and target conduits that are predictive of improved outcomes.

METHODS

We performed a retrospective review of our institutional database of thrombolysis cases for arterial lower extremity disease. Thrombolysis was the index procedure, and any subsequent treatment was a reintervention. Conversion to open surgery perioperatively such as thromboembolectomy or bypass was considered a technical failure. Primary outcomes included primary patency, secondary patency, amputation-free survival (AFS), and survival. Secondary outcomes included conversion to open, reintervention <30 days, and amputation <30 days. Descriptive statistics and analysis of variance were performed for preoperative and intraoperative risk factors. Kaplan-Meier estimation and Cox proportional hazard models were used for primary and secondary outcomes.

RESULTS

Ninety-nine patients with ALI were treated with thrombolysis from 2007 to 2017. Thrombolysis was attempted on native artery (40%), vein bypass (7%), prosthetic bypass (33%), and stent (19%). Rutherford class distribution was 50% class 1, 41% class 2a, 5% class 2b, and 3% class 3. Technical success was 70%, characterized by an all-endovascular approach, patency at 30 days, and AFS for 30 days. Primary patency at 1- and 2-years was 31% and 22%, respectively. Secondary patency at 1- and 2-years was 39% and 27%, respectively. Overall, 30% required conversion to open surgery at the time of the index procedure, 7% reintervention <30 days, 5% mortality <30 days, and 5% major amputation <30 days. Prosthetic grafts and vein bypasses had the worst primary and secondary patency (P < 0.05). Five out of 7 vein bypasses required open conversion. Thrombolysis of native arteries was most successful maintaining primary patency (P < 0.05), secondary patency (P < 0.05), and AFS (P < 0.05). Patients who had adjunctive procedures at the time of thrombolysis had a significantly greater primary patency (P < 0.05) and secondary patency (P < 0.05) but not greater AFS.

CONCLUSION

Outcomes in thrombolysis for ALI have not significantly improved 20 years after the STILE trial. Technical success and mid-term patency rates are modest at best. Thrombolysis of vein bypasses and prosthetic grafts have poor technical success and primary patency compared with native arteries. However, aggressive adjunctive interventions during thrombolysis appear to improve primary and secondary patency.

Intra-arterial thrombolysis in acute popliteal artery occlusion is a safe and effective technique reducing the rate of open surgery

BACKGROUND

Acute popliteal artery occlusion is a frequent clinical entity with a risk of major amputation. Several attitudes are possible and treatment is not standardized. The purpose of this study is to demonstrate safety and effectiveness of intra-arterial thrombolysis in acute popliteal artery occlusion.

METHODS

This is a retrospective analysis of a prospective database of patients treated by intra-arterial thrombolysis for acute lower-limb ischemia due to popliteal artery occlusion between 2001 and 2014.The primary endpoint was technical and clinical success. Etiologies and etiologic treatment, amputation-free survival, in-hospital mortality and bleeding complications rates were secondary endpoints.

RESULTS

Seventy-one patients, with a mean 6-day-old ischemic time before thrombolysis, were analyzed. Technical and clinical success was 90% and 87% respectively. Etiology was embolic in 33 patients (cardiac N.=14, aortic=6, unknown=13) and thrombotic in 38 (atheromatous N.=19, entrapment N.= 4, popliteal aneurysm N.=11, Buerger N.=2, thrombophilia N.=1, hyperhomocysteinemia N.=1). Survival and amputation-free survival at 30 days were 97% and 94% respectively. There were no major bleeding complications.

CONCLUSIONS

Intra-arterial thrombolysis of acute popliteal artery occlusion is an effective technique which reduces the rate of open surgery. The risk of bleeding complications is very low.

Catheter-directed intra-arterial thrombolysis for lower extremity arterial occlusions

Catheter-directed intra-arterial thrombolysis (CDT) is a rational treatment method in patients with acute/subacute and even some chronic occlusions of lower extremity arteries and bypass grafts having salvageable limb ischemia. Immediate vessel patency can be achieved with an acceptable complication rate in many patients, especially those with fresh thrombus or emboli. It can be also an adjuvant treatment modality for endovascular interventions for chronic occlusions. There is no standard method of CDT including thrombolytic agent dose and technique. Selection of treatment strategy should be based on individual judgment based on viability of limb, lesion characteristics, and risks of hemorrhage.

Prognostic risk factors for recurrent acute lower limb ischemia in patients treated with intra-arterial thrombolysis

OBJECTIVE

The objective of this study was to assess factors predisposing patients to recurrent acute lower limb ischemia (RALLI).

METHODS

Acute lower limb ischemia patients treated with catheter-directed thrombolysis (CDT) at Tampere University Hospital and Turku University Hospital between March 2002 and December 2015 were included. The patients' baseline demographics, comorbidities, and other characteristics were assessed retrospectively. Significant factors revealed by univariable analysis were tested in a multivariable model for associations with RALLI. A patency analysis was performed, and the risks of reocclusion were identified. The limb salvage rates after reocclusion were evaluated.

RESULTS

Altogether, 303 consecutive patients with a mean age of 71 years (standard deviation, 11.8 years) were included. Of them, 159 (52.5%) were men. A total of 164 (54.1%) native arterial and 139 (45.9%) bypass graft occlusions were initially treated with CDT. On completion of CDT, 204 additional endovascular or conventional surgical procedures on 203 patients were performed to obtain adequate distal perfusion. During a median follow-up of 40 months (interquartile range, 69 months), 40 (24.4%) cases of RALLI occurred in native arteries and 90 (64.7%) in bypass graft patients (P < .001). In native arteries, the absence of appropriate anticoagulant and antiplatelet medication was independently associated with the development of acute reocclusions (hazard ratio, 6.51) in the Cox multivariable regression analysis. The patency rates were 86.6%, 72.2%, and 68.0% at 1 year, 5 years, and 9 years, respectively. In bypass grafts, worsened tibial runoff (crural index III: hazard ratio, 2.40) was independently associated with RALLI. The respective patency rates were 60.5%, 34.0%, and 29.2% for synthetic conduits and 30.8%, 20.5%, and 13.7% for autologous vein grafts at 1 year, 5 years, and 9 years. Altogether, 38 (29.2%) major amputations were performed on patients with reocclusions. Patients with synthetic conduits demonstrated superior limb salvage rates after reocclusion in comparison to native arteries or vein grafts (P = .025).

CONCLUSIONS

Appropriate post-thrombolytic antiplatelet or anticoagulant treatment after native arterial events is of great importance, but additional data are needed to improve treatment algorithms. Adequate outflow in bypass graft patients is crucial. Patients with prosthetic bypass grafts have superior limb salvage rates after reocclusion.

Contemporary trends and outcomes of thrombolytic therapy for acute lower extremity ischemia

Objective

Acute limb ischemia is a common vascular emergency requiring immediate intervention. Thrombolysis has been widely utilized for acute limb ischemia; the purpose of this study is to analyze contemporary trends, outcomes and complications of thrombolysis for acute limb ischemia.

Methods

Patients were identified from the Nationwide Inpatient Sample (2003–2013) using ICD-9. Patients undergoing emergency thrombolysis for acute limb ischemia were evaluated. Three groups were analyzed: thrombolysis alone, thrombolysis and endovascular procedure (T+ENDO), and failed thrombolysis requiring open surgery (T+OPEN).

Results

A total of 162,240 patients with acute limb ischemia were estimated: 33,615 patients (20.7%) underwent thrombolysis as the initial treatment. Mean age was 66.2 ± 34.9 years with 54% male. The utilization of thrombolysis increased significantly during the study period (16.8–24.2%, p < 0.0001). The most common group was thrombolysis and endovascular procedure (40.7%), followed by thrombolysis alone (34.1%), and T+OPEN (25.2%). Thrombolysis and endovascular procedure increased significantly over time (31.6–47.8%, p < 0.0001) whereas thrombolysis alone and T+OPEN significantly decreased (39.6–28.6% and 28.7–23.6%, respectively, p < 0.0001). Overall mortality was 4.9%; thrombolysis and endovascular procedure compared to thrombolysis alone and T-OPEN had a lower mortality rate (3.2% vs. 6.1% and 5.9%, p < 0001). The overall stroke rate was 1.9%; thrombolysis alone had the highest stroke rate (3.0%, p < 0.0001) with thrombolysis and endovascular procedure the lowest (1.2%) and T+OPEN 1.7%. The highest amputation rate was T+OPEN (11.6%, p < 0.001) compared to thrombolysis and endovascular procedure (5.1%) and thrombolysis alone (5.3%). T+OPEN had the highest incidence of cardiac (5.5%), respiratory (7.3%) and renal complications (12.5%), pneumonia (4.0%), and fasciotomy (16.8%) (all p < 0.0001).

Conclusion

Thrombolysis remains an effective treatment for acute limb ischemia with increased utilization over time. There was a significant increase in thrombolysis and endovascular procedure leading to improved outcomes. Thrombolysis alone carried the highest mortality and stroke rate, with T+OPEN associated with the highest amputation and complications. Although thrombolysis is effective, 25% of patients required an open procedure suggesting that patient selection for thrombolysis first instead of open surgery continues to be a clinical challenge.

Microbubbles and UltraSound-accelerated Thrombolysis (MUST) for peripheral arterial occlusions: protocol for a phase II single-arm trial

INTRODUCTION

Acute peripheral arterial occlusions can be treated with intra-arterial catheter-directed thrombolysis as an alternative to surgical thromboembolectomy. Although less invasive, this treatment is time-consuming and carries a significant risk of haemorrhagic complications. Contrast-enhanced ultrasound using microbubbles could accelerate dissolution of thrombi by thrombolytic medications due to mechanical effects caused by oscillation; this could allow for lower dosages of thrombolytics and faster thrombolysis, thereby reducing the risk of haemorrhagic complications. In this study, the safety and practical applicability of this treatment will be investigated.

METHODS AND ANALYSIS

A single-arm phase II trial will be performed in 20 patients with acute peripheral arterial occlusions eligible for thrombolytic treatment. Low-dose catheter-directed thrombolysis with urokinase will be used. The investigated treatment will be performed during the first hour of thrombolysis, consisting of intravenous infusion of 4 Luminity phials (6 mL in total, diluted with saline 0.9% to 40 mL total) of microbubbles with the use of local ultrasound at the site of occlusion. Primary end points are the incidence of complications and technical feasibility. Secondary end points are angiographic and clinical success, duration of thrombolytic infusion, treatment-related mortality, amputations, additional interventions and quality of life.

ETHICS AND DISSEMINATION

Ethical approval for this study was obtained in 2015 from the Medical Ethics Committee of the VU University Medical Center, Amsterdam, the Netherlands. A statement of consent for this study was given by the Dutch national competent authority. Data will be presented at national and international conferences and published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBERS

Dutch National Trial Registry: NTR4731; European Clinical Trials Database of the European Medicines Agency: 2014-003469-10; Pre-results.

Therapeutic Fibrinolysis: How Efficacy and Safety Can Be Improved

Therapeutic fibrinolysis has been dominated by the experience with tissue-type plasminogen activator (t-PA), which proved little better than streptokinase in acute myocardial infarction. In contrast, endogenous fibrinolysis, using one-thousandth of the t-PA concentration, is regularly lysing fibrin and induced Thrombolysis In Myocardial Infarction flow grade 3 patency in 15% of patients with acute myocardial infarction. This efficacy is due to the effects of t-PA and urokinase plasminogen activator (uPA). They are complementary in fibrinolysis so that in combination, their effect is synergistic. Lysis of intact fibrin is initiated by t-PA, and uPA activates the remaining plasminogens. Knockout of the uPA gene, but not the t-PA gene, inhibited fibrinolysis. In the clinic, a minibolus of t-PA followed by an infusion of uPA was administered to 101 patients with acute myocardial infarction; superior infarct artery patency, no reocclusions, and 1% mortality resulted. Endogenous fibrinolysis may provide a paradigm that is relevant for therapeutic fibrinolysis.

Safety of Intra-arterial Catheter Directed Thrombolysis: Does Level of Care Matter?

OBJECTIVES

The aim was to assess whether the level of care influenced the safety related outcomes of catheter directed thrombolysis (CDT) for patients presenting with limb ischaemia and dialysis access thrombosis.

METHODS

This was a retrospective cohort study. All consecutive patients at two tertiary referral centres for vascular surgery undergoing CDT for limb ischaemia and dialysis access thrombosis (N = 252) between 2012 and 2014 were included. Patients at Centre 1 were cared for on a general vascular ward and patients at Centre 2 were kept on a post-operative recovery unit with an increased level of care including invasive haemodynamic monitoring. Patient medical records were retrospectively scrutinised and data collected on comorbidities, anti-thrombotic medication, indications for CDT, technical success of CDT, bleeding and non-bleeding related complications, and transfer to a higher level of care.

RESULTS

There were no differences in the frequency of non-bleeding related complications between Centre 1 and Centre 2. Patients on the vascular ward had a higher frequency of minor bleeding (p = .002) but there was no difference in major bleeding (p = .12). Eleven patients on the ward required an increased level of care for medical reasons and six were moved for a lack of resources. The presence of cardiac disease was an independent risk factor for patient transfer (OR 3.2; 95% CI 1.04-9.8, p = .04).

CONCLUSIONS

CDT may be undertaken outside of a high dependency setting without a significantly increased risk of complications. Pre-existing cardiac disease was an independent risk factor for transfer to a higher level of care. These findings could have an implication for the clinical cost-effectiveness of CDT.

Dutch randomized trial comparing standard catheter-directed thrombolysis and ultrasound-accelerated thrombolysis for arterial thromboembolic infrainguinal disease (DUET)

PURPOSE

To report the results of the Dutch randomized trial comparing standard catheter-directed and ultrasound-accelerated thrombolysis (UST) for the treatment of arterial thromboembolic occlusions.

METHODS

The DUET study ( controlled-trials.com ; identifier ISRCTN72676102) was designed to assess whether UST can reduce therapy time significantly compared with standard thrombolysis (ST). Sixty patients (44 men; mean age 64 years) with recently (7-49 days) thrombosed infrainguinal native arteries or bypass grafts causing acute limb ischemia (Rutherford category I or IIa) were randomized to ST (n = 32) or UST (n = 28). The primary outcome was the duration of thrombolysis needed for uninterrupted flow (> 95% thrombus lysis), with outflow through at least 1 below-the-knee artery. Continuous data are presented as means ± standard deviations.

RESULTS

Thrombolysis was significantly faster in the UST group (17.7 ± 2.0 hours) than in the ST group (29.5 ± 3.2 hours, p = 0.009) and required significantly fewer units of urokinase (2.8 ± 1.6 × 10(6) IU in the ST group vs. 1.8 ± 1.0 × 10(6) IU in the UST group, p = 0.01) for uninterrupted flow. Technical success was achieved in 27 (84%) patients in the ST group vs. 21 (75%) patients in the UST group (p = 0.52). The combined 30-day death and severe adverse event rate was 19% in the ST group and 29% in the UST group (p = 0.54). The 30-day patency rate was 82% in the ST group as compared with 71% in the UST group (p = 0.35).

CONCLUSION

Thrombolysis time was significantly reduced by UST as compared with ST in patients with recently thrombosed infrainguinal native arteries or bypass grafts.

Acute limb ischemia

Acute limb ischemia is a medical emergency with management options ranging from urgent revascularization to limb amputation. The best patient outcome requires tailoring the treatment to the individual patient. This article describes a step-by-step approach for diagnosis and management of patients presenting with acute limb ischemia.

Intravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) in acute lower limb ischaemia

For various reasons some patients are unable to undergo intra-arterial thrombolysis for acute limb ischaemia. This interventional case series study prospectively evaluated the effect of thrombolytic treatment with 100 mg recombinant tissue plasminogen activator (rt-PA), administered intravenously, in patients with acute thrombosis of the lower limb arteries and onset of symptoms within 12 h prior to treatment. During a 3-year period (2007-2009), 18 of 86 patients satisfied the inclusion criteria and were included in the study (age range 65-80 years; 11 women). Complete and partial thrombolysis was observed in eight (44.4%) and six (33.3%) patients, respectively. All patients experienced clinical improvement. There were no amputations during the 36-month follow-up period and no haemorrhagic complications in the first 30 days post-treatment. Five patients died (27.8%) during follow-up from unrelated causes. This small study demonstrated that thrombolytic treatment with intravenous rt-PA in selected patients with acute limb ischaemia is feasible.

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