Peripheral Arteries: Treatment with Antibodies of Platelet Receptors and Reteplase for Thrombolysis—APART Trial

Anticoagulation and Antiplatelet Agents in Peripheral Arterial Interventions

Effective revascularization of peripheral artery disease relies on periprocedural pharmacological regulation of the clotting cascade. Patient-specific factors such as cardiovascular risk factors, contraindications, and individual psychosocial factors must be considered when initiating post revascularization management. Management with anticoagulant and antiplatelet agents is discussed to guide the interventionalist on which therapy may be appropriate for their patient. While exact treatment may be institution and provider dependent, the interventionist must be familiar with the available classes of medications and how they can be prescribed in the postprocedural setting to improve cardiovascular outcomes.

ACR Appropriateness Criteria® Iliac Artery Occlusive Disease

Iliac artery occlusive disease can present as a sudden-onset acute thrombotic or thromboembolic event or as a chronic progressive atherosclerotic process that presents as claudication progressing to rest pain. Depending on the clinical presentation, the diagnosis is usually confirmed through Doppler vascular ultrasound, CT angiography, or MR angiography; the choice of imaging is usually based on modality availability and the presence of patient comorbidities such as chronic kidney disease. The Trans-Atlantic Inter-Society Consensus II classification system is commonly used to describe the extent of the peripheral vascular disease. Depending on the pathophysiology, clinical presentation, and radiologic extent of the disease process, therapeutic options for acute thrombotic cases can include supportive care, anticoagulation, thrombolytic therapy, surgical or catheter-directed mechanical thrombectomy, and surgical bypass. Therapeutic options for atherosclerotic disease include supportive measures such as behavior modification, a supervised exercise program, adjunctive treatment with anticoagulation and antiplatelet medications, angioplasty, stent placement, stent-graft placement, surgical or catheter-directed endarterectomy or plaque excision, and surgical bypass. This document describes the appropriateness of imaging in this patient population, treatment procedures for specific clinical scenarios, and the likely prognosis for these patients. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Fibrinolytic agents for peripheral arterial occlusion

BACKGROUND

Peripheral arterial thrombolysis is used in the management of peripheral arterial ischaemia. Streptokinase was originally used but safety concerns led to a search for other agents. Urokinase and recombinant tissue plasminogen activator (rt-PA) have increasingly become established as first line agents for peripheral arterial thrombolysis. Potential advantages of these agents include improved safety, greater efficacy and a more rapid response. Recently drugs such as pro-urokinase, recombinant staphylokinase and alfimperase have been introduced. This is an update of a review first published in 2010.

OBJECTIVES

To determine which fibrinolytic agents are most effective in peripheral arterial ischaemia.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator (TSC) searched the Specialised Register (last searched March 2013) and CENTRAL (2013, Issue 3) for randomised controlled trials (RCTs) comparing fibrinolytic agents to treat peripheral arterial ischaemia.

SELECTION CRITERIA

RCTs comparing fibrinolytic agents to treat peripheral arterial occlusion.

DATA COLLECTION AND ANALYSIS

Data were analysed for the outcomes vessel patency, time to lysis, limb salvage, amputation, death, complications including major haemorrhage, stroke, and distal embolization.

MAIN RESULTS

Five RCTs involving a total of 687 participants with a range of clinical indications were included. No new studies were included in this update. In one three-pronged study, vessel patency was greater with intra-arterial recombinant tissue plasminogen activator (rt-PA) than with intra-arterial streptokinase (P < 0.04) or intravenous rt-PA (P < 0.01). In participants with peripheral arterial occlusion there was no statistically significant difference in limb salvage at 30 days with either urokinase or rt-PA, though this may reflect the small numbers in the studies. Incidences of haemorrhagic complications varied with fibrinolytic regime but there was no statistically significant difference between intra-arterial urokinase and intra-arterial rt-PA. In the three-pronged study intravenous rt-PA and intra-arterial streptokinase were associated with a significantly higher risk of haemorrhagic complications than with intra-arterial rt-PA (P < 0.05).

AUTHORS' CONCLUSIONS

There is some evidence to suggest that intra-arterial rt-PA is more effective than intra-arterial streptokinase or intravenous rt-PA in improving vessel patency in people with peripheral arterial occlusion. There was no evidence that rt-PA was more effective than urokinase for patients with peripheral arterial occlusion and some evidence that initial lysis may be more rapid with rt-PA, depending on the regime. Incidences of haemorrhagic complications were not statistically significantly greater with rt-PA than with other regimes. However, all of the findings come from small studies and a general paucity of results means that it is not possible to draw clear conclusions.

Review of Currently Available GP IIb/IIIa Inhibitors and Their Role in Peripheral Vascular Interventions

The glycoprotein IIb/IIIa (GP IIb/IIIa) antagonists are the most recent additions to the antiplatelet agents available to the interventional radiologist. The currently available GP IIb/IIIa antagonists are abciximab, eptifibatide, and tirofiban. These medications have demonstrated excellent safety and efficacy in the setting of coronary arterial interventions. The fundamental benefit of the GP IIb/IIIa antagonists lies in their unique mechanism of action: the ability to prevent platelet aggregation, thrombus formation, and distal thromboembolism while preserving initial platelet binding to damaged vascular surfaces. A paucity of data exists regarding the role of GP IIb/IIIa inhibitors in peripheral vascular interventions. The GP IIb/IIIa antagonists would theoretically provide excellent antiplatelet therapy in patients undergoing any of a variety of endovascular interventions during which thrombosis or thromboembolism may endanger distal perfusion in patients with peripheral vascular disease. The goal of this summary is to review the indications for use, pharmacology, and evidence for efficacy of the GP IIb/IIIa antagonists in hopes of translating these data for application in the peripheral arterial circulation. Further research is necessary to determine how these agents may be safely used in combination with other anticoagulants or with stents, efficacy compared with standard regimens, success at preventing distal thromboembolism, and cost effectiveness.

[Arterial occlusive disease. Catheter-directed thrombolytic therapy]

Local catheter-directed thrombolysis of extremity artery or bypass thromboembolic occlusions is a promising therapeutic option with comparatively low complication rates, if the severity of the ischemia does not require urgent surgical revascularization. This therapeutic decision has to be made by a vascular team taking individual circumstances and contraindications into consideration. Apart from an adequate dosage, a strict intrathrombotic administration of the fibrinolytic agent and careful clinical monitoring including surveillance of the coagulation system is necessary and intensive care unit resources should be used. If necessary the thrombolysis therapy can be combined with mechanical thrombaspiration and balloon dilatation or surgical correction of an underlying lesion.

Acute upper limb ischemia due to cardiac origin thromboembolism: the usefulness of percutaneous aspiration thromboembolectomy via a transbrachial approach

Objective

To evaluate the usefulness of percutaneous aspiration thromboembolectomy (PAT) via a transbrachial approach in patients with acute upper limb ischemia.

Materials and Methods

From July 2004 to March 2008, eleven patients with acute upper limb ischemia were enrolled in this study. They were initially treated with thrombolysis (n = 1), PAT (n = 6), or both (n = 4) via a femoral artery approach. However, all of the patients had residual thrombus in the brachial artery, which was subsequently managed by PAT via the transbrachial approach for removal of residual emboli.

Results

Successful re-canalization after PAT via a transbrachial approach was achieved in all patients. Two patients experienced early complications: one experienced a massive hematoma of the upper arm due to incomplete compression and was treated by stent deployment. The other patient experienced a re-occlusion of the brachial artery the day after the procedure due to excessive manual compression of the puncture site, but did not show recurrence of ischemic symptoms in the artery of the upper arm. Clinical success with complete resolution of ischemic symptoms was achieved in all patients.

Conclusion

PAT via a transbrachial approach is a safe and effective treatment for patients with acute upper limb ischemia.

Fibrinolytic agents for peripheral arterial occlusion

BACKGROUND

Peripheral arterial thrombolysis is used in the management of peripheral arterial ischaemia. Streptokinase was originally used but safety concerns led to a search for other agents. Urokinase and recombinant tissue plasminogen activator (rt-PA) have increasingly become established as first line agents for peripheral arterial thrombolysis. Potential advantages of these agents include improved safety, greater efficacy and a more rapid response. Recently drugs such as pro-urokinase, recombinant staphylokinase and alfimperase have been introduced.

OBJECTIVES

To determine which fibrinolytic agents are most effective in peripheral arterial ischaemia.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched October 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched 2009, Issue 4) for randomised controlled trials (RCTs) comparing fibrinolytic agents to treat peripheral arterial ischaemia.

SELECTION CRITERIA

RCTs comparing fibrinolytic agents to treat peripheral arterial occlusion.

DATA COLLECTION AND ANALYSIS

Data were analysed for the outcomes vessel patency, time to lysis, limb salvage, amputation, death, complications including major haemorrhage, stroke, and distal embolization.

MAIN RESULTS

Five RCTs involving a total of 687 patients with a range of clinical indications were included. In one three-pronged study, vessel patency was greater with intra-arterial recombinant tissue plasminogen activator (rt-PA) than with intra-arterial streptokinase (P < 0.04) or intravenous rt-PA (P < 0.01). In patients with peripheral arterial occlusion there was no statistically significant difference in limb salvage at 30 days with either urokinase or rt-PA, though this may reflect the small numbers in the studies. Incidences of haemorrhagic complications varied with fibrinolytic regime but there was no statistically significant difference between intra-arterial urokinase and intra-arterial rt-PA. In the three-pronged study intravenous rt-PA and intra-arterial streptokinase were associated with a significantly higher risk of haemorrhagic complications than with intra-arterial rt-PA (P < 0.05).

AUTHORS' CONCLUSIONS

There is some evidence to suggest that intra-arterial rt-PA is more effective than intra-arterial streptokinase or intravenous rt-PA in improving vessel patency in people with peripheral arterial occlusion. There was no evidence that rt-PA was more effective than urokinase for patients with peripheral arterial occlusion and some evidence that initial lysis may be more rapid with rt-PA, depending on the regime. Incidences of haemorrhagic complications were not statistically significantly greater with rt-PA than with other regimes. However, all of the findings come from small studies and a general paucity of results means that it is not possible to draw clear conclusions.

[Medicamentous thrombolysis in acute occlusions of extremity arteries]

Local catheter-directed thrombolysis for thromboembolic extremity artery or bypass occlusions is a promising therapeutic option with comparatively low complication rates if the severity of the ischemia does not require an urgent surgical revascularization. This therapeutic decision has to be made by the vascular team under consideration of individual circumstances and contraindications. Apart from an adequate dosage, a strict intrathrombotic application of the fibrinolytic agent and careful clinical monitoring, including surveillance of the coagulation system is necessary. If needed, the thrombolysis therapy can be combined with interventional thrombaspiration and balloon dilatation or surgical correction of an underlying lesion.

Spotlight on Reteplase in Thrombotic Occlusive Disorders1

Reteplase (Retavase) is a plasminogen activator, mimicking endogenous tissue plasminogen activator (t-PA), a serine protease, converting plasminogen to plasmin and thereby precipitating thrombolysis. It is a third-generation recombinant form of t-PA that operates in the presence of fibrin (i.e. it is fibrin specific). Reteplase can be administered as a bolus dose (nonweight-based), rather than an infusion, which promotes rapid and safe administration. The ease of administration of this reteplase dosage regimen (two 10U bolus doses, each over 2 minutes, 30 minutes apart) is conducive to prehospital initiation of thrombolytic treatment in patients with ST-segment elevation myocardial infarction (STEMI), which reduces the time to treatment, a critical factor in improving long-term survival. In large randomized clinical trials of patients with STEMI, reteplase was superior to alteplase for coronary artery patency (according to TIMI [thrombolysis in myocardial infarction] flow) at 60 and 90 minutes, but there was no significant difference between agents for mortality rate and incidence of intracranial bleeding. The 35-day mortality rates were equivalent for reteplase and streptokinase recipients; there was reduced incidence of some cardiac events with reteplase versus streptokinase, but a greater incidence of hemorrhagic stroke. Reteplase has also shown thrombolytic efficacy (in nonapproved indications) as a catheter-directed intra-arterial or intravenous infusion for peripheral vessel occlusions, as 5-minute bolus doses (in 1U increments) for acute ischemic stroke, as a low-dose solution for occluded catheters or grafts, and as an intravenous double bolus for massive pulmonary embolism. Across studies in these indications, the incidence of bleeding complications associated with reteplase treatment appeared to be similar to that associated with other fibrin-specific thrombolytic agents. With its efficacy, and the ease of administration of the bolus doses potentially minimizing dosage errors when treatment is administered under time pressure, reteplase is a valuable option for pre- or in-hospital thrombolytic treatment in patients with STEMI, and is a useful thrombolytic for the treatment of the other thrombotic occlusive disorders described.

Reteplase: a review of its use in the management of thrombotic occlusive disorders

Reteplase (Retavase) is a plasminogen activator, mimicking endogenous tissue plasminogen activator (t-PA), a serine protease, converting plasminogen to plasmin and thereby precipitating thrombolysis. It is a third-generation recombinant form of t-PA that operates in the presence of fibrin (i.e. it is fibrin specific). Reteplase can be administered as a bolus dose (nonweight-based) rather than an infusion, which promotes rapid and safe administration. The ease of administration of this reteplase dosage regimen (two 10U bolus doses, each over 2 minutes, 30 minutes apart) is conducive to prehospital initiation of thrombolytic treatment in patients with ST-segment elevation myocardial infarction (STEMI), which reduces the time to treatment, a critical factor in improving long-term survival. In large randomized clinical trials of patients with STEMI, reteplase was superior to alteplase for coronary artery patency (according to TIMI [thrombolysis in myocardial infarction] flow) at 60 and 90 minutes, but there was no significant difference between agents for mortality rate and incidence of intracranial bleeding. The 35-day mortality rates were equivalent for reteplase and streptokinase recipients; there was reduced incidence of some cardiac events with reteplase versus streptokinase, but a greater incidence of hemorrhagic stroke. Reteplase has also shown thrombolytic efficacy (in nonapproved indications) as a catheter-directed intra-arterial or intravenous infusion for peripheral vessel occlusions, as 5-minute bolus doses (in 1U increments) for acute ischemic stroke, as a low-dose solution for occluded catheters or grafts, and as an intravenous double bolus for massive pulmonary embolism. Across studies in these indications, the incidence of bleeding complications associated with reteplase treatment appeared to be similar to that associated with other thrombolytic agents. With its efficacy, and the ease of administration of the bolus doses potentially minimizing dosage errors when treatment is administered under time pressure, reteplase is a valuable option for pre- or in-hospital thrombolytic treatment in patients with STEMI, and is a useful thrombolytic for the treatment of the other thrombotic occlusive disorders described.