Antithrombotic Therapy in Peripheral Arterial Occlusive Disease: Low-dose streptokinase
In 1974, Dotter et al reported the use of low-dose streptokinase administered locally at the site of the thrombus; they obtained lysis without complication. Since then, efficacy of streptokinase, urokinase, or tissue plasminogen activator (tPA) infused near or into the thrombus has been reported by many investigators. Regional or intra-arterial thrombolytic therapy has become the preferred technique among interventional radiologists and vascular surgeons. The rate of successful reperfusion (50 to 85%) appears higher than with systemic thrombolytic therapy, and an important advantage of the selective approach is that it allows simultaneous angiographic definition of the nature of the occlusion (embolic vs thrombotic) and vessel wall abnormalities that would lead to rethrombosis if not corrected by surgery or balloon angioplasty. A major drawback to this approach is that arterial catheterization is required for prolonged periods (hours to days), leading to major bleeding and thromboembolic complications in 6 to 20% of patients. Despite this, intra-arterial thrombolytic therapy appears superior to systemic treatment. In a randomized trial comparing intra-arterial tPA, IV tPA, and intra-arterial streptokinase, intra-arterial tPA was significantly more effective in establishing reperfusion and had a lower incidence of hemorrhagic complications (level II). Other studies (levels II to IV) have documented the superiority of both urokinase and tPA over streptokinase.
Randomized trials comparing surgical thrombectomy and thrombolytic therapy in patients with acute arterial ischemia provide helpful information. Single-center, small trials (level II) document comparable limb salvage rates with both modes of therapy. In one study, patients given thrombolytic therapy had significandy improved 1-year cumulative survival, which appeared to be the result of fewer in-hospital cardiopulmonary complications that were common postoperative events. Allergy treatment allergy treatment A larger, multicenter trial (level II) compared intra-arterial thrombolytic therapy with urokinase or tPA with surgery in patients presenting with recent-onset lower-limb ischemia due to nonembolic arterial and bypass graft occlusion. The study was stopped prematurely when an interim analysis demonstrated that patients randomized to surgery did significantly better than those given thrombolytic therapy. However, there appeared to be discordant results depending on the clinical presentation. In patients presenting with ischemic symptoms of greater than 2 weeks’ duration, surgical revascularization was clearly superior; in patients presenting with acute ischemia of less than 2 weeks’ duration, amputation rates were lower with thrombolytic therapy.