Adjunctive intracoronary thrombolysis in complicated coronary angioplasty

Percutaneous transluminal coronary angioplasty is complicated by abrupt closure in 4.4-9.5% of procedures. Although the etiology of closure is difficult to determine, arterial dissection and thrombus formation are often involved. When abrupt closure occurs, repeat balloon dilation of the affected vessel is the mainstay of treatment and results in a mean angiographic success rate of 44% (range 35-51%). Other interventions, such as stent implantation and atherectomy, may also be attempted. I.c. thrombolysis is an alternative rescue strategy for the treatment of abrupt coronary closure during angioplasty. Initial angiographic success with i.c. thrombolysis, in combination with repeat balloon dilation ranges from 52% to 90%. These results are encouraging, but vessel reocclusion occurs in up to 55% of patients, resulting in diminished clinical success. Two trials suggest thrombolysis is ineffective or detrimental in this patient population. Most studies evaluating i.c. thrombolysis are retrospective, noncomparative, lack standardized protocols, and evaluate dissimilar patient populations. Therefore, the contribution of confounding variable such as operator experience, balloon size, duration of balloon inflation, and investigator bias cannot be assessed. I.c. thrombolysis has a limited role in the treatment of abrupt closure. This therapy should be considered only if thrombus formation is definitively the cause of occlusion, and avoided if intimal dissection is present, due to possible detrimental effects. The results of thrombolysis as a sole rescue therapy for abrupt closure are disappointing. Therefore, repeat balloon dilation should always be performed concomitantly with drug administration. In select patients, streptokinase, alteplase, or urokinase may be given for abrupt closure. Urokinase is favored due to increased experience with this agent and decreased cost. Ambrose recommends 250,000-1,000,000 units of urokinase, infused for up to 30 minutes (average wholesale price $419-1676). Additional data indicate a lower dose of urokinase may be sufficient for closure resolution, but this has not been adequately assessed. I.c. rather than intravenous thrombolytic administration may cause fewer systemic effects; however, contraindications to thrombolytic therapy should always be evaluated and weighed against potential benefits. The future role of thrombolysis in the treatment of complicated coronary angioplasty is unclear. Only randomized, controlled trials can evaluate the merits of this treatment approach compared with other rescue strategies.