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Summit Meeting on Catheter-directed Thrombolytic Therapy
Concluding Remarks
Summit Meeting on Catheter-directed Thrombolytic Therapy! Michael A. Bettmann, MD
It is clear that catheter-directed thrombolytic therapy has been a major advance in the treatment of patients with acute arterial or graft occlusion. It is also clear that this approach is at worst no more expensive than surgery, and carries, surprisingly, a lower I-year mortality rate. It is also clear that new plasminogen activators, ranging from recombinant urokinase to single-chain urokinase plasminogen activator to recombinant plasminogen activator, hold promise for improved efficacy and safety. Conversely, as these proceedings indicate, many questions remain. Although there are some high-quality data available, much is based on small studies and anecdotal experience. Among the most pressing are the questions of efficacy of thrombolysis in non-acute occlusions, as compared with surgery or, if possible, watchful waiting. Another important question regards technique; while it seems clear that pulsed-spray delivery is not an answer in all cases, does it nonetheless have a role? Does lacing of thrombus help? Does it matter if a single end hole is used versus multiple side holes? What is the role of ancillary
medications, such as heparin or, in the near future, potent antiplatelet medications or thrombin inhibitors? Another set of questions, complex ones, will arise with the coming availability of new plasminogen activators with greater specificity or altered biologic characteristics, such as shorter or longer half lives. These questions can perhaps be considered the "micro" or scientific ones. "Macro" or societal issues are at least as important. There is still a dearth of data regarding outcomes in patients with peripheral vascular disease. Again, much has been written, but it is no longer sufficient to document patency by life-table analysis. The more important questions concern overall survival (factoring in comorbid events), societal costs, and effects of treatments on life style. The extremes-claudication, which severely disrupts life style, or limb-threatening acute ischemia-are relatively easy to address, although with the former, means should be developed to factor in patient preference. In most patients, however, decision making is less clear and data as well as methods must be developed to facilitate such decisions.
These articles, then, suggest that catheter-directed thrombolysis is a significant contribution to patient care. It appears to be cost-effective and may even be the rare example of a new approach that actually results in cost saving-eost-effective rarely means less expensive. It is still, however, a rapidly evolving field. Efforts must be made to gather more objective data, to deal with the rapid advances that are occurring, and to investigate true outcomes from this therapeutic approach, both in nontraditional areas such as acute lower extremity arterial occlusion as well as in promising and exciting frontiers such as cerebrovascular occlusive disease. Over the next few years, it is not likely that all the questions will be answered. It is likely, however, that the next decade will see increased use of thrombolytic therapy. It is our hope that if a similar meeting is held 5-10 years from now, a new set of questions will have been engendered, perhaps in part by work inspired by the findings presented in this issue.
Index term: Thrombolysis JVIR 1995; 6:1258 1 Address correspondence to M.A.B., Department of Radiology, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756.
© 8CVIR, 1995
1258
Summit Meeting on Catheter-directed Thrombolytic Therapy! Michael A. Bettmann, MD
It is clear that catheter-directed thrombolytic therapy has been a major advance in the treatment of patients with acute arterial or graft occlusion. It is also clear that this approach is at worst no more expensive than surgery, and carries, surprisingly, a lower I-year mortality rate. It is also clear that new plasminogen activators, ranging from recombinant urokinase to single-chain urokinase plasminogen activator to recombinant plasminogen activator, hold promise for improved efficacy and safety. Conversely, as these proceedings indicate, many questions remain. Although there are some high-quality data available, much is based on small studies and anecdotal experience. Among the most pressing are the questions of efficacy of thrombolysis in non-acute occlusions, as compared with surgery or, if possible, watchful waiting. Another important question regards technique; while it seems clear that pulsed-spray delivery is not an answer in all cases, does it nonetheless have a role? Does lacing of thrombus help? Does it matter if a single end hole is used versus multiple side holes? What is the role of ancillary
medications, such as heparin or, in the near future, potent antiplatelet medications or thrombin inhibitors? Another set of questions, complex ones, will arise with the coming availability of new plasminogen activators with greater specificity or altered biologic characteristics, such as shorter or longer half lives. These questions can perhaps be considered the "micro" or scientific ones. "Macro" or societal issues are at least as important. There is still a dearth of data regarding outcomes in patients with peripheral vascular disease. Again, much has been written, but it is no longer sufficient to document patency by life-table analysis. The more important questions concern overall survival (factoring in comorbid events), societal costs, and effects of treatments on life style. The extremes-claudication, which severely disrupts life style, or limb-threatening acute ischemia-are relatively easy to address, although with the former, means should be developed to factor in patient preference. In most patients, however, decision making is less clear and data as well as methods must be developed to facilitate such decisions.
These articles, then, suggest that catheter-directed thrombolysis is a significant contribution to patient care. It appears to be cost-effective and may even be the rare example of a new approach that actually results in cost saving-eost-effective rarely means less expensive. It is still, however, a rapidly evolving field. Efforts must be made to gather more objective data, to deal with the rapid advances that are occurring, and to investigate true outcomes from this therapeutic approach, both in nontraditional areas such as acute lower extremity arterial occlusion as well as in promising and exciting frontiers such as cerebrovascular occlusive disease. Over the next few years, it is not likely that all the questions will be answered. It is likely, however, that the next decade will see increased use of thrombolytic therapy. It is our hope that if a similar meeting is held 5-10 years from now, a new set of questions will have been engendered, perhaps in part by work inspired by the findings presented in this issue.
Index term: Thrombolysis JVIR 1995; 6:1258 1 Address correspondence to M.A.B., Department of Radiology, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756.
© 8CVIR, 1995
1258