Estimated gain in life expectancy. A simple tool to select optimal reperfusion treatment in individual patients with evolving myocardial infarction

Abstract

Currently several modes of reperfusion therapy for acute myocardial infarction are available. Streptokinase, accelerated alteplase and direct angioplasty are the most frequently used. These options are increasingly effective, but are also increasingly complex and costly. Since, unfortunately, physicians are often restricted by budget limitations, choices must be made in clinical practice to provide optimal therapy to individual patients. In order to guide such decision making, we developed a model to predict the expected benefit of therapy in terms of gain in life expectancy. Patients' life expectancy will decrease after infarction. Part of this loss can be prevented by early reperfusion therapy. The clinical benefit of therapy ranges from negligible gain in patients with small infarcts treated relatively late to an expected gain of more than 2 years in patients with extensive infarction treated within 3 h of onset of symptoms. The expected benefits are presented in a set of tables and depend on age, previous infarction, estimated infarct size, treatment delay and intracranial bleeding risk. With the help of these table, resources will be allocated in such a manner that patients who will benefit the most will receive the most effective therapy. Patients with similar expected treatment benefit will be offered the same mode of therapy. Future life years were discounted at 5% per year. The arbitrary thresholds currently applied for decision making at the Thoraxcenter are: no reperfusion therapy when the estimated gain in discounted life expectancy was < 1 month, streptokinase for 1-4 months and accelerated alteplase for a gain > or = 5 months. Direct angioplasty is recommended in patients with an estimated gain > or = 12 months, and in patients with an increased risk of intracranial bleeding. In this way, approximately 80% of our patients will be treated with thrombolytics (40% streptokinase and 40% accelerated alteplase), while in 10% direct angioplasty will be initiated. Patients with small infarcts presenting late will not receive reperfusion therapy. These threshold values have been chosen arbitrarily, and different thresholds may be selected in other centres. However, the developed model would guarantee that treatment decisions are made in a consistent manner, to provide optimal therapy for patients with evolving myocardial infarction, in spite of limited resources.