Objective: This study evaluated the impact of early patency of the infarct-related vessel on short-term mortality after thrombolysis for acute myocardial infarction.
Background: Different thrombolytic regimens for acute myocardial infarction proved to be equally effective in large scale mortality trials despite significant differences in their efficacy with respect to early infarct-related vessel patency as shown in smaller angiographic trials.
Methods: Patients from four German multicenter studies of thrombolysis in acute myocardial infarction were retrospectively evaluated. Of 939 patients with acute myocardial infarction (duration of symptoms < 6 h) treated with thrombolysis, 907 (96.6%) had an angiogram of the infarct-related artery 90 min after the initiation of thrombolytic therapy. The perfusion status was graded according to the Thrombolysis in Myocardial Infarction (TIMI) study criteria.
Results: Complete reperfusion (TIMI grade 3) was found in 561 of 907 patients and partial reperfusion (TIMI grade 2) in 122 of 907. Overall, the in-hospital mortality rate was 4.6% (43 patients). In patients with complete reperfusion of the infarct-related vessel, the mortality rate was only 2.7% versus 7.1% in patients with an occluded vessel at the 90-min angiogram. This difference was highly significant in univariate as well as in multivariate analysis. In patients with partial perfusion of the infarct vessel, the mortality rate was 6.6%.
Conclusions: The early perfusion status of the infarct-related artery is an independent predictor of short-term survival. However, only complete early reperfusion is associated with a reduced in-hospital mortality rate whereas patients with partial perfusion (TIMI grade 2) have a short-term prognosis similar to that of patients with persistently occluded infarct vessels. Therefore, when used as a surrogate end point for mortality, only TIMI grade 3 perfusion of the infarct vessel should be interpreted as a treatment success of thrombolysis in acute myocardial infarction.