Impact of early perfusion status of the infarct-related artery on short-term mortality after thrombolysis for acute myocardial infarction: retrospective analysis of four German multicenter studies.

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.