Background: We studied the potential interaction between baseline risk of death and treatment with either standard fibrinolytic monotherapy or combination fibrin and platelet lysis with respect to outcome of patients with ST-elevation myocardial infarction (STEMI) enrolled in the Global Utilization of Strategies To open Occluded arteries (GUSTO) V trial.
Methods: Using the Thrombolysis in Myocardial Infarction (TIMI) risk score (0-14 points) for STEMI, we analyzed the 30-day and 1-year mortality according to treatment assignment and risk category. Multivariable analysis was performed to identify the potential interactions between treatment and baseline risk.
Results: The TIMI risk score could be calculated in 16256 patients (98% of patients enrolled). The median score was 2 (1-4) in each treatment group (P = .07). The risk score was significantly associated with 30-day mortality (hazard ratio [HR], 1.52; 95% CI 1.47-1.56, P < .001, for each additional 1 point), as well as with 1-year mortality (HR 1.51, CI 1.47-1.55, P < .001). The treatment allocation was not significantly related to mortality, and there was no significant interaction between baseline risk score and treatment with respect to either end point. Although combination therapy significantly reduced death or reinfarction at 7 days (HR 0.69, CI 0.54-0.89, P < .01), independent of the risk score, there was no significant statistical interaction between the two (P = .29).
Conclusion: The TIMI risk score accurately predicted early and 1-year mortality in patients with STEMI treated with pharmacological reperfusion. We did not identify any heterogeneity in the response of patients to combination therapy according to their TIMI risk score.