Initial epicardial coronary flow, as assessed by the Thrombolysis in Myocardial Infarction flow grade (TFG), prior to primary percutaneous coronary intervention (pPCI) for ST-segment elevation myocardial infarction (STEMI) has been associated with short- and long-term mortality in randomized clinical trials. This study was designed to determine the relationship between initial TFG and mortality in a large, heterogeneous, real-world population of STEMI patients undergoing pPCI.

The relationship between pre-pPCI TFG among patients undergoing pPCI and in-hospital mortality was evaluated among STEMI patients from 2004 to 2006 in the National Registry of Myocardial Infarction.

Of 8,337 STEMI patients, 6,595 (79.1%) had pre-pPCI TFG 0/1, 1,126 (13.5%) had pre-pPCI TFG 2, and 616 (7.4%) had pre-pPCI TFG 3. TFG 0/1 prior to pPCI was associated with 3.4% in-hospital mortality, whereas TFG 2 (2.0%) and TFG 3 (1.8%) were associated with significantly lower mortality (TFG 0/1 vs TFG 2, P = .013; TFG 0/1 vs TFG 3, P = .035). TFG 0/1 prior to pPCI was also associated with a significant increase in the composite of death, recurrent myocardial infarction, heart failure, and shock (16.1%) when compared with patients presenting with TFG 2 (11.5%; P < .001) and TFG 3 (7.6%; P < .001). The difference in this composite was also significant between patients presenting with TFG 2 and TFG 3 (P = .01).

In a large, heterogeneous group of real-world patients presenting with STEMI, pre-pPCI TFG 0/1 is associated with higher in-hospital mortality and other major adverse cardiovascular events. These results corroborate prior to post hoc analyses from randomized clinical trials and support continued efforts aimed at safely establishing early infarct-related artery patency among patients with STEMI.