Predictors of suboptimal TIMI flow after primary angioplasty for acute myocardial infarction: results from the HORIZONS-AMI trial

Aims: The predictors of TIMI flow <3 after PCI in patients with acute myocardial infarction have not been examined in a contemporary, large-scale multicentre prospective study. Methods and results: The HORIZONS-AMI trial randomised 3,602 patients with STEMI undergoing primary PCI to bivalirudin (n=1,800) vs. unfractionated heparin plus a glycoprotein IIb/IIIa inhibitor (n=1,802). A total of 3,845 treated lesions (3,362 vessels) were analysed by the core lab; 2,942 vessels (87.5%) and 2,758 patients (87.1%) had final TIMI 3 flow, while 407 (12.9%) had TIMI flow <3. The independent predictors of TIMI flow <3 were age (OR 1.23 per 10-year increase; 95% CI: 1.12 to 1.35; p<0.0001), anterior MI (OR 1.65; 95% CI: 1.33 to 2.05; p<0.0001), baseline TIMI flow grade 0/1 (OR 2.79; 95% CI: 2.14 to 3.62; p<0.0001), and lesion length (OR 1.05 per 10 mm increase; 95% CI: 1.02 to 1.09; p=0.005). The three-year mortality of patients in whom final TIMI 3 flow was achieved was significantly lower than that of patients in whom TIMI 3 flow was not achieved (5.5% vs. 10.5%; p<0.0001). Conclusions: In this large-scale, randomised trial, failure to restore normal TIMI flow after primary PCI in STEMI occurred in 12.9% of patients, and was associated with patient-related factors (age), anatomical factors (anterior MI location), and angiographic factors (baseline TIMI 0/1 flow and lesion length). Failure to achieve TIMI 3 flow continues to be a powerful predictor of mortality after primary PCI in the contemporary era.