AIMS: EPHESUS was a multicentre, double-blind clinical trial in which 6632 patients with acute myocardial infarction (AMI) complicated by LV systolic dysfunction (LVSD) were randomized to receive eplerenone (n = 3319) or placebo (n = 3313). A total of 1580 EPHESUS patients were treated with PCI, which is now the standard treatment for AMI. This EPHESUS substudy examined the effects of eplerenone upon cardiovascular outcomes in PCI-treated patients. METHODS AND RESULTS: EPHESUS patients were divided into PCI-treated and non-PCI-treated cohorts, and the effect of eplerenone upon mortality and other major adverse cardiovascular outcomes was assessed in each cohort. The PCI-treated patients (n = 1580) were younger, and had better renal function and fewer co-morbidities than non-PCI-treated patients (n = 5052). Cardiovascular mortality was significantly lower in PCI-treated patients as compared with non-PCI-treated patients (7% vs. 16%, P < 0.0001). However, the incidence of non-fatal events was similar in PCI-treated and non-PCI-treated cohorts. There was no statistical difference between the PCI-treated and non-PCI-treated cohorts in the primary or secondary outcomes of the trial. Eplerenone administration, compared with placebo, in the PCI-treated cohort did not affect PCI-related clinical outcomes, including recurrence of angina, the occurrence of acute coronary syndromes, or the need for further revascularization. CONCLUSIONS: The beneficial effects of eplerenone in the EPHESUS trial exist for both PCI- and non-PCI-treated AMI patients with LVSD. Eplerenone has minimal, if any, effect upon reducing PCI-related adverse events in the PCI-treated cohort.