BACKGROUND AND AIMS: In the Surgical Treatment for Ischaemic Heart Failure Trial Extension Study (STICHES), coronary artery bypass grafting (CABG) improved outcomes of patients with ischaemic left ventricular dysfunction receiving medical therapy, whereas in the Revascularization for Ischaemia Ventricular Dysfunction trial (REVIVED-BCIS2), percutaneous coronary intervention (PCI) did not. The aim of this study was to explore differences in outcomes of participants treated with medical therapy alone in STICHES vs. REVIVED-BCIS2 and to assess the incremental benefit of CABG or PCI. METHODS: Pooled analysis of adjusted individual participant data from two multicentre randomized trials. All patients had left ventricular ejection fraction ≤35% and coronary artery disease and received medical therapy. Participants were randomized 1:1 to CABG (STICHES) or PCI (REVIVED-BCIS2). The primary outcome was the composite of all-cause death and hospitalization for heart failure over all available follow-up. RESULTS: A total of 1912 participants (88% male, 76% white ethnicity) were included with 98.3% completeness of follow-up for the primary outcome. The median follow-up was 118 months in STICHES and 41 months in REVIVED-BCIS2. Those receiving medical therapy alone in REVIVED-BCIS2 had fewer primary outcome events than those receiving medical therapy alone in STICHES (adjusted hazard ratio 0.60, 95% confidence interval 0.48-0.74, P < .001). Patients receiving PCI in REVIVED-BCIS2 were less likely to experience a primary outcome event than those receiving CABG in STICHES. Adjusted outcomes of patients treated with CABG in STICHES were worse than those receiving medical therapy alone in REVIVED-BCIS2. CONCLUSIONS: Patients with ischaemic cardiomyopathy receiving medical therapy in REVIVED-BCIS2 had better outcomes than those in STICHES, with or without CABG surgery. Further trials comparing CABG, PCI, and medical therapy in this population are warranted.