BACKGROUND: There is limited published information on outcome adjudication in heart failure (HF). OBJECTIVES: The authors sought to compare investigator reports (IRs) to a Clinical Events Committee (CEC) and the impact of SCTI (Standardized Clinical Trial Initiative) criteria. METHODS: In the EMPEROR-Reduced trial, the authors compared IRs to the CEC for concordance; treatment effect on primary composite outcome events; and the components first event hospitalization primarily for HF or cardiovascular mortality (CVM), prognosis after hospitalization for heart failure (HHF), total HHFs, and trial duration with and without SCTI criteria. RESULTS: The CEC confirmed 76.3% of IR events for the primary outcome (CVM: 89.1%; HHF: 73.7%). The HR for treatment effect did not differ between adjudication methods for the primary outcome (IR: 0.75 [95% CI: 0.66-0.85]; CEC: 0.75 [95% CI: 0.65-0.86]), its components, or total HHFs. The prognosis after first HHF for all-cause mortality and CVM also did not differ between IR or CEC. Interestingly, IR primary HHF with different CEC primary cause had the highest subsequent fatal event rate. Full SCTI criteria were present in 90% of CEC HHFs-with a similar treatment effect to non-SCTI. The IR primary event reached the protocol target number (841) 3 months earlier than CEC (4 months with full SCTI criteria). CONCLUSIONS: Investigator adjudication is an alternative to a CEC with similar accuracy and faster event accumulation. The use of granular (SCTI) criteria did not improve trial performance. Finally, our data suggest that consideration be given to broadening the HHF definition to include "for or with" worsening disease. (Empagliflozin Outcome Trial in Patients With Chronic Heart Failure With Reduced Ejection Fraction [EMPEROR-Reduced]; NCT03057977).