BACKGROUND: The mode of death has been well characterized in patients with heart failure and a reduced ejection fraction; however, less is known about the mode of death in patients with heart failure and a preserved ejection fraction (HFPEF). The purpose of this study was to examine the mode of death in patients with HFPEF enrolled in the Irbesartan in Heart Failure With Preserved Ejection Fraction Study (I-Preserve) trial and to determine whether irbesartan altered the distribution of mode of death in HFPEF. METHODS AND RESULTS: All deaths were reviewed by a clinical end-point committee, and the mode of death was assigned by consensus of the members. The annual mortality rate was 5.2% in the I-Preserve trial. There were no significant differences in mortality rate between the placebo and irbesartan groups. The mode of death was cardiovascular in 60% (including 26% sudden, 14% heart failure, 5% myocardial infarction, and 9% stroke), noncardiovascular in 30%, and unknown in 10%. There were no differences in the distribution of mode-specific mortality rates between placebo and irbesartan. CONCLUSIONS: Sixty percent of the deaths in patients with HFPEF were cardiovascular, with sudden death and heart failure death being the most common. Treatment with irbesartan did not affect overall mortality or the distribution of mode-specific mortality rates. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00095238.