ABSTRACTAimHeart failure (HF) is a major cause of morbidity and mortality in older adults. Randomized controlled trials (RCTs) inform HF policy and practice, but the accurate interpretation of results is contingent on clear and transparent reporting. The CONsolidated Standards Of Reporting Trials (CONSORT) statement serves as a guide to RCT reporting. We evaluated the quality of reporting in HF RCTs in high‐impact journals by assessing their adherence to CONSORT.Methods and resultsWe searched MEDLINE, EMBASE and CINAHL for HF RCTs published in high‐impact journals 2000–2020. We assessed the proportion of CONSORT criteria that individual HF RCTs adhered to, and used the Jonckheere–Terpstra test to examine temporal trends in adherence. Multivariable linear regression explored the association between trial characteristics and adherence to CONSORT. Primary analysis assessed adherence to CONSORT 2010 update. A sensitivity analysis assessed adherence to the original (1996) CONSORT criteria. Among 221 RCTs analysed, the mean (standard deviation [SD]) adherence was suboptimal overall (mean [SD] adherence 69.7 [11.5]%) (5513/7913 criteria), with a temporal increase in adherence over the 20‐year period (p < 0.001). Factors associated with adherence included publication after versus during/before 2010 (β = 10.17, 95% confidence interval [CI] 7.64–12.70; p < 0.001); two‐group parallel individual‐level randomization versus other (including multi‐group or cluster randomization) (β = 5.81, 95% CI 2.88–8.73; p < 0.001); and multicentre versus single‐centre trials (β = 7.26, 95% CI 3.25–11.27; p < 0.001). There was no difference in trial adherence to the updated CONSORT (2010) versus the original (1996) CONSORT criteria, and temporal trends in adherence to both sets of criteria were similar, likely due to overlap between the two sets of criteria. Trials with greater adherence to CONSORT were published in higher impact factor journals, with a positive correlation (r = 0.312; p < 0.001).ConclusionThe quality of reporting in HF RCTs, as measured by CONSORT adherence, has improved over time but remains suboptimal.