BACKGROUND: Recent data have highlighted shortcomings of the usual blood pressure (BP) hypothesis in several populations, and emphasized the importance of visit-to-visit variability of BP in predicting cardiovascular events. Herein, we aimed at assessing the association between visit-to-visit BP variability and outcomes in chronic heart failure (CHF) patients enrolled in the Heart failure Endpoint evaluation of Angiotensin II Antagonist Losartan (HEAAL). METHODS AND RESULTS: The HEAAL study randomized 3834 patients with HF and reduced ejection fraction administered 150 mg or 50mg losartan daily in a double blind, randomized, controlled trial. The patients were followed up for up to 6.8 years after randomization, and BP was measured at 3 time points in the first year and at semi-annual visits in the years thereafter. Three measures of visit-to-visit BP variability were computed for each subject: the standard deviation, the coefficient of variation and the average absolute visit-to-visit variation. Cox proportional hazard models were used to investigate the relationship between variations in systolic blood pressure, baseline covariates and the time to death or heart failure hospitalization (i.e. primary outcome). In multivariate analyses stratified on baseline BP, the patients with higher visit-to visit BP variability exhibited poorer outcomes (average absolute difference in SBP in mmHg:hazard ratio: 1.023 [95% CI (1.013, 1.034), P<0.0001]), independent from high dose losartan (still beneficial). CONCLUSIONS: For the first time, visit-to-visit BP variability was found elevated in CHF patients with reduced ejection fraction, and associated with poorer cardiovascular outcomes. Such assessments should be prioritized for testing prevention strategies in CHF. CLINICAL TRIAL REGISTRATION: This study is registered with the ClinicalTrials.gov, number NCT00090259