[en] AIM: Heart failure (HF) poses a unique medical burden of high morbidity and mortality. Elevated resting heart rate (HR) is associated with worse outcomes in chronic HF, but little is known about the prognostic impact of serial HR measurement during hospital stay after acute HF. We examined the association between HR obtained at admission at Day 4 and at discharge and long-term mortality in a cohort of 672 patients discharge from hospital after management of acute HF. METHODS AND RESULTS: All patients examined were in sinus rhythm. HR was derived from electrocardiogram and was defined as the first reported HR in the medical record. At 1 year follow up, 60 patients died. Median HR was 86 +/- 17 b.p.m. (first tertile: 75 b.p.m., third tertile: 97 b.p.m.) at admission, 76 +/- 14 b.p.m. (first tertile: 67 b.p.m., third tertile 85 b.p.m.) at Day 4, and 72 +/- 11 b.p.m. (first tertile: 64 b.p.m., third tertile 80 b.p.m.) at discharge. Patients who died were significantly older (75 +/- 11 vs. 71 +/- 12 years; P = 0.027), had more frequently a history of ischemic cardiomyopathy (n = 34/60, P = 0.012) and of chronic obstructive pulmonary disease (n = 26/60, P = 0.027), had higher admission N terminal pro brain natriuretic peptide (14 572 +/- 21 600 vs. 7647 +/- 7964 pg/ml; P = 0.027), had lower systolic and diastolic blood pressures (P < 0.05), haemoglobin level (10.6 +/- 2.2 vs. 12.2 +/- 2.2 g/L; P = 0.005), albumin level (35.2 +/- 4.3 vs 37.1 +/- 4.1 g/dl; P = 0.003) and estimated glomerular filtration rate (47 +/- 21 vs. 60 +/- 28 ml/min/1.73 m(2) ; P = 0.0017). There were no significant differences between survivors and nonsurvivors in left ventricular ejection, the use of beta-blocker and angiotensin-converting enzyme-inhibitor, and the rate of comorbidities (hypertension, diabetes) (P=NS, for all). HR at admission was not significantly associated with 1 year mortality (P = 0.20), whereas there was a significant increase in 1 year mortality for HRs>85 b.p.m. at Day 4 (P < 0.0001) and > 80 b.p.m. at discharge (P < 0.0001). In the multivariable model that included the third tertile at Day 4 and discharge HR and adjusted for all other significant covariates, haemoglobin (P = 0.019), and HR at Day 4 (P = 0.023) were independently associated with 1 year mortality. When only discharge HR was included haemoglobin (P = 0.0004) and HR at discharge (P = 0.00053) remained independently associated with 1 year mortality. CONCLUSIONS: In patients surviving the acute HF phase, a high HR at Day 4, and at a lesser degree at discharge, but not at admission, is a strong predictor of 1 year mortality.