Heart rate – A complex prognostic marker in acute heart failure

Heart rate -A complex prognostic marker in acute heart failureWe read with interest the article by Agra Bermejo et al. [1] on the results of resting heart rate (HR) as a predictor of hospital readmission and mortality in acute heart failure (HF).A plethora of studies have investigated the predictive value of resting HR in acute and chronic HF [2].HR predicts the outcome in chronic HF with a steep rise in cardiovascular mortality at an HR 80 b.p. m. in patients with sinus rhythm [3], whereas an elevated resting HR in atrial fibrillation (AF) patients may not be associated with cardiovascular mortality [4,5].The authors have reported a study population of 1398 consecutive patients admitted for acute HF and investigated the predictive values of discharge HR and the change in HR between admission and discharge on one-year probability of readmission and mortality.Importantly, the authors have analyzed patients in sinus rhythm and in AF separately and include both HF with reduced and preserved ejection fraction in their analysis.In all these groups, HR at discharge predicted one-year mortality, with higher HR portending a higher mortality risk.In contrast, the change of HR between admission and discharge wasn ´t a predictor of mortality in sinus rhythm nor in patients with AF.Of note, after correction for other predictors, readmission for HF was not significantly associated with those two HR-based parameters in this study population.These results are in contrast to findings of Takahama et al.[6], who reported that the difference in HR, but not the discharge HR, was predictive of a composite end point of readmission and allcause death in a registry of 421 Japanese patients hospitalized for acute HF.On the other hand, the current study results are supported by a large American registry by Laskey et al. [7].The authors analyzed 46,217 acutely decompensated HF Medicare patients >65 years and found a significant and linear positive correlation with one-year mortality.Notable differences between the latter two studies are the ethnic origin of the study participants, the definition of heart failure event and study design.Despite all these differences, there are also commonalities.First, crude mortality rates are still sobering.The raw one-year mortality in the study by Agra Bermejo et al. was around 20%.The fact that HR appears to be a better predictor of 30-day mortality than of mortality from day 31 through day 365 is a finding which has also been corroborated by Laskey et al. [7].Also, HR at discharge appears to be not very predictive of readmission for HF as opposed to mortality.This suggests that the readmission and mortality potentially underly different pathophysiological mechanisms.Additionally, this may also indicate, that the probability of readmission seems to be more difficult to predict, even with multivariate models [8].Importantly, HR itself is a complex variable which is influenced by multiple factors: e.