J-Shaped association between heart rate and in-hospital mortality in patients with congestive heart failure in intensive care unit: a retrospective observational study

Background Despite extensive evidence linking heart rate (HR) to the risk of all-cause mortality, little attention has been given to exploring this association in patients with congestive heart failure (CHF). This study aimed to assess the relationship between HR and in-hospital mortality in CHF patients using data from a large clinical population-based sample. Methods This retrospective observational study utilized the Medical Information Mart for Intensive Care IV database to extract all relevant data. In-hospital mortality served as the primary outcome measure. Data analyses involved restricted cubic spline regression, piecewise logistic regression, and multiple logistic regression models. Additionally, subgroup analysis was performed to examine the robustness of the main findings. Results The study included 15,983 participants with CHF, aged 72.9 ± 13.4 years. After adjusting for all factors, with each unit increase in HR, there was a 1% risk increase of patient death (95% confidence interval: 1.01 ~ 1.01, P < 0.001). Compared with individuals with HR Q2 (72–81 beats per minute (bpm) ), the adjusted OR values for HR and in-hospital mortality in Q1 (≤ 72 bpm), Q3 (81–93 bpm), and Q4 (＞93 bpm) were 1.18 (95% CI: 0.99 ~ 1.41, p = 0.07), 1.24 (95% CI: 1.04 ~ 1.47, p = 0.014), and 1.64 (95% CI: 1.39 ~ 1.94, p < 0.001), respectively. A dose-response relationship revealed an J-shaped curve between HR and the risk of in-hospital mortality, with an inflection point at approximately 76 bpm. Stratified analyses confirmed the robustness of this correlation. Conclusions In patients with CHF, there exists a J-shaped relationship between heart rate and in-hospital mortality, with an inflection point at 76 bpm. Nonetheless, further investigation through large randomized controlled trials is warranted in the future.