Association between heart rate fluctuation and mortality in intensive care patients with atrial fibrillation

Atrial fibrillation (AF) is a common arrhythmia associated with increased morbidity and mortality among intensive care unit (ICU) patients. This study aimed to evaluate heart rate fluctuation (HRF) and its association with in-hospital mortality among ICU patients with AF. Atrial fibrillation (AF) is a common arrhythmia associated with increased morbidity and mortality among intensive care unit (ICU) patients. This study aimed to evaluate heart rate fluctuation (HRF) and its association with in-hospital mortality among ICU patients with AF. Atrial fibrillation (AF) is a common arrhythmia associated with increased morbidity and mortality among intensive care unit (ICU) patients. This study aimed to evaluate heart rate fluctuation (HRF) and its association with in-hospital mortality among ICU patients with AF. This study utilized the Medical Information Mart for Intensive Care (MIMIC)-III and MIMIC-IV databases. Patients with recorded AF at ICU admission were included. The primary exposure variables were heart rate change, measured using the initial heart rate at ICU admission and the maximum heart rate within the first six hours, and HRF, assessed by the median absolute deviation (MAD) of all heart rate measurements within the first 24 h. Logistic regression was used to assess the association with in-hospital mortality. A total of 13,475 patients were included in the analysis. For heart rate change, compared to the high to high group (initial and maximum heart rate > 110), the low to high group (initial heart rate ≤ 110 and maximum heart rate > 110) showed a higher mortality risk (Odds ratio [OR]: 1.30, 95% confidence interval [CI] 1.09-1.54; p = 0.003). Higher HRF was associated with increased mortality risk (p for trend = 0.002). Patients in the highest HRF quintile had a higher risk of in-hospital mortality (OR: 1.25, 95% CI 1.07-1.46; p = 0.004). Subgroup analyses revealed significant interactions between HRF and both rate control and initial heart rate. However, in patients receiving rate control therapy, HRF was not associated with mortality. Changes in heart rate and HRF were associated with in-hospital mortality in ICU patients with AF. However, in patients receiving rate control therapy, the impact of HRF on mortality is less significant and may not warrant as much clinical attention.