Key result
In critically ill AF patients, maximal cardiac output peaks at ~98 bpm, below mean heart rates.
Why the study?
AF is common and associated with increased mortality in critically ill patients, but the optimal HR target during heart rate control remains uncertain.
Can echocardiography and physiological signal analysis estimate the target heart rate associated with maximal cardiac output in critically ill patients with atrial fibrillation?
Observational (n=20)
No
Can echocardiography and physiological signal analysis estimate the target heart rate associated with maximal cardiac output in critically ill patients with atrial fibrillation?
Individualized target heart rate associated with maximal cardiac output can be estimated in critically ill AF patients using echocardiography and physiological signal analysis, suggesting the optimal heart rate may be lower than the mean heart rate.
May guide individualized HR targets in ICU AF; leaves open optimal strategy pending randomized validation.
OBJECTIVE: Atrial fibrillation(AF) is common in critically ill patients and is associated with increased mortality. Two treatment strategies are used: rhythm control and heart rate(HR) control; however, the optimal HR target in the latter remains uncertain. This study aimed to develop and compare methods for determining the target HR range using transthoracic echocardiography and physiological signal analysis. Approach. The study was performed in a level 3 medical ICU. A custom software tool was developed to analyse ECG, arterial pressure, and respiratory waveforms; to compute HR(HR_py) and cardiac output (CO)(CO_py). These measurements were compared with echocardiography, which provided five consecutive left ventricular outflow tract velocity-time integrals(VTI_echo) and corresponding HR(HR_echo). In phase one, 7 patients in sinus rhythm were assessed, yielding 31 paired measurements under variable preload and afterload conditions. In phase two, 13 patients with AF contributed 101 paired measurements. For both methods, mean and maximal CO were calculated, and the target HR was defined as the HR at which CO reached its maximum. Main Results. In sinus rhythm, HR_py and CO_py showed minimal bias relative to echocardiography (-1.48 bpm and -0.0003 L/min, respectively) with clinically acceptable agreement. In AF, maximal CO_echo was significantly higher than mean CO_echo (5.24 ± 1.30 vs. 4.79 ± 1.42 L/min; +9%, p < 0.001), and target HR was significantly lower than mean HR_echo (98 ± 19 vs. 110 ± 15 bpm; -11%, p < 0.001). Physiological signal analysis similarly showed higher maximal CO_py compared with mean CO_py (6.03 ± 1.59 vs. 5.32 ± 1.41 L/min; +12%, p < 0.001), and target HR was substantially lower than mean HR_py (89 ± 17 vs. 114 ± 15 bpm; -22%, p < 0.001). Significance. This feasibility study demonstrates that target HR associated with maximal CO can be estimated in critically ill patients with AF using echocardiography and/or physiological signal analysis. These methods may support individualized HR targeted management but require validation in larger multicentre interventional studies. .
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Kus et al. (2026) conducted an observational in Critically ill patients with atrial fibrillation (n=20). Target heart rate estimation using echocardiography and physiological signal analysis vs. Mean heart rate and cardiac output was evaluated on Maximal cardiac output and corresponding target heart rate compared to mean values (p=<0.001). In critically ill patients with AF, target heart rate for maximal cardiac output was significantly lower than mean heart rate using both echocardiography (98 vs 110 bpm) and physiological signals.
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