Key Points
- To assess whether atrial fibrillation in heart failure affects oxygen uptake at the anaerobic threshold and heart rate kinetics during exercise.
- Assessed 15 heart failure patients with atrial fibrillation and 18 heart failure patients in sinus rhythm.
- Administered one maximal incremental and two constant workload cycle ergometer cardiopulmonary exercise tests (at 25% and 75% of maximal workload) to calculate oxygen uptake and heart rate time constants (τ).
- Patients with atrial fibrillation exhibited a similar peak oxygen uptake compared to those in sinus rhythm (16.7 ± 4.5 mL/kg/min vs 16.6 ± 3.9 mL/kg/min), but a significantly higher oxygen uptake at the anaerobic threshold (11.3 ± 2.9 mL/kg/min vs 9.3 ± 2.8 mL/kg/min; P < .05).
- Peak heart rate (149 ± 18.8 bpm vs 116.4 ± 20.4 bpm; P < .001) and heart rate at the anaerobic threshold (125.3 ± 19.1 bpm vs 90.3 ± 15.5 bpm; P < .001) were significantly elevated in atrial fibrillation, whereas time constants (τ) for heart rate and oxygen uptake showed no significant differences.
Structured PICO
Does atrial fibrillation affect oxygen uptake at anaerobic threshold and heart rate kinetics during exercise in patients with heart failure?
PPopulation33 patients with heart failure, including 15 with atrial fibrillation and 18 with sinus rhythm.
IInterventionMaximal incremental and 2 constant workload cycle ergometer cardiopulmonary exercise tests (below and above AT, at 25% and 75% of maximal workload).
CComparatorHeart failure patients with sinus rhythm.
OOutcomeOxygen uptake at anaerobic threshold (VO2 AT) and heart rate (HR) kinetics.surrogate
In heart failure patients, atrial fibrillation is associated with a higher oxygen uptake at the anaerobic threshold due to a greater heart rate increase during exercise, complicating the prognostic interpretation of this parameter.