Left atrial stiffness and exercise tolerance in patients with atrial fibrillation (LAST-AF study)
M Abbas, J A Ariyaratnam, J D Dziano, S E Evans, J F Fitzgerald, S K Kamasani, M J Jayakumar, S P V Pattu Valappil, H J Howie, A E Elliott, P S SandersAbstract
Background
Left atrial (LA) stiffness is an emerging marker of atrial myopathy in patients with atrial fibrillation (AF) and may contribute to symptoms and exercise intolerance. However, the physiological correlates of LA stiffness and its relationship with functional capacity remain poorly defined. This study evaluated the association between invasively measured LA stiffness and markers of exercise tolerance, symptom burden, and atrial remodelling in patients undergoing catheter ablation for AF.
Methods
Patients with symptomatic AF scheduled for catheter ablation underwent comprehensive evaluation. Invasive assessment included LA pressures and LA stiffness measurement at the time of ablation procedure, and non-invasive assessment indcluded transthoracic echocardiography, cardiopulmonary exercise testing (CPET), and standardized symptom evaluation. Patients were stratified into three groups according to LA stiffness (low, intermediate, high).
Results
Across the three stiffness groups, there was a clear stepwise rise in both end-atrial diastolic and peak pressures, with the high-stiffness group demonstrating the greatest hemodynamic burden. Peak LA pressure demonstrated a distinct pattern of rise across the stiffness groups, with progressively higher values from low to high stiffness. RA peak pressure also differed across groups, with higher values observed in patients with greater LA stiffness, indicating bi-atrial involvement in the disease process.
Higher LA stiffness was associated with impaired LA mechanical function, including reduced reservoir strain. Patients with elevated LA stiffness demonstrated significantly lower peak VO2 on CPET, and higher symptom burden scores. Increased LA stiffness also correlated with markers of advanced atrial remodelling, including larger LA size and elevated filling pressures.
Conclusions
In patients with AF, elevated LA stiffness is strongly associated with reduced exercise tolerance, impaired LA mechanical function, and more advanced atrial remodelling. Assessment of LA stiffness may aid in identifying patients with greater functional limitation and could contribute to improved phenotyping and risk stratification in AF.Graphical Abstract