Lower cardiorespiratory fitness is associated with left atrial structural, functional and electrical remodelling in patients with symptomatic atrial fibrillation

Abstract

Abstract Background Preserved cardiorespiratory fitness (CRF) is associated with improved rhythm control in patients with symptomatic atrial fibrillation (AF). However, the pathophysiological features associated with low cardiorespiratory fitness are not well described. Purpose Evaluate the association between cardiorespiratory fitness and structural, functional and electroanatomical features of the left atrium (LA) amongst patients with symptomatic AF. Methods Consecutive patients with symptomatic paroxysmal or persistent AF undergoing AF ablation were recruited. CRF was assessed objectively by peak oxygen consumption (VO2peak) assessed during maximal cycle ergometry. Invasive assessment of LA remodelling involved direct assessment of resting LA pressures (LAP), LA stiffness during saline infusion and LA electrical function using high-density electroanatomical maps. Non-invasive assessment involved 2D transthoracic echocardiography at rest and during exercise. The association between VO2PEAK and atrial parameters were determined using multivariable linear regression models adjusted for age and sex. Results In total, 110 participants were recruited. Mean age was 63±11 and 74.5% of the cohort was male. In adjusted analyses, higher VO2PEAK was associated with lower mean LAP (p<0.001) and invasively assessed LA stiffness (p=0.005). On non-invasive testing, VO2PEAK was positively associated with left atrial emptying fraction (LAEF) (p=0.001) and reservoir strain (p<0.001) at rest. During exercise, VO2PEAK remained associated with LAEF (p<0.001) and LA reservoir strain (p=0.007). Higher VO2peak was positively associated with LA bipolar voltages (p=0.035) but not LA conduction velocities (p=0.131) or LA fractionation (p=0.452) Conclusions In patients with symptomatic AF, lower cardiorespiratory fitness is independently associated with extensive LA remodelling involving impaired LA haemodynamics, increased LA stiffness, LA mechanical dysfunction and LA electrical remodeling.