Ariyaratnam JP; Royal Adelaide Hospital, Adelaide, Australia
Elliott AD; Mishima RS; Kadhim K; Emami M; Fitzgerald JL;
Middeldorp M; Sanders P

JACC. Clinical Electrophysiology. 10(7 Pt 2):1608-1619, 2024 Jul.

BACKGROUND: Reduced cardiorespiratory fitness (CRF) is an independent risk
factor for the progression of atrial fibrillation (AF). We hypothesized
that reduced CRF is associated with structural, functional, and electrical
remodeling of the left atrium.
OBJECTIVES: This study sought to correlate objectively assessed CRF with
functional and electrical left atrial (LA) parameters using invasive and
noninvasive assessments.
METHODS: Consecutive patients with symptomatic AF undergoing catheter
ablation were recruited. CRF was objectively quantified pre-ablation by
using cardiopulmonary exercise testing. Using peak oxygen consumption,
participants were classified as preserved CRF (>20 mL/kg/min) or reduced
CRF (<20 mL/kg/min). LA stiffness was assessed invasively with hemodynamic
monitoring and imaging during high-volume LA saline infusion. LA stiffness
was calculated as DELTALA diameter/DELTALA pressure over the course of the
infusion. LA function was assessed with echocardiographic measures of LA
emptying fraction and LA strain. Electrical remodeling was assessed by
using high-density electroanatomical maps for LA voltage and conduction.
RESULTS: In total, 100 participants were recruited; 43 had reduced CRF
and 57 had preserved CRF. Patients with reduced CRF displayed elevated LA
stiffness (P = 0.004), reduced LA emptying fraction (P = 0.006), and
reduced LA reservoir strain (P < 0.001). Reduced CRF was also associated
with reduced LA voltage (P = 0.039) with greater heterogeneity (P = 0.027)
and conduction slowing (P = 0.04) with greater conduction heterogeneity (P
= 0.02). On multivariable analysis, peak oxygen consumption was
independently associated with LA stiffness (P = 0.003) and LA conduction
velocities (P = 0.04)
CONCLUSIONS: Reduced CRF in patients with AF is independently associated
with worse LA disease involving functional and electrical changes.
Improving CRF may be a target for restoring LA function in AF.