Abstract 16161: Effects of Year Long Aerobic Exercise on Left Atrial Size in Patients With Left Ventricular Hypertrophy

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Introduction: Habitual aerobic exercise is associated with left atrial (LA) enlargement and risk of atrial fibrillation. This risk may be accentuated in patients with increased left ventricular (LV) stiffness due to high LA pressure during exercise. We tested the hypothesis that 1 year long endurance exercise would increase LA size to a greater extent in patients with left ventricular hypertrophy (LVH) at risk for heart failure with preserved ejection fraction (HFpEF) than previously published age appropriate controls. Methods: Middle-aged adults (age 45-64 yrs) with LVH (n=53) enriched for increased HFpEF risk (N-terminal pro-B-type natriuretic peptide >40 pg/mL or high-sensitivity cardiac troponin T >0.6 pg/mL) and healthy subjects (n=58) were randomized to one year of high intensity aerobic exercise or yoga control. LA and LV volumes were measured using 3D echo. Results: Of 111 participants, 83 had complete data available (LVH cohort: 18 exercisers, 10 yoga; healthy cohort: 29 exercisers, 26 yoga). Baseline LA size was larger in LVH vs healthy subjects (42 ± 12 vs 35 ± 9 mL; p=0.005). There was a nominal increase in LA size in LVH exercisers compared to LVH yoga (8 ± 9 vs 4 ± 7 mL; p=0.29) which was proportional to LV size (LA/LV ratio 0.05 ± 0.07 vs 0.06 ± 0.1; p=0.81). Healthy subject exercisers increased LA size compared to healthy yoga controls (4 ± 5 vs 0 ± 6 mL; p=0.02) with no increase in LA/LV ratio (-0.02 ± 0.08 vs -0.03 ± 0.08; p=0.62). Among exercising subjects only, increase in LA size was larger in LVH compared to healthy subjects after year long aerobic training (p=0.04) with greater increase LA/LV ratio (p<0.001). Conclusions: One year of aerobic training resulted in higher LA size in patients with at-risk LVH compared to healthy subjects. The increase in LA size was greater than changes in LV size suggesting chronic aerobic training may preferentially affect LA remodeling.