LAUSR

BACKGROUND Heart failure with preserved ejection fraction (HFpEF) is the fastest growing form of HF and is associated with high morbidity and mortality. The primary chronic symptom in HFpEF is exercise intolerance, associated with reduced quality of life (QoL). Emerging evidence implicates left atrial (LA) dysfunction as an important pathophysiologic mechanism. Here we extend prior observations by relating LA dysfunction to peak oxygen uptake (peak VO2), physical function (distance walked in six minutes, 6MWD) and QoL (Kansas City Cardiomyopathy Questionnaire, KCCQ). METHODS We compared 75 older, obese, HFpEF patients to 53 healthy age-matched controls. LA strain was assessed by magnetic resonance cine imaging using feature tracking. LA function was defined according to its three distinct phases, with the LA serving as a reservoir during systole, as a conduit during early diastole, and as a booster pump at the end of diastole. LA stiffness index was calculated as the ratio of early mitral inflow velocity-to-early annular tissue velocity (E/e', by Doppler ultrasound) and LA reservoir strain. RESULTS HFpEF had decreased reservoir strain (16.4±4.4% vs. 18.2±3.5%, p=0.018), lower conduit strain (7.7±3.3% vs. 9.1±3.4%, p=0.028), and increased stiffness index (0.86±0.39 vs. 0.53±0.18, p<0.001), as well as decreased peak VO2, 6MWD, and lower QoL. Increased LA stiffness was independently associated with impaired peak VO2 (β=9.0±1.6, p<0.001), 6MWD (β=117±22, p=0.003), and KCCQ score (β=-23±5, p=0.001), even after adjusting for clinical covariates. CONCLUSION LA stiffness is independently associated with impaired exercise tolerance and QoL and may be an important therapeutic target in obese HFpEF. REGISTRATION NCT00959660.