Biomarker Profile of Left Atrial Myopathy in Heart Failure With Preserved Ejection Fraction: Insights From the RELAX Trial: Biomarkers in Left Atrial Myopathy

Background: Although left atrial (LA) mechanical dysfunction in heart failure with preserved ejection fraction (HFpEF) is associated with poor clinical outcomes, the influence of LA myopathy on temporal changes in cardiovascular biomarkers is unclear. Methods and Results: We evaluated biomarker correlates of LA myopathy, as defined by reduced LA strain, and the associations of LA strain with longitudinal changes in biomarkers among participants in the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Heart Failure with Preserved Ejection Fraction (RELAX) trial. LA speckle-tracking was performed on baseline echocardiograms of RELAX participants to measure LA reservoir and LA contractile strain. Of the 216 RELAX participants, 169 (78%) had measurable LA strain and biomarker data. Participants with LA reservoir strain below median (13.5%, interquartile range: 10%–22.5%) were older, more likely to have atrial fibrillation, and had higher jugular venous pressure (P < .05 for all). At baseline, higher levels of endothelin-1, N-terminal pro–B-type natriuretic peptide (NT-proBNP), and troponin I were independently associated with lower LA reservoir and contractile strain (P_adjusted < .05 for all comparisons). Higher LA reservoir strain (β coefficient per 1-unit increase: −21.2, 95% CI: −38.8, −3.7; P = .02) was independently associated with reduction in NT-proBNP at 24 weeks. Conclusion: In HFpEF, LA myopathy is characterized by elevation in biomarkers of neurohormonal activation and myocardial necrosis. Lower LA function is associated with continued elevation in NT-proBNP over time, suggesting that LA myopathy is associated with persistent congestion in HFpEF.