Patel RB, et al. - In patients with heart failure with preserved ejection fraction (HFpEF) enrolled in the Nitrate's Effect on Activity Tolerance (NEAT)-HFpEF trial, researchers assessed the link between atrial fibrillation/atrial flutter (AF/AFL) and volitional physical activity, functional performance, NT-proBNP, and quality of life (QOL). Accelerometer data was available in 99 patients, and among these, the presence of AF/AFL was detected in 35 (35%). In baseline average daily accelerometer units, hours active per day, or 6-minute walk distance, no variations were found between AF/AFL vs no AF/AFL. AF/AFL status correlated with higher baseline NT-proBNP and Kansas City Cardiomyopathy Questionnaire scores. Overall, by AF/AFL, no differences were seen in baseline measures and treatment-related changes in volitional physical activity (average daily accelerometer units) and functional performance (6-minute walk distance) in NEAT-HFpEF; differences in NT-proBNP by AF/AFL were evident. As trial endpoints, the possible superiority of functional measures over natriuretic peptides was suggested in HFpEF where AF/AFL prevalence is high.