After adjusting for age, NYHA class, diabetes, atrial fibrillation, CRT/pacemaker, NT-proBNP levels, drug therapy (beta-blockers, ivabradine, and loop diuretics use), maximal ARNI dose reached, and changes in VO2peak, multivariate analysis showed that changes in HRR were significantly associated to changes in VE/VCO2slope (B = −0.975, SE = 0.364, Bstd = −0.304, p = 0.009). Here, NPPB is linked to atrial fibrillation.