At week 24 , the combination-therapy group had greater reductions from baseline in N-terminal pro-brain natriuretic peptide levels than did the pooled-monotherapy group ( mean change , -67.2 % vs. -50.4 % ; P < 0.001 ) , as well as a higher percentage of patients with a satisfactory clinical response ( 39 % vs. 29 % ; odds ratio , 1.56 [ 95 % CI , 1.05 to 2.32 ] ; P = 0.03 ) and a greater improvement in the 6-minute walk distance ( median change from baseline , 48.98 m vs. 23.80 m ; P < 0.001 ) .