Compared with baseline , NYHA functional class remained unchanged at 18 months , distance during 6MWT ( 485 m vs. 517 m ) and LVEF ( 36.7 % vs. 41.8 % ) were increased , but BNP levels were reduced ( 2352 pg/ml vs. 710 pg/ml ) in the RVMSP group compared with those in the RVAP group , especially in patients with LVEF 35 % -40 % ( for all comparisons , P < 0.05 ) .