Pre-Fontan right ventricular ejection fraction was lower in the RVPAS group than in the MBTS group ( 41.75.1 % versus 44.76.0 % ; P = 0.007 ) , and right ventricular ejection fraction deteriorated in RVPAS ( P = 0.004 ) but not MBTS ( P = 0.40 ) subjects ( pre-Fontan minus 14-month mean , -3.258.24 % versus 0.998.80 % ; P = 0.009 ) .