NPPB and heart failure: In the TOPCAT (treatment of preserved cardiac function heart failure with an aldosterone antagonist trial) Bio-repository study (n=247 HFpEF patients), a significant reduction in the BNP levels from the baseline was observed in the spironolactone-treated group (122 ng/L to 102 ng/L) as compared to the placebo-treated group (118 ng/L to 137 ng/L); P=0.003.