NPPB and heart failure: The biomarker NT-proBNP was dramatically increased in IHFHR patients (the index with the highest significance being p = 2.7 × 10−6), confirming the role of NT-proBNP as one of the most useful indices for risk stratification of cardiac death in heart failure patients than other clinical indices (Bayes-Genis et al., 2007; Vazquez et al., 2009).