The primary search terms included 'NT-proBNP,' 'BNP,' 'heart failure,' 'HFpEF,' 'HFrEF,' 'biomarker,' 'prognosis,' 'therapy,' and 'limitations.' The final selection of studies, meta-analyses, and expert guidelines was based on their direct relevance to the role of NT-proBNP across different heart failure phenotypes. The gene discussed is NPPB; the disease is heart failure.