Amino Acids, Peptides, and Proteins Cardiovascular Diseases Diagnosis Diagnostic Techniques and Procedures Diseases Environment and Public Health Epidemiologic Methods Epidemiologic Research Design Health & Biological Sciences Health Care Health Care Evaluation Mechanisms Health Care Quality, Access, and Evaluation Heart Diseases Heart Failure Hormones Hormones, Hormone Substitutes, and Hormone Antagonists Investigative Techniques Natriuretic Peptide, Brain Natriuretic Peptides Nerve Tissue Proteins Peptide Hormones Peptides Pharmacy, Therapeutics, & Pharmacology Predictive Value of Tests Prognosis Proteins Public Health Quality of Health Care Sensitivity and Specificity