GDF15 and heart failure: As previously described [6, 7], we measured 6 batched serum biomarkers associated with myocardial stretch, remodeling, fibrosis, and heart failure (growth differentiation factor 15 [GDF-15; ELISA, R&D Systems], galectin-3 [ELISA, R&D Systems], suppression of tumorogenicity-2 [ST-2; ELISA, R&D Systems], soluble fms-like tyrosine kinase-1 [sFLT-1; ELISA, R&D Systems], cystatin C [nephelometry, Siemens], and N-terminal pro-brain natriuretic peptide [NT-proBNP; electrochemiluminescence, Roche]) from cryopreserved plasma at -80oC in blinded laboratories.