GDF15 and hypertrophy: We also assessed the levels of three well-known HF-related biomarkers52,53: growth differentiation factor-15 (GDF-15, myocardial inflammation), soluble suppression of tumorigenicity-2 receptor (ST2, ventricular remodeling, and hypertrophy), and cardiac troponin I (cTnI, myocardial necrosis) in these sera.