NPPB and heart failure: HHcy is considered a marker of cardiovascular disease[7] and a risk factor for diseases such as breast cancer,[8] Alzheimer's disease,[9] and age-related macular degeneration.[10]Some studies have also found a positive correlation between serum Hcy and BNP, HHcy can increase the 5-year risk of death in patients with heart failure.[11] Tekin[12] found that in patients with heart failure, serum Hcy gradually increased with the severity of cardiac function, and HHcy could reflect the severity of heart failure and may be an important predictor of mid-term death in patients with heart failure.