In another long-term study, Imazu et al. [65] demonstrated that elevated plasma indoxyl sulfate levels independently predicted cardiovascular death and HF rehospitalization over a 5-year follow-up, with particularly strong associations observed in patients with hypertrophic cardiomyopathy, linking indoxyl sulfate burden to adverse cardiac remodeling and elevated BNP. The gene discussed is NPPB; the disease is hydrops fetalis.