REN and anemia (phenotype): Since cardiac sudden death was the leading cause of morality, the hopeful measurement to the improve the prognosis for the elderly cardio-renal syndrome patients might include necessary invasive revascularization intervention, secondary prevention including antiplatelet agents and statin, first-line anti-hypertension recommendation of renin-angiotensin blockers or angiotensin receptor neprilysin inhibitor (ARNI), and anemia improvement with Roxadustat.