Merdler I, Loewenstein I, Zahler D, et al. - Given the precise nature of reciprocal relationship of acute kidney injury (AKI) and anemia in ST-elevation myocardial infarction (STEMI) patients has not been elucidated, and to explore this, researchers undertook this retrospective study with 2,096 patients admitted for STEMI between January 2008 and December 2018 and who underwent primary coronary intervention. Based on the presence of baseline anemia and occurrence of AKI, four groups of patients were defined: without anemia or AKI, baseline anemia without AKI, AKI without baseline anemia and acute cardiorenal anemia syndrome (CRAS), defined as the development of AKI in patients exhibiting baseline anemia. The presence of baseline anemia without AKI was seen in 10% of patients, and 7% had AKI without baseline anemia and 3% were categorized as CRAS. It was revealed in logistic regression models that relative to AKI alone, CRAS was related to a higher risk for long-term mortality than anemia and AKI alone. Overall, findings revealed that the interaction between anemia and AKI in STEMI patients was not only related to worse short and long-term outcomes but also reflected the reciprocity of cardiac and renal exacerbations.