TABLE 1.

Subtypes of cardiorenal syndrome (CRS) according to acute dialysis quality initiative working group classification

Cardiorenal types	Characteristics	Causes of morbidity
Type 1 (acute cardiorenal)	Acute worsening of heart function leading to acute kidney injury and/or dysfunction	Cardiogenic shock and AKI, acute decompensated heart failure (ADHF) resulting in AKI
Type 2 (chronic cardiorenal)	Chronic abnormalities in heart function leading to progressive kidney injury and/or dysfunction	Chronic heart failure with left ventricular remodeling and dysfunction leading to CKD
Type 3 (acute renocardiac)	Acute worsening of kidney function leading to acute heart injury and/or dysfunction	Heart failure in the setting of AKI from volume overload, inflammatory surge (es: pericarditis) and accompanying metabolic disturbances
Type 4 (chronic renocardiac)	Chronic kidney disease leading to heart injury, disease, and/or dysfunction	Myocardial remodeling and heart failure from CKD‐associated cardiomyopathy
Type 5 (secondary cardiorenal)	Systemic conditions leading to simultaneous injury and/or dysfunction of heart and kidney	Diabetes, amyloidosis, sepsis, cirrhosis, hypertension, vasculitis

Abbreviations: ADHF, acute decompensated heart failure; AKI, acute kidney injury; CKD, chronic kidney disease.