ABC | Volume 115, Nº1, July 2020

Review Article Acute Cardiorenal Syndrome: Which Diagnostic Criterion to Use And What is its Importance for Prognosis? Andréa de Melo Leite, 1,2, 3 Bruno Ferraz de Oliveira Gom es, 2 A ndré Casarsa Marques, 2 João Luiz Fernandes Petriz, 2 Denilson Campos Albuquerque, 2,3,4 Pedro Pimenta de Mello Spineti, 4 A ntonio José Lagoeiro Jorge, 1 Humberto Villacorta, 1 Wolney de Andrade Martins 1 Universidade Federal Fluminense - Faculdade de Medicina - Pós-graduação em Ciências Cardiovasculares, 1 Niterói, RJ – Brazil Rede D’Or São Luiz, 2 Rio de Janeiro, RJ – Brazil Instituto D’Or de Pesquisa e Ensino, 3 Rio de Janeiro, RJ – Brazil Universidade do Estado do Rio de Janeiro, 4 Rio de Janeiro, RJ – Brazil Abstract The absence of a consensus about the diagnostic criteria for acute cardiorenal syndrome (ACRS) affects its prognosis. This study aimed at assessing the diagnostic criteria for ACRS and their impact on prognosis. A systematic review was conducted using PRISMA methodology and PICO criteria in the MEDLINE, EMBASE and LILACS databases. The search included original publications, such as clinical trials, cohort studies, case-control studies, and meta-analyses, issued from January 1998 to June 2018. Neither literature nor heart failure guidelines provided a clear definition of the diagnostic criteria for ACRS. The serum creatinine increase by at least 0.3 mg/dL from baseline creatinine is the most used diagnostic criterion. However, the definition of baseline creatinine, as well as which serum creatinine should be used as reference for critical patients, is still controversial. This systematic review suggests that ACRS criteria should be revised to include the diagnosis of ACRS on hospital admission. Reference serum creatinine should reflect baseline renal function before the beginning of acute kidney injury. Introduction Heart failure (HF) is a clinical challenge and a growing epidemiological problem worldwide, with high morbidity and mortality. 1 In the ARIC study, 2 the case fatality rates within 30 days, 1 year and 5 years from hospitalization due to HF were 10.4%, 22.0% and 42.3%, respectively. The I Brazilian Registry of Heart Failure (BREATHE), 3 an observational study with 1263 patients from different Brazilian regions, has shown in-hospital mortality of 12.6%. Cardiorenal syndrome, defined as kidney injury caused by HF, was first described in 1951 4 and categorized into five types in 2008 (Table 1). 5 Type 1 cardiorenal syndrome or acute cardiorenal syndrome (ACRS) is characterized by acute kidney injury (AKI) caused by decompensated HF (DHF). Some authors refer to ACRS as acute worsening of renal function in patients with HF, which is a frequent condition, present in 11% to 40% of hospitalizations due to DHF. 6,7 Worsening of renal function is defined as an absolute increase in serum creatinine by 26.5 μmol/L, equivalent to 0.3 mg/dL, and/or a 25% increase in creatinine or a 20% decrease in glomerular filtration rate (GFR). 8 The criterion of absolute 0.3-mg/dL increase in creatinine has been adopted by most authors as the cutoff point to define ACRS. The North American ADHERE registry 9 is an observational study with more than 100,000 patients hospitalized with DHF, 35% of whom had moderate to severe renal dysfunction. Worsening of renal function occurs in 30% to 50% of patients with DHF, depending on the definition used, and is associated with longer length of hospital stay, as well as higher health care costs and mortality. 10-14 However, the absence of a consensus definition of ACRS contributes to the lack of clarity in its diagnosis and treatment. 15 The choice of reference serum creatinine to anchor the diagnostic criteria for ACRS is a challenge. Ideally, reference serum creatinine should reflect the baseline renal function before AKI begins. Most of the time, however, that information is not available, leading to the use of surrogate reference values, which can Keywords Cardiorenal Syndrome; Renal Insufficiency; Creatinine; Prognosis; Heart Failure; Systematic Review. Mailing Addresss: Andréa de Melo Leite • Universidade Federal Fluminense - Faculdade de Medicina - Pós-graduação em Ciências Cardiovasculares – Av. Marquês do Paraná, 303. Postal Code 24230-030, Niterói, RJ – Brazil E-mail: andreamelo@cardiol.br, andreamelocardiologia@gmail.com Manuscript received April 05, 2019, revised manuscript August 04, 2019, accepted August 18, 2019 DOI: https://doi.org/10.36660/abc.20190207 Table 1 – Types of cardiorenal syndrome Type Name Mechanism 1 Acute CRS AKI induced by acute cardiac dysfunction 2 Chronic CRS Progressive CKF secondary to chronic HF 3 Acute renocardiac syndrome Acute HF precipitated by AKI 4 Chronic renocardiac syndrome HF secondary to CKF 5 Secondary CRS Myocardial and renal dysfunction due to systemic diseases CRS: cardiorenal syndrome; AKI: acute kidney injury; CKF: chronic kidney failure; HF: heart failure. Source: Di Lullo et al. 40 127