Hidden renal dysfunction causes increased in-hospital mortality risk after coronary artery bypass graft surgery.

INTRODUCTION AND OBJECTIVES: Preoperative chronic renal dysfunction is an independent predictor of mortality in cardiac surgery. As normal range serum creatinine is not representative of normal renal function, we compared mortality rates, total hospital stay and post-surgical hospital stay for patients who underwent isolated coronary artery bypass surgery with serum creatinine < 1.5mg/dL as to their estimated creatinine clearance, normal or impaired. METHODS: In 4,765 patients submitted to coronary artery bypass surgery between January/1996 and June/2004, the creatinine clearance was estimated by the Cockroft-Gault equation. Impaired renal function was considered as a creatinine clearance <60 mL/min/1.73 m² (chronic renal disease stage 3 - National Kidney Foundation-USA). In hospital mortality, total hospital stay, and post-surgical hospital stay were compared. RESULTS: 4,688 patients had the required data, and 4,403 presented serum creatinine < 1.5 mg/dL - 3,177 with creatinine clearance > 60 mL/min (Group A), and 1,226 with <60 mL/min (Group B). Group B patients had significantly higher total hospital stay and post-surgical hospital stay than those in Group A (respectively 2.85 and 1.79 more days--P < 0.0001). Relative risk of in-hospital death was 2.09 to Group B (95%CI:1.54-2.84) when compared to Group A. CONCLUSIONS: More than one quarter of the patients with serum creatinine <1.5 mg/dL had creatinine clearance <60 mL/min. This expressive number of patients, that would not have their renal dysfunction detected by the serum creatinine parameter alone, had double the risk of death, longer total hospital stay and post-surgical hospital stay than the other patients with serum creatinine < 1.5mg/dL.

Insuficiência renal oculta acarreta risco elevado de mortalidade após cirurgia de revascularização miocárdica / Hidden renal dysfunction causes increased in-hospital mortality risk after coronary artery bypass graft surgery

INTRODUÇÃO E OBJETIVOS: Insuficiência renal crônica pré operatória é fator preditivo independente para mortalidade em cirurgia cardíaca. Como creatinina sérica normal não representa obrigatoriamente função renal normal, comparamos as taxas de mortalidade, de permanência hospitalar total e de permanência hospitalar pós-operatória em pacientes submetidos à cirurgia de revascularização miocárdica isolada com creatinina < 1,5 mg/dL, de acordo com a depuração estimada, normal ou alterada. MÉTODOS: Em 4.765 pacientes submetidos à revascularização cirúrgica do miocárdio entre janeiro/1996 e junho/2004, a depuração da creatinina foi estimada através da equação de Cockcroft-Gault. Considerou-se função renal alterada uma depuração da creatinina <60 mL/min/1,73m² (doença renal crônica estágio 3 -National Kidney Foundation-EUA). Mortalidade hospitalar, permanência hospitalar total e permanência hospitalar pós-operatória foram comparadas. RESULTADOS: 4.688 pacientes tinham disponíveis os dados necessários para a análise e 4.403 apresentavam creatinina plasmática < 1,5 mg/dL - 3.177 com depuração da creatinina > 60 mL/min (Grupo A) e 1.226 com <60 ml/min (Grupo B). Pacientes no Grupo B apresentaram permanência hospitalar total e permanência hospitalar pós-operatória significativamente maiores do que no Grupo A (respectivamente 2,85 e 1,79 dias a mais -P<0,0001). Risco relativo de morte intra-hospitalar foi de 2,09 no Grupo B (IC 95%:1,54-2,84) comparado ao Grupo A. CONCLUSÕES: Mais de 1/4 dos pacientes com creatinina < 1,5 mg/dL apresentavam depuração inferior a 60mL/min. Esse expressivo número de pacientes, os quais não teriam sua disfunção renal detectada pela creatinina sérica isoladamente, apresentaram o dobro do risco de mortalidade, e permanência hospitalar total e pós-operatória maiores do que os demais pacientes com creatinina < 1,5mg/dL.

INTRODUCTION AND OBJECTIVES: Preoperative chronic renal dysfunction is an independent predictor of mortality in cardiac surgery. As normal range serum creatinine is not representative of normal renal function, we compared mortality rates, total hospital stay and post-surgical hospital stay for patients who underwent isolated coronary artery bypass surgery with serum creatinine < 1.5mg/dL as to their estimated creatinine clearance, normal or impaired. METHODS: In 4,765 patients submitted to coronary artery bypass surgery between January/1996 and June/2004, the creatinine clearance was estimated by the Cockroft-Gault equation. Impaired renal function was considered as a creatinine clearance <60 mL/min/1.73m² (chronic renal disease stage 3 - National Kidney Foundation-USA). In hospital mortality, total hospital stay, and post-surgical hospital stay were compared. RESULTS: 4,688 patients had the required data, and 4,403 presented serum creatinine < 1.5mg/dL - 3,177 with creatinine clearance > 60mL/min (Group A), and 1,226 with <60mL/min (Group B). Group B patients had significantly higher total hospital stay and post-surgical hospital stay than those in Group A (respectively 2.85 and 1.79 more days - P<0.0001). Relative risk of in-hospital death was 2.09 to Group B (95%CI:1.54-2.84) when compared to Group A. CONCLUSIONS: More than one quarter of the patients with serum creatinine <1.5mg/dL had creatinine clearance <60 mL/min. This expressive number of patients, that would not have their renal dysfunction detected by the serum creatinine parameter alone, had double the risk of death, longer total hospital stay and post-surgical hospital stay than the other patients with serum creatinine < 1.5mg/dL.