Coronary artery bypass grafting in non-dialysis-dependent mild-to-moderate renal dysfunction.
OBJECTIVE
The effect of mild-to-moderate elevation of preoperative serum creatinine levels on morbidity and mortality from coronary artery bypass grafting has not been investigated in a large multivariable model incorporating preoperative and intraoperative variables. Our first objective was to ascertain the effect of a mild-to-moderate elevation in the preoperative serum creatinine level on the need for mechanical renal support; the duration of special care and total postoperative stay; the occurrence of infective, respiratory, and neurologic complications; and hospital mortality. Our second objective was to ascertain which patient variables contributed to an increase in the serum creatinine level in association with coronary artery bypass grafting.


METHODS
A total of 1427 patients who had no known pre-existing renal disease and who were undergoing first-time coronary artery bypass grafting with cardiopulmonary bypass were recruited for the study. Patients were divided, on the basis of preoperative serum creatinine level, into 3 groups as follows: creatinine level of less than 130 micromol. L(-1); creatinine level of 130 to 149 micromol. L(-1); and creatinine level of 150 micromol. L(-1) or greater. A multivariable stepwise logistic regression analysis was used, and variables significant at the 5% level were included when developing the final multivariable models.


RESULTS
Multivariable analysis showed that elevation of the preoperative serum creatinine level to 130 micromol. L(-1) or greater increased the likelihood of needing mechanical renal support postoperatively (P <.001), as well as the need for postoperative special care (P <.001) and total hospital stay (P <.001). In-hospital mortality was also significantly elevated as the preoperative creatinine level rose to 130 to 149 micromol. L(-1) (P =.045) and to 150 micromol. L(-1) or greater (P <.001). It was further observed that patients with preoperative serum creatinine levels of 130 to 149 micromol. L(-1) (P =.02), patients with preoperative serum creatinine levels of 150 micromol. L(-1) or greater (P =.001), hypertensive patients (P =.007), patients with angina of New York Heart Association class III or greater (P =.001), patients having a nonelective operation (P =.002), and patients having a prolonged cardiopulmonary bypass time (P =.008) had a significantly greater increase in the serum creatinine level as a result of coronary artery bypass grafting. Of particular note was the finding that the method of myocardial protection (cardioplegia or crossclamp fibrillation) did not significantly influence in-hospital mortality, need for mechanical renal support, or special care or total postoperative hospital stay.


CONCLUSIONS
A mild elevation (130-149 micromol. L(-1)) in the preoperative serum creatinine level significantly increases the need for mechanical renal support, the duration of special care and total postoperative stay, and the in-hospital mortality. As the preoperative serum creatinine level increases further (> or =150 micromol. L(-1)), this effect is more pronounced. No significant difference in outcome was observed between the use of cardioplegia or crossclamp fibrillation for myocardial protection.
Weerasinghe
A
A
Department of Cardiothoracic Surgery, Imperial College School of Medicine, University of London, Hammersmith Hospital, London W12 0HS, United Kingdom. aweerasinghe@ic.ac.uk
Hornick
P
P
Smith
P
P
Taylor
K
K
Ratnatunga
C
C
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000379:methods / Q000401:mortality*; D003327:Coronary Disease / Q000150:complications* / Q000401:mortality / Q000601:surgery*; D003404:Creatinine / Q000097:blood*; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D015999:Multivariate Analysis; D011183:Postoperative Complications / Q000401:mortality*; D011300:Preoperative Care; D011336:Probability; D051437:Renal Insufficiency / Q000150:complications* / Q000175:diagnosis; D012307:Risk Factors; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome
D003404:Creatinine