Elevated preoperative hemoglobin A1c level is associated with reduced long-term survival after coronary artery bypass surgery.
BACKGROUND
The predictive role of hemoglobin A1c (HbA1c) on long-term outcomes after coronary artery bypass surgery has not been evaluated.


METHODS
Preoperative HbA1c levels were obtained in 3,201 patients undergoing primary, elective coronary artery bypass surgery at Emory Healthcare Hospitals from January 2002 to December 2006 and entered prospectively into a computerized database. Long-term survival status was determined by cross-referencing patient records with the Social Security Death Index. Log-rank (unadjusted) and Cox proportional hazards regression models (adjusted) were employed to determine whether HbA1c and diabetes mellitus were independent risk factors for reduced long-term survival, adjusted for 29 covariates. Hazard ratios for each unit increase in continuous HbA1c were calculated.


RESULTS
Patients with HbA1c of 7% or greater had lower unadjusted 5-year survival compared with patients with HbA1c less than 7% (p = 0.001). Similarly, patients with diabetes mellitus had lower unadjusted 5-year survival compared with patients without diabetes (p < 0.001). After multivariable adjustment, higher HbA1c (measured as a continuous variable) was associated with reduced long-term survival for each unit increase in HbA1c (hazard ratio 1.15, p < 0.001), but preoperative diagnosis of diabetes was not associated with reduced long-term survival after coronary artery bypass surgery (p = 0.41). Other multivariable predictors of reduced long-term survival included age, cerebrovascular disease, elevated serum creatinine, renal insufficiency, congestive heart failure, previous myocardial infarction, chronic lung disease, and peripheral vascular disease.


CONCLUSIONS
Poor preoperative glycemic control, as measured by an elevated HbA1c, is associated with reduced long-term survival after coronary artery bypass surgery. Optimizing glucose control in these patients may improve long-term survival.
Halkos
Michael E
ME
Clinical Research Unit, Division of Cardiothoracic Surgery, Rollins School of Public Health, Emory University School of Medicine, Atlanta, Georgia, USA.
Lattouf
Omar M
OM
Puskas
John D
JD
Kilgo
Patrick
P
Cooper
William A
WA
Morris
Cullen D
CD
Guyton
Robert A
RA
Thourani
Vinod H
VH
D002318:Cardiovascular Diseases / Q000453:epidemiology; D015897:Comorbidity; D001026:Coronary Artery Bypass / Q000401:mortality*; D003327:Coronary Disease / Q000453:epidemiology* / Q000601:surgery*; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000378:metabolism*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008171:Lung Diseases / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011300:Preoperative Care; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate
D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human