Hyperglycemia or high hemoglobin A1C: Which one is more associated with morbidity and mortality after coronary artery bypass graft surgery?

Propose: Our aim was to determine which criterion- hyperglycemia or high levels of glycosylated hemoglobin (HbA1C) is more associated with increased mortality and morbidity after coronary artery bypass graft (CABG).

Methods: Two hundred and sixteen patients who underwent elective CABG were enrolled in this prospective study. In order to compare postoperative outcomes regarding HbA1c and fasting blood sugar (FBS) levels, the patients were divided into two groups based on plasma HbA1c levels >7% or ≤7% and FBS >126 mg/dl or ≤126 mg/dl.

Results: Of 216 studied patients, 165 and 51 cases had levels of HbA1C ≤7% and HbA1c >7% respectively. Furthermore, 129 and 87 patients had levels of FBS of ≤126 mg/dl and FBS of >126 mg/dl respectively. Multivariate analyses revealed that patients with high HbA1C levels experienced significantly higher rates of postoperative re-intubation [P = 0.001, OR (95% CI) = 8.15 (2.88-23.09)], wound infection [P = 0.001, OR (95% CI) = 8.15 (2.88-23.09)] and bleeding [P = 0.027, OR (95% CI) = 2.18 (1.10-4.35)]. In addition, hyperglycemic patients had a higher frequency of arrhythmias [P = 0.001, OR (95% CI) = 3.07 (1.69-5.59)], atelectasis [P = 0.029, OR (95% CI) = 1.88 (1.07-3.30)] and wound infection [P = 0.001, OR (95% CI) = 8.75 (2.45-31.25)].

Conclusion: Higher levels of both HbA1C and FBS contribute to the increased risk of morbidity but not mortality rates in post-CABG surgery patients; yet further studies are required to distinguish "a better predictor" of postoperative adverse events.