Effects of Preoperative HbA1c Levels on the Postoperative Outcomes of Coronary Artery Disease Surgical Treatment in Patients with Diabetes Mellitus and Nondiabetic Patients: A Systematic Review and Meta-Analysis

Abstract

Aims. To investigate the effect of preoperative HbA1c levels on the postoperative outcomes of coronary artery disease surgery in diabetic and nondiabetic patients. Methods and Results. The MEDLINE (via PubMed), Cochrane Library, Web of Science, Embase, Wanfang Data, China National Knowledge Infrastructure (CNKI), and Chinese Biology Medicine (CBM) databases were used to search the effects of different preoperative HbA1c levels on the postoperative outcomes of coronary artery disease surgical treatment in diabetic and nondiabetic patients from inception to December 2018. Two review authors worked in an independent and duplicate manner to select eligible studies, extract data, and assess the risk of bias of the included studies. We used a meta-analysis to synthesize data and analyze subgroups, sensitivity, and publication bias as well as the GRADE methodology if appropriate. The literature search retrieved 886 records initially, and 23 cohort studies were included in the meta-analysis. In this meta-analysis, we found that there was a reduced incidence of surgical site infections (OR=2.94, 95% CI 2.18-3.98), renal failure events (OR=1.63, 95% CI 1.13-2.33), and myocardial infarction events (OR=1.69, 95% CI 1.16-2.47), as well as a shortened hospital stay (MD=1.08, 95% CI 0.46-1.71), in diabetic patients after coronary artery disease surgical treatment with lower preoperative HbA1c levels. For nondiabetic patients, a higher preoperative HbA1c level resulted in an increase in the incidence of mortality (OR=2.23, 95% CI 1.01-4.90) and renal failure (OR=2.33, 95% CI 1.32-4.12). No significant difference was found between higher and lower preoperative HbA1c levels in the incidence of mortality (OR=1.06, 95% CI 0.88-1.26), stroke (OR=1.49, 95% CI 0.94-2.37), or atrial fibrillation (OR=0.94, 95% CI 0.67-1.33); the length of ICU stay (MD=0.20, 95% CI -0.14-0.55); or sepsis incidence (OR=2.49, 95% CI 0.99-6.25) for diabetic patients or for myocardial infarction events (OR=1.32, 95% CI 0.27-6.31) or atrial fibrillation events (OR=0.99, 95% CI 0.74-1.33) for nondiabetic patients. The certainty of evidence was judged to be moderate or low. Conclusion. This meta-analysis showed that higher preoperative HbA1c levels may potentially increase the risk of surgical site infections, renal failure, and myocardial infarction and reduce the length of hospital stay in diabetic subjects after coronary artery disease surgical treatment and increase the risk of mortality and renal failure in nondiabetic patients. However, there was great inconsistency in defining higher preoperative HbA1c levels in the studies included; we still need high-quality RCTs with a sufficiently large sample size to further investigate this issue in the future. This trial is registered with CRD42019121531.

Commentary: Addressing glycemic load in the precardiac surgical period: Does one size fit all?

“…Many patients requiring cardiac surgery have a high glycemic load, which is known to increase the risk of adverse postoperative outcomes. 1 Yet, precise estimates associated with a milieu of clinically relevant short-and long-term postoperative outcomes using varying degrees of glycemic thresholds are not available.…”

Effects of antidiabetic medications on cardiovascular outcomes

“…A prospective study has reported an association of acute renal failure as a complication following CABG 39 . Wang et al 40 conducted a meta‐analysis of nine studies, and they have found that poor control of blood sugar is associated with higher risks of renal failure after cardiac surgery (OR, 1.63; 95% CI, 1.13‐2.33). Similarly, Halkos et al 41 showed an increased risk of renal failure (OR, 2.1) following elective CABG at a single academic center.…”

“…27 A prospective study has reported an association of acute renal failure as a complication following CABG. 39 Wang et al 40 43 Due to the limited sample size of one hospital's patient population, whether these results can be generalized, or could other hospital trusts find more success in LOS reduction in postoperative patients remains to be seen. Other studies have shown that poor control of blood sugar levels is associated with and correlated to longer hospital stay than those with optimal glycemic control (mean LOS of 7.5 days vs 6.5 days), or a 1.08-day mean increase in LOS.…”

“…Other studies have shown that poor control of blood sugar levels is associated with and correlated to longer hospital stay than those with optimal glycemic control (mean LOS of 7.5 days vs 6.5 days), or a 1.08-day mean increase in LOS. 40,44 5 | FUTURE DIRECTIONS…”

Glycated Hb levels and its effect on outcomes in Cardiac Surgery

“…However, a larger and more recent meta-analysis (n=5,381) conducted by Wang et al showed that there was no significant difference in stroke incidence between diabetic patients with lower preoperative HbA1c levels and those with higher preoperative HbA1c levels after CABG and PCI (OR 1.49, 95% CI 0.94-2.37, p = 0.37, andI 2 = 8%) 48 . Higher HbA1c levels were defined as preoperative HbA1c [?]…”