Effect of preoperative hemoglobin A1c levels on long-term outcomes for diabetic patients after off-pump coronary artery bypass grafting

Glycosylated Hemoglobin (HbA1C) as a Predictor of Early Postoperative Outcomes After Coronary Artery Bypass Grafting: A Single-Center Observational Study

Background Diabetic patients present a majority of patients undergoing surgical revascularization. Hyperglycemia is associated with increased adverse events. Glycosylated hemoglobin (HbA1c) is an effective biological marker for long-term glycemic control. As a result, there is an increased trend in its use as a predictor of adverse outcomes. This study aims to assess the impact of elevated HbA1c on the occurrence of postoperative complications after coronary artery bypass grafting (CABG). Methods We conducted a retrospective review of medical records from January 2015 to December 2022 for adult patients who underwent isolated CABG. We assessed patient demographics, medication, laboratory results, HbA1c results, and clinical data. The separate statistical models were designed to assess the predictors for the development of postoperative complications.  Results This retrospective single-center study was conducted on 289 consecutive adult patients who underwent on-pump CABG. Patient demographics showed that uncontrolled HbA1c was more in females (p=0.022), and hemodialysis patients (p=0.018). Across different levels of HbA1C, there were no significant differences in terms of the incidence of postoperative complications (p=0.788 for infection, p=0.372 for the need for blood transfusion, p=0.721 for heart failure, p=0.692 for arrhythmia, and p=0.712 for death). HbA1c had no predictive value for postoperative complications as indicated by multivariate and stepwise analysis in a separate model for each complication with receiver operator characteristics curves of each model showing similar strength of both multivariate and stepwise models. Conclusions In our data, elevated preoperative HbA1c had no predictive value for early complications and intermediate postoperative outcomes. We recommend that surgery should proceed without delay, even if patients have elevated HbA1C levels. As for elective patients with low-risk features and anatomy, optimizing preoperative glycemic control can be considered.

Association between HbA1c and deep sternal wound infection after coronary artery bypass: a systematic review and meta-analysis

BACKGROUND

Deep sternal wound infection (DSWI) constitutes a serious complication after coronary artery bypass grafting (CABG) surgery. The aim of this study is to evaluate the dose-response relationship between glycated hemoglobin (HbA1c) level and the risk of DSWI after CABG.

METHODS

PubMed, Scopus, and Cochrane Library databases were searched to identify potentially relevant articles. According to rigorous inclusion and exclusion criteria, fourteen studies including 15,570 patients were enrolled in our meta-analysis. Odds ratio (OR) with 95% confidence intervals (CIs) was used as the summary statistic. The robust-error meta-regression model was used to synthesize the dose-response relationship.

RESULTS

Our meta-analysis shows that among patients undergoing CABG, preoperative elevated HbA1c was associated with the risk of developing DSWI (OR = 2.67, 95% CI 2.00-3.58) but with low prognostic accuracy (diagnostic OR = 2.70, 95% CI 1.96-3.73; area under the curve = 0.66, 95% CI 0.62-0.70) for predicting postoperative DSWI. Subgroup analyses showed the relationship became nonsignificant in patients without diabetes and studies adopting lower HbA1c thresholds. Dose-response analysis showed a significant nonlinear (p = 0.03) relationship between HbA1c and DSWI, with a significantly increased risk of DSWI when HbA1c was > 5.7%.

CONCLUSIONS

An elevated HbA1c level of > 5.7% was related to a higher risk of developing DSWI after CABG, and the risk increased as the HbA1c level grew. The association between HbA1c and DSWI was nonsignificant among nondiabetic patients while significant among diabetic patients.

Management of Hyperglycemia in Hospitalized Adult Patients in Non-Critical Care Settings: An Endocrine Society Clinical Practice Guideline

BACKGROUND

Adult patients with diabetes or newly recognized hyperglycemia account for over 30% of noncritically ill hospitalized patients. These patients are at increased risk for adverse clinical outcomes in the absence of defined approaches to glycemic management.

OBJECTIVE

To review and update the 2012 Management of Hyperglycemia in Hospitalized Patients in Non-Critical Care Settings: An Endocrine Society Clinical Practice Guideline and to address emerging areas specific to the target population of noncritically ill hospitalized patients with diabetes or newly recognized or stress-induced hyperglycemia.

METHODS

A multidisciplinary panel of clinician experts, together with a patient representative and experts in systematic reviews and guideline development, identified and prioritized 10 clinical questions related to inpatient management of patients with diabetes and/or hyperglycemia. The systematic reviews queried electronic databases for studies relevant to the selected questions. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make recommendations.

RESULTS

The panel agreed on 10 frequently encountered areas specific to glycemic management in the hospital for which 15 recommendations were made. The guideline includes conditional recommendations for hospital use of emerging diabetes technologies including continuous glucose monitoring and insulin pump therapy; insulin regimens for prandial insulin dosing, glucocorticoid, and enteral nutrition-associated hyperglycemia; and use of noninsulin therapies. Recommendations were also made for issues relating to preoperative glycemic measures, appropriate use of correctional insulin, and diabetes self-management education in the hospital. A conditional recommendation was made against preoperative use of caloric beverages in patients with diabetes.

CONCLUSION

The recommendations are based on the consideration of important outcomes, practicality, feasibility, and patient values and preferences. These recommendations can be used to inform system improvement and clinical practice for this frequently encountered inpatient population.

A Systematic Review Supporting the Endocrine Society Clinical Practice Guideline for the Management of Hyperglycemia in Adults Hospitalized for Noncritical Illness or Undergoing Elective Surgical Procedures

CONTEXT

Individuals with diabetes or newly recognized hyperglycemia account for over 30% of noncritically ill hospitalized patients. Management of hyperglycemia in these patients is challenging.

OBJECTIVE

To support development of the Endocrine Society Clinical Practice Guideline for management of hyperglycemia in adults hospitalized for noncritical illness or undergoing elective surgical procedures.

METHODS

We searched several databases for studies addressing 10 questions provided by a guideline panel from the Endocrine Society. Meta-analysis was conducted when feasible. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess certainty of evidence.

RESULTS

We included 94 studies reporting on 135 553 patients. Compared with capillary blood glucose, continuous glucose monitoring increased the number of patients identified with hypoglycemia and decreased mean daily blood glucose (BG) (very low certainty). Data on continuation of insulin pump therapy in hospitalized adults were sparse. In hospitalized patients receiving glucocorticoids, combination neutral protamine hagedorn (NPH) and basal-bolus insulin was associated with lower mean BG compared to basal-bolus insulin alone (very low certainty). Data on NPH insulin vs basal-bolus insulin in hospitalized adults receiving enteral nutrition were inconclusive. Inpatient diabetes education was associated with lower HbA1c at 3 and 6 months after discharge (moderate certainty) and reduced hospital readmissions (very low certainty). Preoperative HbA1c level < 7% was associated with shorter length of stay, lower postoperative BG and a lower number of neurological complications and infections, but a higher number of reoperations (very low certainty). Treatment with glucagon-like peptide-1 agonists or dipeptidyl peptidase-4 inhibitors in hospitalized patients with type 2 diabetes and mild hyperglycemia was associated with lower frequency of hypoglycemic events than insulin therapy (low certainty). Caloric oral fluids before surgery in adults with diabetes undergoing surgical procedures did not affect outcomes (very low certainty). Counting carbohydrates for prandial insulin dosing did not affect outcomes (very low certainty). Compared with scheduled insulin (basal-bolus or basal insulin + correctional insulin), correctional insulin was associated with higher mean daily BG and fewer hypoglycemic events (low certainty).

CONCLUSION

The certainty of evidence supporting many hyperglycemia management decisions is low, emphasizing importance of shared decision-making and consideration of other decisional factors.

Hemoglobin A1c and preoperative glycemia as a decision tool to help minimise sternal wound complications: a retrospective study in OPCAB patients

Background

Poor glycemic control has been associated with an increased risk of wound complications after various types of operations. However, it remains unclear how hemoglobin A1c (HbA1c) and preoperative glycemia can be used in clinical decision-making to prevent sternal wound complications (SWC) following off-pump coronary artery bypass grafting (OPCAB).

Methods

We conducted a retrospective study of 1774 consecutive patients who underwent OPCAB surgery between January 2010 and November 2016. A new four-grade classification for SWC was used. The associations of HbA1c and preoperative glycemia with incidence and grade of SWC were analysed using logistic regression analysis and proportional odds models, respectively.

Results

During a median follow-up of 326 days (interquartile range (IQR) 21–1261 days), SWC occurred in 133/1316 (10%) of non-diabetes and 82/458 (18%) of diabetes patients (p < 0.001). Higher HbA1c was significantly associated with a higher incidence of SWC (odds ratio, OR 1.24 per 1% increase, 95% confidence interval, CI 1.04;1.48, p = 0.016) as well as a higher grade of SWC (OR 1.25, 95% CI 1.06;1.48, p = 0.010). There was no association between glycemia and incidence (p = 0.539) nor grade (p = 0.607) of SWC. Significant modifiers of these effects were found: HbA1c was associated with SWC in diabetes patients younger than 70 years (OR 1.41, 95% CI 1.17;1.71, p < 0.001), whereas it was not in those older than 70 years. Glycemia was associated with SWC in patients who underwent non-urgent surgery (OR 2.48, 95% CI 1.26;4.88, p = 0.009), in diabetes patients who received skeletonised grafts (OR 4.83, 95% CI 1.28;18.17, p = 0.020), and in diabetes patients with a BMI < 30 (OR 2.19, 95% CI 1.01;4.76, p = 0.047), whereas it was not in the counterparts of these groups.

Conclusions

Under certain conditions, HbA1c and glycemia are associated SWC following OPCAB. These findings are helpful in planning the procedure with minimal risk of SWC.

Hemoglobin A1c in Patients with Diabetes Predict Long-Term Mortality Following Coronary Artery Surgery

Objective: to estimate the association between preoperative hemoglobin A1c (HbA1c) levels below and above 7%, and the rate of all-cause mortality (ACM) in diabetes mellitus (DM) patients after coronary artery bypass grafting (CABG) within a ten-year follow-up period. Methods: we collected data on patient HbA1c levels that were measured up to 3 months prior to isolated CABG in consecutive patients with DM, and analyzed the rates of ACM over a median of a 5.9-year post-operative period. Results: preoperative HbA1c levels were collected in 579 DM patients. The mean HbA1c was 8.0 ± 1.7%, where 206 (35.6%) patients had an HbA1c ≤ 7% and 373 (64.4%) had an HbA1c > 7%. During the follow-up period, mortality rates were 20.4% and 28.7% in the HbA1c ≤ 7% and HbA1c > 7% groups, respectively (Kaplan-Meier estimates, log-rank p = 0.01). Multivariable Cox proportional hazards regression, adjusted for age, gender, smoking status, chronic obstructive pulmonary disease, hypertension, chronic renal failure, old myocardial infarction, number of coronary artery bypass surgeries, and post-operative glycemic control, showed a hazard ratio of 2.67 for long-term ACM (p = 0.001) in patients with HbA1c > 7%. Conclusions: DM patients with high HbA1c levels prior to CABG are at higher risk for long-term complications, especially late ACM.

Impact of preoperative glycometabolic status on outcomes in cardiac surgery: Systematic review and meta-analysis

BACKGROUND

Historically, impaired glucose metabolism has been associated with early and late complicated clinical outcomes after cardiac surgery; however, such a condition is not specific to subjects with diabetes mellitus and involves a larger patient population.

METHODS

Databases were screened (January 2000 to December 2020) to identify eligible articles; studies that evaluated the association between preoperative metabolic status, as assessed by glycosylated hemoglobin levels and clinical outcomes, were considered. The studies were stratified in thresholds by baseline glycosylated hemoglobin level (lower vs higher).

RESULTS

Thirty studies, involving 34,650 patients, were included in the review. In a meta-analysis stratified by glycosylated hemoglobin levels, early mortality was numerically reduced in each threshold comparison and yielded the highest reductions when less than 5.5% versus greater than 5.5% glycosylated hemoglobin levels were compared (risk ratio, 0.39; 95% confidence interval, 0.18-0.84; P = .02). Comparing higher glycosylated hemoglobin threshold values yielded comparable results. Late mortality was reduced with lower levels of glycosylated hemoglobin. Low preoperative glycosylated hemoglobin was associated with the lowest risk of sternal wound infections (risk ratio, 0.50; 95% confidence interval, 0.32-0.80; P = .003 and risk ratio, 0.53; 95% confidence interval, 0.39-0.70; P < .0001) for comparisons of less than 7.5% versus greater than 7.5% and less than 7.0% versus greater than 7.0% glycosylated hemoglobin thresholds, respectively. Additionally, levels of glycosylated hemoglobin lower than 7% were associated with reduced hospital stay, lower risk of stroke/transient ischemic attack (risk ratio 0.53; 95% confidence interval, 0.39-0.70; P < .0001), and acute kidney injury (risk ratio, 0.65; 95% confidence interval, 0.54-0.79; P < .0001).

CONCLUSIONS

Lower levels of glycosylated hemoglobin in patients undergoing cardiac surgery are associated with a lower risk of early and late mortality, as well as in the incidence of postoperative acute kidney injury, neurologic complications, and wound infection, compared with higher levels.

Clinical significance of diabetes control before metabolic surgery

BACKGROUND

Even though observational studies have suggested that poor preoperative diabetes control increases risk after major abdominal surgery, it is unclear whether this effect is seen in metabolic surgery patients.

OBJECTIVES

To determine whether poor preoperative diabetes control is associated with worse outcomes in patients with obesity and diabetes undergoing metabolic surgery.

SETTING

Metabolic and Bariatric Surgery Quality Improvement Project (MBSAQIP) database.

METHODS

Using the MBSAQIP 2017 and 2018 database and preoperative glycated hemoglobin (HbA1C) as a diabetes control surrogate, we examined the association between diabetes control and major outcomes of primary laparoscopic sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) in patients with diabetes and obesity. Multivariate logistic regression modeling examined five 30-day postoperative outcomes: composite serious complications (composite of 10 adverse events), composite infection (composite of 7 infectious complications), length of stay >5 days, reoperation, and readmission. Models were adjusted for multiple covariates.

RESULTS

In total, 26,674 patients with HbA1C data available within 30 days before metabolic surgery were included in the primary analysis and 35,884 patients with HbA1C data within 90 days before surgery were included in the sensitivity analysis. The mean body mass index (BMI) and preoperative HbA1C were 45.6 ± 8.2 kg/m² and 8.2 ± 2.7%, respectively. The incidence of 30-day postoperative infections and serious complications were 1.62% and 1.35%, respectively. Neither primary analysis nor sensitivity analysis demonstrated any association between higher HbA1C and worsening of 5 primary outcomes of interest. The odds ratio of an overall effect for SG was 1.01 (95% CI .98-1.03; P = .58) and for RYGB was .99 (95% CI .96-1.02; P = .41).

CONCLUSION

Suboptimal preoperative diabetes control is not associated with increased adverse events and should not delay metabolic surgery, as metabolic surgery is generally a safe procedure and intrinsically improves diabetes control.

Atrial fibrillation - Can HbA1c levels really predict the risk?

BACKGROUND

Diabetes is associated with higher mortality and worse post-operative outcomes in patients undergoing coronary artery bypass grafting and HbA1c levels have consistently been reported to be associated with adverse post-operative outcomes. However, the role of HbA1c still remains unclear with regards to the occurrence of atrial fibrillation.

METHOD

Data for the patients undergoing off-pump coronary artery bypass grafting was analysed in a retrospective fashion. Patients were divided into-those with HbA1c < 6.5% and those with HbA1c ≥ 6.5% and the incidence of atrial fibrillation observed in these two groups. We also compared patient who developed atrial fibrillation in the post-operative period and compared them with those who did not.

RESULTS

Of the 5259 patients included in the study HbA1c was <6.5 in 2808 (53.4%) patients and was ≥6.5 in 2451 (46.6%) patients; 623 (11.8%) patients in our study developed atrial fibrillation. Onset of atrial fibrillation in the post-operative period was seen most commonly 235 (38.3%) on between 24 and 48 h after the operation with more than half of them 338 (54.2%) occurring within the first 48 h. On multivariate analysis, HbA1c was not a risk factor for atrial fibrillation (odd's ratio 1.144, 95% confidence interval 0.967-1.354). Only increased age (odd's ratio 1.08; 95% confidence interval 1.069-1.091); EuroSCORE (odd's ratio 1.073; 95% confidence interval 1.048-1.099); history of recent MI (odd's ratio 0.768; 95% confidence interval 0.606-0.971) and peripheral vascular disease (odd's ratio 1.667; 95% confidence interval 1.091-2.517) were found to be independently associated with increased risk of atrial fibrillation in the post-operative period.

CONCLUSIONS

After adjusting for confounders HbA1c levels do not independently predict risk of atrial fibrillation after off-pump coronary artery bypass grafting.

The Effect of Glycemic Control on Cardiac Outcomes in Saudi Diabetic Patients who Underwent Coronary Angiogram

Background:

Diabetes mellitus is a metabolic disorder that causes impaired insulin secretion or cellular dysfunction. Glycated hemoglobin (HbA1c) indicates the long-term level of glucose. Diabetes can lead to cardiovascular complications such as acute coronary syndrome , which might require coronary intervention.

Objectives:

The aim of this study was to estimate the effect of glycemic control measured by HbA1c levels on cardiac complications in Saudi diabetic patients who underwent percutaneous coronary intervention (PCI) or Coronary artery bypass graft (CABG).

Methodology:

It was a cohort retrospective study conducted at King Abdulaziz Cardiac Center with a total sample size of 379 patients. The charts of all those diabetic patients were reviewed and their HbA1c level, type of intervention were compared to determine their effect on cardiac outcomes and complications. Inclusion criteria involved the age group 50–70 years within follow-up period of 3 years. Any patient known to have renal failure, liver dysfunction, type one diabetes, and cancer were excluded. The HbA1c level was divided into two groups (<7.5%, ≥7.5%).

Results:

Total sample size was 379, and the mean age was (60.33 ± 5.98) with male being (66.5%). HbA1c levels at admission were (mean 9.15 ± 2.03), whereas the mean after 3 years was (8.629 ± 1.518). The uncontrolled group was more likely to have PCI (n = 302), in comparison to the controlled group (n = 77) with a P value of 0.04. However, the controlled group was more likely to undergo medical treatment P value of 0.001. Patients with uncontrolled Hba1c after the intervention had a higher readmission rate with a P value of 0.018.

Conclusions:

Patients with an elevated level of HbA1c were more likely to be managed with PCI. Furthermore, they are at a higher risk of multiple readmissions. Patients who had CABG were at a lower risk of cardiac complications. Further studies are required in our population to consider different approaches of diabetes control for preventing adverse outcomes.

Dose-response analysis between hemoglobin A1c and risk of atrial fibrillation in patients with and without known diabetes

Background

The relationship between serum hemoglobin A1c (HbA1c) and atrial fibrillation (AF) or postoperative AF (POAF) in coronary artery bypass (CABG) patients is still under debate. It is also unclear whether there is a dose-response relationship between circulating HbA1c and the risk of AF or POAF.

Methods and results

The Cochrane Library, PubMed, and EMBASE databases were searched. A robust-error meta-regression method was used to summarize the shape of the dose-response relationship. The RR and 95%CI were using a random-effects model. In total, 14 studies were included, totaling 17,914 AF cases among 352,325 participants. The summary RR per 1% increase in HbA1c was 1.16 (95% CI: 1.07–1.27). In the subgroup analysis, the summary RR was 1.13 (95% CI: 1.08–1.19) or 1.12 (95% CI: 1.05–1.20) for patients with diabetes or without known diabetes, respectively. The nonlinear analysis showed a nonlinear (P_nonlinear = 0.04) relationship between HbA1c and AF, with a significantly increased risk of AF if HbA1c was over 6.3%. However, HbA1c (per 1% increase) was not associated with POAF in patients with diabetes (RR: 1.13, P = 0.34) or without known diabetes (RR: 0.91, P = 0.37) among patients undergoing CABG.

Conclusion

Our results suggest that higher HbA1c was associated with an increased risk of AF, both in diabetes and in without diabetes or with unknown diabetes. However, no association was found between HbA1c and POAF in patients undergoing CABG. Further prospective studies with larger population sizes are needed to explore the association between serum HbA1c level and the risk of POAF.

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

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.

Impact of elevated glycosylated hemoglobin on hospital outcome and 1 year survival of primary isolated coronary artery bypass grafting patients

Objective

It is unknown whether adequacy of diabetic control, measured by hemoglobin A1c, is a predictor of adverse outcomes after coronary artery bypass grafting.

Methods

From December 2013 to November 2015, 80 consecutive patients underwent primary isolated CABG surgery at national heart institute, their data were prospectively collected and they were classified according to their HbA1c level into two groups, Group (A): Forty patients with fair glycemic control (HbA1c below or equal to 7%), Group (B): Forty patients with poor glycemic control (HbA1c above 7%). Hospital morbidity, mortality and one year survival were examined in both groups. Telephone conversation was used to call patients or their relatives to determine the one year survival and it was 100% complete. This study had gained the ethical approval from national heart institute ethical committee.

Results

In-hospital mortality for group A was 2.5% (one patient) and 7.5% (3 patients) for group B with no statistical significance. One year mortality was (5.13%) (2 patients for group A) and (8.11%) (3 patients) for group B with no statistical significance. As regard the morbidity there was no statistical significance between the two groups in the incidence of neurological complications whether stroke or coma, atrial fibrillation, postoperative myocardial infarction, low cardiac output syndrome, heart failure, renal failure, need for dialysis, deep sternal wound infection, and readmission. However, group B had lengthy hospital stay, lengthy ventilation hours, more respiratory complications, and more superficial wound infection with a statistical significance when compared to group A, P values were 0.003, 0.003, 0.038, 0.044 respectively.

Conclusions

This study showed that HbA1c is a good predictor of in-hospital morbidity. It worth devoting time and effort to decrease HbA1c level below 7% to decrease possible postoperative complications.

Does HbA1c Level Have Clinical Implications in Diabetic Patients Undergoing Coronary Artery Bypass Grafting? A Systematic Review and Meta-Analysis

AIMS/INTRODUCTION

The aim of the present study was to investigate whether HbA1c was related to clinical outcomes in diabetic patients undergoing CABG surgery.

MATERIALS AND METHODS

A literature search was carried out satisfying the predefined inclusion criteria from Pubmed, Embase, and Cochrane Library. Differences were expressed as odds ratios (ORs) with 95% confidence intervals (CIs) to assess the relationships of preoperative HbA1c levels and clinical prognosis in diabetic patients.

RESULTS

7895 diabetic patients undergoing CABG surgery from eight published studies were finally involved in this meta-analysis. Combined analyses revealed that the higher HbA1c level was significantly associated with increased risks of all-cause mortality (OR 1.56, 95%CI 1.29-1.88), myocardial infarction (OR 2.37, 95%CI 1.21-4.64), and stroke (OR 2.07, 95%CI 1.29-3.32) after CABG surgery. However, there was no significant relationship between HbA1c levels and renal failure (OR 2.08, 95%CI 0.96-4.54) in diabetic patients undergoing CABG surgery.

CONCLUSIONS

Our meta-analysis demonstrated that the HbA1c level is potentially associated with increased risks of all-cause mortality, myocardial infarction, and stroke in diabetic subjects undergoing CABG surgery. However, further clinical studies with larger sample sizes and longer follow-up period are urgently warranted.

Prognostic significance of glycemic variability after cardiac surgery

INTRODUCTION

The prognostic significance of acute glycemic variability (GV) after cardiac surgery is not known. This study was therefore planned to analyze the independent prognostic value of GV after cardiac surgery.

MATERIALS AND METHODS

This is a single center prospective observational study in 870 consecutive cardiac surgery patients over a 3-month period at a tertiary care institute in India.

RESULTS

In linear regression analysis, GV was a significant predictor of length of stay in intensive care unit (LOS-ICU) (beta 0.102, p=0.007) and rise in creatinine after surgery (beta 0.229, p<0.001). Mean POC-BG was a significant positive predictor of length of stay in hospital (LOS-hospital) (beta 0.1, p=0.004). In multivariable logistic regression analysis, GV predicted prolonged LOS-ICU (p=0.006, OR 1.016) and acute kidney injury (p<0.001, OR 1.034).

CONCLUSION

This study showed that GV, as measured by standard deviation, was a predictor of LOS-ICU, rise in creatinine and AKI after cardiac surgery. GV is therefore a new dimension in postoperative glycemic management in cardiac surgery patients, which needs to be explored.

Insulin infusion on postoperative complications of coronary artery bypass graft in patients with diabetes mellitus

Background:

Cardiovascular events are common in patients with diabetes mellitus (DM), which make coronary artery bypass graft (CABG) a highly demanded surgery in this population. Tight control of blood glucose in patients with DM is beneficial in reducing postoperative complications; however, the adequate range has not been determined yet.

Objectives:

This study aimed to investigate the effect of semi-tight (moderate) control of DM on complications and serum glucose levels during and after CABG.

Patients and Methods:

In this prospective clinical trial, 18 and 31 patients with and without DM, respectively, who were referred to Shahid Chamran Hospital, Isfahan, Iran, for elective CABG surgery, were enrolled. For DM group, patients with controlled DM (i.e. glycosylated hemoglobin levels [HgA1C] ≤ 7%) were recruited. Blood glucose level (blood sugar, BS) was measured after anesthesia, during pumping, warming, off pumping, six and 12 hours after Intensive Care Unit (ICU) admission, and at discharging from the hospital. The hemodynamic state of the patients, bleeding, need of blood transfusion, infection, and duration of hospitalization were also monitored and recorded.

Results:

None of the BS measurements (FBS, after anesthesia, on-pump, warming, off pump, six and 12 hours after ICU admission, and at discharge) were significantly different between study groups (P > 0.05). Frequency of surgery site bleeding and blood transfusion need were not significantly different between these groups (P > 0.05).

Conclusions:

Semi-tight control of DM with insulin infusion during operation did not led to any difference in the type and rate of CABG complications between patients with well-controlled and those without DM; however, BS levels in patients with well-controlled DM could be more easily controlled.

Is there a role for HbA1c in predicting mortality and morbidity outcomes after coronary artery bypass graft surgery?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was is there a role for HbA1c in predicting morbidity and mortality outcomes after coronary artery bypass surgery? Eleven studies presented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The studies presented analyse the relationship between preoperative HbA1c levels and postoperative outcomes following coronary artery bypass graft (CABG) in diabetic, non-diabetic or mixed patient groups. Four studies found significant increases in early and late mortality at higher HbA1c levels, regardless of a preoperative diagnosis of diabetes. One study demonstrated that 30-day survival outcomes were significantly worse in patients with previously undiagnosed diabetes and elevated HbA1c compared with those with good control [HbA1c >6%; odds ratio 1.53, confidence interval (CI) (1.24-1.91); P = 0.0005]. However, four studies of early mortality outcomes in diabetic patients only showed no significant differences between patients with normal and those with deranged HbA1c levels (P = 0.99). There were mixed reports on morbidity outcomes. Three studies identified a significant increase in infectious complications in patients with poorly controlled HbA1c, two of which were irrespective of previous diabetic status [deep sternal wound infection (P = 0.014); superficial sternal wound infection (P = 0.007) and minor infections (P = 0.006) in poorly controlled diabetics only]. Four studies presented outcomes for total length of stay (LOS). Three of these papers looked specifically at diabetic patients, of which two found no significant differences in length of stay between good and poor preoperative glycaemic control [LOS: P = 0.59 and 0.86 vs P < 0.001]. However, elevated HbA1c vs normal HbA1c was associated with prolonged stay in hospital and in intensive care unit (ICU) in patients irrespective of previous diabetic status [total LOS (P < 0.001)]. Elevated HbA1c levels were also a significant predictor of reduced intraoperative insulin sensitivity in diabetic patients (R = -0.527; P < 0.001). Furthermore, higher HbA1c levels were associated with a reduced incidence of postoperative atrial fibrillation (P = 0.001). We conclude that elevated HbA1c is a strong predictor of mortality and morbidity irrespective of previous diabetic status. In particular, the mortality risk for CABG is quadrupled at HbA1c levels >8.6%. Some studies have called into question the predictive value of HbA1c on short-term outcomes in well-controlled diabetics; however, long-term outcomes in this population have not been reported.

Gender differences in clinical outcomes among diabetic patients hospitalized for cardiovascular disease

BACKGROUND

The risk of incident cardiovascular disease (CVD) has been shown to be greater among diabetic women than men, but gender differences in clinical outcomes among diabetic patients hospitalized with CVD are not established. We aimed to determine if hemoglobin A1c (HbA1c) was associated with 30-day and 1-year CVD rehospitalization and total mortality among diabetic patients hospitalized for CVD, overall and by gender.

METHODS

This was a prospective analysis of diabetic patients hospitalized for CVD, enrolled in an National Heart, Lung and Blood Institute-sponsored observational clinical outcomes study (N = 902, 39% female, 53% racial/ethnic minority, mean age 67 ± 12 years). Laboratory, rehospitalization, and mortality data were determined by hospital-based electronic medical record. Poor glycemic control was defined as HbA1c ≥7%. The association between HbA1c and clinical outcomes was evaluated using logistic regression; gender modification was evaluated by interaction terms and stratified models.

RESULTS

Hemoglobin A1c ≥7% prevalence was 63% (n = 566) and was similar by gender. Hemoglobin A1c ≥7% vs <7% was associated with increased 30-day CVD rehospitalization in univariate (odds ratio [OR] = 1.63, 95% CI 1.05-2.54) and multivariable-adjusted models (OR 1.74, 95% CI 1.06-2.84). There was an interaction between glycemic control and gender for 30-day CVD rehospitalization risk (P = .005). In stratified univariate models, the association was significant among women (OR 4.83, 95% CI 1.84-12.71) but not among men (OR 1.02, 95% CI 0.60-1.71). The multivariate-adjusted risk for HbA1c ≥7% versus <7% among women was 8.50 (95% CI 2.31-31.27) and 1.02 (95% CI 0.57-1.80) for men. A trend toward increased 30-day/1-year mortality risk was observed for HbA1c <6% vs ≥6% for men and women.

CONCLUSIONS

Risk of 30-day CVD rehospitalization was 8.5-fold higher among diabetic women hospitalized for CVD with HbA1c ≥7% vs <7%; no association was observed among men. A trend for increased 30-day/1-year mortality risk with HbA1c <6% deserves further study.

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.

Off-pump coronary artery bypass grafting revisited: experience and evidence from Japan

Off-pump coronary artery bypass grafting (OPCAB) is performed in about 65% of patients who require surgical coronary revascularization, and has become the standard procedure in coronary artery bypass grafting (CABG) in Japan. As a background of the high rate of OPCAB, many clinical and experimental studies have been performed and reported in Japan. In this review, several factors associated with OPCAB are discussed based on relevant and important clinical studies published in Japan in the English language.

Effect of cardiac rehabilitation on muscle mass, muscle strength, and exercise tolerance in diabetic patients after coronary artery bypass grafting

BACKGROUND

The effects of cardiac rehabilitation (CR) on muscle mass, muscle strength, and exercise tolerance in patients with diabetes mellitus (DM) who received CR after coronary artery bypass grafting (CABG) have not been fully elucidated.

METHODS

We enrolled 78 consecutive patients who completed a supervised CR for 6 months after CABG (DM group, n=37; non-DM group, n=41). We measured mid-upper arm muscle area (MAMA), handgrip power (HGP), muscle strength of the knee extensor (Ext) and flexor (Flex), and exercise tolerance at the beginning and end of CR.

RESULTS

No significant differences in confounding factors, including age, gender, ejection fraction, or number of CR sessions, were observed between the two groups. At the beginning of CR, the levels of Ext muscle strength and peak VO2 were significantly lower in the DM group than in the non-DM group. At the end of CR, significant improvement in the levels of muscle strength, HGP, and exercise tolerance was observed in both groups. However, the levels of Ext muscle strength, HGP, peak VO2, thigh circumference, and MAMA were significantly lower in the DM group than in the non-DM group. In addition, no significant improvement in thigh circumference and MAMA was observed in the DM group. At the end of CR, the levels of thigh circumference and MAMA correlated with Ext and Flex muscle strength as well as with HGP. Percent changes in the levels of Ext muscle strength were significantly correlated with those of MAMA and hemoglobin A1c.

CONCLUSIONS

These data suggest that improvement in muscle strength may be influenced by changes in muscle mass and high glucose levels in DM patients undergoing CR after CABG. A CR program, including muscle mass intervention and blood glucose control, may improve deterioration in exercise tolerance in DM patients after CABG.

Prognostic significance of hemoglobin A1c level in patients hospitalized with coronary artery disease. A systematic review and meta-analysis

BACKGROUND

The prognostic value of hemoglobin A1c (HbA1c) in coronary artery disease (CAD) remains controversial. Herein, we conducted a systematic review to quantify the association between elevated HbA1c levels and all-cause mortality among patients hospitalized with CAD.

METHODS

A systematic search of electronic databases (PubMed, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1970 to May 2011 was performed. Cohort, case-control studies, and randomized controlled trials that examined the effect of HbA1c on all-cause mortality were included.

RESULTS

Twenty studies met final inclusion criteria (total n = 13, 224). From the pooled analyses, elevated HbA1c level was significantly associated with increased short-term (OR 2.32, 95% CI, 1.61 to 3.35) and long-term (OR 1.54, 95% CI, 1.23 to 1.94) mortality risk. Subgroup analyses suggested elevated HbA1c level predicted higher mortality risk in patients without diabetes (OR 1.84, 95% CI, 1.51 to 2.24). In contrast, in patients with diabetes, elevated HbA1c level was not associated with increased risk of mortality (OR 0.95, 95% CI, 0.70 to 1.28). In a risk-adjusted sensitivity analyses, elevated HbA1c was also associated with a significantly high risk of adjusted mortality in patients without diabetes (adjusted OR 1.49, 95% CI, 1.24 to 1.79), but had a borderline effect in patients with diabetes (adjusted OR 1.05, 95% CI, 1.00 to 1.11).

CONCLUSIONS

Our findings demonstrate that elevated HbA1c level is an independent risk factor for mortality in CAD patients without diabetes, but not in patients with established diabetes. Prospective studies should further investigate whether glycemic control might improve outcomes in CAD patients without previously diagnosed diabetes.