Improved survival after coronary artery bypass grafting has not influenced the mortality disadvantage in patients with diabetes mellitus

Epidemiology of Coronary Artery Disease

Although the mortality of coronary artery disease (CAD) has declined over recent decades, CAD remains the leading cause of death in the United States (US) and presents a significant economic burden. Epidemiologic studies have identified numerous risk factors for CAD. Some risk factors-including smoking, hypertension, dyslipidemia, and physical inactivity-are decreasing within the US population while Others, including advanced age, diabetes, and obesity are increasing. The most significant historic advances in CAD therapy were the development of coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), and lipid-lowering medications. Contemporary management of CAD includes primary and secondary prevention via medical management and revascularization when appropriate based on best available evidence. Despite the increasing prevalence of CAD nationwide, there has been a steady decline in the number of CABGs and PCIs performed in the US for the past decade. Patients with CABG are becoming older and with more comorbid conditions, although mortality associated with CABG has remained steady.

Bilateral Internal Thoracic Artery Grafting Improves Survival for Severe Left Ventricular Dysfunction and Diabetes

BACKGROUND

In patients with severe left ventricular (LV) dysfunction requiring coronary artery bypass grafting (CABG), the association between diabetic status and outcomes after surgery, as well as with survival benefit following bilateral internal thoracic artery (ITA) grafting, remain largely unknown.Methods and Results:Patients (n=188; mean [±SD] age 67±9 years) with LV ejection fraction ≤40% who underwent isolated initial CABG were classified into non-diabetic (n=64), non-insulin-dependent diabetic (NIDM; n=74), and insulin-dependent diabetic (IDM; n=50) groups. During follow-up (mean [±SD] 68±47 months), the 5-year survival rate was 84% and 65% among non-diabetic and diabetic patients, respectively (P=0.034). After adjusting for all covariates, both NIDM and IDM were associated with increased mortality, with hazard ratios (HRs) of 1.9 (95% confidence interval [CI] 1.0-3.7; P=0.049) and 2.4 (95% CI 1.2-4.8; P=0.016), respectively. Among non-diabetic patients, there was no difference in the 5-year survival rate between single and bilateral ITA grafting (86% vs. 80%, respectively; P=0.95), whereas bilateral ITA grafting increased survival among diabetic patients (57% vs. 81%; P=0.004). Multivariate analysis revealed that bilateral ITA was significantly associated with a decreased risk of mortality (HR 0.3; 95% CI 0.1-0.8; P=0.024).

CONCLUSIONS

NIDM and IDM were significantly associated with worse long-term clinical outcome after CABG for severe LV dysfunction. Bilateral ITA grafting has the potential to improve survival in diabetic patients with severe LV dysfunction.

Glycated Hemoglobin as a Predictor of the Length of Hospital Stay in Patients Following Coronary Bypass Graft Surgery in the Saudi Population

Objective

The diabetic population has a high prevalence of coronary artery disease, and frequently patients with diabetes undergo coronary artery bypass graft (CABG) surgery. Elevated glycated hemoglobin (HbA1c) in diabetics is shown to be associated with morbidity and mortality, but the association of HbA1c with postoperative length of hospital stay (LOS) has conflicting results. In this study, we aim to identify if elevated HbA1c levels are associated with prolonged LOS after CABG surgery.

Methods

A retrospective chart review study was performed, using a total of 305 patients who were referred for CABG surgery. HbA1c levels were measured before the day of surgery. Patients were classified into two groups according to HbA1c levels: <7% and ≥7%. A LOS of more than 14 days was proposed as an extended LOS. HbA1c and the LOS relationship were assessed using appropriate statistical methods.

Results

Patients who had diabetes mellitus comprised 81.6% of our studied population. Sixty-four percent had HbA1c levels ≥ 7%. There was no significant difference in the total LOS in HbA1c <7% compared to HbA1c ≥7% patients (P=0.367).

Conclusion

Our study results rejected the proposed hypothesis that elevated HbA1c levels ≥7% would be associated with prolonged hospital stay following CABG surgery in a Saudi population.

Effect of type 2 diabetes, surgical incision, and volatile anesthesia on hemodynamics in the rat

Diabetic patients have increased cardiac complications during surgery, possibly due to impaired autonomic regulation. Anesthesia lowers blood pressure and heart rate (HR), whereas surgical intervention has opposing effects. The interaction of anesthesia and surgical intervention on hemodynamics in diabetes is unknown, despite being a potential perioperative risk factor. We aimed to determine the effect of diabetes on the integrative interaction between hemodynamics, anesthesia, and surgical incision. Zucker type 2 diabetic rats (DM) and their nondiabetic littermates (ND) were implanted with an intravenous port for drug delivery, and a radiotelemeter to measure mean arterial blood pressure (MAP) and derive HR (total n = 50). Hemodynamic pharmacological responses were assessed under conscious, isoflurane anesthesia (~2-2.5%), and anesthesia-surgical conditions; the latter performed as a laparotomy. MAP was not different between groups under conscious conditions (ND 120 ± 6 vs. DM 131 ± 4 mmHg, P > 0.05). Anesthesia reduced MAP, but not differently in DM (ND -30 ± 6 vs. DM -38 ± 4 ΔmmHg, P > 0.05). Despite adequate anesthesia, surgical incision increased MAP, which tended to be less in DM (ND +21 ± 4 vs. DM +13 ± 2 ΔmmHg, P = 0.052). Anesthesia disrupted central baroreflex HR responses to sympathetic activation (sodium nitroprusside 10 μg·kg^-1, ND conscious 83 ± 13 vs. anesthetized 16 ± 5 Δbpm; P < 0.05) or to sympathetic withdrawal (phenylephrine 10 μg·kg^-1, ND conscious -168 ± 37 vs. anesthetized -20 ± 6 Δbpm; P < 0.05) with no additional changes observed after surgical incision or during diabetes. During perioperative conditions, type 2 diabetes did not impact on short-term hemodynamic regulation. Anesthesia had the largest hemodynamic impact, whereas surgical effects were limited to modulation of baseline blood pressure.

Comparison of endothelial function of coronary artery bypass grafts in diabetic and nondiabetic patients: Which graft offers the best?

OBJECTIVE

Diabetes associated endothelial dysfunction, which determines both long and short term graft patency, is not uniform in all coronary artery bypass surgery (CABG) grafts. Herein this study, we aimed to investigate the degree of endothelial dysfunction in diabetic radial artery (RA), internal mammarian artery (IMA) and saphenous vein (SV) grafts in vitro tissue bath system.

METHODS

This is a prospective experimental study. Fifteen diabetic and 15 non-diabetic patients were included to the study. A total number of 96 graft samples were collected; 16 graft samples for each graft type from both diabetic and non-diabetic patients. Arterial grafts were harvested with pedicles and SV grafts were harvested by 'no touch' technique. Vasodilatation response of vascular rings to carbachol, which induces nitric oxide (NO) mediated vasodilatation, was designated as the measure of endothelial function.

RESULTS

The IMA grafts had the most prominent NO mediated vasodilatation in both diabetic and non-diabetic patients, concluding a better preserved endothelial function than SV and RA. The 'no- touch' SV and RA grafts had similar vasodilatation responses in non-diabetic patients. In diabetic patients, on the other hand, RA grafts exhibited the least vasodilatation response (ie. worst endothelial function), even less vasodilatation than 'no touch' SV grafts (p<0.0001).

CONCLUSION

Deteriorated function of RA grafts in diabetic patients, even worse than SV grafts made evident by this study, encourages the use of 'no touch' technique as the method of SV harvesting and more meticulous imaging of RA before its use as a graft in diabetic patients.

The current status of multi-arterial off-pump coronary artery bypass grafting

PURPOSE

Off-pump coronary artery bypass surgery has not become widespread because of its technical difficulty. However, especially in Asia, pioneer surgeons continue with efforts to develop the off-pump technique.

METHOD

By reviewing past studies, mainly retrospective single-center reports, an up-to-date profile of off-pump surgery was assembled.

RESULTS

Many of the past randomized trials failed to demonstrate the advantages of off-pump surgery. Although many of these were single-center retrospective studies, the data presented, mostly from world-famous surgeons, show that off-pump surgery does have advantages in high-risk patients and results in reduced rates of postoperative morbidity and equal rates of mortality in both the short- and long terms. Moreover, almost all experienced off-pump surgeons noted the benefit of multiple uses of arterial grafts, skeletonization harvesting of arterial conduits and the aorta no-touch technique.

CONCLUSION

The off-pump procedure has not become a standard technique performed by the average surgeon in daily practice. However, off-pump surgery will continue to provide a significant benefit to high-risk patients with coronary disease.

Present-Day Hospital Readmissions after Left Ventricular Assist Device Implantation: A Large Single-Center Study

Left ventricular assist device (LVAD) therapy improves survival, hemodynamic status, and end-organ perfusion in patients with refractory advanced heart failure. Hospital readmission is an important measure of the intensity of LVAD support care. We analyzed readmissions of 148 patients (mean age, 53.6 ± 12.7 yr; 83% male) who received a HeartMate II LVAD from April 2008 through June 2012. The patients had severe heart failure; 60.1% were in Interagency Registry for Mechanically Assisted Circulatory Support class 1 or 2. All patients were observed for at least 12 months, and readmissions were classified as planned or unplanned. Descriptive and multivariate regression analyses were used to identify predictors of unplanned readmission. Twenty-seven patients (18.2%) had no readmissions or 69 planned readmissions, and 121 patients (81.8%) had 460 unplanned readmissions. The LVAD-related readmissions were for bleeding, thrombosis, and anticoagulation (n=103; 49.1%), pump-related infections (n=60; 28.6%), and neurologic events (n=28; 13.3%). The readmission rate was 2.1 per patient-year. Unplanned readmissions were for comorbidities and underlying cardiac disease (54.3%) or LVAD-related causes (45.7%). In the unplanned-readmission rate, there was no significant difference between bridge-to-transplantation and destination-therapy patients. Unplanned readmissions were associated with diabetes mellitus (odds ratio [OR]=3.3; P=0.04) and with shorter mileage from residence to hospital (OR=0.998; P=0.046). Unplanned admissions for LVAD-related sequelae and ongoing comorbidities were common. Diabetes mellitus and shorter distance from residence to hospital were significant predictors of readmission. We project that improved management of comorbidities and of anticoagulation therapy will reduce unplanned readmissions of LVAD patients in the future.

Total arterial off-pump coronary artery bypass grafting was not associated with inferior outcomes for diabetic when compared with non-diabetic patients

OBJECTIVES

Diabetes mellitus is a strong risk factor that worsens the clinical outcome of patients undergoing coronary artery bypass grafting (CABG). With the development of the off-pump CABG technique, there is a current trend in revascularization strategies towards in situ all-arterial grafting. We were interested in whether total arterial off-pump CABG could improve the outcome for diabetic patients.

METHODS

From January 2002 to December 2013, a total of 1064 patients underwent off-pump CABG at our institution, with total arterial reconstruction carried out in 775 cases. Of the 775 patients, 436 had diabetes (DM) and 339 did not (nDM). After propensity score matching, 301 cases from each group were successfully matched.

RESULTS

All procedures were performed via the off-pump technique without conversion to on-pump. Four patients in the DM group and 1 in the nDM group died in hospital. Multivariate analysis revealed that chronic pulmonary disease [odds ratio (OR) 7.04, P = 0.036] and low (<40%) ejection fraction (OR 11.3, P = 0.009) are independent risk factors for hospital death, and advanced age for deep sternal infection (OR 1.07, P = 0.04). Follow-up was completed in 97.7% of the patients to a maximum of 11.9 years. The rate of 10-year freedom from all-cause mortality was 84.2% in the DM and 74.3% in the nDM group (P = 0.45). The corresponding rates for major adverse cardiac event were 93.3 and 86.9% (P = 0.09). Multivariate Cox regression analysis revealed chronic renal failure, older age, cerebrovascular accident, low ejection fraction and urgency as significant predictors of late death. Diabetes was not associated with any long- or short-term outcome.

CONCLUSIONS

Total arterial off-pump CABG using skeletonization technique can provide similar clinical outcome for diabetic patients in the long as well as in the short term as that for non-diabetic patients.

Increased haemodynamic adrenergic load with isoflurane anaesthesia in type 2 diabetic and obese rats in vivo

Background

Increasing numbers of type 2 diabetic and obese patients with enhanced rates of cardiovascular complications require surgical interventions, however they have a higher incidence of perioperative haemodynamic complications, which has been linked to adrenergic dysfunction. Therefore, we aimed to determine how α- and β-adrenoceptor (AR)-mediated haemodynamic responses are affected by isoflurane anaesthesia in experimental type 2 diabetes and obesity in vivo.

Methods

Sixteen-week old male Zucker type 2 Diabetic Fatty (ZDF) rats, Zucker Obese rats and their lean counterparts (n = 7-9 per group) were instrumented with radio telemeters to record blood pressure and heart rate and with vascular access ports for non-invasive intravenous drug delivery in vivo. Haemodynamic effects of α-AR (phenylephrine; 1-100 μg.kg⁻¹) or β-AR (dobutamine; 2-120 μg.kg⁻¹) stimulation were assessed under conscious and anaesthetised (isoflurane; 2%) conditions.

Results

Vascular α-AR sensitivity was increased in both diabetic (non-diabetic 80 ± 3 vs. diabetic 95 ± 4 ΔmmHg at 100 μg.kg⁻¹; p < 0.05) and obese (lean 65 ± 6 vs. obese 84 ± 6 ΔmmHg at 20 μg.kg⁻¹; p < 0.05) conscious rats. Interestingly, anaesthesia exacerbated and prolonged the increased α-AR function in both diabetic and obese animals (non-diabetic 51 ± 1 vs. diabetic 68 ± 4 ΔmmHg, lean 61 ± 5 vs. obese 84 ± 2 ΔmmHg at 20 μg.kg⁻¹; p < 0.05). Meanwhile, β-AR chronotropic sensitivity was reduced in conscious diabetic and obese rats (non-diabetic 58 ± 7 vs. diabetic 27 ± 8 Δbpm, lean 103 ± 12 vs. obese 61 ± 9 Δbpm at 15 μg.kg⁻¹; p < 0.05). Anaesthesia normalised chronotropic β-AR responses, via either a limited reduction in obese (lean 51 ± 3 vs. obese 66 ± 5 Δbpm; NS at 15 μg.kg⁻¹) or increased responses in diabetic animals (non-diabetic 49 ± 8 vs. diabetic 63 ± 8 Δbpm, at 15 μg.kg⁻¹; NS at 15 μg.kg⁻¹).

Conclusions

Long term metabolic stress, such as during type 2 diabetes and obesity, alters α- and β-AR function, its dynamics and the interaction with isoflurane anaesthesia. During anaesthesia, enhanced α-AR sensitivity and normalised β-AR function may impair cardiovascular function in experimental type 2 diabetes and obesity.

A modified portfolio diet complements medical management to reduce cardiovascular risk factors in diabetic patients with coronary artery disease

BACKGROUND & AIMS

Secondary prevention can improve outcomes in high risk patients. This study investigated the magnitude of cardiovascular risk reduction associated with consumption of a modified portfolio diet in parallel with medical management.

DESIGN

30 patients with type II diabetes, 6 weeks post bypass surgery received dietary counseling on a Modified Portfolio Diet (MPD) (low fat, 8 g/1000 kcal viscous fibres, 17 g/1000 kcal soy protein and 22 g/1000 kcal almonds). Lipid profiles, endothelial function and markers of glycemic control, oxidative stress and inflammation were measured at baseline and following two and four weeks of intervention. Seven patients with no diet therapy served as time controls.

RESULTS

Consumption of the MPD resulted in a 19% relative reduction in LDL (1.9 ± 0.8 vs 1.6 ± 0.6 mmol/L, p < 0.001) with no change in HDL cholesterol. Homocysteine levels dropped significantly (10.1 ± 2.7 vs 7.9 ± 4 μmol/L, p = 0.006) over the study period. Flow mediated dilatation increased significantly in treated patients (3.8 ± 3.8% to 6.5 ± 3.6%, p = 0.004) while remaining constant in controls (p = 0.6). Endothelial progenitor cells numbers (CD34+, CD 133+ and UEA-1+) increased significantly following MPD consumption (p < 0.02) with no difference in migratory capacity. In contrast, time controls showed no significant changes.

CONCLUSION

Dietary intervention in medically managed, high risk patients resulted in important reductions in risk factors. Clinical Trials registry number NCT00462436.

Improving long term outcome for diabetic patients undergoing surgical revascularization by use of the radial artery conduit: a propensity matched study

Background

Diabetes predicts worse outcomes after coronary artery bypass grafting (CABG) We hypothesized that a strategy using radial artery (RA) conduit(s) would improve outcomes and long term survival for diabetic patients undergoing CABG with Left Internal Thoracic Artery (LITA) and RA grafts, with or without additional saphenous vein (SV) when compared with outcomes for patients bypassed with LITA and SV but no RA.

Methods

A propensity matched study of long term survival in diabetic patients who had isolated first time CABG from January 1995 to June 2010 at an urban academic medical center in New York City. Our primary endpoint was all cause mortality determined from the Social Security Death Index in December 2010.

Results

We compared our 15 year outcomes in diabetic patients after isolated, primary CABG: 642 patients received LITA + RA +/− SV (RA group) vs. 1201 patients who had LITA + SV only (SV group). Propensity scoring for multiple preoperative and operative variables matched 409 patients from each group: 68% were male with an average age of 61 years and ejection fraction averaged 47%. Average grafts per patient was 3.7 for both groups with 2.3 arterial grafts per patient for the RA group. Operative (30 day) mortality was 0.1% RA vs. 1.9% SV, (p<0.0001) For propensity matched patients, mortality was 0.25 RA vs 0.5% SV. (p<0.001) The incidence of major complications was similar in both groups. Kaplan Meier actuarial survival at 1, 5, 10 and 12 years was 98%, 89%, 77 and 70% for RA vs. 96%, 87%, 64% and 59% for SV (p<0.006.) By Cox multivariate analysis significant predictors of mortality were: age, stroke, peripheral vascular disease, COPD, creatinine > 2.5mg/dl and low ejection fraction but only RA use predicted better survival [HR 0.683, CI 0.507- 0.920, p=0.0122].

Conclusion

For diabetic patients having CABG with LITA, use of radial artery conduit adds a substantial and sustained survival advantage compared to LITA and vein. Optimal revascularization for diabetics with multi vessel disease is redefined.

Impact of hyperglycemia on perioperative mortality after coronary artery bypass graft surgery

OBJECTIVE

The roles of perioperative hyperglycemia and diabetes in the risk stratification of patients undergoing coronary artery bypass graft surgery are unclear. The aim of this study is to explore the influence of perioperative hyperglycemia on postoperative mortality.

METHOD

A prospective, observational study of 5050 patients undergoing cardiopulmonary bypass for coronary artery bypass graft surgery at 70 international centers was conducted, with 7500 measured variables per patient and outcomes adjudicated centrally. Postoperative blood glucose levels measured from the day of surgery to postoperative day 3 were available for 4799 patients. Multivariable logistic regression was used to determine the association of hyperglycemia with hospital mortality.

RESULTS

A total of 164 patients died during hospitalization (3.2%). Mortality was significantly higher in the diabetic population compared with the nondiabetic population (4.2% vs 2.9%; P = .02). In nondiabetic patients, maximum postoperative blood glucose between 250 and 300 mg/dL (adjusted odds ratio, 2.56; 95% confidence interval, 1.18-5.57; P = .02) and maximum blood glucose of 300 mg/dL or greater (adjusted odds ratio, 2.74; 95% confidence interval, 1.22-6.16; P = .01), compared with maximum blood glucose less than 200 mg/dL, and postoperative insulin treatment (adjusted odds ratio, 2.04; 95% confidence interval, 1.12-3.70), were independent risk factors for an increased risk of in-hospital mortality. In diabetic patients, hyperglycemia was not associated with a higher mortality risk.

CONCLUSIONS

Postoperative hyperglycemia is associated with increased in-hospital mortality in nondiabetic patients after coronary artery bypass graft surgery. In diabetic patients, hyperglycemia was not associated with mortality.