A BMI >35 does not protect patients undergoing cardiac bypass surgery from red blood cell transfusion.

The effect of obesity on allogeneic intraoperative blood product transfusion in patients undergoing coronary artery bypass graft surgery (CABG) is poorly understood. We analyzed the influence of obesity on the risk of intraoperative red blood cell (RBC) transfusion among 45,200 consecutive non-reoperative CABG procedures from a multi-institutional perfusion database. A body mass index (BMI) in obese I category was associated with a 9.9% decrease in transfusion risk (p<0.05). Compared to patients with a normal BMI, obese I and obese III patients do not have any change in the relative risk of RBC transfusion. Overweight and mild obesity have a protective role in reducing intraoperative blood transfusion during cardiopulmonary bypass (CPB) surgery. However, logistic regression analysis showed that much of the observed reduction in transfusion rates for obese patients can be accounted for by other known confounds. The lack of a linear effect of increasing BMI on blood transfusion risk is a novel finding and warrants further investigation.

Seasonal Incidence of Emergent Coronary Artery Bypass Grafting Surgery.

BACKGROUND: Emergent coronary artery bypass grafting (CABG) surgery is often required in the case of severe coronary artery disease, which is refractory to traditional management. The objective of our study was to test the hypothesis that there is seasonal variation in the incidence of emergent CABG. METHODS: A sinusoidal logistic regression model was used to analyze operative data at our cardiovascular institute of 270 cases spanning 5939 calendar days. RESULTS: A cyclic peak risk for emergent CABG was observed for late winter (calendar day 66; P = .036). The odds ratios for the 1-, 2- and 3-month window surrounding this peak were 1.8 (95% CI = 0.94-3.5, P = .072), 1.6 (95% CI = 1.06-2.5, P = .024) and 1.4 (95% CI = 0.9-1.8, P = .066), respectively. CONCLUSION: Our results suggest that a seasonal variation may exist in the incidence of patients presenting with severe coronary artery disease requiring emergent CABG. This information is useful in the scheduling of hospital resources and staff. It also provides important etiology clues underlying coronary artery disease that may lead to future interventions or targeted therapies.

Race and survival among diabetic patients after coronary artery bypass grafting.

BACKGROUND: Diabetes is a known predictor of decreased long-term survival after coronary artery bypass grafting (CABG). Differences in survival by race have not been examined. METHODS: A retrospective cohort study was conducted for CABG patients between 1992 and 2011. Long-term survival was compared in patients with and without diabetes and stratified by race. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. RESULTS: Out of the 13,053 patients undergoing CABG, 35% (black n = 1,655; white n = 2,884) had diabetes at the time of surgery. The median follow-up for study participants was 8.2 years. Long-term survival after CABG was similar between black and white diabetic patients (no diabetes, HR = 1.0; white diabetic patients, adjusted HR = 1.5, 95%CI = 1.4-1.6; black diabetic patients, adjusted HR = 1.5, 95%CI = 1.4-1.7). CONCLUSION: A survival disadvantage after CABG was not observed among black versus white diabetic patients in our study.

The effect of preoperative ß-blocker use and race on long-term survival after coronary artery bypass grafting.

OBJECTIVE: To date, racial differences in the long-term survival of coronary artery bypass grafting (CABG) patients who receive preoperative ß-blockers have not been specifically examined. The purpose of this study was to examine the effect of preoperative ß-blockers on long-term survival among black CABG patients and to compare the magnitude of this effect with white patients. DESIGN: A retrospective cohort study. SETTING: A tertiary referral heart hospital. PARTICIPANTS: 13,354 patients undergoing CABG between 1992 and 2011. MEASUREMENTS AND MAIN RESULTS: Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. A total of 1,448 (62%) black and 6,094 (55%) white patients had a history of preoperative ß-blocker use. Among black patients, those receiving ß-blockers survived longer than those not receiving ß-blockers (adjusted HR = 0.77, 95% CI = 0.67-0.88). The survival advantage was comparable to that observed among white patients (adjusted HR = 0.88, 95% CI = 0.82-0.93). CONCLUSION: Black CABG patients benefited from preoperative ß-blockers and the magnitude of the effect was comparable to that among white patients.

Operative status and survival after coronary artery bypass grafting.

BACKGROUND: The effect of race on long-term survival of patients undergoing elective and nonelective coronary artery bypass grafting (CABG) is currently unknown. The purpose of this study was to compare long-term survival between black and white CABG patients by operative status. METHODS: Long-term survival of black versus white patients undergoing elective and nonelective CABG procedures between 1992 and 2011 was compared. Survival probabilities were computed using the Kaplan-Meier product-limit method and stratified by race. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. RESULTS: A total of 13,774 patients were included in this study. The median follow-up time for study participants was 8.2 years. Black patients undergoing elective CABG died sooner than whites (adjusted HR = 1.4, 95% CI = 1.2-1.5). Survival was similar between blacks and whites in the nonelective population (adjusted HR = 1.0, 95% CI = 0.96-1.1). CONCLUSIONS: Black race was a statistically significant predictor of long-term survival after elective but not nonelective CABG.

Impact of race and postoperative atrial fibrillation on long-term survival after coronary artery bypass grafting.

BACKGROUND AND AIM: Postoperative atrial fibrillation (POAF) is a known predictor of in-hospital morbidity and short-term survival after coronary artery bypass grafting (CABG). The impact of race and long-term survival has not been examined in this population. We aimed to examine the influence of these factors on long-term survival in patients undergoing CABG. METHODS: Patients undergoing first-time, isolated CABG between 1992 and 2011 were included in this study. Long-term survival was compared in patients with and without POAF and stratified by race. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. RESULTS: A total of 2,907 (22%) patients developed POAF (black n=370; white n=2,537) following CABG (N=13,165). Median follow-up for study participants was 8.2 years. Long-term survival after CABG differed by POAF status and race (no POAF: HR=1.0; white POAF: adjusted HR=1.1, 95% CI=1.06-1.2; black POAF: adjusted HR=1.4, 95% CI=1.2-1.6; pTrend=0.0002). lack POAF patients also died sooner after surgery than their white counterparts (adjusted HR=1.2, 95% CI=1.02-1.4). CONCLUSION: Black race was a statistically significant predictor of decreased survival among POAF patients after CABG. This finding provides useful outcome information for surgeons and their patients.

The impact of prior percutaneous coronary intervention on long-term survival after coronary artery bypass grafting.

BACKGROUND: Previous studies examining the influence of prior percutaneous coronary intervention (PCI) on long-term survival after coronary artery bypass grafting (CABG) have reported conflicting results. The purpose of this study was to further examine the influence of prior PCI on long-term survival after CABG at a large tertiary referral heart institute. METHODS: Long-term survival between 1992 and 2011 was compared in non-emergent CABG cases with and without prior PCI. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. RESULTS: A total of 2532 (19%) patients had prior PCI before CABG (n=13,354). The median follow-up for study participants was 8.1 years. The median survival for patients with and without prior PCI was 15 years and 14 years, respectively (p<0.0001). Long-term survival was similar between patients with and without prior PCI after adjusting for age, sex, race, hypertension, coronary artery disease severity, congestive heart failure, and prior stroke (adjusted HR=0.99, 95%CI=0.91-1.06). CONCLUSION: Findings from outcomes research are important in the planning of appropriate postoperative patient care. Our study provides additional evidence that prior PCI is not a significant predictor of long-term survival after CABG.

Delayed left ventricle-to-right atrial fistula following aortic valve replacement.

Fistula development between the left ventricular outflow tract and right atrium is a rare complication of aortic valve replacement (AVR), typically seen with calcific aortic stenosis or endocarditis. The case is reported of a left ventricle-to-right atrial fistula following mechanical AVR for aortic insufficiency.

An acute animal model of aortic stenosis: initial attempts at leaflet modification.

BACKGROUND AND AIM OF THE STUDY: Percutaneous valve insertion is an emerging treatment for aortic stenosis (AS). To date, no large animal model exists that replicates human calcific AS; moreover, the absence of any valve pathology in currently available animal models prevents their use in any realistic assessment of percutaneous aortic valve therapy. Hence, the aim of the present study was to create an acute large animal model in which human calcific AS could be simulated. METHODS: Ten domestic swine underwent open-heart surgery utilizing cardiopulmonary bypass (CPB) and cardioplegic arrest. The aortic valve annulus and leaflets were injected with cyanoacrylate, after which epicardial echocardiography was used to assess the creation of AS. At the time of animal sacrifice, the hearts were harvested for gross and histopathological examination. RESULTS: The leaflet and annular injections were performed successfully in all animals. Subsequently, seven animals were weaned from CPB and underwent post procedural echocardiographic evaluations, whereby the treated valves were harvested for gross and histological examination. CONCLUSION: Cyanoacrylate can be injected into the porcine aortic valve and annulus to create a model that resembles human calcific AS in the acute setting. Additional long-term follow up studies must be conducted, however, before this model can be utilized in the development of percutaneous valve therapy.

Three-dimensional echocardiographic features of unicuspid aortic valve stenosis correlate with surgical findings.

A unicuspid aortic valve (UAV) is a rare congenital defect that may manifest clinically as severe aortic stenosis or regurgitation in the third to fifth decade of life. This report describes two cases of UAV stenosis in adult patients diagnosed by transesophageal echocardiography (TEE). The utility of three-dimensional TEE in confirming valve morphology and its relevance to transcatheter valve replacement are discussed.

Increased propensity for cell death in diabetic human heart is mediated by mitochondrial-dependent pathways.

Progressive energy deficiency and loss of cardiomyocyte numbers are two prominent factors that lead to heart failure in experimental models. Signals that mediate cardiomyocyte cell death have been suggested to come from both extrinsic (e.g., cytokines) and intrinsic (e.g., mitochondria) sources, but the evidence supporting these mechanisms remains unclear, and virtually nonexistent in humans. In this study, we investigated the sensitivity of the mitochondrial permeability transition pore (mPTP) to calcium (Ca(2+)) using permeabilized myofibers of right atrium obtained from diabetic (n = 9) and nondiabetic (n = 12) patients with coronary artery disease undergoing nonemergent coronary revascularization surgery. Under conditions that mimic the energetic state of the heart in vivo (pyruvate, glutamate, malate, and 100 µM ADP), cardiac mitochondria from diabetic patients show an increased sensitivity to Ca(2+)-induced mPTP opening compared with nondiabetic patients. This increased mPTP Ca(2+) sensitivity in diabetic heart mitochondria is accompanied by a substantially greater rate of mitochondrial H(2)O(2) emission under identical conditions, despite no differences in respiratory capacity under these conditions or mitochondrial enzyme content. Activity of the intrinsic apoptosis pathway mediator caspase-9 was greater in diabetic atrial tissue, whereas activity of the extrinsic pathway mediator caspase-8 was unchanged between groups. Furthermore, caspase-3 activity was not significantly increased in diabetic atrial tissue. These data collectively suggest that the myocardium in diabetic patients has a greater overall propensity for mitochondrial-dependent cell death, possibly as a result of metabolic stress-imposed changes that have occurred within the mitochondria, rendering them more susceptible to insults such as Ca(2+) overload. In addition, they lend further support to the notion that mitochondria represent a viable target for future therapies directed at ameliorating heart failure and other comorbidities that come with diabetes.

Factors Associated with Discharge to a Skilled Nursing Facility after Transcatheter Aortic Valve Replacement Surgery.

An assumption regarding transcatheter aortic valve replacement (TAVR), a minimally invasive procedure for treating aortic stenosis, is that patients remain at, or near baseline and soon return to their presurgical home to resume activities of daily living. However, this does not consistently occur. The purpose of this study was to identify preoperative factors that optimally predict discharge to a skilled nursing facility (SNF) after TAVR. Delineation of these conditions is an important step in developing a risk stratification model to assist in making informed decisions. Data was extracted from the American College of Cardiology (ACC) transcatheter valve therapy (TVT) registry and the Society of Thoracic Surgeons (STS) database on 285 patients discharged from 2012⁻2017 at a tertiary referral heart institute located in the southeastern region of the United States. An analysis of assessment, clinical and demographic variables was used to estimate relative risk (RR) of discharge to a SNF. The majority of participants were female (55%) and white (84%), with a median age of 82 years (interquartile range = 9). Approximately 27% (n = 77) were discharged to a SNF. Age > 75 years (RR = 2.3, p = 0.0026), female (RR = 1.6, p = 0.019), 5-meter walk test (5MWT) >7 s (RR = 2.0, p = 0.0002) and not using home oxygen (RR = 2.9, p = 0.0084) were identified as independent predictive factors for discharge to a SNF. We report a parsimonious risk-stratification model that estimates the probability of being discharged to a SNF following TAVR. Our findings will facilitate making informed treatment decisions regarding this older patient population.

Increased risk of atrial fibrillation among patients undergoing coronary artery bypass graft surgery while receiving nitrates and antiplatelet agents.

Background Postoperative atrial fibrillation (POAF) is a frequent complication of coronary artery bypass graft (CABG) surgery. This arrhythmia occurs more frequently among patients who receive perioperative inotropic therapy (PINOT). Administration of nitrates with antiplatelet agents reduces the conversion rate of cyclic guanosine monophosphate to guanosine monophosphate. This process is associated with increased concentrations of free radicals, catecholamines, and blood plasma volume. We hypothesized that patients undergoing CABG surgery who receive PINOT may be more susceptible to POAF when nitrates are administered with antiplatelet agents. Methods Clinical records were examined from a prospectively maintained cohort of 4,124 patients undergoing primary isolated CABG surgery to identify POAF-associated factors. Results POAF risk was increased among patients receiving PINOT, and the greatest effect was observed when nitrates were administered with antiplatelet therapy. Adjustment for comorbidities did not substantively change the study results. Conclusions Administration of nitrates with certain antiplatelet agents was associated with an increased POAF risk among patients undergoing CABG surgery. Additional studies are needed to determine whether preventive strategies such as administration of antioxidants will reduce this risk.

Recent trends in minimally invasive cardiac surgery.

Evolving technologies have resulted in an increase in minimally invasive cardiac surgery. Currently, robotic systems allow surgeons to perform a variety of procedures through small incisions. This changing paradigm is reviewed.

Quantum dot labeling of mesenchymal stem cells.

BACKGROUND: Mesenchymal stem cells (MSCs) are multipotent cells with the potential to differentiate into bone, cartilage, fat and muscle cells and are being investigated for their utility in cell-based transplantation therapy. Yet, adequate methods to track transplanted MSCs in vivo are limited, precluding functional studies. Quantum Dots (QDs) offer an alternative to organic dyes and fluorescent proteins to label and track cells in vitro and in vivo. These nanoparticles are resistant to chemical and metabolic degradation, demonstrating long term photostability. Here, we investigate the cytotoxic effects of in vitro QD labeling on MSC proliferation and differentiation and use as a cell label in a cardiomyocyte co-culture. RESULTS: A dose-response to QDs in rat bone marrow MSCs was assessed in Control (no-QDs), Low concentration (LC, 5 nmol/L) and High concentration (HC, 20 nmol/L) groups. QD yield and retention, MSC survival, proinflammatory cytokines, proliferation and DNA damage were evaluated in MSCs, 24 -120 hrs post QD labeling. In addition, functional integration of QD labeled MSCs in an in vitro cardiomyocyte co-culture was assessed. A dose-dependent effect was measured with increased yield in HC vs. LC labeled MSCs (93 +/- 3% vs. 50% +/- 15%, p < 0.05), with a larger number of QD aggregates per cell in HC vs. LC MSCs at each time point (p < 0.05). At 24 hrs >90% of QD labeled cells were viable in all groups, however, at 120 hrs increased apoptosis was measured in HC vs. Control MSCs (7.2% +/- 2.7% vs. 0.5% +/- 0.4%, p < 0.05). MCP-1 and IL-6 levels doubled in HC MSCs when measured 24 hrs after QD labeling. No change in MSC proliferation or DNA damage was observed in QD labeled MSCs at 24, 72 and 120 hrs post labeling. Finally, in a cardiomyocyte co-culture QD labeled MSCs were easy to locate and formed functional cell-to-cell couplings, assessed by dye diffusion. CONCLUSION: Fluorescent QDs label MSC effectively in an in vitro co-culture model. QDs are easy to use, show a high yield and survival rate with minimal cytotoxic effects. Dose-dependent effects suggest limiting MSC QD exposure.

Plasma Catecholamine Levels on the Morning of Surgery Predict Post-Operative Atrial Fibrillation.

OBJECTIVES: This study sought to determine whether plasma catecholamines and monoamine oxidase-B (MOA-B) are associated with post-operative atrial fibrillation (POAF) in patients undergoing elective cardiac surgery. BACKGROUND: Although intra- and post-operative adrenergic tone has been demonstrated to be an causative factor for POAF, the role and association of pre-operative plasma catecholamines remains unclear. METHODS: Prior to administration of anesthesia on the morning of surgery, blood samples were obtained from 324 patients undergoing nonemergent coronary artery bypass graft and/or aortic valve surgery with cardiopulmonary bypass at East Carolina Heart Institute. The concentrations of norepinephrine (NE), dopamine (DA), epinephrine (EPI), and enzyme MAO-B were assessed in platelet-rich plasma. A log-binomial regression model was used to determine the association between quartiles of these variables and POAF. RESULTS: Levels of NE (p = 0.0006) and EPI (p = 0.047) in the 4th quartile [Formula: see text] were positively associated with POAF, whereas DA (p = 0.0034) levels in the 4th quartile [Formula: see text] were inversely associated with POAF. Adjusting for age, heart failure (HF), and history of atrial fibrillation, the composite pre-operative (adrenergic) plasma marker [Formula: see text] was associated with a 4-fold increased occurrence of POAF (adjusted p = 0.0001). No association between plasma MAO-B and POAF was observed. CONCLUSIONS: Our results suggest that pre-operative adrenergic tone is an important factor underlying POAF. This information provides evidence that assessment of plasma catecholamines may be a low-cost method that is easy to implement for predicting which patients are likely to develop POAF. More investigation in a multicentric setting is needed to validate our results.

Perioperative Inotrope Therapy and Atrial Fibrillation Following Coronary Artery Bypass Graft Surgery: Evidence of a Racial Disparity.

BACKGROUND AND OBJECTIVE: Following coronary artery bypass graft (CABG) surgery, mortality rates are significantly higher among black patients who experience postoperative atrial fibrillation (POAF). Perioperative inotropic therapy (PINOT) was associated with POAF in previous reports, but the extent to which race influences this association is unknown. In the present study, the relationship between PINOT, race, and POAF was examined in patients undergoing CABG surgery. METHODS AND SETTING: Clinical records were examined from a prospectively maintained cohort of 11,855 patients (median age 64 yrs; 70% male; 16% black) undergoing primary isolated CABG at a large cardiovascular institute in the southeastern region of the United States. Relative risk (RR) and 95% confidence intervals (CIs) were computed using log-binomial regression. MAIN RESULTS: The association between PINOT and POAF was significantly increased among black patients (adjusted RR 1.7, CI 1.4-2.0) compared with white patients (adjusted RR 1.3, CI 1.2-1.4) (pinteraction  = 0.013). CONCLUSIONS: These findings suggest that PINOT may be disproportionately associated with POAF among black patients undergoing CABG surgery. Additional studies are needed to examine further the potential underlying mechanisms of this association.

Robotic cardiovascular surgery.

Cardiovascular surgery has traditionally been performed through a median sternotomy, allowing the surgeon generous access to the heart and surrounding great vessels. Recently, less invasive methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart, thus resulting in a paradigm shift in cardiac surgery. Originally, long instruments without pivot points were used, however; with the application of robotic telemanipulation systems that allow for improved dexterity, the surgeon is able to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, this article reviews the recent history and clinical results of robotics in cardiovascular surgery.

Long-Term Survival after Cardiac Surgery in Patients with Chronic Obstructive Pulmonary Disease.

BACKGROUND: Although many patients with chronic obstructive pulmonary disease (COPD) require a prolonged length of stay (PLOS) following coronary artery bypass grafting (CABG), the impact of PLOS on long-term survival has not been examined in this population. OBJECTIVES: To determine the association between PLOS and long-term survival among COPD and non-COPD patients after CABG and to examine consequent policy and practice-based implications. METHODS: A retrospective cohort study of CABG patients was conducted between 2002 and 2011. Long-term survival was compared in patients with and without COPD and stratified by PLOS. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. RESULTS: A total of 203 patients (4.2%) had PLOS after nonemergent CABG (N = 4801). PLOS was an important independent predictor of decreased long-term survival (no COPD, no PLOS: HR = 1.0; COPD, no PLOS: adjusted HR [95% CI], 1.8 [1.5-2.1]; no COPD, PLOS: 3.3 [2.5-4.4]; COPD, PLOS: 6.0 [4.4-8.2]; PTrend < .001). CONCLUSIONS: COPD and PLOS are 2 of many factors that affect long-term mortality in postoperative CABG patients. Aggressive treatment strategies aimed at early weaning off of mechanical ventilation and prevention of reintubation among COPD patients must be considered carefully as a means to reduce length of stay after CABG. Our results also have important implications for the long-term management of these patients and strategies for containing costs over the life course of the patient.

Comparison of Risk of Atrial Fibrillation in Black Versus White Patients After Coronary Artery Bypass Grafting.

Obesity has been identified as a risk factor for postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG). However, no studies have addressed the influence of race on this association. A total of 13,594 patients undergoing first-time, isolated CABG without preoperative AF between 1992 and 2011 were included in our study. The association between body mass index and POAF was compared by race. Relative risk and 95% CIs were computed using maximum likelihood log-binomial regression. Increasing levels of body mass index were associated with higher POAF risk after CABG in black but not white patients (pinteraction = 0.0009).