Cardiac procedures in patients with a body mass index exceeding 45: outcomes and long-term results

Association Between Body Mass Index, Obesity, and Clinical Outcomes Following Coronary Artery Bypass Grafting in Brazil: An Analysis of One Year of Follow-up of BYPASS Registry Patients

OBJECTIVE

To investigate the association between body mass index (BMI), obesity, clinical outcomes, and mortality following coronary artery bypass grafting (CABG) in Brazil using a large sample with one year of follow-up from the Brazilian Registry of Cardiovascular Surgeries in Adults (or BYPASS) Registry database.

METHODS

A multicenter cohort-study enrolled 2,589 patients submitted to isolated CABG and divided them into normal weight (BMI 20.0-24.9 kg/m2), overweight (BMI 25.0-29.9 kg/m2), and obesity (BMI > 30.0 kg/m2) groups. Inpatient postoperative outcomes included the most frequently described complications and events. Collected post-discharge outcomes included rehospitalization and mortality rates within 30 days, six months, and one year of follow-up.

RESULTS

Sternal wound infections (SWI) rate was higher in obese compared to normal-weight patients (relative risk [RR]=5.89, 95% confidence interval [CI]=2.37-17.82; P=0.001). Rehospitalization rates in six months after discharge were higher in obesity and overweight groups than in normal weight group (χ=6.03, P=0.049); obese patients presented a 2.2-fold increase in the risk for rehospitalization within six months compared to normal-weight patients (RR=2.16, 95% CI=1.17-4.09; P=0.045). Postoperative complications and mortality rates did not differ among groups during time periods.

CONCLUSION

Obesity increased the risk for SWI, leading to higher rehospitalization rates and need for surgical interventions within six months following CABG. Age, female sex, and diabetes were associated with a higher risk of mortality. The obesity paradox remains controversial since BMI may not be sufficient to assess postoperative risk in light of more complex and dynamic evaluations of body composition and physical fitness.

Pedicle flap reconstruction for treatment of infected median sternotomy wounds after cardiac surgery in overweight and obese patients: proposal of a management algorithm based on a case series analysis

Background

A relationship between obesity and adverse outcomes in patients with post-sternotomy wounds undergoing pedicle flap reconstruction is not well-documented. In this study, we present a single-centre retrospective case series analysis of early postoperative outcomes of patients with infected post-sternotomy wounds undergoing pedicle flap reconstruction. We also propose a management algorithm for such patients, based on BMI and wound width.

Methods

We retrospectively analyzed all patients, who underwent pedicle flap reconstruction for major sternal wound infections after sternotomy for cardiac surgery in a tertiary hospital in Germany during a 5-year period. Exclusion criteria included patients younger than 18 years of age and patients with BMI < 18.5 kg/m². Patients were divided into 2 groups according to BMI: normal-weight (NW; BMI < 25 kg/m²) and overweight/obese (OB/OW; BMI > 25 kg/m²). Both groups were compared in terms of preoperative parameters and early postoperative outcomes. Preoperative parameters included demographics, wound bacteria and comorbidities. Postoperative outcomes included duration of surgery time (from incision to skin closure), transfusion requirement (during surgery and entire hospital stay), onset of flap and donor-site complications, length of stay and 30-day mortality. We employed the two-tailed t-test to compare continuous variables and the two-sided Fischer’s exact test to compare categorical variables. Statistical significance was set at p < 0.05.

Results

The total sample consisted of 48 patients. Overall mean BMI was 28.4 (6.1) kg/m². Mean age was 67 (12) years. The study group consisted of 28 patients with BMI > 25 kg/m², who were compared with 20 normal-weight patients. There was a significant difference amongst both groups regarding duration of surgery (120 vs. 174 min, p < 0.05). Donor-site complications requiring intervention were observed in 30% of patients in both groups. Flap-related complications were recorded in 16 (57%) cases in the study group and 7 cases in the control group (35%, p = 0.15).

Conclusions

We conclude that wound width and BMI can aid the decision-making process for patients with infected sternal wounds after cardiac surgery requiring pedicle flap reconstruction. However, in our case series analysis, OB/OW patients were not found to be at statistically significantly increased risk for worse postoperative outcomes, but were associated with a longer duration of surgery.

Complications and 30-Day Mortality Rate After Hip Fracture Surgery in Superobese Patients

OBJECTIVE

Paradoxically, overweight and obesity are associated with lower odds of complications and death after hip fracture surgery. Our objective was to determine whether this "obesity paradox" extends to patients with "superobesity." In this study, we compared rates of complications and death among superobese patients with those of patients in other body mass index (BMI) categories.

METHODS

Using the National Surgical Quality Improvement Program database, we identified >100,000 hip fracture surgeries performed from 2012 to 2018. Patients were categorized as underweight (BMI <18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9), obese (BMI 30-39.9), morbidly obese (BMI 40-49.9), or superobese (BMI ≥50). We analyzed patient characteristics, surgical characteristics, and 30-day outcomes. Using multivariate regression with normal-weight patients as the referent, we determined odds of major complications, minor complications, and death within 30 days by BMI category.

RESULTS

Of 440 superobese patients, 20% had major complications, 33% had minor complications, and 5.2% died within 30 days after surgery. When comparing patients in other BMI categories with normal-weight patients, superobese patients had the highest odds of major complications [odds ratio (OR): 1.6, 95% confidence interval (CI), 1.2-2.0] but did not have significantly different odds of death (OR: 0.91, 95% CI, 0.59-1.4) or minor complications (OR: 1.2, 95% CI, 0.94-1.4).

CONCLUSION

Superobese patients had significantly higher odds of major complications within 30 days after hip fracture surgery compared with all other patients. This "obesity paradox" did not apply to superobese patients.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a Complete Description of Levels of Evidence.

Impact of Obesity on Postoperative Outcomes following cardiac Surgery (The OPOS study): rationale and design of an investigator-initiated prospective study

INTRODUCTION

Increasing levels of obesity worldwide have led to a rise in the prevalence of obesity-related complications including cardiovascular risk factors such as diabetes, hypertension and dyslipidaemia. Healthcare providers believe that overweight and obese cardiac surgery patients are more likely to experience adverse postoperative outcomes. The body mass index (BMI) is the primary measure of obesity in clinical practice, without accounting for a patient's level of cardiopulmonary fitness or muscle mass. The objective of this study is to determine whether fitness capacity of obese cardiac surgical patients and biomarkers, alone or in combination, will help identify patients at risk for adverse outcomes when undergoing cardiac surgery.

METHODS AND ANALYSIS

Patients between the ages of 18 and 75 years undergoing elective cardiac surgery are consented to participate in this prospective observational study. Patients will be invited to participate in measures of obesity, functional capacity and exercise capacity assessments, quality of life questionnaires, and blood and tissue sampling for biomarker analysis. The endpoints evaluated are measures other than BMI that could be predictive of short-term and long-term postoperative outcomes. Clinical outcomes of interest are prolonged ventilation, hospital length of stay, renal failure and all-cause mortality. Biomarkers of interest will largely focus on metabolism (lipids, amino acids) and inflammation (adipokines, cytokines and chemokines).

ETHICS AND DISSEMINATION

This study has been approved by the institutional review board at the Horizon Health Network. On completion of the study, the results shall be disseminated through conference presentations and publications in peer-reviewed journals. Additionally, the report shall also be diffused more broadly to the general public and the cardiovascular community.

TRIAL REGISTRATION NUMBER

NCT03248921.

No more broken hearts: weight loss after bariatric surgery returns patients' postoperative risk to baseline following coronary surgery

BACKGROUND

The obesity epidemic is associated with a rise in coronary surgeries because obesity is a risk factor for coronary artery disease. Bariatric surgery is linked to improvement in cardiovascular co-morbidities and left ventricular function. No studies have investigated survival advantage in postoperative bariatric patients after coronary surgery.

OBJECTIVES

To determine if there is a benefit after coronary surgery in patients who have previously undergone bariatric surgery.

SETTING

National Inpatient Sample.

METHODS

We performed a retrospective, cross-sectional analysis of the National Inpatient Sample database from 2003 to 2010. We selected bariatric surgical patients who later underwent coronary surgery (n = 257). A comparison of postoperative complications and mortality after coronary surgery were compared with controls (n = 1442) using χ² tests, linear regression analysis, and multivariate logistical regression models.

RESULTS

A subset population was identified as having undergone coronary surgery (n = 1699); of this population, 257 patients had previously undergone bariatric surgery. They were compared with 1442 controls. The majority was male (67.2%), white (82.6%), and treated in an urban environment (96.8%). Patients with bariatric surgery assumed the risk of postoperative complications after coronary surgery that was associated with their new body mass index (BMI) (BMI<25 kg/m²: odds ratio (OR) 1.01, 95% CI .76-1.34, P = .94; BMI 25 to<35 kg/m²: OR .20, 95% CI .02-².16, P = .19; BMI≥35 kg/m²: OR>999.9, 95% CI .18 to>999.9, P = .07). Length of stay was significantly longer in postbariatric patients (BMI<25, OR 1.62, 95% CI 1.14-2.30, P = .007).

CONCLUSIONS

Postoperative bariatric patients have a return to baseline risk of morbidity and mortality after coronary surgery.

Body Mass Index, Outcomes, and Mortality Following Cardiac Surgery in Ontario, Canada

BACKGROUND

The "obesity paradox" reflects an observed relationship between obesity and decreased morbidity and mortality, suggesting improved health outcomes for obese individuals. Studies examining the relationship between high body mass index (BMI) and adverse outcomes after cardiac surgery have reported conflicting results.

METHODS AND RESULTS

The study population (N=78 762) was comprised of adult patients who had undergone first-time coronary artery bypass (CABG) or combined CABG/aortic valve replacement (AVR) surgery from April 1, 1998 to October 31, 2011 in Ontario (data from the Institute for Clinical Evaluative Sciences). Perioperative outcomes and 5-year mortality among pre-defined BMI (kg/m(2)) categories (underweight <20, normal weight 20 to 24.9, overweight 25 to 29.9, obese 30 to 34.9, morbidly obese >34.9) were compared using Bivariate analyses and Cox multivariate regression analysis to investigate multiple confounders on the relationship between BMI and adverse outcomes. A reverse J-shaped curve was found between BMI and mortality with their respective hazard ratios. Independent of confounding variables, 30-day, 1-year, and 5-year survival rates were highest for the obese group of patients (99.1% [95% Confidence Interval {CI}, 98.9 to 99.2], 97.6% [95% CI, 97.3 to 97.8], and 90.0% [95% CI, 89.5 to 90.5], respectively), and perioperative complications lowest. Underweight and morbidly obese patients had higher mortality and incidence of adverse outcomes.

CONCLUSIONS

Overweight and obese patients had lower mortality and adverse perioperative outcomes after cardiac surgery compared with normal weight, underweight, and morbidly obese patients. The "obesity paradox" was confirmed for overweight and moderately obese patients. This may impact health resource planning, shifting the focus to morbidly obese and underweight patients prior to, during, and after cardiac surgery.

Body Mass Index or Serum Albumin Levels: Which is further Prognostic following Cardiac Surgery?

Introduction: Patients with low serum albumin and abnormal BMI may be at the risk of death and other complications after surgery. This could be remarkable in patients with coronary arteries bypass graft surgery. Therefore, we decided to evaluate the impact of these factors associated with survival and outcome after cardiac surgery.

Methods: A cross-sectional study was performed from 2009 until 2012 on 345 patients who underwent coronary artery bypass grafts. Also Patients were monitored for a year. Patients’ information was collected and then the patients were analyzed for body mass index (BMI) and serum albumin and their effects on postoperative outcomes. P value <0.05 was considered statistically significant.

Results: Mortality after CABG operation was not of a significant relation in patients with low BMI (BMI <20), normal and high (BMI> 30). Obese patients are more susceptible to myocardial infarction in postoperative period (P=0.02). Pneumonia after surgery in these patients was more common than others (P= 0.023); however, low serum albumin was significantly associated with mortality following operation (P<0.001). Reoperation due to bleeding (P<0.001) and required mechanical ventilation for more than a day (P=0.019) were significantly associated with low serum albumin.

Conclusion: In conclusion, the high or low BMI alone did not increase mortality after cardiac surgery. However, postoperative morbidity in obese patients may be greater than others. Low serum albumin may increase the risk of mortality and postoperative complications as well. Therefore, it seems ameliorating serum albumin can be effective more than body mass index in improving the outcome of patients after CABG surgery.

Predicting 30-day mortality of aortic valve replacement by the AVR score

OBJECTIVES

The objective of this study is to develop a simple risk score to predict 30-day mortality of aortic valve replacement (AVR).

METHODS

In a development set of 673 consecutive patients who underwent AVR between 1990 and 1993, four independent predictors for 30-day mortality were identified: body mass index (BMI) ≥30, BMI <20, previous coronary artery bypass grafting (CABG) and recent myocardial infarction. Based on these predictors, a 30-day mortality risk score-the AVR score-was developed. The AVR score was validated on a validation set of 673 consecutive patients who underwent AVR almost two decennia later in the same hospital.

RESULTS

Thirty-day mortality in the development set was ≤2% in the absence of any predictor (class I, low risk), 2-5% in the solitary presence of BMI ≥30 (class II, mild risk), 5-15% in the solitary presence of previous CABG or recent myocardial infarction (class III, moderate risk), and >15% in the solitary presence of BMI <20, or any combination of BMI ≥30, previous CABG or recent myocardial infarction (class IV, high risk). The AVR score correctly predicted 30-day mortality in the validation set: observed 30-day mortality in the validation set was 2.3% in 487 class I patients, 4.4% in 137 class II patients, 13.3% in 30 class III patients and 15.8% in 19 class IV patients.

CONCLUSIONS

The AVR score is a simple risk score validated to predict 30-day mortality of AVR.

Albumin is a better predictor of outcomes than body mass index following coronary artery bypass grafting

OBJECTIVE

Body mass index (BMI) influences risk in coronary artery bypass grafting (CABG) patients, but albumin level is not collected by the Society of Thoracic Surgeons database. We postulate that preoperative albumin is a better predictor of mortality than BMI following CABG.

METHODS

BMI from patients with serum albumin level within 6 months of isolated CABG during 1995-2010 from our institutional databases were identified. Patients were stratified by National Heart, Lung, and Blood Institute (NHLBI) BMI class, and by preoperative albumin. Regression models were used to assess predictors of morbidity and mortality.

RESULTS

We analyzed 2,794 isolated CABG patients at our institution. Unadjusted mortality was highest with lowest BMI (P ≤ .05), and in patients with 2-3 g/dL albumin (P = .02). Ejection fraction (EF) and intra-aortic balloon pump (IABP) use were similar despite BMI; however, EF was lowest and IABP use highest in the 2-3 g/dL albumin group (P < .001, respectively). Unlike BMI groups, increasing albumin was associated with lower major complication rates (P = .001). Similarly, adjusted mortality was not influenced by BMI (AOR 0.97, 95% CI 0.93-1.02), but increasing albumin levels reduced the adjusted odds of death (AOR 0.61, 95% CI 0.42-0.90).

CONCLUSION

Albumin, more than body mass index, is associated with mortality and morbidity in isolated CABG recipients and may be a better indicator for outcomes.

Isolated coronary artery bypass grafting in obese individuals: a propensity matched analysis of outcomes

BACKGROUND

There is conflicting data regarding the impact of obesity on morbidity and mortality in patients undergoing isolated coronary artery bypass grafting (CABG).

METHODS AND RESULTS

Retrospective cohort analysis of patients who underwent CABG from January 1, 1995, through July 31, 2010 was performed. Patients were classified as obese or non-obese (body mass index ≥ 30.0 kg/m(2) and <30.0 kg/m(2), respectively). The primary outcome was in-hospital mortality. Secondary outcomes included postoperative respiratory failure, postoperative stroke, postoperative myocardial infarction, sternal and leg wound infections, postoperative atrial fibrillation, postoperative ventricular tachycardia, postoperative renal failure and length of hospital stay. Propensity-matched stepwise multivariable logistic regression was performed. Of 13,115 patients, 4,619 (35.2%) were obese. In the propensity-matched logistic regression models (n = 8,442), obesity was not associated with postoperative mortality (odds ratio = 1.13, 95% confidence interval 0.86-1.48). However, obesity was associated with postoperative respiratory failure, postoperative renal insufficiency, sternal wound infection, and leg wound infection. Obesity was also associated with a decreased risk of postoperative bleeding and re-operation from bleeding.

CONCLUSIONS

Obesity was associated with an increased risk of postoperative respiratory failure, postoperative renal failure, and surgical site infections. However, obesity was not associated with in-hospital mortality in patients undergoing CABG.

Novel aspects of pharmacological therapies for acute renal failure

Acute renal failure (ARF) comprises several syndromes that are associated with a sudden decrease in renal function. ARF is common among critically ill patients, is typically multifactorial and is of great prognostic significance. Indeed, even moderate changes in renal function significantly add to the morbidity and worsen mortality associated with ARF. Recent definitions, namely the renal Risk, Injury, Failure, Loss of renal function and End-stage kidney disease (RIFLE) classification or Acute Kidney Injury Network (AKIN) criteria, which incorporate the levels of oliguria in addition to fractional serum creatinine elevation, are important because the magnitude of kidney injury according to those definitions correlates very well with both short- and long-term patient survival. However, preventive strategies are most effective when started before oliguria or elevated serum creatinine is detectable, as those criteria already reflect established renal tubular cell injury. New biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) or kidney injury molecule-1 (KIM-1) that increase prior to the serum creatinine elevation are promising and have been proven to be useful in this regard in a few clinical trials. In addition, genetic profiling may define patients at risk earlier and help to individualize preventive strategies. Well established strategies include limiting dehydration and hypotension by the use of intravenous isotonic fluids at an optimal and individualized rate, as well as avoiding exposure to nephrotoxins, which include aminoglycosides, amphotericin or non-ionic contrast. Generally accepted and evidence-based pharmacological preventive or therapeutic options have not yet been established, although many drugs (e.g. renal vasodilators, diuretics and HMG-CoA reductase inhibitors [statins]) have been tested. New promising agents interfere with the apoptotic signalling that can occur in the setting of toxin exposure or ischaemia-reperfusion injury, limit inflammatory responses or modulate endothelial cell activation. In the future, these new approaches will enable us to extend our therapeutic repertoire.

Challenges of treating a 466-kilogram man with acute kidney injury

Caring for super obese patients (body mass index > 50 kg/m(2)) presents a number of complex and unique clinical challenges, particularly when acute kidney injury is present. We describe our experience treating the heaviest individual with acute kidney injury requiring renal replacement therapy reported to date. A 24-year-old black man was admitted to our hospital with fever, vomiting, progressive weakness, shortness of breath, and hemoptysis. Admission weight was 1,024 lbs (466 kg), height was 6 ft 4 in (1.9 m), and body mass index was 125 kg/m(2). During hospitalization, the patient experienced oligoanuric acute kidney injury and required initiation of continuous and subsequently intermittent renal replacement therapy. This clinical scenario identifies the many challenges involved in caring for super obese patients with acute kidney injury and may be a harbinger of what awaits the nephrology community in the obesity pandemic era.