Effect of Body Mass Index on Early Morbidity and Mortality After Isolated Coronary Artery Bypass Graft Surgery

Comparative effects of minimally invasive approaches vs. conventional for obese patients undergoing aortic valve replacement: a systematic review and network meta-analysis

BACKGROUND

Minimally invasive approaches like mini-thoracotomy and mini-sternotomy for Aortic Valve Replacement (AVR) showed impressive outcomes. However, their advantages for obese patients are questionable. We aimed in this network meta-analysis to compare three surgical approaches: Full sternotomy (FS), Mini-sternotomy (MS), and Mini-thoracotomy (MT) for obese patients undergoing AVR.

METHODS

We followed the PRISMA extension for this network meta-analysis. PubMed/Medline, Scopus, Web of Science, and Cochrane searched through March 2023 for relevant articles. The analysis was performed using R version 4.2.3.

RESULTS

Out of 344, 8 articles met the criteria with 1392 patients. The main outcomes assessed were perioperative mortality, re-exploration, atrial fibrillation, renal failure, ICU stay, hospital stay, cross-clamp time, and bypass time. In favor of MS, the length of ICU stay and hospital stay was significantly lower than for FS [MD -0.84, 95%CI (-1.26; -0.43)], and [MD -2.56, 95%CI (-3.90; -1.22)], respectively. Regarding peri-operative mortality, FS showed a significantly higher risk compared to MS [RR 2.28, 95%CI (1.01;5.16)]. Also, patients who underwent minimally invasive approaches; MT and MS, required less need of re-exploration compared to FS [RR 0.10, 95%CI (0.02;0.45)], and [RR 0.33, 95%CI (0.14;0.79)], respectively. However, Intraoperative timings; including aortic cross-clamp, and cardiopulmonary bypass time, were significantly lower with FS than for MS [MD -9.16, 95%CI (-1.88; -16.45)], [MD -9.61, 95%CI (-18.64; -0.59)], respectively.

CONCLUSION

Our network meta-analysis shows that minimally invasive approaches offer some advantages for obese patients undergoing AVR over full sternotomy. Suggesting that these approaches might be considered more beneficial alternatives for obese patients undergoing AVR.

Do obese patients benefit from isolated aortic valve replacement through a partial upper sternotomy?

OBJECTIVE

Controversial opinions exist for aortic valve replacement (AVR) through partial upper sternotomy in obese patients. Moreover, this study sought to investigate the potential clinical advantage of partial upper sternotomy aortic valve replacement (mini-AVR) over conventional full sternotomy aortic valve replacement (con-AVR) in obese patients.

METHODS

This was a retrospective and observational study. From January 2015 to December 2020, a total of 184 obese [body mass index (BMI) ≥ 30 kg  m²] patients undergoing isolated primary AVR were included: 98 patients underwent conventional full sternotomy, and 86 patients underwent partial upper sternotomy. Propensity score (PS) matching was applied to eliminate the bassline imbalances in the mini-AVR and the con-AVR groups.

RESULTS

After one-to-one propensity score matching, two groups of 60 patients were obtained. No in-hospital death occurred in the two groups. In addition, cardiopulmonary bypass time and total operative time were similar across the 2 groups, but the aortic cross-clamp time was significantly shorter in the con-AVR group (P = .0.022). The amount of mediastinal drainage at 48 h after surgery (P =  0.018) and postoperative blood transfusions (P =  0.014) were significantly lower in the mini-AVR group. There was no difference in ventilation time (P = .0.145), but a shorter intensive care unit stay time (P =  0.021) in the mini-AVR group.

CONCLUSION

This study demonstrates that aortic valve replacement through a mini-AVR in obese patients is a safe and effective procedure. It outperformed con-AVR in terms of blood loss, blood product transfusion, and ICU stay.

Factors affecting mortality after coronary bypass surgery: a scoping review

Objectives

Previous research reports numerous factors of post-operative mortality in patients undergoing isolated coronary artery bypass graft surgery. However, this evidence has not been mapped to the conceptual framework of care improvement. Without such mapping, interventions designed to improve care quality remain unfounded.

Methods

We identified reported factors of in-hospital mortality post isolated coronary artery bypass graft surgery in adults over the age of 19, published in English between January 1, 2000 and December 31, 2019, indexed in PubMed, CINAHL, and EMBASE. We grouped factors and their underlying mechanism for association with in-hospital mortality according to the augmented Donabedian framework for quality of care.

Results

We selected 52 factors reported in 83 articles and mapped them by case-mix, structure, process, and intermediary outcomes. The most reported factors were related to case-mix (characteristics of patients, their disease, and their preoperative health status) (37 articles, 27 factors). Factors related to care processes (27 articles, 12 factors) and structures (11 articles, 6 factors) were reported less frequently; most proposed mechanisms for their mortality effects.

Conclusions

Few papers reported on factors of in-hospital mortality related to structures and processes of care, where intervention for care quality improvement is possible. Therefore, there is limited evidence to support quality improvement efforts that will reduce variation in mortality after coronary artery bypass graft surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-022-01784-z.

The effects of body mass index on outcomes for patients undergoing surgical aortic valve replacement

Background

Most of the studies of obesity and postoperative outcome have looked predominantly at coronary artery bypass grafting with fewer focused on valvular disease. The purpose of this study was to compare the outcomes of patients undergoing aortic valve replacement stratified by body mass index (BMI, kg/m^2).

Methods

The Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease registry captured 4780 aortic valve replacements in Alberta, Canada from January 2004 to December 2018. All recipients were stratified by BMI into five groups (BMI: < 20, 20–24.9, 25–29.9, 30–34.9, and > = 35). Log-rank test and Cox regression were used to examine the crude and adjusted survival differences.

Results

Intra-operative clamp time and pump time were similar among the five groups. Significant statistical differences between groups existed for the incidence of isolated AVR, AVR and CABG, hemorrhage, septic infection, and deep sternal infection (p < 0.05). While there was no significant statistical difference in the mortality rate across the BMI groups, the underweight AVR patients (BMI < 20) were associated with increased hazard ratio (1.519; 95% confidence interval: 1.028–2.245) with regards to all-cause mortality at the longest follow-up compared with normal weight patients.

Conclusion

Overweight and obese patients should be considered as readily for AVR as normal BMI patients.

Adiposity in relation to readmission and all-cause mortality following coronary artery bypass grafting: A systematic review and meta-analysis

This study systemically reviewed evidence linking adiposity to readmission and all-cause mortality in post-coronary artery bypass grafting (CABG) patients. Keyword/reference search was performed in PubMed, Web of Science, CINAHL, and Cochrane Library for articles published before June, 2018. Eligibility criteria included study designs: experimental/observational studies; subjects: adult patients undergoing CABG; and outcomes: hospital/clinic readmissions, and short-term (≤30 days) and mid-to-long-term (>30 days) all-cause mortality. Seventy-two studies were identified. Meta-analysis showed that the odds of post-CABG readmission among patients with overweight was 30% lower than their normal-weight counterparts and the odds of mid-to-long-term post-CABG mortality among patients with overweight were 20% lower than their normal-weight counterparts. In contrast, no difference in post-CABG readmission rate was found between patients with obesity and their nonobese counterparts; no difference in short-term or in-hospital post-CABG mortality rate was found between patients with overweight or obesity and their normal-weight counterparts; and no difference in mid-to-long-term post-CABG mortality rate was found between patients with obesity and their normal-weight counterparts. In conclusion, patients with overweight but not obesity had a lower readmission and mid-to-long-term mortality rate following CABG relative to their normal-weight counterparts. Preoperative weight loss may not be advised to patients with overweight undergoing CABG.

Does body mass index truly affect mortality and cardiovascular outcomes in patients after coronary revascularization with percutaneous coronary intervention or coronary artery bypass graft? A systematic review and network meta-analysis

BACKGROUND

Obesity, a comorbid medical condition, is usually observed in patients with established coronary artery disease. Paradoxically, patients with a higher body mass index (BMI) usually have better clinical outcomes after coronary revascularization.

METHODS

We searched five online databases through December 2017. We identified studies reporting the rate of all-cause mortality or cardiovascular-related outcomes among patients after coronary revascularization with percutaneous coronary intervention or coronary artery bypass graft based on various BMI categories. Network meta-analysis was performed using Bayesian methods.

RESULTS

Sixty-five records involving 865,774 participants were included in our study. A U-shaped association was observed across BMI categories for all-cause mortality. Using normal weight as the reference, all-cause mortality was increased for (relative risk [RR]: 2.4; 95% credibility interval [CrI]: 2.1-2.7) patients with underweight, whereas it was lowered in patients with overweight, obese, and severely obese. This association remained significant in many subgroups. We also observed that the risk of major adverse cardiovascular events (MACE) was lowest among patients with overweight. Furthermore, patients with underweight were associated with greater risks of myocardial infarction (RR: 1.9; 95% CrI: 1.4-2.5), cardiovascular-related mortality (RR: 2.8; 95% CrI: 1.6-4.7), stroke (RR: 2.0; 95% CrI: 1.3-3.3) and heart failure (RR: 1.7; 95% CrI: 1.1-2.7) compared with normal weight patients; no significant association was observed among individuals with higher BMI.

CONCLUSIONS

The 'obesity paradox' does exist in patients after coronary revascularization, especially for patients with post-percutaneous coronary intervention. All-cause mortality in patients with high BMI is significantly lower compared with patients with normal weight. Furthermore, patients with underweight experience higher rates of cardiovascular outcomes compared with patients with normal weight.

Effect of Body Mass Index on Postoperative Complications in Beating Coronary Artery Surgery

BACKGROUND

Body Mass Index (BMI) is considered as an important risk factor in cardiovascular surgery. We designed a historical cohort study for the evaluation of perioperative complications related to BMI in patients who underwent off-pump coronary artery bypass grafting (OPCAB).

METHODS

We studied 1120 consecutive patients who underwent OPCAB between January 2008 and December 2011 in Imam Ali Hospital, Kermanshah, Iran. Patients were divided into four groups according to BMI: underweight/low BMI (< 18.5 kg/m²), healthy weight (between 18.5 kg/m² and 24.9 kg/m²), overweight/high BMI (between 25 kg/m² and 30 kg/m²), and obese/very high BMI (> 30 kg/m²).

RESULTS

In multivariable regression analysis, an important correlation between the underweight/low BMI group and mortality was observed (p=0.037). Postoperative stroke, postoperative atrial fibrillation (AF) and intra-aortic balloon pump (IABP) use were not associated with BMI. In linear regression analysis, significant correlations between low BMI, reintubation, ICU stay time and intubation time were found. Re-exploration for bleeding was significantly correlated with having a low or high BMI.

CONCLUSION

Having a low BMI (which is association with malnutrition and respiratory muscles weakness) was significantly associated with reintubation, prolonged intubation time and ICU stay time. The obese group was also associated with postoperative atelectasia and fever.

Impact of Obesity on Intensive Care Unit Resource Utilization After Cardiac Operations

BACKGROUND

Much has been published about the effect of obesity on adverse outcomes after cardiac operations, yet little is known regarding the effect of obesity on intensive care unit (ICU) resource utilization. This study examined the effect of obesity on ICU resource utilization after cardiac operations.

METHODS

All patients with a body mass index (BMI) of 18.5 kg/m² or higher who underwent a cardiac surgical procedure between 2006 and 2013 were stratified into the following weight categories: normal (BMI 18.5 to 24.99 kg/m²), preobese (BMI 25 to 29.99 kg/m²), obese class I (BMI 30 to 34.99 kg/m²), obese class II (BMI 35 to 39.99 kg/m²), and obese class III (BMI ≥40 kg/m²). Comparisons between weight categories were done, and the risk-adjusted effect of weight category on prolonged ICU stay, prolonged ventilation, and ICU readmission was determined.

RESULTS

Of the 5,365 included patients, 1,948 were obese. Patients with greater obesity experienced longer ICU time, longer ventilation time, and increased ICU readmission. After adjustment, increasing obesity remained independently associated with greater likelihood of prolonged ICU stay (obese class II: odds ratio [OR], 2.4; 95% confidence interval [CI], 1.55 to 3.61; obese class III: OR, 4.1; 95% CI, 2.38 to 7.05), prolonged ventilation (obese class III: OR, 3.4; 95% CI, 1.57 to 7.22), and ICU readmission (obese class II: OR, 3.0; 95% CI, 1.70 to 5.31; obese class III: OR, 2.9; 95% CI, 1.32 to 6.36).

CONCLUSIONS

Increasing obesity was associated with a significant increase in ICU resource utilization after cardiac operations. Further study is needed to determine the mechanisms underlying this association and how the adverse effects of obesity may be mitigated.

Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery: A Nationwide Study With a Systematic Review and Meta-Analysis

BACKGROUND

In an apparent paradox, morbidity and mortality are lower in obese patients undergoing cardiac surgery, although the nature of this association is unclear. We sought to determine whether the obesity paradox observed in cardiac surgery is attributable to reverse epidemiology, bias, or confounding.

METHODS

Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.

RESULTS

A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.

CONCLUSIONS

Obesity is associated with lower risks after cardiac surgery, with consistent effects noted in multiple analyses attempting to address residual confounding and reverse causation.

Severe Obesity Is Associated With Increased Risk of Early Complications and Extended Length of Stay Following Coronary Artery Bypass Grafting Surgery

Background

Better understanding of the relationship between obesity and postsurgical adverse outcomes is needed to provide quality and efficient care. We examined the relationship of obesity with the incidence of early adverse outcomes and in‐hospital length of stay following coronary artery bypass grafting surgery.

Methods and Results

We analyzed data from 7560 patients who underwent coronary artery bypass grafting. Using body mass index (BMI; in kg/m²) of 18.5 to 24.9 as a reference, the associations of 4 BMI categories (25.0–29.9, 30.0–34.9, 35.0–39.9, and ≥40.0) with rates of operative mortality, overall early complications, subgroups of early complications (ie, infection, renal and pulmonary complications), and length of stay were assessed while adjusting for clinical covariates. There was no difference in operative mortality; however, higher risks of overall complications were observed for patients with BMI 35.0 to 39.9 (adjusted odds ratio 1.35, 95% CI 1.11–1.63) and ≥40.0 (adjusted odds ratio 1.56, 95% CI 1.21–2.01). Subgroup analyses identified obesity as an independent risk factor for infection (BMI 30.0–34.9: adjusted odds ratio 1.60, 95% CI 1.24–2.05; BMI 35.0–39.9: adjusted odds ratio 2.34, 95% CI 1.73–3.17; BMI ≥40.0: adjusted odds ratio 3.29, 95% CI 2.30–4.71). Median length of stay was longer with BMI ≥40.0 than with BMI 18.5 to 24.9 (median 7.0 days [interquartile range 5 to 10] versus 6.0 days [interquartile range 5 to 9], P=0.026).

Conclusions

BMI ≥40.0 was an independent risk factor for longer length of stay, and infection was a potentially modifiable risk factor. Greater perioperative attention and intervention to control the risks associated with infection and length of stay in patients with BMI ≥40.0 may improve patient care quality and efficiency.

Surgical site infection and transfusion rates are higher in underweight total knee arthroplasty patients

Background

Underweight (UW) patients undergoing total hip arthroplasty have exhibited higher complication rates, including infection and transfusion. No study to our knowledge has evaluated UW total knee arthroplasty (TKA) patients. We, therefore, conducted a study to investigate if these patients are at increased risk for complications, including infection and transfusion.

Methods

A case-control study was conducted using a prospectively collected institutional database. Twenty-seven TKA patients were identified as UW (body mass index [BMI] < 18.5 kg/m²) from 2000-2012 and were matched for age, gender, date of surgery, age-adjusted Charlson comorbidity index, rheumatoid arthritis, and diabetes. These patients were compared to 81 normal weight patients (BMI 18.5-24 kg/m²). Demographic variables were compared, along with wound complications, surgical site infection (SSI), blistering, deep vein thrombosis, pulmonary embolism, transfusion, revision, flexion contracture, hematoma formation, and patellar clunk.

Results

The average BMI was 17.1 kg/m² (range 12.8-18.4) for UW and 23.0 kg/m² (range 19.0-25.0) for normal weight patients (P < .001). UW TKA patients were more likely to develop SSIs (3/27, 11.1% vs 0/81, 0.0%, P = .01) and were more likely to require transfusions (odds ratio = 3.4, confidence interval 1.3-9.1; P = .02).

Conclusions

Our study demonstrates that UW TKA patients have a higher likelihood of developing SSI and requiring blood transfusions. The specific reasons are unclear, but we conjecture that it may be related to decreased wound healing capabilities and low preoperative hemoglobin. Investigation of local tissue coverage and hematologic status may be beneficial in this patient population to prevent SSI. Based on the results of this study, a prospective evaluation of these factors should be undertaken.

Impact of body mass index on outcome in patients undergoing coronary artery bypass grafting and/or valve replacement surgery

Objective

This study aimed to analyze the impact of body mass index on outcomes of 101 patients undergoing coronary artery bypass grafting, valve replacement, or combined valve/ coronary artery bypass grafting surgery in a private hospital in Belo Horizonte, Brazil.

Methods

This was a prospective cross-sectional study of patients undergoing cardiac surgery from May 2009 to December 2012. All patients were followed up from the first day of admission until discharge or death. Patients were divided into three groups according to BMI: normal weight, overweight, and obese. The main outcome measure was the association between BMI and postoperative morbidities and mortality.

Results

Multivariate analysis identified obesity as an independent predictor of increased risk of surgical reintervention (odds ratio [OR] 13.6; 95%CI 1.1 - 162.9; P=0.046) and reduced risk of bleeding (OR 0.05; 95% CI 0.09 - 0.69; P=0.025). Univariate analysis showed that obesity was associated with increased frequency of wound dehiscence (P=0.021). There was no association between BMI and other complications or mortality in univariate analysis. There was also no association between body mass index and duration of cardiopulmonary bypass, aortic clamping, mechanical ventilation, and intensive care unit or hospital stay.

Conclusion

Obese individuals undergoing coronary artery bypass grafting, valve replacement, or combined surgery have a higher postoperative risk of surgical reintervention and lower chances of bleeding.