Is Body Mass Index a Risk Factor for Isolated Off-Pump Coronary Revascularization?

The effect of body mass index on short-term outcomes in patients undergoing off-pump coronary artery bypass grafting surgery: a retrospective study from a single cardiovascular center

OBJECTIVE

This study is designed to investigate the impact of body mass index (BMI) on the short-term outcomes of patients undergoing off-pump coronary artery bypass graft (OPCAB) surgery.

METHODS

Data was obtained from 1006 Chinese patients who underwent isolated, primary OPCAB at a high-traffic cardiovascular center during 2020. Subjects were categorized, by BMI, into a low & normal weight (LN) group (BMI < 24 kg/m2), an overweight (OVW) group (24 ≤ BMI < 28 kg/m2), and an obese (OBS) group (BMI ≥ 28 kg/m2). Information pertaining to patients' short-term outcomes (including incidence of mortality and morbidities; duration of postoperative mechanical ventilation; length of stay in the ICU and hospital; postoperative bleeding; etc.) were extracted, and the data from each group were compared.

RESULTS

The incidences of in-hospital mortality and morbidities were similar for all three groups. The volume of fluid infusion, postoperative bleeding within 24 h and total bleeding in LN group were higher than those in the OBS group (P < 0.001). The hemoglobin level was lower in the LN group than that in the OBS group (P < 0.001). Duration of mechanical ventilation and length of stay in the ICU in the LN group were longer than those in the OBS group (P < 0.001).

CONCLUSIONS

Our results demonstrate that BMI is not significantly related with short-term outcomes in OPCAB patients. However, we suggest that OPCAB patients with low-normal BMI are more susceptible to post-operative blood loss.

Consequences of Obesity on Short-Term Outcomes in Patients Who Underwent Off-Pump Coronary Artery Bypass Grafting Surgery

The correlation between off-pump coronary artery bypass (OPCAB) surgery and obesity-related outcomes is still uncertain. The aim of our study was to analyse the pre-, intra-, and postoperative short-term outcomes between obese and non-obese patients after off-pump bypass surgery. We performed a retrospective analysis from January 2017 until November 2022, including a total of 332 (non-obese (n = 193) and obese (n = 139)) patients who underwent an OPCAB procedure due to coronary artery disease (CAD). The primary outcome was all-cause in-hospital mortality. Our results showed no difference regarding mean age of the study population between both groups. The use of the T-graft technique was significantly higher (p = 0.045) in the non-obese group compared to the obese group. The dialysis rate was significantly lower in non-obese patients (p = 0.019). In contrast, the wound infection rate was significantly higher (p = 0.014) in the non-obese group compared to the obese group. The all-cause in-hospital mortality rate did not differ significantly (p = 0.651) between the two groups. Furthermore, ST-elevation myocardial infarction (STEMI) and reoperation were relevant predictors for in-hospital mortality. Therefore, OPCAB surgery remains a safe procedure even in obese patients.

Association of body mass index and all-cause mortality in patients after cardiac surgery: A dose-response meta-analysis

Ample studies have reported the effect of body mass index (BMI) on the prognosis of patients undergoing cardiac surgery, but the results remain inconsistent. Therefore, we aimed to conduct a dose-response meta-analysis to clarify the relationship between BMI and all-cause mortality in this population. A systematic search was performed in the PubMed and Embase databases through April 2019 for studies that reported the impact of BMI on all-cause mortality in patients after cardiac surgery. Pooled risk ratios (RRs) were calculated using a random-effects model. Non-linear associations were explored with restricted cubic spline models. Forty-one studies with a total of 54,300 cases/1,774,387 patients were included. The pooled RR for all-cause mortality was 0.93 (95% CI 0.89-0.97) for every 5-unit increment in BMI, indicating that higher BMI did not increase the risk of all-cause mortality in patients after cardiac surgery. A U-shaped association with the nadir of risk at a BMI of 25-27.5 kg/m² was observed, as well as a higher mortality risk for the underweight and the extremely obese patients. The subgroup analysis revealed that this phenomenon remained regardless of mean age, surgery type, geographic location and number of cases. Overall, for patients after cardiac surgery, a slightly higher BMI may be instrumental in survival, whereas underweight and extreme obesity is associated with a worse prognosis.

Categorizing body mass index biases assessment of the association with post-coronary artery bypass graft mortality

OBJECTIVES

The high prevalence of obesity makes accurately estimating the impact of anthropometric measures on cardiac surgery outcomes critical. The Society of Thoracic Surgeons coronary artery bypass graft (CABG) surgery risk model includes body surface area (as a continuous variable, using spline functions), but most studies apply various categorizations of body mass index (BMI)-contributing to the contradictory published findings. We assessed the association between BMI (modelled as a continuous variable without assumptions of linearity) and CABG operative mortality and examined the impact of applying previous studies' BMI modelling strategies.

METHODS

We identified 25 studies investigating the BMI-operative mortality association: 22 categorized BMI, 2 as a linear continuous variable,1 used spline functions. Our cohort of 12 715 consecutive patients underwent isolated CABG at 32 cardiac surgery programmes in North Texas from 1 January 2008-31 December 2012. BMI was modelled using restricted cubic spline functions in a propensity-adjusted model (controlling for Society of Thoracic Surgeons risk factors) estimating operative mortality. The analysis was repeated using each categorization identified and modelling BMI as a linear continuous variable.

RESULTS

BMI (modelled with a restricted cubic spline) was significantly associated with operative mortality (P < 0.0001). Risk was lowest for BMI near 30 kg/m2 and highest below 20 kg/m2 and above 40 kg/m2. No categorization, nor the linear continuous model, fully captured this association.

CONCLUSIONS

BMI is strongly associated with CABG operative mortality. Categorizing BMI (or assuming a linear relationship) heavily biases estimates of its association with post-CABG mortality. In general, smoothing techniques should be used for all continuous risk factors to avoid bias.

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.

Obesity and coronary artery disease: evaluation and treatment

With the increasing prevalence of obesity, clinicians are now facing a growing population of patients with specific features of clinical presentation, diagnostic challenges, and interventional, medical, and surgical management. After briefly discussing the effect of obesity on atherosclerotic burden in this review, we will focus on strategies clinicians might use to ensure better outcomes when performing revascularization in obese and severely obese patients. These patients tend to present comorbidities at a younger age, and their anthropometric features might limit the use of traditional cardiovascular risk stratification approaches for ischemic disease. Alternative techniques have emerged, especially in nuclear medicine. Positron emission tomography-computed tomography might be the diagnostic imaging technique of choice. When revascularization is considered, features associated with obesity must be considered to guide therapeutic strategies. In percutaneous coronary intervention, a radial approach should be favoured, and adequate antiplatelet therapy with new and more potent agents should be initiated. Weight-based anticoagulation should be contemplated if needed, with the use of drug-eluting stents. An "off-pump" approach for coronary artery bypass grafting might be preferable to the use of cardiopulmonary bypass. For patients who undergo bilateral internal thoracic artery grafting, harvesting using skeletonization might prevent deep sternal wound infections. In contrast to percutaneous coronary intervention, lower surgical bleeding has been observed when lean body mass is used for perioperative heparin dose determination.