Operative and early results of coronary artery bypass grafting in female patients in different body mass indexes

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.

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.

Subxiphoid incisional hernia development after coronary artery bypass grafting

Background

Median sternotomy can weaken the upper abdominal wall and result in subxiphoid incisional hernia. We evaluated risk factors associated with the development of subxiphoid incisional hernias after coronary artery bypass grafting (CABG).

Materials and Methods

Of 1,656 isolated CABGs performed between January 2001 and July 2010, 1,599 patients who were completely followed up were analyzed. The mean follow-up duration was 49.5±34.3 months. Subxiphoid incisional hernia requiring surgical repair developed in 13 patients (0.8%). The hernia was diagnosed 16.3±10.3 months postoperatively, and hernia repair was performed 25.0±26.1 months after the initial operation. Risk factors associated with the development of subxiphoid incisional hernia were analyzed with the Cox proportional hazard model.

Results

Five-year freedom from the hernia was 99.0%. Univariate analysis revealed that female sex (p=0.019), height (p=0.019), body surface area (p=0.046), redo operation (p=0.012), off-pump CABG (p=0.049), a postoperative wound problem (p=0.041), postoperative bleeding (p=0.046), and low cardiac output syndrome (p<0.001) were risk factors for the development of the hernia. Multivariable analysis showed that female sex (p=0.01) and low cardiac output syndrome (p<0.001) were associated with subxiphoid hernia formation.

Conclusion

Female sex and postoperative low cardiac output syndrome were risk factors of subxiphoid hernia. Therefore, special attention is needed for patients with high-risk factors.