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

Abstract

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.

Heart valve surgery and the obesity paradox: A systematic review

“…DSWI occurred in 0.9%, 0.5%, 0.2%, 0.1% and 0.9% (p = .016) of patients with underweight, normal weight, overweight, obesity and morbid obesity, respectively. 16 In the study by Ho et al, there were significantly higher reoperation rates in the normal-weight group; 6.1%, 4.0% and 2.5% (p = .007) of patients with normal weight, overweight and obesity, respectively, required reoperation. 46 In the study by Kalbacher et al, there were significant differences in rates of severe postoperative bleeding or requirement of blood transfusions.…”

“…Data were provided for 30-day, 1-year, 5-year and longest follow-up mortality as well as postoperative MI, stroke, reoperation rates and DSWI. 16 Ho et al collected retrospective data from 2131 patients who underwent valve surgery, CABG or a combination of the two with approximately 52% undergoing valve surgery or a combination.…”

“…32 The studies conducted by Aljanadi, Bruno, De Marzo, Forgie, Ho, Keller, Nazir, Rapetto, Smith and van der Boon did not find significant differences in mortality rates between their groups. 11,15,16,25,40,43,46,48,49,52…”

“…Even with additional preoperative comorbidities and increased incidence of postoperative complications, patients with obesity have often demonstrated equivalent or even improved rates of mortality after cardiac surgery when compared to their normal and underweight counterparts. 2,5,11,[14][15][16][17][18][19] This finding has been coined "the obesity paradox" and describes the incongruence between what is expected for patients with obesity and what is demonstrated in the literature.…”

Comparison of Microcirculatory Perfusion in Obese and Non-Obese Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass

“…Impaired vasodilation [ 24 ] and decreased levels of nitric oxide [ 19 ] may further impair vasoreactivity. In contrast, obesity also may play a protective role during cardiac surgery [ 25 , 26 ], which has been described as the “obesity paradox” [ 27 ].…”