Impact of body mass index on outcome in patients after coronary artery bypass grafting with and without valve surgery

Abstract

Background Among other preoperative parameters, extremely low or extremely high body mass index (BMI) has been discussed as a substantial risk factor for postoperative complications after cardiac surgery. However, the exact relationship between BMI and postoperative risk has not yet been defined. Methods We retrospectively investigated consecutive patients (n=22 666) who underwent coronary artery bypass grafting with or without concomitant valve surgery between 1990 and 2001 in our institution. A number of preoperative and intraoperative variables and BMI (as a quadratic term) were used in a logistic regression model as covariates. Further, the patients were divided into 20 groups each with an increase in BMI of 1 kg/m 2 (BMI as a categorical variable). The calculations of odds ratios (ORs) for re-intubation, infection, re-exploration, prolonged stay (>1 day) on the intensive care unit (ICU) and 30-day mortality were adjusted for age, gender and type of surgery. Results In the multivariate analysis only age (OR between 1.01 and 1.038, P<0.01), additional aortic valve (OR between 1.335 and 2.977, P<0.01) or mitral valve surgery (OR between 2.123 and 3.301, P<0.01) showed significant impact on all five endpoints. Patients with BMI between 25 and 35 kg/m 2 were not at elevated risk for any of the investigated end-points, except for infection. Patients with BMI between 21 and 27 kg/m 2 were not at elevated risk for infection. The ORs for postoperative complications were significantly higher in underweight patients compared with obese or severely obese patients, except those for infection. Further, the underweight patients presented significantly more comorbidity. Conclusion Patients with low BMI are at higher risk after cardiac surgery than obese or severely obese patients. We hypothesize that a preoperative focus on avoiding and/or reversing cachexia may be more efficacious than reducing obesity in reducing the overall risk associated with heart surgery.

Generic, Simple Risk Stratification Model for Heart Valve Surgery

“…These findings are supported by previous studies. 3,4,6,[11][12][13] Our risk model contains relatively few preoperative predictors, 13 all of which are routinely collected in most institu- Some approaches could be adopted even if these predictors were missing for some patients. One would be to calculate a range containing the minimum and maximum risks for a patient by assuming the 2 extreme possibilities for a missing predictor value.…”

Generic, Simple Risk Stratification Model for Heart Valve Surgery

“…1,[3][4][5][6] Although several studies have investigated potential predictors of short-term mortality after heart valve surgery, 3,[11][12][13] there are few risk models specifically for heart valve patients that present all the information necessary for use in health institutions. 4,6,14 Nowicki and colleagues 6 used 8943 patients from 8 New England medical centers to derive separate risk models for in-hospital mortality after isolated aortic valve and isolated mitral valve surgery and provided simplified risk scores complete with a lookup table.…”

“…The following preoperative patient characteristics were chosen in advance as candidate predictors from clinical knowledge and previous research 3,4,[11][12][13] : age, gender, body mass index (BMI), number and position of implanted heart valves, hypertension (no/yes; treated or blood pressure Ͼ140/90 mm Hg), diabetes (no/yes; managed by diet, oral therapy, or insulin), renal failure (none or functioning transplant/creatinine Ͼ200 moL/dialysis dependency), respiratory disease (no/chronic obstructive pulmonary disease), ejection fraction (Ͻ30%/30% to 50%/Ͼ50%), arrhythmias (no/atrial fibrillation or heart block/ventricular tachycardia or fibrillation), active endocarditis (no/yes), operative priority (elective/urgent/emergency), operation sequence (previous sternotomy; first/second/third or more), concomitant CABG surgery (no/yes), concomitant tricuspid surgery (no/yes), valve regurgitation or stenosis (no/yes), left ventricular end-diastolic pressure and pulmonary artery wedge pressure, and aortic valve gradient.…”

“…[7][8][9][10] However, most of these models have been developed for CABG surgery. Although some studies have investigated potential predictors of short-term mortality after heart valve surgery, 3,[11][12][13] there are few risk models specifically for heart valve patients. 4,6,14 We propose a simple, generic risk model that may be used to predict in-hospital mortality for patients undergoing heart valve surgery with or without concomitant CABG surgery.…”

Effects of body mass index on the early surgical outcomes after coronary artery bypass grafting

“…Despite a worldwide epidemic of obesity and its associated comorbidities, which include diabetes mellitus (DM), hypertension (HT), coronary artery disease (CAD), and their consequences, [1][2][3] there is still a big debate regarding the adverse effects of obesity on the early and late outcomes of coronary artery bypass graft (CABG) surgery. [4][5][6][7] Although several studies have proposed obesity as a cause of increased mortality and morbidity after this procedure, [8,9] some authors believe that it plays no role.…”