Effects of obesity on outcomes in endoscopically assisted coronary artery bypass operations

Obesity has been shown to be an independent risk factor for adverse outcomes and prolonged hospitalization following conventional coronary artery bypass (CAB). For this reason and because of increased technical challenges, obesity has been considered a relative contraindication for minimally invasive bypass. The purpose of this study was to determine if in fact severe or morbid obesity is an independent risk factor for patients undergoing minimally invasive CAB.

Outcome data of 350 consecutive endoscopic, atraumatic CAB procedures performed at our institution over a 4-year period were reviewed with respect to patient body mass index (BMI). All operations consisted of thoracoscopic left or right internal mammary artery (IMA) harvesting followed by off-pump grafting of the left anterior descending (with/without diagonal coronary artery) or right coronary artery via a 4-cm thoracotomy. Patients were divided into 4 groups: small (BMI = 24 kg/m2), normal to mild obesity (24 kg/m2 < BMI = 34 kg/m2), severe obesity (34 kg/m2 < BMI = 40 kg/m2), and morbid obesity (BMI >40 kg/m2).

Although the BMI >34 kg/m2 groups had a higher incidence of hypertension, diabetes, and hypercholesterolemia, there was no statistical difference in operative risk between groups. Thirty-day mortality, conversion to sternotomy, transfusion rate, and wound, pulmonary, neurological, and myocardial complications were not significantly different between groups. The BMI >34 kg/m2 patients required longer IMA harvest times and total operating times, but the intensive care unit length of stay was not significantly different between groups. Hospital length of stay was longer for the BMI =24 kg/m2 group than for the BMI 18 to 34 kg/m2 group (P =.025).

Despite increased technical difficulty caused by obesity, it is not an independent risk factor for patients undergoing minimally invasive CAB.