Is extreme obesity a risk factor for cardiac surgery? An analysis of patients with a BMI > or = 40

The increasing prevalence of obesity is a public health concern and perceived as a potential risk factor in open heart surgery. We critically appraised the literature available regarding postoperative complications in obese patients.

A single-center retrospective evaluation of complication rates (1999-2004) in cardiac surgical patients categorized by body mass index (BMI) was conducted. The overall incidence of complications (CX), renal failure (RF), hemodialysis (HD), atrial fibrillation (AF), cardiac arrest (CA), infections (INF), stroke (CVA and TIA), prolonged ventilation (VENT), and pulmonary embolism (PE) were observed. Patients with normal BMI (20-30) served for comparison, obesity and extreme obesity (ExtOb) were defined as BMI 30-40 and > or =40, respectively.

In our institutional review of 1920 patients, 1780 met the inclusion criteria with BMI<20 (n=53), 20-30 (n=1056), 30-40 (n=592), and > or =40 (n=79) based on National Health and Nutrition Examination Survey (NHANES) criteria. Significant increase in complications (STS database guideline definitions) were observed with a BMI> or =40, 58% versus 47% (p=0.04). Extremely obese patients (ExtOb) had increased length of stay (LOS) (11.4 days vs 9.6 days; p< or =0.01), rate of renal failure (14.3% vs 5%; p< or =0.01) and prolonged ventilation (39%; p=0.01) compared to non-obese patients. Extremely obese had no significant increase in hemodialysis (7.3% vs 3.2%; p=0.11) or stroke (5.2% vs 2.9%; p=0.29). Obese patients (Ob) had increased LOS (10 days vs 9.6 days; p=0.04) and prolonged ventilation (28.3% vs 23.5%; p=0.03).

Cardiac surgery can be performed without significant increase in perioperative and 30-day mortality in obese and extremely obese patients. Overall complication rates and LOS in patients with BMI> or =40 is increased and demands attention. We provide evidence that rates of few specific complications increase with extreme obesity. For risk stratification in the setting of an obesity epidemic, we advocate an interdisciplinary approach in obese patients undergoing elective cardiac surgery.