Obesity Raises Risk of Infection Post Cardiac Bypass

Health Writer

The Obesity Society defines obesity as “excess of adipose tissue.” The disease is pervasive and chronic and often diagnosed using (body mass index) BMI as a measurement. Obesity currently affects more than one third of the U.S. adult population (about 78.5 million Americans) and the rate of obesity among adults and children has been on an uptick since the early 1960s. Currently 69 percent of adults in the U.S. are overweight or have obesity.

If you have obesity you are at risk of having a shorter lifespan. You are also at risk of developing close to 30 chronic health conditions including: Type 2 diabetes, gallstones, fatty liver disease, sleep apnea, GERD, stress incontinence, degenerative joint disease, birth defects, miscarriages, asthma, certain cancers and other respiratory conditions. Heart disease including hypertension, heart failure and high cholesterol is also associated with having obesity. Coronary artery bypass surgery (CABG) may be necessary to treat plaque-filled coronary arteries. Research suggests that obesity raises the risk of post-surgical infection during coronary artery bypass graft surgery.

Researchers at the University of Alberta conducted a series of studies to examine the association between BMI and different outcomes following CABG and coronary angioplasty also called percutaneous coronary intervention (PCI). Results of the study series were published in the Canadian Journal of Cardiology.

Why choose PCI instead of CABG to treat coronary artery disease (CAD)? Having more than one arterial blood vessel narrowed or blocked, compared to just one vessel, raises the risk of mortality significantly. CABG is considered major open heart surgery and therefore has a number of possible post-surgical complications. PCI formerly known as angioplasty with stent is a non-surgical procedure that uses a catheter to place a stent into an artery (cardiac catheterization) narrowed by plaque buildup or atherosclerosis. It’s used to also reduce heart damage during or after a heart attack. A 2014 study published in Circulation found similar mortality rates between CABG and PCI (using cobalt-chromium everolimus-eluding stent) in patients with diabetes and heart disease.

In this more recent study, researchers analyzed data from 56,722 patients compiled in a large registry, and found that patients who had a BMI over 30, were 1.9 times more likely to report infections post-surgery. Another study in the series found that 88 percent of patients who had PCI were classified as obese, compared to 55 percent of patients who received CABG. The researchers theorized that PCI was being considered more often than CABG in the patient with obesity because of the notable increased postoperative rate of infection after CABG in this population. When patients develop infections after surgery, healthcare costs rise significantly. A big part of the cost is a longer hospital stay.

One theory offered regarding the higher infection rate was the possibility that chest binders used to support the wound site may not have optimal fit in patients with central obesity, (may not keep the incision edges well approximated) and allow wound infections to occur more easily.

A previous Canadian study published in 2016 noted that severely obese patients (BMI greater than 40) were most likely to have longer hospital stays compared to normal-weight patients. In fact, severely obese patients had triple the risk of infection after bypass surgery, compared to normal weight people. On average these individuals spent one extra day in the hospital. If the patients had comorbid diabetes, the hospital stay was three times longer compared to patients with neither condition. Severely obese patients were also 56 percent more likely to have complications a month after surgery, while moderately obese patients were 35 percent more likely to have complications thirty days after surgery. A study published in JAHA found higher post-operative complication rates for individuals who had obesity at the time of surgery.

Weight loss after CABG has had some perplexing results. A study in 2012 suggested that patients who remained at the same weight faced lower mortality rates than patients who lost weight after CABG. On the other hand, gaining weight post CABG (in already overweight patients or patients diagnosed with obesity) also resulted in increased rates of mortality. So though it may seem to be intuitive to try and lose weight after bypass, studies thus far have not supported that approach.

It may be beneficial to swap out poor quality foods for more nutritious foods, foods that actually support heart health. Heart patients might benefit from:

If you are significantly overweight or diagnosed with obesity and have CAD that necessitates treatment, talk to your doctor about the best approach – CABG, PCI or other options – best suited for the severity of your disease and your current state of health. Given the rates of childhood obesity and the associated risk of early heart disease, weight management in this population is crucial, long before cardiac intervention is necessary. If you’re having general elective surgery, it’s always best to be in optimal shape before the procedure. Do talk to your doctor about whether weight loss can reduce risk of complications.