We all know that heart surgery is a serious procedure, and that just like any other surgery, there is always a risk for major infection.

But recently, a group of researchers were shocked when their study showed that the kind of major infection most frequently associated with heart surgery wasn’t at all what they expected (an infection at the site of the incision)—it was pneumonia.

And even more surprisingly, this dangerous condition often either didn’t occur or wasn’t diagnosed while the patient was still in the hospital during the post-op stay. The researchers had hypothesized that any such dangerous condition would be evident during this critical period. Instead, it was usually diagnosed about two full weeks after the operation!


The objective of the study was to find out what types of major infections occur after heart surgery and when they occur. So researchers collected clinical records of 5,185 male and female heart surgery patients with an average age of 64 at 10 medical centers—nine in the US and one in Canada—over the course of eight months. The surgeries included coronary artery bypass and aortic valve and/or mitral valve procedures.

First major finding: Researchers discovered that about 5% of heart surgery patients contracted major infections. And at the top of the list was not an infection at the site of the surgical incision, as the researchers had expected.

Pneumonia, a lung infection, was the most common infection. It was followed by clostridium difficile colitis (an infection in the colon that can cause diarrhea, abdominal cramps and sometimes fever, nausea, weight loss and dehydration)…bloodstream infection…infection at the site of the surgical incisions…and, lastly, mediastinitis (the infection and inflammation of the area between the lungs).

I don’t have to tell you that pneumonia and these other types of infections can cause weeks and sometimes even months of discomfort, serious complications or even death.

John Puskas, MD, MSc, a coauthor of the study and the head of cardiac surgery at Emory University Hospital in Atlanta, said that he’s not entirely sure why pneumonia came out on top, but he has some theories. For one thing, after a heart operation, breathing is often uncomfortable, which causes recovering patients to take shallow breaths. As a result, the lungs are not well-aerated, and bacteria that would normally be exhaled with deep breaths are left inside to multiply. Moreover, heart disease itself can cause fluid to build up in the lungs. Another potential conduit for infection is the breathing tube that’s inserted into the lungs during surgery.

I asked Dr. Puskas whether these infections implied hospital error, such as using unsterile instruments or other supplies. He said that the study uncovered no evidence of that and that these serious post-op infections most likely occur because patients have low-level, preexisting infections before surgery…or because their immune systems are too weak to fight off bacteria that are naturally present in the air, in their lungs or on their skin after surgery. Dr. Puskas added that the risks for infection during a heart operation can be reduced by appropriate safety procedures, but they can’t be eliminated.


The second major finding of the study was equally important: Only about half of the infections were diagnosed during patients’ post-op hospital stays of five to seven days. The other half were diagnosed much later—about 14 days after the surgery, on average.

This is worrisome, because patients may assume that once they’re home, they’re healthy, so there’s no need to look out for symptoms of infection. It’s also concerning, said Dr. Puskas, because patients at home are not prompted by nurses and respiratory therapists to walk around, breathe deeply and clear mucus from their lungs, which can help prevent and treat infection. And they won’t get immediate care if they need it.

Dr. Puskas said that this time frame might illustrate how long it takes some infections to appear. And sometimes, he added, the reason for the delay is that diagnosis itself can be a lengthy process that can require multiple visits over the course of a few days or weeks.


Dr. Puskas said that it’s important for heart surgery patients to be on the lookout for symptoms of infection after the surgery—even after they return home feeling fine. Be especially alert for symptoms of pneumonia, which may include chills, fever, cough, shortness of breath, a sharp chest pain when you inhale, headache or pain anywhere in your body, said Dr. Puskas. Call your doctor immediately if you experience any of these. And be diligent about following your doctor’s post-op advice—walk around regularly, cough to clear mucus from your lungs, and breathe deeply.