A brand new hip or knee may be just what you need – but if you’re considering joint replacement and you have atrial fibrillation (A-fib), you could be looking at a rougher-than-average ride, according to a study published recently in The Journal of Bone & Joint Surgery.

“The study found that A-fib patients had a longer length of stay [in the hospital], an increased cost of medical care and higher complication rates,” says senior study author Alvin C. Ong, MD, assistant professor of orthopaedic surgery at the Rothman Institute at Thomas Jefferson University Hospital in Philadelphia. In fact, the complication rates  were around 27 percent higher in patients who had A-fib compared with those who didn’t. The complications included infections around the new joint, the need for blood transfusions and later readmission to the hospital.

In A-fib, faulty electrical signals cause the upper chambers of the heart (the atria) to “fibrillate,” or contract irregularly and, usually, too fast. As a result, blood isn’t pumped effectively to the heart’s lower chambers and out through the body. Blood thinners (also called anti-coagulants) such as warfarin (Coumadin) are used to prevent blood clots that can result from the pooling of blood in the heart – and it’s these blood thinners that make joint replacement surgery more risky.

People with rheumatoid arthritis (RA) are up to 60 percent more likely than people without RA to develop A-fib, either due to the disease itself or the medications (such as corticosteroids) used to treat it. Additionally, the chances of anyone developing A-fib increase greatly with age.

Lead study author Vinay K. Aggarwal, MD, an orthopaedic surgery resident at the Rothman Institute, notes, “Given that elderly patients very frequently have chronic A-fib and also very frequently undergo total joint arthroplasty [repair or replacement], it made sense to examine the two distinct variables together.”

The study set out to learn more about the monetary costs of joint replacement in patients with A-fib. It involved 161 patients with A-fib, who were compared with 161 similar patients (called “matched controls”) who did not have A-fib. A total of 112 hips and 210 knees underwent 239 first time joint surgeries and 83 revisions (do-over surgery to repair problems with a previous replacement).

The patients with A-fib had a longer pre-operative hospital stay (1.7 days versus 0.2 days), a longer postoperative stay (4.6 days vs. 3.2 days) and were significantly more likely to develop a joint infection and need a blood transfusion. They were also four times more likely to be unexpectedly readmitted to the hospital after their release.