Joint replacement heart attack risk is a well known, well studied, phenomenon. This Harvard study caught my eye as it was looking to replicate findings that in the UK population, total hip replacements and total knee replacements reduce the risk of a heart attack! Huh? Maybe the rain?
So what is the connection between heart attacks and joint replacement? To begin with, the word “replacement” is misleading and conjures up visions of replacing a part in your car. But while a new radiator is equal to and better than the broken one it replaces, there are no replacement body parts that function like the original. Unlike replacing a car part, these surgeries are an amputation with the insertion of an artificial prosthesis that will always be inferior to the original equipment. The heart attack connection is easy to understand when you put into context that when you completely chop out a joint there is severe trauma to the blood vessels and bone marrow space. This likely leads to a higher risk of blood clots, some of which may make it to the heart. In addition, for some patients, the stress of undergoing the joint amputation may be enough alone
The Harvard study was large and used subjects 50 and over who had been diagnosed with osteoarthritis. The goal was to further investigate prior studies that suggested that the hip (THA) and knee replacement (TKA) surgeries in the UK carried less of a risk of heart attack than those performed in the US. A matched set of the same number of U.K. subjects underwent THA and TKA, and the control group did not. Their incidence of MI (heart attack) was tracked from 2000 to 2012. Despite the intent to replicate the findings of the previous UK study, their findings indicated that after both total hip and knee replacements, during the first month after surgery, the incidence of heart attack increased by 95%! This risk eventually cancelled itself out with a lower subsequent risk. A finding which is not dissimilar to what was seen in previous studies. So if you make it through the first month without a heart attack you’re fine! The more interesting result was that the risk of blood clots was ongoing for many years!
The upshot? While heart attack risk in the UK may be a little different than in the US with our studies showing a larger increased risk for heart attacks for longer, the fact that the blood clot risk continues for years is really concerning. The moral of the story in all of these studies seems to be to avoid joint replacements whenever possible. They are definitely not like going in for a quick tune up!