The Controversy.. Take Them .. Take Them ..Take Them …. Don’t take them
In 2007 the American Heart Association (AHA) released an updated set of guidelines regarding the use of antibiotics to prevent heart valve infection in patients undergoing procedures such as certain dental procedures. The guidelines caused a great deal of controversy at the time, but why? Whereas guidelines before that had advised that most patients with mitral valve prolapse (MVP) to take antibiotics around the time of many dental procedures, the new set of recommendations, in a dramatic turnaround, advised against this. But the AHA had been advising the use of antibiotics in this setting since 1955! Of course this was difficult to understand for patients that had been taking antibiotics, felt comfortable with this, and wanted to continue to do so, and did not easily understand the new stance of their physicians. To the same tune, this was difficult to comprehend for many physicians that had been advocating antibiotics all that time, to suddenly accept the new recommendations and change their views.
Why did the old guidelines say what they did?
Infective endocarditis, which is infection within the heart (usually of the valves), is a serious complication of MVP. In fact in most studies looking at these infections, MVP was reported as the major heart diagnosis in those patients going on to develop these infections, and this was the main drive behind using antibiotics to try and prevent infection. However, it’s very important to realize that when looking at the entire population of patients with MVP, very few would ever develop such infections, in fact less than 2 in 1000. These patients were more likely to have thickened, heavily prolapsing and leaky valves. In those patients with a MVP and a leaky valve (murmur), the rate of infection approaches 5 in 1000, but in those without a leaky valve it is about the same as the general population.
One article in the Lancet in 2005, reviewing the topic of mitral valve prolapse, reported that ‘antibiotic prophylaxis remains one of the most important medical interventions in patients with MVP.’ Particularly pertaining to those with murmurs and high-risk features (can be determined from the echocardiogram). Those that had prolapsing valves that were not particularly degenerated and that did not leak were not felt to require antibiotics.
The amazing thing is that unlike a lot of major topics in cardiology such as treatment of heart attacks, there were actually no good studies that these recommendations were based on. Part of that reason is that such a study would be almost impossible to do given the extremely low number of people that actually developed these infections. To put it simply the recommendations were made by a group of ‘experienced experts’ sitting at a round table (in a smoky room of course!). But most people would agree that is better than no guidance whatsoever.
Why did the guidelines change?
In 2007 the new guidelines came out. Suddenly most people with MVP were told not to take antibiotics when undergoing dental procedures but why? It’s those ‘experts’ in a smoky room again, but this time they were trying to be a little more scientific with their recommendations.
It was now determined that although we were routinely giving antibiotics to many patients with MVP, that there was no evidence to do so because we had never done any good trials proving that they were a) useful and b) not harmful and c) justified given the very small number of people that would ever develop these infections. It was also felt that the usefulness of antibiotics for dental procedures in MVP was limited because in fact someone is more likely to be exposed to the bacteria that cause the heart infections from routine daily activities like brushing teeth, chewing gum or flossing, and were were certainly not giving antibiotics for those activities! It was also recognized that there were some potential serious effects from antibiotics such as reactions and other side effects and so they couldn’t justify recommending a treatment that wasn’t proven to work and may even be harmful.
So what now?
As I’ve stated above the biggest problem here is that there are no good studies guiding what we do in the case of antibiotics for MVP. There is no doubt that MVP patients with degenerated and / or leaky valves are at increased risk of developing infections of the heart. The truth is the chance of developing an infection for these people is tiny, however the consequences of developing an infection are very serious. Can we justify using antibiotics in all patients with MVP at risk of developing an infection, when we don’t know if they work, especially when the chance of side effects from antibiotics may be more serious? On the other hand, the true risk of antibiotics is very small, and some think that it is more than justifiable in some high-risk patients.
The truth is that the new guidelines are likely a safe approach, there’s no way the writers of them would allow it to be any other way. There is recognition in the guidelines that some clinicians may feel more comfortable continuing to prescribe antibiotics particularly in those patients with severe MVP, very degenerated valves and a significant leak. At the same time if antibiotics are not prescribed, as per the guidelines, you can be reassured that no one is taking an unnecessary risk with your health and that the guidelines are created and endorsed by the major heart societies who tend to have your best interests at heart.
I’m going to stop short of making generalized recommendations here; I don’t feel a blog is the right place to do that. If there are any concerns or doubts then these should be discussed with a physician who you are comfortable with and that is knowledgeable about the subject. The information in this post should certainly leave you in a position to have a reasoned discussion about the matter. If you have had a heart infection before and you have MVP you should certainly make sure you take antibiotics before dental procedures. If you have MVP and your physician, (like most physicians now), has decided not to give you antibiotics, be reassured that he is acting within current guideline recommendations. If your physician does prescribe antibiotics then they should know why they are doing so and have their reasons. They consider you to be at high risk and you should certainly discuss this with them.