Surprising Findings from the Framingham Heart Study: EP Lab Digest Interviews Anne B. Curtis, MD, Professor of Medicine, Directo

Interviewed by Jodie Miller
Interviewed by Jodie Miller
For those who might be unfamiliar, describe the Framingham Heart Study. The Framingham Heart Study has been going on for many years. The study was a means of following a large cohort of patients over many, many years to look at the epidemiology of heart disease. It is the long-term follow-up of a large number of patients involved that allows you to gain information that you can t get from short-term studies of smaller groups of patients. Were you involved with this research? No. When did the Framingham Study begin researching the possible genetic link of AF? According to the article that was published in JAMA, this was a prospective study; they had been studying people from 1971 to 2002. There were over 2,200 offspring that they were looking at, and everyone was at least 30 years old, free of atrial fibrillation, and their parents had been evaluated in the original cohort of people in the study back when it began. Who was studied? Of the 2,243 participants in this study, there were 1,165 women and 1,078 men. Researchers looked at the development of new markers of AF and then looked at whether the parents had been documented to have atrial fibrillation as well. Thus, out of the total offspring in the study, there were 681 (or 30%) who had at least 1 parent who had a history of documented AF. Of that group, seventy patients of whom 23 were women developed atrial fibrillation during the course of the study. The mean age of the patients was 62 at the time that they were followed up. What were the findings? Compared to having no parents with AF, if these offspring had a parent with AF, that increased their risk of having AF: the odds ratio was 1.85. Please note that if you have an odds ratio of 2 it means approximately double the risk, and an odds ratio of 1 means it doesn t make any difference. Therefore, an odds ratio of 1.85 means it comes close to doubling the risk of having AF. Atrial fibrillation has also been seen as a problem that develops in people as they get older. So in the study, as researchers limited the patients they were looking at, they found that if these parents and their offspring were less than 75 years old when they developed AF, the association was even stronger. Here the odds ratio came out to be 3.23 triple the risk! In other words, if you have a parent who develops AF when they are 85 years old, that may be simply because they are getting older and not be a genetic issue. It would not necessarily increase your own risk of getting atrial fibrillation. However, if your parent develops AF at a young age for example, in their 40s or 50s and they do not have any other heart disease, then there may be a genetic reason for it, and your risk of getting AF goes up by about triple. Have EP physicians ever suspected in the past that AF appeared genetic or inherited? There has certainly been that thought, but proving it has been a different story. When you have patients who develop atrial fibrillation, most patients who develop it have heart disease or there is already something wrong with them a common association is hypertension. They may have hypertension, valve disease, or have had heart attacks, which all set them up for developing atrial fibrillation. However, when the patient has none of these factors and they are still relatively young (middle age), but still develop atrial fibrillation, then as their physician you have to say there has to be some reason for it. The reason could be either because it is genetic or because of some sort of virus or inflammation that we can t really measure. Therefore, the notion that there might be a genetic connection in people with otherwise structurally normal hearts would be something that we would suspect, but it has now shown that this is likely to be true in some of these patients. Do you think further genetic studies will be done? Yes, I think that we will start figuring out where the genetic defects are in these patients and then come up with the capability of screening for them. AF is a much less serious rhythm problem than some other heart ailments, but the risk of AF still relates to factors like stroke and quality of life as people get older. If we could at the present time identify the genetic defect that causes AF, I am not sure what you could do to prevent someone from developing atrial fibrillation in the future, other than possibly to help control hypertension better. However, for the future, research that helps us to understand the genetic defect(s) may also help us to learn what treatments might possibly work to prevent it. What does this mean for the future treatment of atrial fibrillation? How do you think treatment strategies will change? At the present time, I don t think anything will change. However, I think it will encourage physicians and researchers to look for ways to prevent patients from getting AF. If we can identify what the genetic defect is and identify people with parents that have it and are at risk for it, then we will be able to test therapies to try to prevent AF from happening. Currently, this doesn t exist we can potentially identify someone, but aside from telling them they are at higher risk from other people, there really isn t anything else we can do right now. However, it is certainly a place where we want to do more research. How will this affect the way both patients and physicians approach and deal with AF? When will this information be readily available for patients? Unfortunately, there is nothing we can do about it yet. It s not like detecting a cancer gene where knowing you have it could be a life-saving thing. We are saying there is a higher risk of AF, but this information is still preliminary just because your parent had atrial fibrillation certainly doesn t guarantee you are going to have it. For example, based on these results, let s say you happen to have a parent that develops AF at age 45 or 50. The best thing you can do for yourself is the type of things we should all be doing, such as watching out for cardiovascular risk factors, eating a healthy diet, exercising, etc. In particular, since hypertension is the most common association, people who are likely to be more at risk for AF should certainly be sure that their blood pressure is well controlled that is one of the best things you can do. Thank you! For more information about the Framingham Heart Study, please visit: www.framingham.com/heart