Jan 29, 2019
Host: Welcome to the Society of Cardiovascular Anesthesiologists podcast. This podcast series discusses the latest advancements in cardiovascular and thoracic anesthesiology, including practice guidelines, perioperative care, research and other scientific updates.
Dr. J. Danny Muehlschlegel: Hi, I’m Danny Muehlschlegel. I am the chair of the Atrial Fibrillation Working Group for the Society of Cardiovascular Anesthesiologists. I’m also a practicing cardiac anesthesiologist at Brigham and Women’s Hospital in Boston, as well as an Associate Professor at Harvard Medical School and the Vice-Chair of Research in our department.
Dr. Ben O’Brien: Hi, my name is Ben O’Brien. First and foremost I’m a practicing clinician at the Bart’s Heart Centre in London. My specialty is perioperative medicine, which includes all aspects of critical care and cardiac anesthesiology for cardiac surgical patients. I am a professor of perioperative medicine with a particular research interest in AF after cardiac surgery, and I serve on the Council for the European Association of Cardiac Thoracic Anesthesiologists.
Together with Danny I’ve been the European co-chair of the Clinical Practice Advisory Group between the SCA and EACTA.
Dr. J. Danny Muehlschlegel: So the Society of Cardiovascular Anesthesiologists Clinical and Practice Improvement Committee, in collaboration with the European Association of Cardio Thoracic Anesthetists developed this multidisciplinary atrial fibrillation working group. Now this working group deserves a huge part of credit for establishing and creating this manuscript and this practice advisory.
It was composed of multidisciplinary practitioners, including cardiac anesthesiologists, electrophysiology, cardiologists, so EP cardiologists, as well as cardiac surgeons from the United States, Canada as well as from Europe.
Dr. Ben O’Brien: Thank you for listening to this podcast. It corresponds to the publication of our manuscript called Society of Cardiovascular Anesthesiologists, European Association of Cardio Thoracic Anesthetists, Practice Advisory for the Management of Perioperative Atrial Fibrillation in Patients Undergoing Cardiac Surgery. A bit of a mouthful, but the link to these publications can be found both on the SCA and the EACTA websites. The publication will appear in the January edition of Anesthesia Analgesia, as well as the Journal of Cardio Thoracic and Vascular Anesthesia.
Dr. J. Danny Muehlschlegel: Great Ben. Well, we’re going to get started to talk about our manuscript. Atrial fibrillation is the most common cardiac arrhythmia and affects approximately 33 million people worldwide. This prevalence leads to a 37% lifetime risk of developing atrial fibrillation, especially in those older than 55 years of age.
The healthcare costs are enormous. Just in the US alone it’s approximately $26 billion, and this is expected to double in the next 25 years. Now specifically in the cardiac surgical population, post-operative atrial fibrillation is the most common adverse event. And it increases with older age, increased surgical complexity and especially a past history of atrial fibrillation.
Across numerous studies, the instance of post-op atrial fibrillation is anywhere from 30 to 50%, depending on the type of operation. Ranging from the low end during CABG surgery, to anywhere to 50% and higher for valvular procedures. So despite multiple therapies, there aren’t many that have been shown to markedly reduce the incidence of post-op atrial fibrillation. We hope to show you some that have been shown to be effective, as well as reasons for others not being utilized.
Dr. Ben O’Brien: So Danny, if it’s such a common and relevant problem, one really would have thought that there will be ample and clear guidance around. But it seems that the guideline landscape is somewhat fractionated. And the subset of AF, that is AF after cardiac surgery, is often not the main focus of those guidelines, isn’t that right?
Dr. J. Danny Muehlschlegel: That’s right. Many of these guidelines—and we’re talking about guidelines dealing with cardiology and surgical patient in general—not so much the cardiac surgical patient and postoperative atrial fibrillation, have dealt with this. So as part of our study we looked at all the national and international guidelines with recommendations for the prevention and treatment of postoperative atrial fibrillation after cardiac surgery. We looked at those that were written in English and published by a society that’s directly involved in the care of these cardiac surgical patients.
Now this seems like a daunting task because there are many guidelines out there. But upon further review, we were able to narrow it down to just six guidelines. Now these six guidelines were published jointly by the most prominent societies out there. So it would take too long to list every single one of them. But they do include the societies for thoracic surgery, cardiac surgery, cardiology, electrophysiology, heart rhythm societies, spanning multiple countries and continents.
So this includes the United States, well as Europe and Canada. We reviewed these guidelines and came up with six that encompassed the newest recommendations. These are updated every several years. So we had to stop in 2018 when this manuscript was published. But we did include all recommendations with class 2B or better and level of evidence, ARB. Now to briefly review what we mean by this, so class of recommendations are – a class one would be evidence and – or general agreement that a treatment is beneficial, useful or effective.
So this is absolutely recommended and indicated. And the class 2B, which is where we drew the cutoff, would be that the usefulness and efficacy is less well established by evidence opinion, and it may be considered. So this still is a suggestion to use this recommendation, and it definitely will not cause harm.
As far as the level of evidence that we included, level of evidence A would be, this is the classic multiple randomized clinical trials or meta-analysis. And down to C would be just a consensus of opinion of the experts and/or small studies, retrospective studies and registries.
Dr. Ben O’Brien: All those data and all this information was then reviewed by the Clinical Practice Improvement Group. This is a multidisciplinary group that came together by the initiation of the Society of Cardiovascular Anesthesiologists, the SCA in the United States and was strengthened through a collaboration with the European Association of Cardiac Thoracic Anesthesiology, a professional group of cardio thoracic anesthesiologists in Europe that actually goes far beyond the geographical boundaries of Europe and includes members from Australia, South America, Africa and the Middle East.
So this multidisciplinary expert group included cardiac anesthesiologists from the two societies, but also cardiologists with an interest in heart rhythm disturbance and cardiac surgeons. So this group reviewed all the guidelines and the data that Danny just outlined. And the group hypothesized that practices seem to be variable or not always in line with this guidance that is available.
To corroborate this feeling we surveyed the SCA and the active membership and just to explore caregivers’ awareness of those guidelines and also the compliance with current best evidence-based care. The survey results was there are some methodological limitations with the survey, did support the idea that practices variable are not always consistently applied as best evidence-based strategies.
A good example of how heterogeneous practice is was the topic that we evaluated through the survey on beta blockers and their use for the prevention and treatment of AF after cardiac surgery. Continuing beta blockers throughout the pre and postoperative course has level one class A evidence behind it. So those are data that are derived from randomized control trials and the guidelines are unequivocal in their recommendation of usage of beta blockers in this context.
The survey results however did show that there seemed to be a bimodal distribution of what people actually do on the shop floor. So about a third of caregivers that responded to our survey stringently comply with this recommendation, yet another third rarely use beta blockers in this context. So whilst there are methodological limitations with the survey, it would suggest that practice is highly variable, and it’s not consistently applied despite best evidence.
Dr. J. Danny Muehlschlegel: You know Ben, I think that’s really astounding that we have these level one class A recommendations, yet a third of our practitioners aren’t adhering to them. What do you hypothesize is the reason for this?
Dr. Ben O’Brien: Well, you’re right Danny, it is rather surprising, and we did discuss it widely in the group. And really we came to realize that probably the plethora of guidelines that are out there and the fact that most guidelines as you mentioned mainly deal with a different subject matter and the specifics of AF after cardiac surgery are often just a small chapter within a wider guideline that deals with, say AF as a primary diagnosis or a particular cardiac surgical procedure. That all of that contribute to caregiver’s limited acceptance in implementation of the recommendations made.
So to overcome this barrier the group then decided to provide caregivers with an easy to access practice advisory. And Danny, maybe you just want to explain to us what the output there was.
Dr. J. Danny Muehlschlegel: Absolutely. So the practice advisory will be visible on our webpage at the Society of Cardiovascular Anesthesiologists, as well as in print. So it’s best to take a look at that directly. But briefly what we did was we divided it up into the prevention and treatment of atrial fibrillation. Now for the prevention of atrial fibrillation in cardiac surgical patients, all guidelines stratify between normal risk patients and elevated risk patients, yet don’t really give us any ideas of how to do that.
Nevertheless, there really isn’t any difference in prevention for those two, except for Amiodarone. So the prophylactic administration of Amiodarone would be a class of a recommendation 2A and the level of evidence for that is pretty strong. It’s A and B in the various guidelines. So that is recommended for elevated risk patients. Ben will tell us in a little bit what that actually means and how we came to define elevated risk for our practice advisory.
The other recommendations are the same for normal and elevated risk. So that would be continuing beta blockers to avoid withdrawal. It is a class one level of evidence A and B. And this includes the pre-op, interop and postoperative phase. So absolutely continue beta blockers on all your patients.
In addition, another class one recommendation would be the administration of beta blockers, which is unequivocally a level of evidence A. And this applies to the postoperative period. So as soon as your patient is able to tolerate it, beta blockers should be administered in the post-op period to prevent atrial fibrillation.
Now for the treatment of afib, there are also four recommendations that we’ve included in our practice advisory. So for one, we know as a class one recommendation would be the non dehydro purity in calcium channel blockers or beta blockers for rate control. We know that electrical or chemical cardioversion for hemodynamic instability is a class one recommendation. And then two class 2A recommendations would be Amiodarone for rhythm control, as well as the consideration of anticoagulation when the duration of AF exceed 48 hours.
Now we did not want to ignore the class 2B recommendations, which as I told you earlier, there is evidence for use. It may be considered, but it’s not the strongest level of recommendation. And those would be Sotalol, as well as post-op corticosteroids, post-op Colchicine and intra-op biatrial pacing.
Now many of you might question these recommendations because you are aware of recent literature showing that corticosteroids as well as Colchicine did not show significant evidence for utility in our patient population. But you have to remember that the goal of our practice advisory and of this manuscript was not to come up with new recommendations that we validate. But rather to critically evaluate the current guidelines and literature. So we did not take those studies into account. We focused on the existing guidelines. Now Ben, could you tell us a little bit more about how we divided up the normal versus the higher elevated risk patients?
Dr. Ben O’Brien: Sure Danny. So as Danny already explained, there is an evidence gap for the stratification of patients into normal or elevated risk categories. Several risk scores have been published, but they all have methodological shortcomings. So that there is currently no fully validated risk score with weighted risk factors in the public domain. There’s been extensive discussion about best (inaudible) within the expert group and laterally with the editors and reviewers from both journals in which this practice advisory is published.
And ultimately the feeling was that the best we can do at this stage is to list the six risk factors that are unequivocally recognized as elevating a patient’s risk for developing AF after cardiac surgery. So those are age, history of AF, renal failure, mitral valve surgery and mitral valve disease, heart failure and chronic obstructive pulmonary disease. We cannot at this stage put any weighting to these risk factors, but certainly as we will hear later, this is a work in progress as the evidence gap in this space has been clearly recognized during this work.
Dr. J. Danny Muehlschlegel: So Ben, these risk factors are interesting and can you tell us a little bit more about how we identified those? I know you said we didn’t want to weight them for reasons of not being able to validate them. But how did we come about picking those six? And if you had to choose two, which ones were by far the strongest risk factors for developing post-op atrial fibrillation?
Dr. Ben O’Brien: Yes, so in the absence of a fully validated risk score, we undertook a structured literature rich review of what has been published in this space of risk of AF after cardiac surgery. And after looking at all the published data, we recognized that there are six factors that are unequivocally recognized to elevate patient’s risk, as mentioned before.
Now out of those, the two that are definitely the strongest and come up in each risk score as a strong predictor of elevated risk for the development of AF after cardiac surgery are age, and this is a fairly continuous increase of risk with every year or every decade that passes, and of course previous history of AF, which feels intuitively right. That if a patient had already declared themselves as being susceptible to AF previously and prior to their cardiac surgery, that the risk of recurrence will be higher.
So Danny, whilst we hope and believe that this effort will make it easier to access current best evidence and for caregivers to familiarize themselves with what they probably ought to be doing if they want to practice in line with the current knowledge. There are certain limitations around all aspects of this manuscript, and we should probably freely acknowledge these and briefly discuss them. Danny, do you want to take this?
Dr. J. Danny Muehlschlegel: Sure Ben. So I think one of the main criticisms which is reflected in many surveys is the low response rate, which we acknowledge we also had in ours. So we would have loved for our membership to answer more questions and we have learned from our own mistakes. What we can say is despite the survey responses being on the low side, it corroborated what we discussed in our expert working group. That there’s a wide variability in practice patterns, which the survey actually reflected.
And his was not exclusive to academic versus private practice. This was across the board. So we do know we have a problem as a specialty. We do go into these practice patterns in our manuscript, and this would be too much to discuss why this is. But we can only hypothesize that there are multiple reasons for the lack of uptake. And we do sincerely hope that with our practice advisory with the manuscript and with this podcast, we can raise awareness for the importance of adhering to a set of guidelines.
In addition, the lack of a well validated risk score could also be seen as a detriment to applying the practice advisory. But we believe that just being more knowledgeable about the existing risk factors will help practitioners identify patients that might benefit from prophylactic Amiodarone use in the perioperative setting.
Dr. Ben O’Brien: So I agree with all the shortcomings you just mentioned. But on the upside, I do believe that the simplicity and the fact that we’ve tried to really distill the current best evidence into an easily accessible format, is one of the strengths of this publication. So to simplify it even further Danny and sorry to put you on the spot here, but if you could just reiterate three take home messages for the listeners of this podcast Danny, what would they be?
Dr. J. Danny Muehlschlegel: So Ben I think the three take home points would be number one, there is a wide variability of practice patterns, and they don’t reflect the existing guidelines. So I would urge practitioners to familiarize themselves with the guidelines. We have done our best to simplify them in our practice advisory as well as our manuscript.
Number two, the risk factors are real. Age is by far the biggest predictor for post-op atrial fibrillation. Atrial fibrillation is a huge problem. It is by far the number one complication and reason for increased morbidity in our patient population. So if you have a patient who is old and has a history of atrial fibrillation, every step possible should be taken to prevent them from experiencing this morbidity.
And number three Ben, I think the lack of a truly validated risk score that is applicable to many institutions. The problem with the current risk scores are that they’re highly specialized. They include risk factors that only certain institutions have. For example, beta blocker withdrawal or certain medications that are not common in many databases, make generalizability a big problem. Can you tell us a little bit more about what could be done and what we are doing to address this issue?
Dr. Ben O’Brien: Yes indeed. So the collaboration between the SCA and EACTA in this clinical practice improvement group, together with experts from other professional backgrounds, such as electrophysiology, heart rhythm disturbance cardiologist and cardiac surgeons, has largely been very successful and constructive. And it certainly shouldn’t stop with this publication. So the group will undertake further work to actually try and provide caregivers with a validated risk score. Now this will be a major project.
In the interim we do envisage that the clinical practice advisory as it currently stands will require further updates as new guidelines and new evidence emerges. So the group meetings will continue, and we will mainly focus on those two areas. The updates for the current practice advisory, as well as the development (inaudible) of a risk score that will hopefully fill the evidence gap that you’ve currently mentioned.
Dr. J. Danny Muehlschlegel: Thank you for those closing remarks Ben. So in summary I would encourage all practitioners who are interested in reducing the incidence of post-op atrial fibrillation after cardiac surgery to get involved with their societies, be it the Society of Cardiovascular Anesthesiologists or the European Association of Cardiac Thoracic Anesthesiologists and help us address this problem.
Dr. Ben O’Brien: And Danny and I would both like to thank our colleagues from the multidisciplinary working group, as well as the professionals from SCA and EACTA supporting us, and of course the editorial staff at ANA and JPDA. Thank you very much.
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