New guidelines on ventricular arrhythmias and sudden cardiac death were recently released by the main cardiology organizations in the US and Europe; these updated recommendations provide consensus on the management, treatment, and prevention of these heart-related conditions. In this feature interview, we speak with Dwight W. Reynolds, MD, FHRS, and President of the Heart Rhythm Society, about how the guidelines have changed. Dr. Reynolds is also a professor and chief of cardiology at The University of Oklahoma College of Medicine in Oklahoma City. 

Why was it important for the medical community to clarify sudden cardiac death (SCD) from heart attacks? Do you think there is still some confusion in the non-medical community regarding recognizing sudden cardiac arrest (SCA) and SCD?
       I think there is no question that there is confusion about the relationship between SCA and heart attacks in the lay public. I think the medical community grasps it pretty well, though perhaps not having completely mastered the latest nuances of the indications for prevention; however, it is problematic for the lay community to understand, and it is our responsibility to fix. I believe that many times when people think about sudden cardiac arrest, they think about it as being a heart attack, and unfortunately we in the medical community have been lax in correcting that misperception. We’ve done better over the last several years as we’ve become a little more engaged on the prevention of sudden cardiac arrest. We are doing a better job, but I think we still must work to educate the public about the differences and the relationships between the two.

How have the guidelines changed? For example, one of the changes includes recommendations for a range of ejection fractions for device/ICD implantation. Please describe.
       What has happened over the last few years is that we’ve seen several studies completed and published that have specifically focused on primary prevention of sudden cardiac arrest — in other words, the prevention of cardiac arrest in patients in whom there has not been a previously known sustained ventricular arrhythmia or a previous history of cardiac arrest. These studies used different left ventricular ejection fractions (LVEF) for inclusion criteria. The new guidelines provide some cohesiveness to the topic of ejection fractions in spite of some heterogeneity in the studies; specifically, the writing committee has tried to provide a range of EF values rather than a single value in defining a criterion for implantation of an ICD in a SCA prevention indication. For example, there have been studies that used a left ventricular ejection fraction of equal to or less than 30%, some that used equal to or less than 35%, and others that have used less than 40%. What the new guidelines recommend specifically about primary prevention is: less than 35–40% range in Class II and Class III heart failure patients is a Class I indication, and less than 30–35% in patients that are Class I heart failure status are a Class IIa indication in patients with previous MI and an ischemic cardiomyopathy and Class IIb in patients with non-ischemic cardiomyopathy. This is just an example — the authors of the guidelines have given a range that recognize that these studies used different ejection fractions. However, what is important to understand is that measurement of LVEF, with most of the methodologies, isn’t so precise that statistically speaking there can be a big difference in an individual patient; for example, using echocardiography, one patient can be said to have a 35% ejection fraction by one and a 40% ejection fraction by another interpreter. Current measurement techniques are good, but they are not so precise that two different people might not measure or interpret ejection fraction a bit differently.

The issue of sudden death in athletes also remains a hot topic. For example, one recommendation suggests performing a 12-lead ECG and possible echocardiography in athletes as preparticipation screening for heart disorders. Is this a new guideline? What is the general consensus on this recommendation and other recommendations for athletes?
       The recommendation you mentioned is a Class IIb recommendation. First, though, let me quickly talk about the different classifications of recommendations for those who might not understand. Class I describes the classification in which there is general agreement in favor of doing something; it doesn’t necessarily mean that you have to do the Class I recommendation, but you need to be able to explain why you didn’t if you make the decision to not follow the recommendation. Class II describes a divergence of opinion with subsets “IIa” and “IIb”. Class IIa describes the situation in which, while not unanimous, there is general consensus in favor of usefulness, and IIb the situation when the support for the recommendation is generally less than that. There are also levels of evidence: “A” in which there are two or more studies that validate the recommendation, “B” in which there is only a single study in support, and “C” in which support is based on opinion and practice but without compelling studies.
       To talk specifically about athletes, the Class I recommendations ask for a history and a physical. For any athlete who experiences any type of symptoms or has evidence of an arrhythmia or underlying heart disease, there is a recommendation for a more extensive evaluation. In addition, any athlete who passes out should certainly be evaluated more completely, and any athlete who has serious symptoms should not compete until they are fully evaluated.
       There is no IIa recommendation for testing in athletes, but there is a IIb recommendation that suggests performing a 12-lead ECG and possible echocardiography on athletes. Here is where the crux of the problem is. This is an issue that has been debated heavily, and there are several different views of this, including differing views on both sides of the Atlantic. For instance, the Italians have been leaders in screening of athletes for problems. However, in the US, the magnitude of a requirement to screen with electrocardiograms and possibly echocardiograms for every child that is going to compete in athletics is somewhat overwhelming. The cost-benefit ratio of doing that is at issue — overall, the view historically in the US is that routine ECG and echocardiographic testing is not very cost effective. Therefore, in general, if one has any kind of a suspicion that there is a problem, whether that suspicion is based on symptoms, a family history of rhythm problems or of sudden cardiac death or unexplained significant murmurs, then a more extensive evaluation potentially with ECG and echocardiography certainly makes sense. However, it is not a Class I or Class II indication to screen everyone who is planning to compete with ECG and echocardiography.

What, if anything, has changed in the pharmacological treatment of ventricular arrhythmia (VA) or SCD?
       Not a lot has changed in the past year or so. We already know from several significant studies, most recently SCD-HeFT, that current pharmacological agents do not have a major role to play in preventing sudden cardiac death. However, we do know that beta blockers can be helpful; there are some types of ventricular arrhythmias that can be very effectively treated with beta blockers, even to the point where an implantable defibrillator might not necessary. However, generally speaking, the vast majority of SCA and the causative arrhythmias associated with it occur in patients with structural heart disease such as ischemic or hypertensive damage to the heart muscle, and pharmacologic therapy just isn’t effective in preventing or treating them; I think the new guidelines highlight that. There is still use of antiarrhythmic drugs as adjunctive therapy for ICD patients who are having frequent episodes requiring shocks to try and reduce those shocks. You can also make a case based on the guidelines for patients in whom an ICD can’t be implanted for whatever reason or the patient decides not to have an ICD that antiarrhythmic drugs can be considered, but I think these guidelines really emphasize the fact that antiarrhythmic drugs haven’t been helpful so far. There are new drugs on the horizon, but so far we haven’t seen any antiarrhythmic drug that is adequately preventative of SCA.

Is there any one example in which recommendations for diagnosis or treatment of VA or SCD have changed dramatically?
       I don’t believe there is anything extremely dramatic in the new guidelines, at least compared to the way we have been managing patients for the last couple of years. One exception in these guidelines that is a bit different, though, is that resynchronization therapy — with or without defibrillation — is considered a Class IIa indication for patients that are considered Class III or Class IV heart failure patients. This is an issue that I’m sure was a challenge for the writing group — it relates to the differences in the way we approach patients for primary prevention of sudden cardiac arrest in the US versus in Europe. In the US there is a much greater use of ICDs in primary prevention of sudden cardiac arrest than is the case in Europe. In the new guidelines, biventricular pacing, even without ICD therapy, is considered reasonable (Class IIa) for the prevention of sudden cardiac death in patients with NYHA functional Class III or IV with a LVEF less than or equal to 35% and a wide (?120 ms) QRS complex. In the US, we would be much more likely in that population of patients to implant biventricular ICDs, whereas in Europe, biventricular pacemakers are more frequently chosen.

Why is it important to have a streamlined, joint document for all cardiology groups worldwide? What were some of the ways European guidelines for treating VA and SCD were different?
       If you think about it, most of these are common illnesses throughout the world, so it is important for the whole international community to come together on these guidelines. From a practical standpoint, it is somewhat difficult to engage more than the US and Europe in these writing committees; the discipline of heart rhythm management or electrophysiology is much further along in terms of regulations and documentation in North America and Europe than they are anywhere else. However, sudden cardiac arrest is caused by a heart attack in the US just the same as in Zurich or in Beijing or in Buenos Aires. Therefore, the more collaborative we can be, the more widely accepted the recommendations will be.

Do you know of any new or ongoing trials in electrophysiology that continue to study VA and SCD?
       There are quite a few studies that are focused on subset populations at risk for sudden cardiac arrest. Many of those are focusing more on the value of biventricular pacing in different subsets of populations, but I’m not aware of any new or larger trials that are looking at the issue of primary prevention of sudden cardiac arrest. I believe we’ve addressed some of the main issues affecting big populations, such as heart attack and heart failure, but some genetic conditions such as long QT syndrome, hypertrophic cardiomyopathy, Brugada syndrome, and ARVC need more focus and research. Some of these disorders, though, don’t lend themselves well to big trials because there are just not that many patients with them. Management of these disorders remains controversial, not in small measure due to the relative infrequency of the problems.
       One of the technologies on the horizon involves ICDs without intravascular leads. At least two or three companies are working on subcutaneous ICDs that do not have leads placed in the heart. I’m not sure yet if this new technology will be evaluated in large trials, but it is one possibility for large clinical trials in the future in terms of primary, if not secondary, prevention of sudden cardiac arrest.

Will these new guidelines help physicians treat VA and SCD more aggressively?
       These are the best set of recommendations that can be relied upon to guide and support decisions to do what is right, as best we understand it today, in late 2006. There are always challenges in educating the vast array of physicians who are involved in the care of patients at risk of SCA. We’ve proven that SCA is a problem that can be addressed with modern technology. While much remains to be accomplished in understanding and predicting SCA risks, it is important that we attack the problem as best we know how. Dissemination of the guidelines certainly will help. The Heart Rhythm Society has SCA as one of its principal targets for the coming years and I anticipate a major initiative by HRS in this area that will help with education and, in turn, prevention of this most important health problem.

I see that the guidelines for patients with supraventricular arrhythmias and atrial fibrillation (AF) have also been addressed in separate documents. What are some of the ways in which the guidelines for these patients have changed or been updated?
       For non-AF supraventricular arrhythmias, we’ve known for some time now that cure rates with catheter ablation are very high and have relatively low complication rates. However, the real news right now with supraventricular arrhythmias is the changing shoreline with catheter ablation as a treatment for atrial fibrillation. The Heart Rhythm Society (HRS) is extremely focused at this time on the problem of atrial fibrillation. Most of us believe that we know how to approach non-AF supraventricular arrhythmias fairly well; however, atrial fibrillation remains a bit of a conundrum. Therefore, HRS made the decision this past spring to spend this entire year on what we’re calling “Atrial Fibrillation 360”; during this time we hope to create consensus and consistency about how to manage atrial fibrillation. By acknowledging atrial fibrillation as a disease that has an immensely varied spectrum and is caused by a number of different problems — not unlike sudden cardiac arrest — we know that there won’t be a single approach to atrial fibrillation that fits all sizes. In acknowledgement of the evolution in techniques and efficacy in catheter ablation of atrial fibrillation, the Heart Rhythm Society also has convened a task force of international experts in the field to aggressively develop and publish a consensus document on this topic. We anticipate this document will be published in May 2007. We expect it to be the sentinel guide for catheter ablation of atrial fibrillation and will be consistent with the recently released guidelines on the broader topic of atrial fibrillation. Additionally, the HRS is holding an “AF Summit”, which will be a two-day meeting during our May 2007 Scientific Sessions in Denver. For those who want to be educated on the topic of atrial fibrillation, this will be a very comprehensive look at atrial fibrillation.
       HRS is working on two other projects on atrial fibrillation: one is with the FDA on regulatory issues of catheter ablation of atrial fibrillation, the other a public educational initiative in atrial fibrillation.

How far have we come in successfully treating SCD? In what areas do we still need more research?
       We know the best thing we can do, obviously, is to prevent it, and the best way to prevent it is to effectively treat the underlying causes, not just treat the associated arrhythmias. To be truly successful in this area we must treat the coronary disease and prevent heart attacks, treat high blood pressure and valvular heart disease that can eventually lead to a high risk of SCA. It is always much better to prevent a heart attack, and in doing so prevent the damage to the heart muscle that leads to SCA, than it is to wait and have to treat SCA. It is the same with treating hypertension — this is a risk factor for coronary disease and thereby heart attack, but it is also a major risk factor for developing heart failure even without heart attacks. Therefore, by treating the hypertension, we can prevent the structural problems with the heart that lead to a high risk of SCA.
       Having said all of that, the evolution and availability of ICDs has been incredibly important, and I think this exciting and effective therapy brings a lot of appropriate focus to the problem of SCA. One of the historical problems before the existence of ICDs is that we didn’t have a very effective way of obviating risk in the high-risk patients. There was little we could do when a patient needed preventative SCA therapy. However, with ICDs we do have effective therapy. We have proven that it is useful in treating SCA, so we are more focused on it now.
       The other part of this that is important and probably needs further evaluation is how we get to better acute resuscitation of SCA patients in the public more successfully. Unfortunately, for a majority of patients, the first awareness that they have of the risk of SCA is the sudden cardiac arrest event itself; there is no warning. Certainly public education about SCA and the risk factors of SCA are important. However, we also need to figure out ways in the population at large to be more successful in resuscitation of patients who experience cardiac arrest in the field — this potentially involves public access defibrillation with dissemination of both EMT services and automatic external defibrillators (AEDs). We know that we have to get SCA patients resuscitated extremely quickly, literally within a matter of minutes of “going down”, and get them successfully resuscitated. I think you’re going to see a greater emphasis on this over the coming years.

It seems as though atrial fibrillation and SCA are the two main issues that still need to be addressed and researched.
       You have it right. These are the two biggest heart rhythm issues — they are not the only two, but they are the biggest ones right now in which we still have a lot of work to do.