The Scoop on the New Syncope Guidelines

Peter Noseworthy, MD; Win-Kuang Shen, MD


May 08, 2017

Editorial Collaboration

Medscape &

Peter A Noseworthy, MD: Greetings, I am Dr Peter Noseworthy, an electrophysiologist at Mayo Clinic in Rochester, Minnesota. During today's commentary, we will be discussing the recently released [American College of Cardiology/American Heart Association] ACC/AHA Syncope Guidelines.[1] I am joined by my colleague, Dr Win Shen, who is the lead author of these guidelines and the chair of the division of cardiovascular diseases at Mayo Clinic in Arizona. Welcome, Win.

Win-Kuang Shen, MD: Thank you so much, Peter.

Dr Noseworthy: First off, congratulations on these guidelines. I know your team has put a lot of work into this, and speaking as a clinician, I know we are all going to be very happy to have some guidance on the issue.

Dr Shen: Yes, thank you. It took real teamwork for 2 years before we got to this point.

Goals of Syncope Guidelines

Dr Noseworthy: Yes. Now, syncope is common; 40% of us will have syncope at some point in our lives. I was surprised to see that these were the first formal guidelines from the AHA and ACC regarding syncope, but why do you think they were so long in coming?

Dr Shen: That is a great question, and I can give you only my perspective. Syncope is so common, and it is a symptom. So, it can be associated with many conditions. In the past, there were reviews, summaries, and statements from different societies. The AHA, ACC, and the Heart Rhythm Society published a scientific statement onsyncope about 10 years ago with a focus on sudden death prevention.[2] So, when the syncope proposal was put forth to the guideline task force at ACC and AHA, it was immediately recognized that we should provide a more comprehensive recommendation for this very diverse patient population. So, this was commissioned about 2 to 3 years ago and we started working on this paper.

Dr Noseworthy: Syncope, of course, is a very broad topic, so what were your overall goals of these guidelines?

Dr Shen: There were several. The first goal was to set the standard definition for syncope and many other associated conditions. The reason that was so important is because if you look at current papers and studies, the definitions for different conditions can vary quite a bit.

The second goal, of course, was to recommend and set the standard practice for a large body of physicians and healthcare providers: cardiologists, electrophysiologists, internists, neurologists, and emergency-room physicians. And in this document, we also included the pediatric population.

The third was to identify some of the areas where we are in need of additional data and to then facilitate future clinical studies. These were the three main goals.

Diagnosis: How Much Testing is Sufficient?

Dr Noseworthy: Getting to the meat of the guidelines, let us start with making a diagnosis. One challenge in syncope is how much testing to do. We try to avoid unnecessary testing. Can you tell me what is essential in the workup for everyone with syncope?

Dr Shen: You will see that the writing committee came to a consensus uniformly recommending that a detailed history and examination for the initial evaluation is obligatory. Second is that, after a lot of debate and deliberation, we recognized that even though the diagnostic value of electrocardiogram (ECG) is at a low yield, it does carry a significant prognostic value. So we also recommended ECG as part of the initial evaluation. And it is absolutely correct that in this guideline, you will see that we recommend not doing broad diagnostic testing or broad blood tests and imaging modalities.

Dr Noseworthy: For patients with clear-cut vasovagal syncope, a history and physical and an ECG is sufficient.

Dr Shen: That is correct.

Dr Noseworthy: Are there any tests that are not recommended, the class III recommendations, for instance?

Dr Shen: There are several class III recommendations, but perhaps I should qualify what I am going to say by saying that we frequently evoke the phrase "in selected patient populations."

For instance, we made a recommendation not to do broad blood testing in patients presenting with simple and vasovagal syncope. On the other hand, if a person comes in with chest pain, of course, additional blood testing should be considered. The other areas that we made class III recommendations in would be imaging. For instance, we do not recommend broad-scope cardiac imaging, computed tomography (CT), or MRI for patients with a normal ECG without a prior history of heart disease. And we also recommend not doing broad neurological imaging like carotid ultrasounds, CT scans, and MRI scans of the head and neck.

In the ED: To Admit or Not to Admit

Dr Noseworthy: In the emergency department, a common challenge is who should be admitted to the hospital. Do the guidelines give any recommendations on this?

Dr Shen: Yes, in this guideline, we made very clear recommendations in a summary table of "serious medical conditions." If a patient presents with one or more of the conditions that are listed as serious medical conditions, then admission to the hospital would be recommended. These are fairly intuitive. For instance, a patient presented with syncope, with ventricular tachycardia, or a patient presented with syncope and although that etiology has not been confirmed, it was associated with serious head trauma. These are the conditions that admission for evaluation should be considered.

Electrophysiology and Tilt-Table Testing in Select Patients

Dr Noseworthy: As an electrophysiologist, I find that we are doing fewer and fewer EP studies, but there is still probably a role for an EP study in selected patients. Can you expand on that?

Dr Shen: Yes, EP study, as we know 20 or 30 years ago, was viewed as the "court of final appeal" for syncope evaluation. Through the years, we learned the value of the EP study and that perhaps the sensitivity and specificity vary depending on different conditions.

The second reason that the EP study has decreased through the years is because, as we know, patients with structural heart disease with nonischemic cardiomyopathy with reduced ejection fraction (<35%) with or without syncope—these patients qualified for an implantable cardioverter defibrillator (ICD). Furthermore, we have so many different monitoring devices today that allow us to monitor these intermittent episodes.

As a result, the value of the EP study has diminished. But in patients after myocardial infarction and with a preserved ejection fraction at say 30% or 45%, EP study can be useful.

Dr Noseworthy: Similarly, for tilt-table testing, although we still do tilt-table testing at Mayo Clinic—and I know other centers do—some have entirely abandoned the process or the test altogether. What are the recommendations for tilt-tablet testing?

Dr Shen: Most times, the diagnosis of vasovagal syncope can be made after a thorough initial evaluation with a history and physical examination. In patients where the recurrent episodes are not very well defined or when the presentation is not typical of vasovagal syncope, tilt-table testing can be useful.

Management of Recurrent Vasovagal Syncope

Dr Noseworthy: Moving on, the management of recurrent vasovagal syncope is a major challenge for cardiologists, and the various therapies—beta-blockers, [fludrocortisone] Florinef, midodrine, selective serotonin-reuptake inhibitors (SSRIs), pacemakers, compression stockings, salt tablets, and so on—have had limited benefit. What are the evidence-based recommendations for management of recurrent vasovagal or neurocardiogenic syncope?

Dr Shen: You already mentioned the use of pharmacological interventions. When we reviewed the evidence, sure there are some clinical trials and many observational studies. But if we combined the scope, the quantity, and quality of the data, most of these recommendations for pharmacological therapy actually became a class IIb.

We made one class I recommendation based upon expert opinion, and that is to educate the patient to ensure they understand that vasovagal syncope, overall, is a benign condition. If [patients] can prevent triggers and pay attention to the initiating prodromes, then vasovagal syncope can often be prevented.

Dr Noseworthy: Should any of these patients receive a pacemaker?

Dr Shen: Yes, a lot of studies have been performed—randomized trials, double-blinded, and non–double-blinded studies. As a matter of fact, this was the question we put forth to the evidence review committee, and you were a member of the writing committee on the evidence review. We did extensive literature research, and we specified the studies as to their type, duration, and whether the inclusion/exclusion criteria meet the criteria to be analyzed in the meta-analyses.

After this process, the writing committee for the guidelines [decided to categorize pacemaker implantation] as a class IIb recommendation in patients who are older than age 40 with recurrent vasovagal syncope with documented spontaneous pauses.

Dr Noseworthy: What qualifies as a significant pause for pacemaker implantation?

Dr Shen: They followed the exact definition from the clinical trials, and that is when the documented pause associated with symptoms of syncope is defined as ≥3 seconds. And in a person without syncope, a [significant] pause is documented to be ≥6 seconds. Those situations would qualify as a pause, and the pacemaker could be considered in patients with recurrent syncope and older than age 40.

Driving After Syncope

Dr Noseworthy: Another thing that comes up a lot in practice is driving. Do these guidelines make recommendations about driving after syncope?

Dr Shen: This was a very, very important topic but, at the same time, very challenging. The writing committee discussed, deliberated, and reviewed extensively the evidence. We could not reach the level of consensus on recommendations.

After discussion with the task force committee, with the chair of the task force, and after reviewing all of the evidence, we did the following:

  1. We made one recommendation that physicians and healthcare providers should be familiar with both the local and federal laws about driving after syncope.

  2. When it comes to commercial driving, we recognize that it is not the healthcare providers who are making the recommendations about commercial drivers, but it is the Department of Transportation, which has strict guidelines about whether commercial drivers could drive. So we defer to federal law from the Department of Transportation.

  3. When it comes to private driving, the writing committee made a summary table of all of the conditions to suggest that, after an observational period without recurrent syncope, the patients would be allowed to resume driving. There was no formal recommendation for private driving, but we did make suggestions with a summary table.

Dr Noseworthy: Thank you. That is very useful. I would like to thank Dr Shen for joining us today to review the new ACC/AHA Syncope Guidelines, and thank you for joining us on on Medscape.


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