EP Guidelines

New 2017 ACC/AHA/HRS Syncope Guidelines: Interview with Dr. Win-Kuang Shen

On March 9, 2017, guidelines on the evaluation and management of patients with syncope were issued by the American College of Cardiology, with the American Heart Association and Heart Rhythm Society. In this brief interview, we speak with Win-Kuang Shen, MD, FACC, FAHA, FHRS, chair of the writing committee. The guidelines were developed in collaboration with the American College of Emergency Physicians and Society for Academic Emergency Medicine, and were copublished in the Journal of the American College of Cardiology, Circulation, and Heart Rhythm.1

What are the goals of these published guidelines? 

The 3 main goals were to 1) define syncope as a symptom, with different causes, in different populations and circumstances; 2) provide guidance and recommendations on the evaluation and management of patients with suspected syncope in the context of different clinical settings, specific causes, or selected circumstances, and 3) identify key areas in which knowledge is lacking, to foster future collaborative research opportunities and efforts. 

Tell us about the demographics associated with syncope. How prevalent is syncope, and what patients is it most common in? 

Syncope is common — occurring in thousands of patients every day. One-third to one-half of the U.S. population have experienced syncope at some point in their lifetime. 

The prevalence of syncope follows a bimodal or a trimodal distribution in the general population. It occurs frequently in the young and elderly. Gender distribution is somewhat variable. 

In the initial evaluation of patients with syncope, a detailed history and physical examination should be performed. Tell us about some of the characteristics more often associated with cardiac causes of syncope. 

I would refer your readers to the guidelines for a complete review and list. In brief, there are clinical characteristics (by a detailed hx) that are fairly typical for different causes of syncope. For instance, this would likely include a young patient who felt lightheaded before fainting after standing in the hot sun while at an outdoor concert. This is fairly typical for vasovagal syncope (common faint). No additional, extensive evaluation is necessary after reassuring the patient. For an older patient with a history of heart disease, who had syncope after feeling palpitations while in the chair watching TV, their history warrants additional evaluation.

If the initial evaluation suggests CV abnormalities, what additional testing is recommended for evaluation and diagnosis of syncope? 

In brief, there are several approaches based upon the initial evaluation, including additional evaluation for diagnosis (cause of syncope) and prognosis (what is the patient’s risk of recurrent syncope, trauma associated with syncope or mortality). In the guidelines, recommendations of additional diagnostic and prognostic evaluation are made.

What are the Class I recommendations for managing patients with ARVC or long QT syndrome? 

Class I recommendations are aligned with previously published guidelines on these specific conditions (if already existing), in the context of syncope. It is critically important to differentiate (but not to separate) the evaluation of the cause (diagnosis) of syncope and the future risk of sudden death (prognosis) in these congenital conditions. For instance, a patient with LQTS could have a vasovagal syncope that is benign. This patient’s risk of sudden death will need to be assessed by established risk stratification schemes for this condition.

What are the Class I recommendations for special populations such as pediatric patients or athletes who experience syncope? 

At large, recommendations (not always Class I) are made to seek additional evaluation from healthcare providers who have expertise in patients who belong to these special populations. 

Describe some of the Class III recommendations in these guidelines that showed no benefit.

Class III recommendations are important. Broad approaches with blood (laboratory) testing, and cardiac and neurological imaging are not recommended. Although these approaches are minimally invasive (low risk), there is no benefit.

What Class III recommendations were included in these guidelines as showing harm? 

Invasive testing without established indications would potentially do harm to patients. One example would be doing EP studies or implanting cardiac devices without indications.

What are some of the knowledge gaps identified by the writing committee that are still present in the evaluation and management of patients presenting with syncope?

Several areas require investigation. Just to highlight a few, there is now a provided definition of syncope and other associated conditions, so we can better determine the types and epidemiology of syncope in different populations. We will need focused data on risk stratification and clinical outcomes divided according to the underlying disease. New monitoring technology is rapidly evolving. The role of these devices needs to be determined by randomized clinical trials. Furthermore, there are uncommon conditions associated with syncope with increased risk of sudden death. We need to identify how to best evaluate these patients. Finally, we need further investigation in specific populations — the young, the older, athletes, etc. — in order to improve efficiency and effectiveness of evaluation and treatment.


  1. Shen WK, Sheldon RS, Benditt DG, et al. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. J Am Coll Cardiol. 2017 Mar 9. pii: S0735-1097(17)30792-1. doi: 10.1016/j.jacc.2017.03.002. [Epub ahead of print]