New AHA Syncope Guidelines - Spoon Feed

Written by Thomas Davis, MD.

Spoon Feed
The new AHA syncope guidelines have useful information for us clinically, but slogging through this 232 page tome wasn't easy. Thomas Davis highlights what's most important.  This is a huge time saver - take advantage of this.

Buckle up for this whirlwind syncope tour

1.  H&P - Start with a good history and physical including orthostatic vitals.

  • History: Ask about preceding symptoms that may raise your suspicion of SAH, PE, thoracic aortic dissection, or ACS since up to 10% of these conditions will present with syncope.
  • Physical exam: Listen closely for a murmur. Check orthostatic vital signs on standing - classic orthostatic hypotension (OH) - and 3 minutes later, delayed OH.

2.  Keeping Score - The AHA states that scoring systems (e.g. San Francisco Syncope Rule, Boston Rule, Syncope Risk Score, etc.) identify patients at increased risk of serious events within the next 1 week to 1 year but do not identify patients who benefit from inpatient admission. Therefore, it offers its own criteria for observation and admission. Yet as we will see, its criteria for admission are strikingly similar to the San Francisco Syncope Rule.

3.  Obs Units - Based on a couple small RCTs in Circulation and Annals of Emergency Medicine, the AHA calls for the formation of a “structured ED observation protocol” or observation unit for patients with intermediate risk. This unit allows for telemetry, echocardiography, +/- tilt table testing, and cardiology/EP consultation. Intermediate risk was defined as: age > 50, prior cardiac disease, abnormal ECG such as bundle branch block or Q waves, family history of early sudden cardiac death, cardiac device without evidence of dysfunction, and symptoms not consistent with reflex-mediated or vasovagal syncope.

4.  Admission Criteria - The guidelines suggest several types of patients who are higher risk and may warrant hospital admission (Table 7), which I have re-organized as “modified San Francisco Syncope Rule” using the ubiquitous CHESS mnemonic.

  • CHF: acute heart failure or moderate to severe LV dysfunction (50% of these patients have arrhythmias
  • Hematocrit or hemorrhage: severe anemia or GI bleed
  • ECG abnormalities (see links to Dr. Smith's ECG blog for examples)
    • Cardiac ischemia
    • VT or SVT
    • Symptomatic bradycardia or sinus pauses
    • Symptomatic conduction system disease
    • ICD/pacemaker malfunction
    • Inheritable/congenital arrhythmias
    • Short QT (QTc < 340ms)
    • Long QT (QTc > 500ms or QTc > 480ms in setting of syncope)
    • WPW
    • Brugada
    • ARVC, aka ARVD (arrhythmogenic right ventricular cardiomyopathy or dysplasia)
    • HCM (hypertrophic cardiomyopathy)
  • Shortness of breath - Consider pulmonary embolism, aortic stenosis or other valve dysfunction, ACS, tamponade
  • Sustained abnormal vital signs

5.  Outpatient Monitoring - Outpatient monitors should be selected based on the frequency of syncope and the duration of a prodrome. Holter monitors are only useful if they are likely to capture an event within 24-72 hours. Otherwise, patients should be referred for one of several monitoring options such as event monitors, patch recorders, or implantable cardiac monitors (ICM). New data suggest that ICMs have a higher diagnostic yield (55% vs 19%) than conventional workup, which includes external loop recorder followed by tilt table testing and electrophysiological study.

6.  Falls in Elderly - As many as 30% of unexplained falls in elderly patients may be due to syncope. Use caution in elderly patients who fall and maintain suspicion for syncope.

7.  Vasovagal syncope: This is the most common form of syncope in the general population. Preferred initial treatment includes trigger avoidance, reassurance of benign nature, and teaching physical counter pressure movements. These maneuvers include leg crossing, limb/abdominal contraction, and squatting. Patients with recurrent VVS may be prescribed other medicines, particularly midodrine if no history of HTN, heart failure, or urinary retention.

8.  Carotid sinus syndrome: This is potentially the most common cause of syncope in the elderly population based on some studies referenced in the AHA guidelines. There are three subtypes: cardioinhibitory (sinus pause > 3 seconds), vasodepressor (drop in systolic blood pressure > 50 mmHg), and mixed. Diagnosis is made by longitudinally massaging each carotid artery sequentially (not simultaneously) for 5 seconds and checking vitals. However, do not perform this test if the patient has a history of CVA, TIA, or ACS unless carotid artery disease has been excluded. You may want to refer these patients for tilt table testing where this test is routinely performed.

9.  Orthostatic hypotension is most commonly due to dehydration and medicines. However, a substantial subset of patients has neurogenic OH due to diabetes, Parkinson’s or other neurodegenerative disease. For all types, ED treatment should include avoidance of precipitating medicines, physical counter pressure maneuvers, and oral fluid loading which is preferred to IV hydration given its pressor effect. For neurogenic OH, plain water (250-500 mL) is preferred to maximally increase blood pressure. For dehydration causing OH, a more physiologic salt solution (e.g. Gatorade) offers faster rehydration. 

10.  Driving Rules - See Table 10 for how long patients should stop driving following certain types of syncope. In general, all types of syncope should wait at least one month to drive (aka "do not drive until you see your PCP/cardiologist") unless it is vasovagal syncope with no prior syncopal events in the past year. These recommendations do not supersede local driving laws.

2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2017 Aug 1;136(5):e60-e122. doi: 10.1161/CIR.0000000000000499. Epub 2017 Mar 9.

Peer reviewed by Clay Smith, MD.