Primary Care Corner with Geoffrey Modest MD: Syncope Guidelines

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By Dr. Geoffrey Modest

Finally a guideline on syncope management (See http://www.onlinejacc.org/content/early/2017/03/03/j.jacc.2017.03.003​ ​, or 10.1016/j.jacc.2017.03.003), these from the Am Heart Assn/Am College of Cardiology. Many of us, I think, have been relying on suggestions from such sources as UpToDate, which are not rigorously evaluated and validated by at least a semi-independent association (the American Heart Association, though does have intrinsic potential biases for more cardiologic workup and investigation than a truly independent organization such as the National Institutes of Health in the US or National Institute for Health and Care Excellence NICE in the UK, does take the issue of upfront conflicts of interest more seriously than most other specialty groups, in this case with neither the chair nor vice-chair with any stated conflicts of interest, as well as 8 of the 15 committee members without stated conflicts).

Details:

  • Syncope is a common condition: estimates of prevalence as high as 41%, recurrent syncope in 13.5%. Mayo Clinic report of 19% prevalence in selected community residents over 45 years old (mean age of 62, more often in females, 22% vs 15%). Trimodal age distribution: first episode age 20, 60, or 80 yo. Different etiologies by age: older people more often associated with cardiac causes/meds/comorbidities: esp aortic stenosis, renal dysfunction, AV or left bundle-branch blocks, and meds associated with orthostatic hypotension. Also syncope in 12-15% of those with heart failure. younger people: more likely noncardiac
  • Initial evaluation:
    • History
      • Focus on prognosis, diagnosis, reversible or amelioratable factors, comorbidities, medication use, and patient/family needs
      • Prognostic factors depend on separating neural from cardiac causes (the latter being worse), assessing prodromal symptoms (e.g. the most common cause of syncope being vasovagal, a reflex syncope that has typical features of upright posture, exposure to emotional stress, pain; associated with diaphorsesis, warmth, nausea, pallor), family history, meds and comorbidities
    • PE
      • Especially orthostatic blood pressure and pulse changes, murmurs/gallops/rubs, basic neuro exam for focal abnormalities that would lead to a more detailed exam
    • ECG
      • Especially bradyarrhythmias with sinus pauses or high-grade conduction block; ventricular tachyarrhythmias. Or arrhythmogenic substrate (WPW, Brugada, long-QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy ARVC)
    • Then risk assessment
      • Stratify by cause of syncope/reversibility of underlying condition (vasovagal has better prognosis than heart failure with preserved ejection fraction, which is better than advanced cardiomyopathy, which is better than acute aortic dissection)
      • Data not really available on stratifying by high vs intermediate vs low-risk groups. There are some data on short and long-term risk factors (30 days after ER visit or 12 months later, showing the usual culprits
        • Short-term: male, older than 60 yo, no prodrome, prior palpitations, exertional syncope, history of structural heart disease, heart failure, cerebrovasc disease, fam history of sudden cardiac death, persistent bleeding, positive troponins
        • Long-term: many of same, but added diabetes, high CHADS-2 score, cancer, low GFR
        • And there are some studies suggesting “risk scores”, but they have different definitions of syncope, outcomes, etc., so not so practical, but typically include some of the above: age cutoff (45 or 65), abnormal ECG, prodrome, exertional, signs of volume depletion, etc.
      • Further testing: costly and often ineffective as a general rule and should be guided by the above initial exam. in particular, if the initial exam is not reasonably definitive:
        • Targeted blood testing:
          • CBC and lytes have low yield when done routinely, and should be guided by history/physical (moderate recommendation, nonrandomized trials)
          • Brain natriuretic peptide and troponins, uncertain evidence, though they do comment that BNP “is elevated in patients whose subsequent cause for syncope is determined to be cardiac”
        • If eval suggestive of cardiovascular abnormalities, consider further cardiac workup (not recommended as routine)
          • Transthoracic echo, if structural heart disease suspected, esp valvular disease, HCM, LV dysfunction (moderate recommendation, nonrandomized trials)
          • CT/MRI: MRI if suspect infiltrative disease such as sarcoid, or if suspect ARVC; CT esp if suspect pulmonary embolism (weak recommendation, nonrandomized trials)
          • Stress testing: esp if syncope during exertion (moderate recommendation​, limited design)
          • Cardiac monitoring: if suspected arrhythmia, choice dependent on likely timing of next syncope (Holter if likely in next 24-72 hours, others if longer). (moderate recommendation​, limited design). BUT they do push some for implantable cardiac monitors, which has the highest yield for those with no answer from noninvasive testing (moderate recommendation, with RCTs)
          • In-hospital monitoring: good to do telemetry
          • Electrophysiological studies: recommendations based on older studies. Can be useful in those with syncope from suspected arrhythmia, mostly useful in those with structural heart disease (yield of 50% vs 10%). (Moderate recommendation, nonrandomized trials)
          • Tilt-table testing: though they give this a moderate recommendation with RCTs to support, they do note that the utility is highest in patients with suspected recurrent vasovagal syncope, BUT there is overall only “moderate sensitivity, specificity, and reproducibility,” with “the presence of false-positives in controls”, and the diagnosis can typically be made through structured history taking as well and long-term cardiac monitoring.
        • If eval suggestive of neurogenic orthostatic hypotension, also not to be done routinely. Can be associated with multiple system atrophy, Parkinson’s, Lewy Body dementia, or peripheral autonomic dysfunction from diabetes, amyloidosis, immune-mediated neuropathies, hereditary sensory or autonomic neuropathies, inflammatory neuropathies. Less commonly with B12 deficiency, neurotoxins, porphyria, HIV or other infections
          • EEG during tilt-testing: patients can have both epileptic convulsions as well as pseudosyncope, which can be sorted out by doing tilt-testing with EEG monitoring (moderate recommendation​, limited design)
          • Head MRI and CT: no benefit in absence of focal neuro deficits or head injury
          • Carotid artery imaging: no benefit without focal neuro deficits
          • Plain EEG: no benefit unless symptoms suggestive of a seizure
        • Then treatment decision
          • There is a large section on guideline-based therapies for arrhythmias and structuralcardiac disorders, which i will not review here
          • Vasovagal syncope: patient education on diagnosis and triggers, lying down when symptoms begin (if sufficiently long prodrome), and in recurrent syncope:
            • Midodrine if no history of hypertension, heart failure or urinary retention. Studies suggest 43% reduction in symptoms. (moderate recommendation, RCTs)
            • Orthostatic training: e.g. repetitive tilt-table tests, or daily standing against a wall in the house for prolonged time periods (weak recommendation, RCTs)
            • Fludrocortisone, esp if inadequate response to fluids and salt (weak recommendation, nonrandomized trials)
            • Other approaches with weak recommendations include: b-blockers in those >42 years old (poor performance in younger patients), encouraging increased salt and fluid intake, decreasing meds that cause hypotension, SSRIs

Commentary:

  • Though CBC and lytes do have a low yield, I personally will continue to do them regularly, since they are cheap/easy and may unexpectedly lead to an important intervention by finding an unexpected anemia or hypokalemia, etc.
  • I would reinforce the importance of manually checking baseline and orthostatic blood pressure. See (See https://stg-blogs.bmj.com/bmjebmspotlight/2016/05/20/primary-care-corner-with-geoffrey-modest-md-orthostatic-hypotension-revisited/for more studies on orthostatic hypotension, including the finding that initial hypotension on standing is in fact much more common than standard orthostatic hypotension after a couple minutes)
  • In terms of vasovagal syncope, which is so common: if the patient has baseline lowish blood pressure which decreases on standing, I do recommend fluids and salt (with limited effect though), and there was a recent article not included in the guidelines above which did show benefit of fludrocortisone (see https://stg-blogs.bmj.com/bmjebmspotlight/2016/09/22/primary-care-corner-with-geoffrey-modest-md-fludrocortisone-for-vasovagal-syncope/), which I have used on several patients, sometimes with midodrine, to good effect.​
  • As noted, the guidelines do go through lots of details on the treatment of the cardiac conditions associated with syncope, and can be referenced in the paper itself.​

So, overall I think this is a very useful guideline, which appropriately minimizes routine testing beyond the history, physical and EKG (though, as mentioned, I do usually check a CBC and lytes even in otherwise asymptomatic patients).

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