Vasovagal syncope/NCS is a largely clinical diagnosis. Because the biggest challenge for the emergency clinician is to evaluate whether or not a patient’s syncope is from a benign or vasovagal etiology or from a more concerning cause such as cardiac syncope, the most useful test is an ECG (though they are only diagnostic a small portion of the time). While there are no definitive data to suggest that a normal ECG ensures a patient’s syncope is vasovagal, the majority of current algorithms in the literature include an ECG as part of the evaluation of syncope. More specifically, in several current algorithms to evaluate for syncope, a normal ECG is a common branch point when distinguishing between vasovagal syncope and other more concerning etiologies. In studies that attempt to distinguish cardiac versus noncardiac causes of syncope, an ECG is used in both decision rules and algorithms.2,3,5,10,11,47,63-65 Additionally, there are no studies that have specifically demonstrated the negative predictive value of a normal ECG in the evaluation of routine syncope, but there are multiple studies that have evaluated the negative predictive value of a normal ECG in cardiac syncope.46,47 Because of the low cost and noninvasive nature of an ECG, it is recommended to include a screening ECG in the evaluation of routine syncope.
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