Heart Rate Variability Differentiates Between Vasovagal Syncope and Palpitation Related Fainting

Vasovagal syncope is a transient loss of consciousness, which can occur due to neurological, metabolic, psychiatric, and cardiac causes. Palpitations are characterized by abnormally rapid or irregular heartbeats and in some cases fainting. Determination of cause may be undertaken by patient history and physical examination including an ECG and head-up tilt testing (HUTT). However, HUTT bears some risks such as fainting and arrhythmia in syncope patients as well as being uncomfortable and unable to distinguish between palpitations and vasovagal syncope. Alternative diagnostic tools are therefore of interest and this work examines the usefulness of Heart Rate Variability (HRV) obtained from 24-hour ECG recordings. A range of entropy measures were calculated for each recording and Mann-Whitney tests were used to compare groups. Ré nyi entropy provides a significant result for positive exponents, for q=5, where the 2-group comparison has a p-value of 0.00031. Tsallis, Norm, SB, Beta, and Gamma entropies show similar results. These results suggest that short heart rate recordings, possibly during a clinic visit can differentiate between syncope and palpitations and hence HUTT is not required.