Key result
SymEn of heart rate dynamics correctly identifies ~89% of positive head-up tilt tests.
Why the study?
Baseline entropy measures of heart rate dynamics during daily activity in patients with alleged neurocardiogenic syncope and their relation to head-up tilt test results were unclear.
Does decreased entropy of symbolic heart rate dynamics during daily activity predict a positive head-up tilt test in patients with alleged neurocardiogenic syncope?
Case-Control (n=60)
Does decreased entropy of symbolic heart rate dynamics during daily activity predict a positive head-up tilt test in patients with alleged neurocardiogenic syncope?
Decreased entropy of symbolic heart rate dynamics during daily activity may serve as a predictive marker for a positive head-up tilt test in patients with suspected neurocardiogenic syncope.
Lower entropy of 24h RR variability was associated with positive HUT in suspected syncope; hypothesis-generating for diagnostic utility, prospective validation required.
Entropy measures of RR interval variability during daily activity over a 24h period were compared in 30 patients with a positive head-up tilt (HUT) test and 30 patients with a negative HUT test who had a history of alleged neurocardiogenic syncope. Two different entropies, approximate entropy (ApEn) and entropy of symbolic dynamics (SymEn), were employed. In patients showing a positive HUT test, the entropies were significantly decreased when compared with the patients with a negative HUT test. In addition, SymEn in the patients with a negative HUT test was significantly lower than in the normal controls. Discriminant analysis using SymEn could correctly identify 89.3% (520/582) of the 1 h RR interval data of the patients with a positive HUT test regardless of the time of day. Baseline entropies of heart rate dynamics during daily activity were found to be significantly lower in patients with alleged neurocardiogenic syncope and a positive HUT test than in those with the same history but with a negative HUT test. The decreased entropy of symbolic heart rate dynamics may be of predictive value of a positive HUT test in patients with alleged neurocardiogenic syncope.
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Kim et al. (2000) conducted a case-control in Alleged neurocardiogenic syncope (n=60). Entropy of symbolic heart rate dynamics (SymEn and ApEn) vs. Negative HUT test and normal controls was evaluated on Identification of positive head-up tilt (HUT) test. Entropy of symbolic heart rate dynamics (SymEn) correctly identified 89.3% (520/582) of the 1-hour RR interval data of patients with a positive head-up tilt test.
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