Key result
Patients with a positive tilt table test had a significantly higher mean Schwartz score for long QT syndrome compared to those with a negative test (2.77 vs 1.99, p<0.001).
Why the study?
Parasympathetic overstimulation seen in positive Tilt Table Tests may affect QTc measurement via rate modulation and potassium ionic channels, potentially impacting Schwartz score calculation.
Does a positive tilt table test affect the Schwartz score in patients with syncope of unknown origin?
Cross-Sectional (n=478)
No
Does a positive tilt table test affect the Schwartz score in patients with syncope of unknown origin?
Absolute Event Rate: 2.77% vs 1.99%
p-value: p=<0.001
A positive tilt table test is associated with a higher Schwartz score, suggesting that parasympathetic overactivation may confound the diagnosis of Long QT syndrome.
Positive TTT may artifactually affect QTc; leaves open whether this confounds LQTS diagnosis in syncope.
Background Tilt Table Test (TTT) is usually used for assessment of syncope with undefined etiology. Positive test occurs in those with parasympathetic overstimulation. This overactivation of parasympathetic system may affect QTc measurement; not only through rate modulation, but also from through potassium ionic channels as muscarinic activated inward rectifying K + current. Methods and Materials: in this cross-sectional study, 478 patients with syncopal attacks of unknown origin underwent evaluation with TTT as well as 24-hour Holter electrocardiogram monitoring. Schwartz score (for diagnosis of Long QT syndrome) was calculated for all of them. Those with secondary causes of long QT excluded from survey. Then the association of positive TTT and Schwartz score was assessed. Results 478 patients entered the study 208 (43.4%) of whom were male and 270 (56.4%) were female. The mean age of the patients was 42.43 ± 17.979 years old. TTT was positive in 289 (60.46%) patients and was negative in 189 (39.54%) patients. the mean Schwartz score was significantly higher in patients with positive TTT (2.77 ± 0.08 vs. 1.99 ± 0.12) (P < 0.001). Conclusion Diagnosis of long QT syndrome as a cause of syncope should not be made hesitantly by the use of Schwartz score as this scoring system might need to be modified based on the results of tilt table test.
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Nikoo et al. (2023) conducted a cross-sectional in Syncope of unknown etiology (n=478). Positive Tilt Table Test vs. Negative Tilt Table Test was evaluated on Mean Schwartz score for Long QT syndrome (p=<0.001). Patients with a positive tilt table test had a significantly higher mean Schwartz score for long QT syndrome compared to those with a negative test (2.77 vs 1.99, p<0.001).
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