Heart Rate Influence on the QT Variability Risk Factors

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Authors

ANDRŠOVÁ Irena HNATKOVA Katerina ŠIŠÁKOVÁ Martina TOMAN Ondřej SMETANA Peter HUSTER Katharina M. BARTHEL Petra NOVOTNÝ Tomáš SCHMIDT Georg MALÍK Marek

Year of publication 2020
Type Article in Periodical
Magazine / Source Diagnostics
MU Faculty or unit

Faculty of Medicine

Citation
Web https://www.mdpi.com/2075-4418/10/12/1096
Doi http://dx.doi.org/10.3390/diagnostics10121096
Keywords QT variability; RR variability; QT variability index; underlying heart rate; sequential analysis of regression variance
Description QT interval variability, mostly expressed by QT variability index (QTVi), has repeatedly been used in risk diagnostics. Physiologic correlates of QT variability expressions have been little researched especially when measured in short 10-second electrocardiograms (ECGs). This study investigated different QT variability indices, including QTVi and the standard deviation of QT interval durations (SDQT) in 657,287 10-second ECGs recorded in 523 healthy subjects (259 females). The indices were related to the underlying heart rate and to the 10-second standard deviation of RR intervals (SDRR). The analyses showed that both QTVi and SDQT (as well as other QT variability indices) were highly statistically significantly (p < 0.00001) influenced by heart rate and that QTVi showed poor intra-subject reproducibility (coefficient of variance approaching 200%). Furthermore, sequential analysis of regression variance showed that SDQT was more strongly related to the underlying heart rate than to SDRR, and that QTVi was influenced by the underlying heart rate and SDRR more strongly than by SDQT (p < 0.00001 for these comparisons of regression dependency). The study concludes that instead of QTVi, simpler expressions of QT interval variability, such as SDQT, appear preferable for future applications especially if multivariable combination with the underlying heart rate is used.
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