Assessment of the Stability of the Individual-Based Correction of QT Interval for Heart Rate

Heart Research Follow-up Program, Cardiology Department, University of Rochester, Rochester, New York 14642, USA.
Annals of Noninvasive Electrocardiology (Impact Factor: 1.13). 02/2005; 10(1):25-34. DOI: 10.1111/j.1542-474X.2005.00593.x
Source: PubMed


Modeling the relationship between QT intervals and previous R-R values remains a challenge of modern quantitative electrocardiography. The technique based on an individual regression model computed from a set of QT-R-R measurements is presented as a promising alternative. However, a large set of QT-R-R measurements is not always available in clinical trials and there is no study that has investigated the minimum number of QT-R-R measurements needed to obtain a reliable individual QT-R-R model. In this study, we propose guidelines to ensure appropriate use of the regression technique for heart rate correction of QT intervals.
Holter recordings from 205 healthy subjects were included in the study. QT-R-R relationships were modeled using both linear and parabolic regression techniques. Using a bootstrapping technique, we computed the stability of the individual correction models as a function of the number of measurements, the range of heart rate, and the variance of R-R values.
The results show that the stability of QT-R-R individual models was dependent on three factors: the number of measurements included in its design, the heart-rate range used to design the model, and the T-wave amplitude. Practically our results showed that a set of 400 QT-R-R measurements with R-R values ranging from 600 to 1000 ms ensure a stable and reliable individual correction model if the amplitude of the T wave is at least 0.3 mV. Reducing the range of heart rate or the number of measurements may significantly impact the correction model.
We demonstrated that a large number of QT-R-R measurements (approximately 400) is required to ensure reliable individual correction of QT intervals for heart rate.

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Available from: Jean-Philippe Couderc, Jan 09, 2015
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    • "All study participants signed consent forms before entering the study. The research involved analysis of existing data, specifically digital electrocardiograms of the Intercity Digital Electrocardiogram Alliance (IDEAL) study [10], database of high resolution orthogonal ECGs, provided by NIH-funded The Telemetric and Holter ECG Warehouse (THEW) initiative [11] under the data usage agreement. Data have been recorded in such a manner that the subjects cannot be identified, directly or through identifiers linked to the subject. "
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    • "In general, van de Water's correction is used for dogs and minipigs, while Fridericia's or Bazett's corrections are used in either non-human primates or guinea-pigs, depending upon the experimental conditions. However, due to significant inter-individual variation (Malik et al., 2002), an individual correction formula that utilises a complex model of linear regression is applied; however, it requires a large number of HR measurements to obtain an acceptable level of accuracy (Couderc et al., 2005). Finally, other factors such as changes in body temperature and plasma concentrations of electrolytes (e.g. "

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    • ". However, these correction methods are based on population mean correction factor and do not address intra-or inter-individual variability. As there is now a strong evidence for significant inter-individual variability, the best HR correction for QT should be estimated for each individual [Batchvarov et al. 2002; Malik et al. 2002; Couderc et al. 2005]. "
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