The QT interval is a marker for drug-induced cardiac toxicity, electrolyte abnormalities and genetic mutations with a high risk of sudden death.
The objective was to determine the optimal QT-heart rate correction when heart rate is increased.
Materials and Methods
A total of 40 persons had QT interval measured before at the end of each stage of a Bruce protocol. Currently used heart rate correction formulae (QTc) were compared to recently proposed QTc formulae derived from large population studies.
Comparing the data at each stage of exercise found that QTc using the Bazett formula (QTcBZT) increased with exercise while the QTc proposed by Fridericia (QTcFRD) and by Framingham (QTcFRM) decreased with exercise. In contrast QTc proposed by Dmitrienko (QTcDMT) and Rautaharju (QTcRTHa) were relatively constant despite the increase in heart rate during exercise, whereas QTc proposed by Hodges (QTcHDG) was more variable. With exercise, the differences between QTcBZT or QTcFRD and the other correction formulae became greater and highly significant. Next, the slope of QTc or RR regression was calculated for each individual during the exercise test. The rank order of the slopes (from the smallest to largest absolute value) was QTcRTHa, QTcDMT, QTcBZT, QTcHDG, QTcFRD and QTcFRM. Furthermore the slope of the QT/heart rate relationship was significantly (P < 0.0001) different between the older formulae proposed by Bazett or Fridericia compared to the newer formulae QTcDMT or QTcRTHa.
The 2 newer QT-heart rate correction formula should be used when evaluating QT interval at faster heart rates especially those associated with exercise.
Key Indexing Terms
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to The American Journal of the Medical Sciences
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Aging effects on QT interval: implications for cardiac safety of antipsychotic drugs.J Geriatr Cardiol. 2014; 11: 20-25
- The QT interval historically treated.Pediatr Cardiol. 1983; 4: 139-148
- Drug-induced prolongation of the QT interval.N Engl J Med. 2004; 350: 1013-1022
- Exercise-induced changes in the QT interval duration and dispersion in patients with sudden cardiac death after myocardial infarction.Int J Cardiol. 1998; 63: 271-279
- Genotype- and mutation site-specific QT adaptation during exercise, recovery, and postural changes in children with long-QT syndrome.Circ Arrhythmia Electrophysiol. 2011; 4: 867-873
- Effects of exercise on heart rate, QT, QTc and QT/QS2 in the Romano-Ward inherited long QT syndrome.Am J Cardiol. 1991; 68: 498-503
- Derivation and validation of a simple exercise-based algorithm for prediction of genetic testing in relatives of LQTS probands.Circulation. 2011; 124: 2187-2194
- Nomenclature, categorization and usage of formulae to adjust QT interval for heart rate.World J Cardiol. 2015; 7: 315-325
- An analysis of the time-relations of electrocardiograms.Heart. 1920; 7: 353-367
- Observations on the change of ventricular systole (QT interval) during exercise.J Clin Invest. 1950; 29: 279-289
- The QT interval during reflex cardiovascular adaptation.Circulation. 1984; 69: 22-25
- QTc behavior during treadmill exercise as a function of the underlying QT-heart rate relationship.J Electrocardiol. 1995; 28: 206-210https://doi.org/10.1016/S0022-0736(95)80058-1
- An exponential formula for heart rate dependence of QT interval during exercise and cardiac pacing in humans: reevaluation of Bazett׳s formula.Am J Cardiol. 1984; 54: 103-108
- The duration of systole in an electrocardiogram in normal humans and in patients with heart disease. 1920.Ann Noninvasive Electrocardiol. 2003; 8: 343-351
- Comparison of formulae for heart rate correction of QT interval in exercise electrocardiograms.Pacing Clin Electrophysiol. 1999; 22: 1397-1401
- Comparison of formulae for heart rate correction of QT interval in exercise ECGs from healthy children.Heart. 2001; 86: 199-202
- Electrocardiogram reference ranges derived from a standardized clinical trial population.Drug Inf J. 2005; 39: 395-405
- New age- and sex-specific criteria for QT prolongation based on rate correction formulas that minimize bias at the upper normal limits.Int J Cardiol. 2014; 174: 535-540
- correction reviewed: evidence that a linear QT correction for heart rate is better.J Am Coll Cardiol. 1983; 1: 694
- An improved method for adjusting the QT interval for heart rate (the Framingham Heart Study).Am J Cardiol. 1992; 70: 797-801
- The normal duration of the electrocardiographic ventricular complex.J Clin Invest. 1936; 15: 335-342
- Linear relationship between electrical systole, mechanical systole, and heart rate.Chest. 1981; 80: 613-617
- QT interval-heart rate relation during exercise in normal men and women: definition by linear regression analysis.J Am Coll Cardiol. 1996; 28: 1547-1555
- American Heart Association Electrocardi C on CCAC of CFHRS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias C.J Am Coll Cardiol. 2009; 53: 982-991
- Correction of the QT interval for heart rate: review of different formulas and the use of Bazett׳s formula in myocardial infarction.Am Heart J. 1985; 109: 568-574
- Applicability of correcting the QT interval for heart rate.Am Heart J. 1980; 99: 678
- Evaluation of 10 QT prediction formulas in 881 middle-aged men from the seven countries study: emphasis on the cubic root Fridericia׳s equation.J Electrocardiol. 1988; 21: 219-229
- The relationship between QT interval and heart rate during physiological exercise and pacing.Jpn Heart J. 1981; 22: 345-351
- Modulation of the QT interval: effects of graded exercise and reflex cardiovascular stimulation.J Appl Physiol. 1993; 75: 2217-2223
- Evaluation of a subject-specific transfer-function-based nonlinear QT interval rate-correction method.Physiol Meas. 2011; 32: 619-635
- Exercise-induced QT/R-R-interval hysteresis as a predictor of myocardial ischemia.J Electrocardiol. 2006; 39: 315-323
Accepted: September 1, 2015
Received: May 28, 2015
The authors have no financial or other conflicts of interest to disclose.
© 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.