Abstract
Background: Prolonged QT offset dispersion (QToD), an index of heterogeneity of ventricular repolarization, is thought to be an independent predictor of all‐cause and cardiovascular mortality. However the influence of gender and autonomic tone in healthy adults on age‐related changes in measures of ventricular repolarization are not well characterized.
Methods: QToD and T wave complexity were measured in 56 healthy subjects with no detectable heart disease (by echo and stress test)—38 young subjects with a mean age of 28 ± 4 years and 18 old subjects with a mean age of 71 ± 7 years. QToD and T wave complexity were computed from 12‐lead ECGs using the GE Marquette QT Guard automated analysis program with manual over‐reading at rest (baseline), following exercise, and double autonomic blockade with atropine and propranolol. Data was analyzed using factorial ANOVA.
Results: Young males had a significantly greater QToD than young and old females at baseline (28 ± 5 ms, 23 ± 5 ms, and 22 ± 5 ms, respectively, P < 0.01), an intrinsic effect independent of changes in autonomic tone. In contrast, females had significantly greater T wave complexity than males following exercise and double autonomic blockade with a definite trend at baseline. There was no correlation between T wave complexity and QToD.
Conclusions: Age and gender demonstrate a complex interaction on indices of myocardial repolarization with different measures behaving differently. These findings have implications for better understanding age and gender effects on myocardial electrophysiology. A.N.E. 2001;6(4):290–297
Keywords: age, gender, autonomic, ventricular, repolarization
REFERENCES
- 1. Kuo C‐S, Munakata K, Reddy P, et al. Characteristics and possible mechanism of ventricular arrhythmia dependant on the dispersion of action potential durations. Circulation 1983;6:1356–1367. [DOI] [PubMed] [Google Scholar]
- 2. Day C, McComb J, Campbell R. QT dispersion: An indication of arrhythmia risk in patients with long QT intervals. Br Heart J 1990;63:342–344. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Antzelevitch C, Shimizu W, Yan G, Sicouri S. Cellular basis for QT dispersion. J Electrocardiol 1998;30(Suppl.):168–175. [DOI] [PubMed] [Google Scholar]
- 4. de Bruyne M, Hoes A, Kors J, et al. QTc dispersion predicts cardiac mortality in the elderly: The Rotterdam Study. Circulation 1998;97:467–472. [DOI] [PubMed] [Google Scholar]
- 5. Elming H, Holm E, Jun L, et al. The prognostic value of the QT interval and QT interval dispersion in all‐cause and cardiac mortality and morbidity in a population of Danish citizens. Eur Heart J 1998;19:1391–1400. [DOI] [PubMed] [Google Scholar]
- 6. Okin P, Devereux R, Horward B, et al. Assessment of QT interval and QT dispersion for prediction of all‐cause and cardiovascular mortality in American Indians: The Strong Heart Study. Circulation 2000;101:61. [DOI] [PubMed] [Google Scholar]
- 7. Zabel M, Klingenheben T, Franz R, et al. Assessment of QT dispersion for prediction of mortality or arrhythmic events after myocardial infarction. Results of a prospective, long‐term follow‐up study. Circulation 1998;97: 2543–2550. [DOI] [PubMed] [Google Scholar]
- 8. Priori SG, Mortara DW, Napolitano C, et al. Evaluation of the spatial aspects of T‐wave complexity in the long QT syndrome. Circulation 1997;96:3006–3012. [DOI] [PubMed] [Google Scholar]
- 9. de Ambroggi L, Aime E, Ceriotti C, et al. Mapping of ventricular repolarization potentials in patients with arrhythmogenic right ventricular dysplasia. Circulation 1997;96:4314–4318. [DOI] [PubMed] [Google Scholar]
- 10. Jose A, Taylor R. Autonomic blockade by propranolol and atropine to study intrinsic myocardial function in man. J Clin Invest 1969;48:2019–2031. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11. Xue Q, Reddy S. Algorithms for computerized QT analysis. J Electrocardiol 1998;30:181–186. [DOI] [PubMed] [Google Scholar]
- 12. Golub G, Van Loan C. Matrix Commutation. 2nd ed. Baltimore , John Hopkins University Press, 1989. [Google Scholar]
- 13. Napolitano C, Diehl L, Paganini V, et al. Principal component analysis identifies abnormal complexity of repolarization in postmyocardial infarction patients. JACC 1996;74:121A. [Google Scholar]
- 14. de Ambroggi L, Negroni MS, Monza E, et al. Dispersion of ventricular repolarization in the long QT syndrome. Am J Cardiol 1991;68:614–620. [DOI] [PubMed] [Google Scholar]
- 15. Fei L, Statters D, Camm A. QT‐dispersion in the 12‐lead electrocardiogram in normal subjects: Its reproducibility and relation to the T wave. Am Heart J 1994;127:1654–1655. [DOI] [PubMed] [Google Scholar]
- 16. Challapalli S, Lingammeni R, Horvath G, et al. Twelve lead QT dispersion is lower in women. Ann Noninv Electrocardiol 1998;3:25–31. [Google Scholar]
- 17. Antzelevitch C, Sicouri S, Litovsky SH, et al. Heterogeneity within the ventricular wall. Electrophysiology and pharmacology of epicardial, endocardial, and M cells. Circ Res 1991;69: 1427–1449. [DOI] [PubMed] [Google Scholar]
- 18. Sicouri S, Antzelevitch C. A subpopulation of cells with unique electrophysiological properties in the deep subepicardium of the canine ventricle. The M cell. Circ Res 1991;68: 1729–1741. [DOI] [PubMed] [Google Scholar]
- 19. Sicouri S, Fish J, Antzelevitch C. Distribution of M cells in the canine ventricle. J Cardiovasc Electrophysiol 1994;5:824–837. [DOI] [PubMed] [Google Scholar]
- 20. Sicouri S, Quist M, Antzelevitch C. Evidence for the presence of M cells in the guinea pig ventricle. J Cardiovasc Electrophysiol 1996;7:503–511. [DOI] [PubMed] [Google Scholar]
- 21. MacFarlane P, McLaughlin S, Rodger J. Influence of lead selection and population automated measurement of QT dispersion. Circulation 1998;98:2160–2167. [DOI] [PubMed] [Google Scholar]
- 22. Coumel P, Maison‐Blanche P, Badilini F. Dispersion of ventricular repolarization: Reality Illusion? Significance? Circulation 1998;97:2491–2493. [DOI] [PubMed] [Google Scholar]
- 23. Rautaharju P. QT and dispersion of ventricular repolarization: the greatest fallacy in electrocardiography in the 1990s. Circulation 1999;99:2477–2478. [PubMed] [Google Scholar]
- 24. Kors J, Van Herpen G, Van Bemmel J. QT dispersion as an attribute of T‐loop morphology. Circulation 1999;99:1458–1463. [DOI] [PubMed] [Google Scholar]
- 25. Lux R, Kerry E, Burgess M, et al. Redundancy reduction for improved display and analysis of body surface potential maps. Circ Res 1981;49:186–196. [DOI] [PubMed] [Google Scholar]
- 26. Wolbrette D, Patel H. Arrhythmias and women. Curr Opin Cardiol 1999;14:36–43. [DOI] [PubMed] [Google Scholar]