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QT dispersion: Clinical applications

Authors
Velislav Batchvarov, MD
A John Camm, MD
Section Editor
Bernard J Gersh, MB, ChB, DPhil, FRCP, MACC
Deputy Editor
Brian C Downey, MD, FACC

INTRODUCTION

The QT interval duration varies between leads on the standard electrocardiogram (ECG), Frank orthogonal leads, and body surface potential maps [1-6]. These interlead differences, called QT dispersion or QT range, were proposed as an index of the spatial dispersion of the ventricular recovery times [7]. This measurement was an attempt to distinguish between myocardium that is homogeneous from myocardium that displays inhomogeneity, which is accompanied by increased dispersion of the ventricular recovery times and prolongation of repolarization. In reality, QT dispersion is a crude and approximate measure of a general abnormality of repolarization [8].

QT dispersion was developed in an effort to improve on ECG measures used in clinical practice, including the QT interval and its heart rate-corrected value (QTc) and the description of the ST-T morphology, often using vague terms such as "non-specific ST-T wave changes." However, there has been much concern about the validity of the concept and the methodology of the measurement. Despite ongoing controversy, there are a number of reasonable conclusions about the reliability and applicability of the technique [8,9].

The clinical application of QT dispersion will be reviewed here. The pathophysiology and measurement of QT dispersion are discussed elsewhere. (See "QT dispersion: Measurement and interpretation".)

NORMAL VALUES AND LIMITATIONS OF QT DISPERSION

Reported values of QT dispersion vary widely, ranging from 10 to 71 msec in normal subjects [8,10-13]. In a review of 8455 healthy control subjects of various ages, including healthy children, the mean QT dispersion values ranged from 10 to 71 msec (mean 33 msec; median 37 msec) (figure 1) [8]. There is little or no sex difference in QT dispersion [14-16]. Age-related differences, if present, appear to be small (<10 msec) [13,17].

Similar values have been noted in large studies and literature reviews that suggested that the upper normal limit of QT dispersion in normal and healthy subjects is 65 msec [10,18]. In contrast, other reports claim that QT dispersion >40 ms has a sensitivity and specificity of 88 and 57 percent, respectively, for predicting the inducibility of sustained ventricular tachycardia during an electrophysiology study [19]. However, in most of the studies with positive results, values for QT dispersion are well within the demonstrated measurement error of both manual and automatic methods. Another problem is that some prospective studies only provided data for the heart rate-corrected QT (QTc) dispersion [20,21].

              

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Literature review current through: Nov 2016. | This topic last updated: Tue Oct 28 00:00:00 GMT+00:00 2014.
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References
Top
  1. Wilson FN, Macleod AG, Barker PS, Johnston FD. Determination of the significance of the areas of the ventricular deflections of the electrocardiogram. Am Heart J 1934; 10:46.
  2. Rudehill A, Sundqvist K, Sylvén C. QT and QT-peak interval measurements. A methodological study in patients with subarachnoid haemorrhage compared to a reference group. Clin Physiol 1986; 6:23.
  3. Campbell RW, Gardiner P, Amos PA, et al. Measurement of the QT interval. Eur Heart J 1985; 6 Suppl D:81.
  4. Cowan JC, Yusoff K, Moore M, et al. Importance of lead selection in QT interval measurement. Am J Cardiol 1988; 61:83.
  5. Butrous GS, Dabbas N, Patel PR, et al. Measurement of the QT Interval. In: Clinical Aspects of Ventricular Repolarization, Butrous GS, Schwartz PJ (Eds), Farrand Press, London 1989. p.41.
  6. Mirvis DM. Spatial variation of QT intervals in normal persons and patients with acute myocardial infarction. J Am Coll Cardiol 1985; 5:625.
  7. Day CP, McComb JM, Campbell RW. QT dispersion: an indication of arrhythmia risk in patients with long QT intervals. Br Heart J 1990; 63:342.
  8. Malik M, Batchvarov VN. Measurement, interpretation and clinical potential of QT dispersion. J Am Coll Cardiol 2000; 36:1749.
  9. Rautaharju PM. QT and dispersion of ventricular repolarization: the greatest fallacy in electrocardiography in the 1990s. Circulation 1999; 99:2477.
  10. Surawicz B. Will QT dispersion play a role in clinical decision-making? J Cardiovasc Electrophysiol 1996; 7:777.
  11. Kautzner J, Malik M. QT interval dispersion and its clinical utility. Pacing Clin Electrophysiol 1997; 20:2625.
  12. Statters DJ, Malik M, Ward DE, Camm AJ. QT dispersion: problems of methodology and clinical significance. J Cardiovasc Electrophysiol 1994; 5:672.
  13. Macfarlane PW, McLaughlin SC, Rodger JC. Influence of lead selection and population on automated measurement of QT dispersion. Circulation 1998; 98:2160.
  14. Tutar HE, Ocal B, Imamoglu A, Atalay S. Dispersion of QT and QTc interval in healthy children, and effects of sinus arrhythmia on QT dispersion. Heart 1998; 80:77.
  15. Challapalli S, Lingamneni R, Horvath G, et al. Twelve-lead QT dispersion is smaller in women than in men. Ann Noninvas Electrocardiol 1998; 3:25.
  16. Savelieva I, Camm AJ, Malik M. Gender-specific differences on QT dispersion measured in 1100 healthy subjects (abstract). Pacing Clin Electrophysiol 1999; 22:885.
  17. Savelieva I, Camm AJ, Malik M. Do we need age-adjustment of QT dispersion? Observations from 1096 normal subjects (abstract). Heart 1999; 81:P47.
  18. Zaidi M, Robert A, Fesler R, et al. Dispersion of ventricular repolarisation: a marker of ventricular arrhythmias in patients with previous myocardial infarction. Heart 1997; 78:371.
  19. Goldner B, Brandspiegel HZ, Horwitz L, et al. Utility of QT dispersion combined with the signal-averaged electrocardiogram in detecting patients susceptible to ventricular tachyarrhythmia. Am J Cardiol 1995; 76:1192.
  20. de Bruyne MC, Hoes AW, Kors JA, et al. QTc dispersion predicts cardiac mortality in the elderly: the Rotterdam Study. Circulation 1998; 97:467.
  21. Okin PM, Devereux RB, Howard BV, 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.
  22. Macfarlane PW. QT dispersion — Lack of discriminating power (abstract). Circulation 1998; 98:I81.
  23. Ali A, Mehra MR, Malik FS, et al. Insights into ventricular repolarization abnormalities in cardiac allograft vasculopathy. Am J Cardiol 2001; 87:367.
  24. Shah CP, Thakur RK, Reisdorff EJ, et al. QT dispersion may be a useful adjunct for detection of myocardial infarction in the chest pain center. Am Heart J 1998; 136:496.
  25. Glancy JM, Garratt CJ, de Bono DP. Dynamics of QT dispersion during myocardial infarction and ischaemia. Int J Cardiol 1996; 57:55.
  26. Ashikaga T, Nishizaki M, Arita M, et al. Effect of dipyridamole on QT dispersion in vasospastic angina pectoris. Am J Cardiol 1999; 84:807.
  27. Sporton SC, Taggart P, Sutton PM, et al. Acute ischaemia: a dynamic influence on QT dispersion. Lancet 1997; 349:306.
  28. Sakabe K, Fukuda N, Fukuda Y, et al. QT-interval dispersion in type 2 diabetic and non-diabetic patients with post-myocardial infarction. Nutr Metab Cardiovasc Dis 2008; 18:121.
  29. Fei L, Goldman JH, Prasad K, et al. QT dispersion and RR variations on 12-lead ECGs in patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy. Eur Heart J 1996; 17:258.
  30. Pye M, Quinn AC, Cobbe SM. QT interval dispersion: a non-invasive marker of susceptibility to arrhythmia in patients with sustained ventricular arrhythmias? Br Heart J 1994; 71:511.
  31. Zaidi M, Robert A, Fesler R, et al. Dispersion of ventricular repolarization in dilated cardiomyopathy. Eur Heart J 1997; 18:1129.
  32. Bonnar CE, Davie AP, Caruana L, et al. QT dispersion in patients with chronic heart failure: beta blockers are associated with a reduction in QT dispersion. Heart 1999; 81:297.
  33. Yi G, Elliott P, McKenna WJ, et al. QT dispersion and risk factors for sudden cardiac death in patients with hypertrophic cardiomyopathy. Am J Cardiol 1998; 82:1514.
  34. Calo L, Sciarra L, Sabina F, et al. QT dispersion and late potentials in hypertrophic cardiomyopathy (abstract). J Am Coll Cardiol 1996; 27:59A.
  35. Dritsas A, Sbarouni E, Gilligan D, et al. QT-interval abnormalities in hypertrophic cardiomyopathy. Clin Cardiol 1992; 15:739.
  36. Zaidi M, Robert A, Fesler R, et al. Dispersion of ventricular repolarization in hypertrophic cardiomyopathy. J Electrocardiol 1996; 29 Suppl:89.
  37. Ichkhan K, Molnar J, Somberg J. Relation of left ventricular mass and QT dispersion in patients with systematic hypertension. Am J Cardiol 1997; 79:508.
  38. Perkiömäki JS, Ikäheimo MJ, Pikkujämsä SM, et al. Dispersion of the QT interval and autonomic modulation of heart rate in hypertensive men with and without left ventricular hypertrophy. Hypertension 1996; 28:16.
  39. Mayet J, Shahi M, McGrath K, et al. Left ventricular hypertrophy and QT dispersion in hypertension. Hypertension 1996; 28:791.
  40. Lim PO, Nys M, Naas AA, et al. Irbesartan reduces QT dispersion in hypertensive individuals. Hypertension 1999; 33:713.
  41. Karpanou EA, Vyssoulis GP, Psichogios A, et al. Regression of left ventricular hypertrophy results in improvement of QT dispersion in patients with hypertension. Am Heart J 1998; 136:765.
  42. González-Juanatey JR, García-Acuña JM, Pose A, et al. Reduction of QT and QTc dispersion during long-term treatment of systemic hypertension with enalapril. Am J Cardiol 1998; 81:170.
  43. Tomiyama H, Doba N, Fu Y, et al. Left ventricular geometric patterns and QT dispersion in borderline and mild hypertension: their evolution and regression. Am J Hypertens 1998; 11:286.
  44. Muir DF, Love MW, MacGregor GD, et al. Athletic left ventricular hypertrophy is associated with increased QT dispersion: An observational study (abstract). J Am Coll Cardiol 1999; 33:510A.
  45. Stolt A, Karila T, Viitasalo M, et al. QT interval and QT dispersion in endurance athletes and in power athletes using large doses of anabolic steroids. Am J Cardiol 1999; 84:364.
  46. Halle M, Huonker M, Hohnloser SH, et al. QT dispersion in exercise-induced myocardial hypertrophy. Am Heart J 1999; 138:309.
  47. Mayet J, Kanagaratnam P, Shahi M, et al. QT dispersion in athletic left ventricular hypertrophy. Am Heart J 1999; 137:678.
  48. Priori SG, Napolitano C, Diehl L, Schwartz PJ. Dispersion of the QT interval. A marker of therapeutic efficacy in the idiopathic long QT syndrome. Circulation 1994; 89:1681.
  49. Gavrilescu S, Luca C. Right ventricular monophasic action potentials in patients with long QT syndrome. Br Heart J 1978; 40:1014.
  50. Bonatti V, Rolli A, Botti G. Recording of monophasic action potentials of the right ventricle in long QT syndromes complicated by severe ventricular arrhythmias. Eur Heart J 1983; 4:168.
  51. Zareba W, Moss AJ, Konecki J. TU wave area-derived measures of repolarization dispersion in the long QT syndrome. J Electrocardiol 1998; 30 Suppl:191.
  52. Yap, YG, Yi, G, Guo, XH, et al. Dynamic changes of QT dispersion and Its relationship with clinical variables and arrhythmic events after myocardial infarction (abstract). J Am Coll Cardiol 1999; 33:107A.
  53. Paventi S, Bevilacqua U, Parafati MA, et al. QT dispersion and early arrhythmic risk during acute myocardial infarction. Angiology 1999; 50:209.
  54. Bennemeier H, Hartmann F, Giannitsis E, et al. Effects of primary angioplasty on the course of QT dispersion after myocardial infarction and its association with infarct size (abstract). Pacing Clin Electrophysiol 1999; 22:A19.
  55. Puljevic D, Smalcelj A, Durakovic Z, Goldner V. Effects of postmyocardial infarction scar size, cardiac function, and severity of coronary artery disease on QT interval dispersion as a risk factor for complex ventricular arrhythmia. Pacing Clin Electrophysiol 1998; 21:1508.
  56. Kluger J, Hathaway L, Giedrimiene D. Does left ventricular function influence QT dispersion in patients with previous myocardial infarction and ventricular tachyarrhythmias? (abstract). J Am Coll Cardiol 1997; 29:510A.
  57. Schneider CA, Voth E, Baer FM, et al. QT dispersion is determined by the extent of viable myocardium in patients with chronic Q-wave myocardial infarction. Circulation 1997; 96:3913.
  58. Lyras TG, Papapanagiotou VA, Foukarakis MG, et al. Evaluation of serial QT dispersion in patients with first non-Q-wave myocardial infarction: relation to the severity of underlying coronary artery disease. Clin Cardiol 2003; 26:189.
  59. Clarkson PB, Naas AA, McMahon A, et al. QT dispersion in essential hypertension. QJM 1995; 88:327.
  60. Kohno I, Takusagawa M, Yin D, et al. QT dispersion in dipper- and nondipper-type hypertension. Am J Hypertens 1998; 11:280.
  61. Buğra Z, Koylan N, Vural A, et al. Left ventricular geometric patterns and QT dispersion in untreated essential hypertension. Am J Hypertens 1998; 11:1164.
  62. Higham PD, Furniss SS, Campbell RW. QT dispersion and components of the QT interval in ischaemia and infarction. Br Heart J 1995; 73:32.
  63. Hansen S, Rasmussen V, Torp-Pedersen C, Jensen GB. QT intervals and QT dispersion determined from a 12-lead 24-hour Holter recording in patients with coronary artery disease and patients with heart failure. Ann Noninvasive Electrocardiol 2008; 13:22.
  64. Gunes Y, Tuncer M, Guntekin U, et al. Lack of diurnal variation of P-wave and QT dispersions in patients with heart failure. Pacing Clin Electrophysiol 2008; 31:974.
  65. Aytemir K, Bavafa V, Ozer N, et al. Effect of balloon inflation-induced acute ischemia on QT dispersion during percutaneous transluminal coronary angioplasty. Clin Cardiol 1999; 22:21.
  66. Okishige K, Yamashita K, Yoshinaga H, et al. Electrophysiologic effects of ischemic preconditioning on QT dispersion during coronary angioplasty. J Am Coll Cardiol 1996; 28:70.
  67. Tarabey R, Sukenik D, Molnar J, Somberg JC. Effect of intracoronary balloon inflation at percutaneous transluminal coronary angioplasty on QT dispersion. Am Heart J 1998; 135:519.
  68. Yi G, Crook R, Guo XH, et al. 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.
  69. Michelucci A, Padeletti L, Frati M, et al. Effects of ischemia and reperfusion on QT dispersion during coronary angioplasty. Pacing Clin Electrophysiol 1996; 19:1905.
  70. Koide Y, Yotsukura M, Yoshino H, Ishikawa K. Usefulness of QT dispersion immediately after exercise as an indicator of coronary stenosis independent of gender or exercise-induced ST-segment depression. Am J Cardiol 2000; 86:1312.
  71. Gabrielli F, Balzotti L, Bandiera A. QT dispersion variability and myocardial viability in acute myocardial infarction. Int J Cardiol 1997; 61:61.
  72. Moreno V, Marín F, Monmeneu JV, de la Morena G. QT-interval dispersion and myocardial viability. Rev Esp Cardiol 2009; 62:461.
  73. Galetta F, Franzoni F, Fallahi P, et al. Effect of telmisartan on QT interval variability and autonomic control in hypertensive patients with left ventricular hypertrophy. Biomed Pharmacother 2010; 64:516.
  74. Moreno FL, Villanueva T, Karagounis LA, Anderson JL. Reduction in QT interval dispersion by successful thrombolytic therapy in acute myocardial infarction. TEAM-2 Study Investigators. Circulation 1994; 90:94.
  75. Karagounis LA, Anderson JL, Moreno FL, Sorensen SG. Multivariate associates of QT dispersion in patients with acute myocardial infarction: primacy of patency status of the infarct-related artery. TEAM-3 Investigators. Third trial of Thrombolysis with Eminase in Acute Myocardial Infarction. Am Heart J 1998; 135:1027.
  76. Kelly RF, Parillo JE, Hollenberg SM. Effect of coronary angioplasty on QT dispersion. Am Heart J 1997; 134:399.
  77. Szydlo K, Trusz-Gluza M, Drzewiecki J, et al. Correlation of heart rate variability parameters and QT interval in patients after PTCA of infarct related coronary artery as an indicator of improved autonomic regulation. Pacing Clin Electrophysiol 1998; 21:2407.
  78. Bonnemeier H, Hartmann F, Wiegand UK, et al. Course and prognostic implications of QT interval and QT interval variability after primary coronary angioplasty in acute myocardial infarction. J Am Coll Cardiol 2001; 37:44.
  79. Jiménez-Candil J, Hernández Hernández J, Aguero VL, et al. Early reduction of QT dispersion after primary percutaneous intervention in ST-segment elevation acute myocardial infarction. Mechanisms and clinical implications. Cardiology 2009; 113:172.
  80. Brooksby P, Robinson PJ, Segal R, et al. Effects of losartan and captopril on QT dispersion in elderly patients with heart failure. ELITE study group. Lancet 1999; 354:395.
  81. Wang CH, Chen CL, Hsiao CK, et al. Arsenic-induced QT dispersion is associated with atherosclerotic diseases and predicts long-term cardiovascular mortality in subjects with previous exposure to arsenic: A 17-Year follow-up study. Cardiovasc Toxicol 2010; 10:17.
  82. Tamaki S, Yamada T, Okuyama Y, et al. Cardiac iodine-123 metaiodobenzylguanidine imaging predicts sudden cardiac death independently of left ventricular ejection fraction in patients with chronic heart failure and left ventricular systolic dysfunction: results from a comparative study with signal-averaged electrocardiogram, heart rate variability, and QT dispersion. J Am Coll Cardiol 2009; 53:426.
  83. Surawicz B. Long QT: Good, bad, indifferent and fascinating. ACC Current J Rev 1999; pp. 19-21.
  84. Zaputović L, Mavrić Z, Zaninović-Jurjević T, et al. Relationship between QT dispersion and the incidence of early ventricular arrhythmias in patients with acute myocardial infarction. Int J Cardiol 1997; 62:211.
  85. Zareba W, Moss AJ, le Cessie S. Dispersion of ventricular repolarization and arrhythmic cardiac death in coronary artery disease. Am J Cardiol 1994; 74:550.
  86. Wahab A, Zaheer MS, Rabbani MU, Wahab S. A study of heart rate variability and QT dispersion in patients of acute ST elevation myocardial infarction. Indian Heart J 2009; 61:261.
  87. Zabel M, Klingenheben T, Franz MR, Hohnloser SH. 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.
  88. Tavernier R, Jordaens L. Repolarisation characteristics and sudden death after myocardial infarction: A case control study (abstract). J Am Coll Cardiol 1999; 33:146A.
  89. Aitchison JD, Campbell RW, Higham PD. Time dependent variability of QT dispersion after acute myocardial infarction and its relation to ventricular fibrillation: a prospective study. Heart 2000; 84:504.
  90. Jordaens L, Tavernier R, MIRRACLE Investigators. Determinants of sudden death after discharge from hospital for myocardial infarction in the thrombolytic era. Eur Heart J 2001; 22:1214.
  91. Huikuri HV, Tapanainen JM, Lindgren K, et al. Prediction of sudden cardiac death after myocardial infarction in the beta-blocking era. J Am Coll Cardiol 2003; 42:652.
  92. Ueda H, Hayashi T, Tsumura K, et al. QT dispersion and prognosis after coronary stent placement in acute myocardial infarction. Clin Cardiol 2007; 30:229.
  93. Dabrowski A, Kramarz E, Piotrowicz R, Kubik L. Predictive power of increased QT dispersion in ventricular extrasystoles and in sinus beats for risk stratification after myocardial infarction. Circulation 2000; 101:1693.
  94. Bogun F, Chan KK, Harvey M, et al. QT dispersion in nonsustained ventricular tachycardia and coronary artery disease. Am J Cardiol 1996; 77:256.
  95. Lee KW, Okin PM, Kligfield P, et al. Precordial QT dispersion and inducible ventricular tachycardia. Am Heart J 1997; 134:1005.
  96. Gillis AM, Traboulsi M, Hii JT, et al. Antiarrhythmic drug effects on QT interval dispersion in patients undergoing electropharmacologic testing for ventricular tachycardia and fibrillation. Am J Cardiol 1998; 81:588.
  97. Armoundas AA, Osaka M, Mela T, et al. T-wave alternans and dispersion of the QT interval as risk stratification markers in patients susceptible to sustained ventricular arrhythmias. Am J Cardiol 1998; 82:1127.
  98. Zabel M, Klingenheben T, Sticherling C, et al. QT-dispersion does not predict inducibility or adequate device treatment in patients with malignant ventricular tachyarrhythmias (abstract). Eur Heart J 1998; 19:600.
  99. De Sutter J, Tavernier R, Van De Wiele C, et al. QT dispersion is not related to infarct size or inducibility in patients with coronary artery disease and life threatening ventricular arrhythmias. Heart 1999; 81:533.
  100. Fu GS, Meissner A, Simon R. Repolarization dispersion and sudden cardiac death in patients with impaired left ventricular function. Eur Heart J 1997; 18:281.
  101. Galinier M, Vialette JC, Fourcade J, et al. QT interval dispersion as a predictor of arrhythmic events in congestive heart failure. Importance of aetiology. Eur Heart J 1998; 19:1054.
  102. Anastasiou-Nana MI, Nanas JN, Karagounis LA, et al. Dispersion od QRS and QT in patients with advanced congestive heart failure: relation to cardiac and sudden cardiac death mortality (abstract). Eur Heart J 1999; 20:117.
  103. Brendorp B, Elming H, Jun L, et al. Qt dispersion has no prognostic information for patients with advanced congestive heart failure and reduced left ventricular systolic function. Circulation 2001; 103:831.
  104. Brooksby P, Batin PD, Nolan J, et al. The relationship between QT intervals and mortality in ambulant patients with chronic heart failure. The united kingdom heart failure evaluation and assessment of risk trial (UK-HEART). Eur Heart J 1999; 20:1335.
  105. Radmanabhan S, Amin J, Silvet H, Pai RG. QT dispersion has no impact on mortality in patients with moderate and severe left ventricular dysfunction: Results from a cohort of 2263 patients (abstract). J Am Coll Cardiol 1999; 33:107A.
  106. Brendorp B, Elming H, Jun L, et al. Effect of dofetilide on QT dispersion and the prognostic implications of changes in QT dispersion for patients with congestive heart failure. Eur J Heart Fail 2002; 4:201.
  107. Iacoviello M, Forleo C, Guida P, et al. Ventricular repolarization dynamicity provides independent prognostic information toward major arrhythmic events in patients with idiopathic dilated cardiomyopathy. J Am Coll Cardiol 2007; 50:225.
  108. Galinier M, Balanescu S, Fourcade J, et al. Prognostic value of arrhythmogenic markers in systemic hypertension. Eur Heart J 1997; 18:1484.
  109. Buja G, Miorelli M, Turrini P, et al. Comparison of QT dispersion in hypertrophic cardiomyopathy between patients with and without ventricular arrhythmias and sudden death. Am J Cardiol 1993; 72:973.
  110. Miorelli M, Buja G, Melacini P, et al. QT-interval variability in hypertrophic cardiomyopathy patients with cardiac arrest. Int J Cardiol 1994; 45:121.
  111. Bayrak F, Kahveci G, Mutlu B, et al. Usefulness of surface electrocardiogram in predicting the clinical course of patients with hypertrophic cardiomyopathy. Anadolu Kardiyol Derg 2007; 7 Suppl 1:178.
  112. Maron BJ, Leyhe MJ 3rd, Casey SA, et al. Assessment of QT dispersion as a prognostic marker for sudden death in a regional nonreferred hypertrophic cardiomyopathy cohort. Am J Cardiol 2001; 87:114.
  113. Chalil S, Yousef ZR, Muyhaldeen SA, et al. Pacing-induced increase in QT dispersion predicts sudden cardiac death following cardiac resynchronization therapy. J Am Coll Cardiol 2006; 47:2486.
  114. Hina K, Kawamura H, Murakami T, et al. Association of corrected QT dispersion with symptoms improvement in patients receiving cardiac resynchronization therapy. Heart Vessels 2008; 23:325.
  115. Dilaveris P, Giannopoulos G, Synetos A, et al. Effect of biventricular pacing on ventricular repolarization and functional indices in patients with heart failure: lack of association with arrhythmic events. Europace 2009; 11:741.
  116. Lellouche N, De Diego C, Akopyan G, et al. Changes and predictive value of dispersion of repolarization parameters for appropriate therapy in patients with biventricular implantable cardioverter-defibrillators. Heart Rhythm 2007; 4:1274.
  117. Haverkamp W, Breithardt G, Camm AJ, et al. The potential for QT prolongation and proarrhythmia by non-antiarrhythmic drugs: clinical and regulatory implications. Report on a policy conference of the European Society of Cardiology. Eur Heart J 2000; 21:1216.
  118. Moss AJ. Drugs that prolong the QT interval: Regulatory and QT measurement issues from the United States and European perspectives. Ann Noninvas Electrocardiol 1999; 4:255.
  119. Shah RR. Drug-induced QT dispersion: does it predict the risk of torsade de pointes? J Electrocardiol 2005; 38:10.
  120. Cui G, Sager PT, Singh BN, Sen L. Different Effects of Amiodarone and Quinidine on the Homogeneity of Myocardial Refractoriness in Patients With Intraventricular Conduction Delay. J Cardiovasc Pharmacol Ther 1998; 3:201.
  121. Hii JT, Wyse DG, Gillis AM, et al. Precordial QT interval dispersion as a marker of torsade de pointes. Disparate effects of class Ia antiarrhythmic drugs and amiodarone. Circulation 1992; 86:1376.
  122. Hohnloser SH, van de Loo A, Baedeker F. Efficacy and proarrhythmic hazards of pharmacologic cardioversion of atrial fibrillation: prospective comparison of sotalol versus quinidine. J Am Coll Cardiol 1995; 26:852.
  123. Day CP, McComb JM, Matthews J, Campbell RW. Reduction in QT dispersion by sotalol following myocardial infarction. Eur Heart J 1991; 12:423.
  124. Cui G, Sen L, Sager P, et al. Effects of amiodarone, sematilide, and sotalol on QT dispersion. Am J Cardiol 1994; 74:896.
  125. Hohnloser SH, van de Loo A, Kalusche D, et al. Does sotalol-induced alteration of QT-dispersion predict drug effectiveness or proarrhythmic hazards? (abstract). Circulation 1993; 88:397.
  126. Dritsas A, Gilligan D, Nihoyannopoulos P, Oakley CM. Amiodarone reduces QT dispersion in patients with hypertrophic cardiomyopathy. Int J Cardiol 1992; 36:345.
  127. Meierhenrich R, Helguera ME, Kidwell GA, Tebbe U. Influence of amiodarone on QT dispersion in patients with life-threatening ventricular arrhythmias and clinical outcome. Int J Cardiol 1997; 60:289.
  128. Grimm W, Steder U, Menz V, et al. Effect of amiodarone on QT dispersion in the 12-lead standard electrocardiogram and its significance for subsequent arrhythmic events. Clin Cardiol 1997; 20:107.
  129. van de Loo A, Klingenheben T, Hohnloser SH. [Amiodarone therapy after sotalol-induced torsade de pointes: prolonged QT interval and QT dispersion in differentiation of pro-arrhythmic effects]. Z Kardiol 1994; 83:887.
  130. Tran HT, Chow MS, Kluger J. Amiodarone induced torsades de pointes with excessive QT dispersion following quinidine induced polymorphic ventricular tachycardia. Pacing Clin Electrophysiol 1997; 20:2275.
  131. Yadav A, Paquette M, Newman D, et al. Amiodarone is associated with increased QT dispersion but low mortality in a CIDS cohort (abstract). Pacing Clin Electrophysiol 1999; 22:896.
  132. Faber TS, Zehender M, Krahnefeld O, et al. Propafenone during acute myocardial ischemia in patients: a double-blind, randomized, placebo-controlled study. J Am Coll Cardiol 1997; 29:561.
  133. Trusz-Gluza M, Swiderska E, Smieja-Jaroczynska B, et al. Factors influencing dispersion of repolarisation under antiarrhythmic treatment (abstract). Ann Noninvas Electrocardiol 1998; 3:S18.
  134. Houltz B, Darpö B, Edvardsson N, et al. Electrocardiographic and clinical predictors of torsades de pointes induced by almokalant infusion in patients with chronic atrial fibrillation or flutter: a prospective study. Pacing Clin Electrophysiol 1998; 21:1044.
  135. Sedgwick ML, Rasmussen HS, Cobbe SM. Effects of the class III antiarrhythmic drug dofetilide on ventricular monophasic action potential duration and QT interval dispersion in stable angina pectoris. Am J Cardiol 1992; 70:1432.
  136. Démolis JL, Funck-Brentano C, Ropers J, et al. Influence of dofetilide on QT-interval duration and dispersion at various heart rates during exercise in humans. Circulation 1996; 94:1592.
  137. Brum J, Alkhalidi H, Karam R, Marcello S. Effects of azimilide, an IKs/IKr blocking anti-arrhythmic on QT and QTc dispersion, in patients with ventricular tachycardia (VT) (abstract). Pacing Clin Electrophysiol 1999; 22:A13.
  138. Parikka H, Toivonen L, Naukkarinen V, et al. Decreases by magnesium of QT dispersion and ventricular arrhythmias in patients with acute myocardial infarction. Eur Heart J 1999; 20:111.
  139. Leonardo F, Fragasso G, Rosano GM, et al. Effect of atenolol on QT interval and dispersion in patients with syndrome X. Am J Cardiol 1997; 80:789.
  140. Aygul N, Ozdemir K, Duzenli MA, Aygul MU. The comparative effects of long-term carvedilol versus bisoprolol therapy on QT dispersion in patients with chronic heart failure. Cardiology 2009; 112:168.
  141. Mir TS, Läer S, Eiselt M, et al. Effect of Carvedilol on QT Duration in Paediatric Patients with Congestive Heart Failure. Clin Drug Investig 2004; 24:9.
  142. Shehab A, Elnour AA, Struthers AD. A randomised, controlled, double-blind, cross-over pilot study assessing the effects of spironolactone, losartan and their combination on heart rate variability and QT dispersion in patients with chronic heart failure. Cardiovasc J Afr 2008; 19:292.
  143. Xie RQ, Cui W, Liu F, et al. Statin therapy shortens QTc, QTcd, and improves cardiac function in patients with chronic heart failure. Int J Cardiol 2010; 140:255.
  144. Yamaguchi M, Shimizu M, Ino H, et al. T wave peak-to-end interval and QT dispersion in acquired long QT syndrome: a new index for arrhythmogenicity. Clin Sci (Lond) 2003; 105:671.
  145. Chevalier P, Rodriguez C, Bontemps L, et al. Non-invasive testing of acquired long QT syndrome: evidence for multiple arrhythmogenic substrates. Cardiovasc Res 2001; 50:386.
  146. Cubeddu LX. Iatrogenic QT Abnormalities and Fatal Arrhythmias: Mechanisms and Clinical Significance. Curr Cardiol Rev 2009; 5:166.
  147. Drew BJ, Ackerman MJ, Funk M, et al. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. J Am Coll Cardiol 2010; 55:934.
  148. Yan GX, Wu Y, Liu T, et al. Phase 2 early afterdepolarization as a trigger of polymorphic ventricular tachycardia in acquired long-QT syndrome : direct evidence from intracellular recordings in the intact left ventricular wall. Circulation 2001; 103:2851.
  149. Di Diego JM, Belardinelli L, Antzelevitch C. Cisapride-induced transmural dispersion of repolarization and torsade de pointes in the canine left ventricular wedge preparation during epicardial stimulation. Circulation 2003; 108:1027.
  150. Liu T, Brown BS, Wu Y, et al. Blinded validation of the isolated arterially perfused rabbit ventricular wedge in preclinical assessment of drug-induced proarrhythmias. Heart Rhythm 2006; 3:948.
  151. Fenichel RR, Malik M, Antzelevitch C, et al. Drug-induced torsades de pointes and implications for drug development. J Cardiovasc Electrophysiol 2004; 15:475.
  152. Yan GX, Lankipalli RS, Burke JF, et al. Ventricular repolarization components on the electrocardiogram: cellular basis and clinical significance. J Am Coll Cardiol 2003; 42:401.
  153. Taggart P, Sutton PM, Opthof T, et al. Transmural repolarisation in the left ventricle in humans during normoxia and ischaemia. Cardiovasc Res 2001; 50:454.