INCREASE IN QTC DISPERSION PREDICTS ARRHYTHMIC EVENTS IN PATIENTS WITH CARDIAC RESYNCHRONIZATION THERAPY

Aim. Benefits of CRT on mortality and morbidity in patients with severe CHF are clear but the effect of CRT on sudden cardiac death is more controversial. It has been suggested that CRT may catalyze arrhythmogenicity by reversing the normal depolarization pattern. The purpose of this study was to examine the effect of CRT on dispersion of repolarization as assessed by ECG. We also sought to determine the value of dispersion of repolarization ECG parameters in predicting the occurrence of major arrhythmic events (MAE) in follow-up.

Material and methods. A total of 48 patients with end-stage heart failure and QRS duration >120 ms underwent CRT. QT dispersion (QTd), T peak t end interval (Tpe) and T peak t end dispersion (Tpe dispersion) were measured before and immediately after CRT implantation. All patients were followed at least 12 months for ventricular tachycardia or fibrillation that were treated with antitachicardia pace or cardioversion.

Results. Over 16±7.1 months, 14 patients had a MAE. Compared to baseline, after CRT, QTc dispersion (84.66±37.7 vs 100.36±47.4, p=0.04) and Tpe interval (104.1±20.4 vs 122.03±33, p=0.02) increased significantly. Increase in QTD (ΔQTD) (31.66±39.5 vs 5.57±5.59, p=0.03), and QTc dispersion (ΔQTc dispersion) (40.19±46.6 vs 4.39±14.35, p=0.04) from baseline was signifcantly higher in MAE group. In multiple regression analyses, ΔQTc dispersion predicted MAE (p=0.045, CI: 1.000–1.033).

Conclusion. Immediately after CRT implantation QTc dispersion and Tpe interval increases and increase in QTc dispersion predicts MAE in one year follow up.

1. Cleland J, Daubert JC, Erdmann E, et al. Cardiac Resynchronization–Heart Failure (CARE– HF) Study Investigators. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med 2005;352: 1539–49.

2. Lindenfeld J, Feldman AM, Saxon L, et al. Effects of cardiac resynchronization therapy with or without a defibrillator on survival and hospitalizations in patients with New York Heart Association class IV heart failure. Circulation. 2007;115: 204–12.

3. Prinzen FW, Vernooy K, De Boeck BWL, et al. Mechano-energetics of the asynchronous and resynchronized heart. Heart Fail Rev. 2011;16: 215–24.

4. Ukkonen H, Sundell J, Knuuti J. Effects of CRT on myocardial innervation, perfusion and metabolism. Europace. 2008;10 Suppl 3: iii114–7.

5. Bristow MR, Saxon LA, Boehmer J, et al. Comparison of Medical Therapy, Pacing and Defibrillation in heart failure (COMPANION) Investigators. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med 2004;350: 2140–50.

6. Carson P, Anand I, O’Connor C, et al. The comparison of Medical Therapy, Pacing and Defibrillation in heart failure (COMPANION) Trial. J Am Coll Cardiol 2005;46:2329–34.

7. Fish JM, Di Diego JM, Nesterenko V, et al. Epicardial activation of left ventricular wall prolongs QT interval and transmural dispersion of repolarization. Circulation 2004;109: 2136–42.

8. Erikssen G, Liestøl K, Gullestad L, et al. The terminal part of the QT interval (T peak to T end): a predictor of mortality after acute myocardial infarction. Ann Noninvasive Electrocardiol. 2012 Apr;17 (2): 85–94.

9. Vaseghi M, Lux RL, Mahajan A, et al. Sympathetic stimulation increases dispersion of repolarization in humans with myocardial infarction. Am J Physiol Heart Circ Physiol. 2012 May 1;302 (9): H1838–46.

10. Xu T, Wang H, Zhang JY, et al. Effects of mid-myocardial pacing on transmural dispersion of repolarization and arrhythmogenesis. Europace. 2012 Sep;14 (9): 1363–8.

11. Bernus O, Zemlin CW, Zaritsky RM, et al. Alternating conduction in the ischaemic border zone as precursor of reentrant arrhythmias: a simulation study. Europace. 2005 Sep;7 Suppl 2: 93–104.

12. Antzelevitch C. Role of transmural dispersion of repolarization in the genesis of druginduced torsades de pointes. Heart Rhythm 2005;2:9–15.

13. Opthof T, Coronel R, Wilms-Schopman FJG, et al. Dispersion of repolarization in canine ventricle and the electrocardiographic T wave. The Tp–e interval does not reflect transmural dispersion. Heart Rhythm 2007;4: 341–8.

14. Fish JM, Di Diego JM, Nesterenko V, et al. Epicardial activation of left ventricular wall prolongs QT interval and transmural dispersion of repolarization. Circulation 2004;109: 2136–42.

15. Fish JM, Brugada J, Antzelevitch C. Potential proarrhythmic effects of biventricular pacing. J Am Coll Cardiol 2005;46: 2340–7.

16. Santangelo L, Ammendola E, Russo V, et al. Influence of biventricular pacing on myocardial dispersion of repolarization in dilated cardiomyopathy patients. Europace. 2006 Jul;8 (7): 502–5.

17. 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: 2486–92.

18. 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 Oct;4 (10): 1274–83.

19. Ermis C, Seutter R, Zhu AX, et al. Impact of upgrade to cardiac resynchronization therapy on ventricular arrhythmia frequency in patients with implantable cardioverter-defibrillators. J Am Coll Cardiol. 2005 Dec 20;46 (12): 2258–63.

20. Cleland JGF, Daubert JC, Erdmann E, et al. on behalf of the CARE–HF Study Investigators. Longer-term effects of cardiac resynchronization therapy on mortality in heart failure [the Cardiac Resynchronization-Heart Failure (CARE-HF) trial extensive phase]. Eur Heart J 2006;27: 1928–32.