title: Temporary disturbances of the QT interval precede the onset of ventricular tachyarrhythmias in patients with structural heart diseases.
abstract: An increase in sinus rate prior to ventricular tachyarrhythmias has been demonstrated in previous studies. There is no clear data available concerning changes in ventricular de- and repolarization prior to ventricular tachyarrhythmias, especially in patients with structural heart disease. Therefore, the aim of this study was to analyze the QT and QTc interval (Bazett's formula immediately before the onset of ventricular tachyarrhythmias in stored electrograms of patients with ICDs. The study analyzed 228 spontaneous ventricular tachyarrhythmia episodes in 52 patients (mean age 64 +/- 10 years, 49 men, 3 women) and compared them with 146 electrograms of baseline rhythm recorded during regular ICD follow-up. Mean ventricular cycle length (CL), QT interval, and QTc were measured before the onset of ventricular tachyarrhythmia and during baseline rhythm. Prior to ventricular tachyarrhythmias onset, CL was significantly shorter than during baseline rhythm (714 +/- 139 vs 828 +/- 149 ms, P < 0.0001). By contrast, the QT interval (430 +/- 67 ms) and QTc interval (518 +/- 67 ms) were significantly prolonged before the onset of ventricular tachyarrhythmias as compared to baseline rhythm (QT 406 +/- 67 ms, QTc 450 +/- 61 ms; P < 0.0001). CL, QT, and QTc changes were independent of concomitant treatment with antiarrhythmic drugs. Ventricular tachyarrhythmias are preceded by a significant prolongation of the QT and QTc intervals. This phenomenon may represent a greater than normal disparity of repolarization recovery times possibly facilitating the development of ventricular tachyarrhythmias.
authors.affiliation: Medical Clinic I, RWTH Aachen, Germany. bdie@pcserver.mk1.rwth-aachen.de
authors.forename: Björn Henrik
authors.initials: BH
authors.lastname: Diem
authors.forename: Christoph
authors.initials: C
authors.lastname: Stellbrink
authors.forename: Mathias
authors.initials: M
authors.lastname: Michel
authors.forename: Patrick
authors.initials: P
authors.lastname: Schauerte
authors.forename: Peter
authors.initials: P
authors.lastname: Hanrath
mesh_terms: D009202:Cardiomyopathies / Q000150:complications*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000150:complications / Q000503:physiopathology* / Q000628:therapy