Dynamics of ventricular repolarization in patients with dilated cardiomyopathy versus healthy subjects.
BACKGROUND
Patients with impaired left ventricular function have a high risk of developing ventricular arrhythmias and sudden death. Among different markers of risk, the prolongation and regional heterogeneity of repolarization are of increasing interest. However, there are limited data regarding feasibility of analyzing repolarization parameters and their dynamics in 24-hour Holter ECG recordings.


METHODS
Dynamic behavior of repolarization parameters was studied with a new automatic algorithm in digital 24-hour Holter recordings of 60 healthy subjects and 55 patients with idiopathic dilated cardiomyopathy (IDC). Repolarization parameters included the mean value of QT and QTc durations, QT dispersion, and peaks of QT duration and QT dispersion above prespecified thresholds.


RESULTS
In comparison to healthy subjects, patients with IDC had lower heart rate variability, longer mean QT and QTc durations, higher content of QTc peaks >500 ms, longer QT dispersion and its standard deviation, and a higher content of peaks >100 ms of QT dispersion (P < 0.01 for all comparisons). These repolarization parameters were significantly higher in IDC patients after adjustment for age, sex, and heart rate variability. The parameters of repolarization dynamics correlated with SDNN in healthy subjects but not in dilated cardiomyopathy patients.


CONCLUSIONS
The automatic assessment of repolarization parameters in 24-hour digital ECG recordings is feasible and differentiates dilated cardiomyopathy patients from healthy subjects. Patients with dilated cardiomyopathy have increased QT duration, QT dispersion, and increased variability of QT dispersion reflecting variations in T-wave morphology, the factors which might predispose them to the development of arrhythmic events.
Alonso
Jose Luis
JL
University Hospital of St. Pau (Cardiology), Barcelona, Spain.
Martínez
Pablo
P
Vallverdú
Montserrat
M
Cygankiewicz
Iwona
I
Pitzalis
Maria Vittoria
MV
Bayés Genís
Antoni
A
Cinca
Juan
J
Rizzon
Paolo
P
Caminal
Pere
P
Zareba
Wojciech
W
Bayés de Luna
Antoni
A
D000328:Adult; D000465:Algorithms; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted; D016277:Ventricular Function, Left