Background The purpose of this study was to examine the effects of carvedilol therapy on autonomic control of the heart and
QT-interval dispersion (QTd) among children with idiopathic dilated cardiomyopathy (DCM) whose symptoms were not adequately
controlled with standard congestive heart failure therapy. Material and Methods Patients with DCM who were treated with carvedilol
were enrolled in the study. All patients had undergone carvedilol therapy in addition to standard therapy for at least 6 months.
Clinical, echocardiographic, and electrocardiographic parameters, and 24-h Holter records of patients were retrospectively
evaluated before and after carvedilol treatment. Results A total 34 patients (mean age: 7.4±4.3 years) with DCM were analyzed
in the study. The median follow-up period was 9.5 months. After the 6 months of carvedilol therapy the clinical score significantly
improved, left ventricular ejection fraction (LVEF) and fractional shortening (LVFS) significantly increased, and left ventricle
end-diastolic dimensions and end-systolic dimensions significantly decreased. There were statistically significant increases
in mean SDNN, SDANN, rMSSD, and pNN50 (p=0.002, p=0.001, p=0.008, and p=0.026, respectively). After the carvedilol therapy,
SDNN was correlated with the clinical score, heart rate, LVEF, LVFS, and total premature ventricular contractions (PVCs).
In addition, rMSSD and pNN50 were correlated with heart rate, LVEF and LVFS. A significant reduction was observed in QTc-minimum,
QTc-maximum, and QTd values (434.9±40.7 vs. 416.1±36.5, 497.8±43.6 vs. 456.3±41.7, 58.6±17.1 vs. 49.3±15.6; p<0.001, p=0.001,
and p=0.008, respectively). QTd was significantly related to PVCs (r=0.62, p=0.02). Conclusions We conclude that the addition
of carvedilol to standard therapy can improve clinical symptoms and heart rate variability, and reduce in arrhythmia markers
in children with DCM.