Background and Methods: We observed 17 children at the age from 6 months to 17,5 yrs (mean age 10 yrs), 10 girls and 7 boys, with diagnosed long QT syndrome. Patients were divided into 2 groups: Group I – 11 children ( 7 females, 4 males) with symptomatic long QT syndrome ( syncope, dyspnoe); group II – 6 pts (3 girls and 3 boys) with prolongation of QTc segment in ECG but without any clinical symptoms. All patients were in long term follow-up from 19 months till 7 years (mean observation time - 3,5 yrs). Standard 12 leads ECG with assessment of QT interval, corrected QT interval according to Bazzet formula and QTc dispersion were done at the beginning and the end of observation period. 24-hour Holter ECG monitoring with QT evaluation was also performed in all patients. All patients from group I were administered of beta blockers (propranolol or metoprolol) with mean dose 1,2mg/kg.
Results: Mean standard ECG QTC duration in pts in group I was significantly higher than in group II both in the beginning and in the end of observation period ( 471,82 vs 435 ms and 460,91 vs 423,33 ms). The similar result was observed in Qtc duration in Holter monitoring (535 vs 455 ms; 515,91 vs 452,5 ms.)There were no significant differences between QTc duration before and after beta-blocker treatment in group I (471,82 vs 460,91 ms) although frequency and intensity of symptoms in this group of pts was expressively diminished.
3 patients (27,3%) from group I were referred to ICD implantation.
Conclusions: 1. Beta blockers diminished clinical symptoms in long QT syndrome. 2. Syncope can be evident risk factor of sudden cardiac death in children. 3. Pharmacological treatment could decreased the SCD risk in children with long QT syndrome.