Long QT syndrome in children in the era of implantable defibrillators.
OBJECTIVE
We sought to assess the spectrum and outcome of young long QT syndrome (LQTS) patients, addressing treatment including device indications, risks, and benefits.


BACKGROUND
Long QT syndrome has a phenotype ranging from asymptomatic electrocardiogram (ECG) abnormalities to sudden death. Treatments include beta-blockers and device implantation in high-risk individuals. Despite genetic testing, accurate risk stratification remains challenging.


METHODS
A database search at 3 institutions identified all pediatric LQTS patients. Records were reviewed for demographics, criteria for diagnosis, treatment, follow-up, and ECG and device data.


RESULTS
We identified 128 patients ages 8.0 +/- 5.4 years with QTc of 487 +/- 39 ms and follow-up of 4.4 +/- 3.5 years. Most were diagnosed because of an abnormal ECG in a patient with a family history (53%). Genetic mutations were identified in 51 patients. Beta-blockers were used in 126 (98%) and pacemaker/implantable cardioverter-defibrillator implantation in 27 (21%) patients, usually because of symptoms despite use of beta-blockers. Pacing was common; 22% received an appropriate shock but device-related re-intervention occurred in 48%. Device patients had longer QTc intervals (p = 0.03) and more symptoms (p < 0.001). No one with an isolated KCNQ1 and all patients with an SCN5A mutation had device implantation. During the study period, there were 2 deaths.


CONCLUSIONS
Long QT syndrome without symptoms is increasingly recognized as family members are screened. Evaluation of this minimally symptomatic population offers an evolving understanding of LQTS. Previous studies of highly symptomatic patients were more worrisome. In the era of genetic testing and device implantation, overall mortality is low with treatment. Device therapy, although effective, is not without complications and should be reserved for high-risk patients.
Etheridge
Susan P
SP
University of Utah, Salt Lake City, Utah, USA. pcsether@ihc.com
Sanatani
Shubhayan
S
Cohen
Mitchell I
MI
Albaro
Cecilia A
CA
Saarel
Elizabeth V
EV
Bradley
David J
DJ
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D001130:Arizona / Q000453:epidemiology; D001955:British Columbia / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D005820:Genetic Testing / Q000706:statistics & numerical data; D006801:Humans; D051657:KCNQ1 Potassium Channel / Q000235:genetics; D008133:Long QT Syndrome / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics / Q000628:therapy*; D008297:Male; D009154:Mutation; D010043:Outcome and Process Assessment, Health Care; D010372:Pediatrics / Q000379:methods / Q000706:statistics & numerical data*; D018570:Risk Assessment / Q000379:methods; D016019:Survival Analysis; D014589:Utah / Q000453:epidemiology
D000319:Adrenergic beta-Antagonists; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human