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CLINICAL RESEARCH

Long QT Syndrome in Children in the Era of Implantable Defibrillators

Susan P. Etheridge, MD, FACC^_*,_*, Shubhayan Sanatani, MD, Mitchell I. Cohen, MD, FACC, Cecilia A. Albaro, MD^_*, Elizabeth V. Saarel, MD, FACC^_* and David J. Bradley, MD, FACC^_*

^_* University of Utah, Salt Lake City, Utah
University of British Columbia, Vancouver, British Columbia, Canada
Phoenix Children's Hospital and Arizona Pediatric Consults/Pediatrix, Phoenix, Arizona

Manuscript received March 16, 2007; revised manuscript received April 25, 2007, accepted May 5, 2007.

^_* Reprint requests and correspondence: Dr. Susan P. Etheridge, 100 North Medical Drive, Salt Lake City, Utah 84113. (Email: pcsether{at}ihc.com).

Objectives: 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.

Abbreviations and Acronyms   ECG = electrocardiogram   ICD = implantable cardioverter-defibrillator   LQTS = long QT syndrome   TdP = torsades de pointes

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