Implantable cardioverter defibrillator therapy for congenital long QT syndrome: a single-center experience.
BACKGROUND
Long QT syndrome's (LQTS) marked heterogeneity necessitates both evidence-based and individualized therapeutic approaches.


OBJECTIVE
This study sought to analyze a single LQTS specialty center's experience regarding the relationship between risk factors and appropriate ventricular fibrillation (VF)-terminating therapies among LQTS patients treated with an implantable cardioverter-defibrillator (ICD).


METHODS
An internal review board-approved, retrospective analysis of the electronic medical records of 459 patients with genetically confirmed LQTS including the 51 patients (14 LQT1, 22 LQT2, and 15 LQT3) who received an ICD from 2000 to 2010 was performed.


RESULTS
Twelve patients (24%, 4 LQT1, 8 LQT2) experienced an appropriate, VF-terminating therapy with an average follow-up of 7.3 years, including 7 of 17 LQT2 female patients but none of the 15 LQT3 patients. Conversely, 15 (29%) patients (8 LQT3) have experienced an inappropriate shock. Secondary prevention indications (P = .008), non-LQT3 genotype (P = .02), QTc ≥ 500 ms (P = .0008), documented syncope (P = .05), documented torsades de pointes (P = .003), and a negative family history (P = .0001) were most predictive of an appropriate therapy. Importantly, no LQT-related deaths have occurred among the 408 non-ICD-treated patients.


CONCLUSIONS
The vast majority of LQTS patients can be treated effectively without an ICD. Potentially life-saving therapies were rendered at a 5% to 6% per year rate among those selected for ICD therapy; similar inappropriate shock frequencies were also noted. Secondary prevention, genotype, and QTc predicted those most likely to receive appropriate therapy. Although the ICD implant frequency is greatest among LQT3 patients, the greatest "save" rate has occurred among LQT2 women, who were assessed to be at high risk.
Horner
Justin M
JM
Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
Kinoshita
Masayoshi
M
Webster
Tracy L
TL
Haglund
Carla M
CM
Friedman
Paul A
PA
Ackerman
Michael J
MJ
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000628:therapy*