Ten-year experience in atenolol use and exercise evaluation in children with genetically proven long QT syndrome

Sit-Yee Kwok; Andreas Pflaumer; Sarah-Jane Pantaleo; Erin Date; Mangesh Jadhav; Andrew Mark Davis

doi:10.1016/j.joa.2017.08.004

Ten-year experience in atenolol use and exercise evaluation in children with genetically proven long QT syndrome

J Arrhythm. 2017 Dec;33(6):624-629. doi: 10.1016/j.joa.2017.08.004. Epub 2017 Oct 12.

Authors

Sit-Yee Kwok¹, Andreas Pflaumer^{1

2

3}, Sarah-Jane Pantaleo⁴, Erin Date¹, Mangesh Jadhav¹, Andrew Mark Davis^{1

2

3}

Affiliations

¹ Department of Cardiology, Royal Children's Hospital, Melbourne, Australia.
² Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.
³ Department of Paediatrics, Melbourne University, Australia.
⁴ Victorian Clinical Genetics Services, Parkville, VIC 3052, Australia.

Abstract

Background: Due to its availability, atenolol is the primary beta-blocker used in Australia for children with long QT syndrome. There is limited data on long-term follow-up of its use.

Methods: A single-tertiary-center, retrospective, observational study investigating all children and adolescents who had genetically proven long QT syndrome type 1 (LQT1) and type 2 (LQT2) was conducted. Their pretreatment exercise tests were evaluated for QTc intervals into the recovery phase of exercise.

Results: Eighty six patients were identified (LQT1, 67, and LQT2, 19) from 2004 to 2014. The majority (86%) of patients were initially referred for family screening. Atenolol was administered at a mean dose of 1.58 ± 0.51 mg/kg/day. During the median follow-up period of 4.29 years, only one proband developed ventricular arrhythmia whilst taking atenolol, No patient had cardiac arrest or aborted cardiac arrest. With respect to side effects of atenolol, only two patients had intolerable side effects necessitating changes of medication. Evaluation of exercise tests (pretreatment) demonstrated that corrected QT (QTc) intervals at 2-3 min into the recovery phase of exercise were significantly prolonged for LQT1 patients. LQT1 patients with transmembrane mutation had longer QTc intervals than their C-terminus mutation counterparts, reaching statistical significance at 3 min into the recovery phase of exercise.

Conclusions: Atenolol is an effective treatment for genetically proven LQT1 and LQT2 children and adolescents, with good tolerability. In LQT1 patients, QTc intervals at 2-3 min into the recovery phase of exercise were significantly prolonged, particularly in patients with transmembrane mutations.

Keywords: Atenolol; Beta-blocker; ECG, Electrocardiogram; Exercise; ICD, Implantable cardioverter-defibrillator; LCSD, Left cardiac sympathetic denervation; LQT1, Long QT syndrome type 1; LQT2, Long QT syndrome type 2; LQTS, Long QT syndrome; Long QT syndrome; Pediatrics; QTc, Corrected QT; SD, Standard deviation; SFM, Screened family members; TdP, Torsade de pointes; min, Minutes; s, Seconds.