No abstract

OBJECTIVE The study sought to examine the prevalence and outcomes of sports participation (both competitive and recreational) in our single-center LQTS genotype positive pediatric population. BACKGROUND The risks of sports participation in patients with long QT syndrome (LQTS) are not clearly elucidated. METHODS A retrospective review was performed on genotype positive patients referred for the evaluation and management of LQTS between 1998 and 2013 at the Children’s Hospital of Philadelphia. Pediatric patients participating in competitive or recreational sports were included in the analysis and their charts were reviewed for documented LQTS events during follow-up. RESULTS The cohort of genotype-positive LQTS patients included 212 patients, and 103 patients (49%, female n = 53, average follow-up 7.1 ± 4.0 years, average QTc 468 ± 42 ms) participated in sports. A total of 105 LQTS disease-causing mutations were identified: KCNQ1 n = 60 (58%), KCNH2 n = 36 (35%), SCN5A n = 6 (6%), KCNE1 n = 1 (1%), and KCNE2 n = 2 (2%). All patients were treated with beta-blockade, with noncompliance in 1 patient and intolerance in 1 patient. Twenty-six patients participated in competitive sports (26%, female n = 15, average follow-up 6.9 ± 4.1 years, average QTc 461 ± 35 ms). Seventy-seven patients (75%, female n = 35, average follow-up 7.3 ± 3.9 years, average QTc 470 ± 43 ms) participated in recreational sports. No patients had LQTS symptoms during sports participation. Five appropriate implantable cardioverter-defibrillator shocks occurred in 2 patients, though none were related to sports participation. CONCLUSIONS In this series no cardiac events and no deaths were observed in treatment-compliant LQTS children while participating in sports in 755 patient-years of follow-up.

The characteristics of Ca2+ signaling in fura 2-loaded whole cell-clamped myocytes obtained from samples of human atrial appendages of 3-day to 4-yr-old patients were examined. In isolated myocytes, activation of Ca2+ current (ICa) (2.47 +/- 0.23 pA/pF) at 0 mV elicited sizable intracellular Ca2+ (Cai) transients (240 +/- 45 nM), which were caused by the release of Ca2+ from intracellular stores as they were suppressed in the presence of ryanodine or caffeine. The voltage dependence of both Cai transients and ICa were similar and bell shaped. The rate of release of Ca2+, normalized for the maximal Ca2+ release, increased with age, indicating increased efficiency of Ca2+ signaling in more mature myocytes. The results suggest that ICa-gated release of Ca2+ from the sarcoplasmic reticulum is the primary mechanism regulating the signaling of contraction in early postnatal as well as older human atrial myocytes.

OBJECTIVE-The study sought to examine the prevalence and outcomes of sports participation (both competitive and recreational) in our single-center LQTS genotype positive pediatric population. BACKGROUND-The risks of sports participation in patients with long QT syndrome (LQTS)are not clearly elucidated.