Abstract 18004: Diagnosis of Obstructive Sleep Apnea in Patients With Congenital Long QT Syndrome

Introduction: Obstructive sleep apnea (OSA) is a common health problem which affects about a quarter of US adults. OSA is increasingly linked to cardiovascular diseases including hypertension, heart failure, myocardial infarction, cardiac arrhythmias and sudden cardiac death (SCD). Congenital long QT syndrome (LQTS) is a common cause of SCD in children and young adults during exercise and sleep. LQT3 (SCN5A) and LQT2 (HERG) genotypes are particularly at increased risk for SCD during sleep. We tested the hypothesis that increased numbers of patients with congenital LQTS have OSA compared to controls matched for age gender and BMI. Methods: A complete medical history and a standard 12-lead surface ECG were obtained in LQTS and controls. Polysomnography (PSG) was conducted in 32 LQTS patients (20 LQT1 and 12 LQT2) and 40 controls matched for age, gender and BMI. Blinded interpretation of the sleep studies were carried out by a single investigator board certified in Sleep Medicine. OSA was defined by the presence of AHI ≥5 events/hour for adults (≥18 years) and >1 event/hour for children (<18 years). Results: The PSG results show that 16 LQTS patients (50%) have clinically significant OSA compared to 6 controls (15%) in the controls. There are 7 LQTS patients who have history of early childhood adenotonsillectomy and only 2 of them have OSA on the PSG results. Considering very close relationship between adenotonsillar hypertrophy in children and OSA, these children might have OSA in early childhood. Therefore, total 21 LQTS patients (65%) have OSA on the PSG and/or adenotonsillectomy. Presence of OSA is equally distributed in LQT1 and LQT2 genotypes. Conclusion: OSA is more common in patients with congenital LQTS compared to healthy matched controls. Apneic events during sleep are associated with exaggerated sympathetic responses which might be potential mechanisms for triggering arrhythmias and thus increased risk of SCD during sleep.