Trigger-specific ion-channel mechanisms, risk factors, and response to therapy in type 1 long QT syndrome

Background Arrhythmic events in long-QT syndrome type 1 (LQT1) may be associated with exercise, acute arousal, or rest/sleep. Objectives We aimed to identify trigger-specific risk factors for cardiac events in patients with LQT1. Methods The study population comprised 721 genetically confirmed patients with LQT1 from the US portion of the International LQTS Registry. Multivariate analysis was used to assess the independent contribution of prespecified clinical and mutation-specific factors to the development of a first reported triggered event, associated with exercise, arousal, or sleep/rest. Results Cardiac events occurred in 221 study patients, of whom 121 (55%) were associated with exercise, 30 (14%) with arousal, 47 (21%) with sleep/rest, and 23 (10%) with other triggers. Multivariate analysis showed that males