Gender Differences in the Effect of Auditory Stimuli on Ventricular Repolarization in Healthy Subjects

Introduction: Gender differences in the incidence of ventricular arrhythmias have been reported and torsade de pointes associated with long-QT syndrome (LQTS) is more common in women than men. Although auditory stimulation has been recognized as an important trigger of torsade de pointes in LQT2 patients, the normal response and gender differences in ventricular repolarization induced by auditory stimuli remained to be evaluated systematically.
Methods: Holter ECGs were recorded in 30 healthy volunteers (14 men aged 25 ± 4 years and 16 women aged 23 ± 2 years). They were awakened by an alarm clock at 5:00 am. The RR and QT (QTc) intervals and the T-wave amplitude were measured before and after alarm ringing.
Results: The morphology of the T-wave changed dynamically and transiently during awakening. The RR interval significantly decreased just after sounding of the alarm in both sexes (P < 0.0001). The QT interval changed little after the alarm ringing and was significantly longer in women than men (P < 0.0001). The QTc intervals were significantly prolonged just after alarm ringing in both sexes (P < 0.0001); QTc prolongation was significantly longer and more sustained in women than men (P < 0.0001). The T-wave amplitude decreased after the alarm and was significantly lower in women than men (P = 0.0001).
Conclusion: Auditory stimulation abruptly and abnormally modulated the dynamics of ventricular repolarization in healthy subjects; the effect was more pronounced in women than men. This gender difference may partially account for the increased susceptibility of women with electrically unstable hearts to arrhythmogenesis.