The QRS and T wave alternans — a new ECG pattern in Long QT syndrome

We present a case of a new ECG phenomenon that has not been described previously in patients with long QT syndrome (LQTS). Prolongation of the QT interval (QTc) to 568 ms were revealed in girl 6 years old on the resting ECG. There were no symptoms, syncope or family history of sudden death. A molecular genetic study revealed mutation «de novo» in the SCN5A gene (p.Val1411Met), a pathogenic class V that typical for the third molecular genetic variant of LQTS (LQT3). During Holter monitoring a «hyperadaptation» of the QT interval was noted (slope QT/RR 0.37 with normal limit till 0,24). New ECG pattern of the combination T wave alternans and QRS alternans (AT/AQRS) at the night sleep (possibly in REM sleep) were recorded. This pattern has not been described previously in patients with LQTS. Atenolol 1 mg/kg was prescribed. During therapy, AT/AQRS did not record after 2 months. Possible mechanisms and prognostic significance of the identified ECG pattern, issues of treatment of patients with LQT3 are discussed. Conclusions: Combined of T wave alternans and QRS alternans (AT/AQRS) is a new ECG pattern in patients with LQTS that is likely to increase the risk of cardiac events. “Hyperadaptation” of the QT interval may be one of the electrocardiological features of LQT3. The emergence of the AT/AQRS pattern during REM sleep makes this period perhaps the most dangerous for the development of cardiac events in patients with LQT3.