LAUSR

A 29‐year‐old male patient was referred to our center for malfunctioning (lead failure) of his implantable cardioverter defibrillator (ICD). He was known to be affected by a familial channelopathy, and one decade ago he underwent implantation of a transvenous, single chamber, ICD for secondary prevention. On admission, his basal 12‐lead electrocardiography (ECG) showed sinus rhythm with remarkable repolarization abnormalities (Figure 1A). What is the likely underlying channelopathy in this patient? Figure 1A reveals sinus rhythm at 60 bpm with a prolonged QTc interval (~520 ms) showing the classical morphology of type 3 long QT syndrome (LQTS3) with a prolonged isoelectric ST segment, followed by a delayed normal T wave. Indeed, the patient was known to be affected by a familial LQTS3 that was confirmed by genetic testing. Interestingly, the right chest leads (V1 and V2) show a spontaneous type I Brugada pattern (diagnostic coved‐ type). Of note, the patient was not taking any therapy with Na blockade properties (eg, flecainide). Reviewing the previous 12‐lead ECGs revealed a type II (saddle‐back) Brugada along with the known LQTS3 pattern (Figure 1B). The patient underwent uneventful extraction of the malfunctioning transvenous ICD system and subsequent implantation of a subcutaneous ICD. Though pharmacological challenge (ajmaline or flecainide) has been reported to induce Brugada pattern in some LQTS3 patients, the electrocardiographic combination of LQTS3 and a spontaneous type I Brugada pattern is quite unusual. Unfortunately, genetic test details were not available for our review to define the involved genetic mutation/s. However, both Brugada and LQTS3 syndromes typically affect the sodium channels (SCN5A) causing loss and gain of function, respectively. Interestingly, such paradoxical duality has been related to single SCN5A mutations by having opposite effects, influenced by heart rates, on different kinetic components (fast and slow inactivation) of sodium channel gating. Nevertheless, the coexistence of multiple genetic mutations affecting different components of ionic channels cannot be excluded as the underlying mechanism. Our patient has been already protected by an ICD, but such combination of repolarization abnormalities may influence pharmacologic therapy options or predispose to a higher arrhythmic risk. On discharge, he was educated to avoid conditions known to be proarrhythmic in Brugada syndrome (certain drugs, excessive alcohol intake, and fever), and his family members were encouraged to undergo further electrocardiographic screening to check for Brugada pattern. Finally, it may be reasonable to screen LQTS3 patients for a potential concealed Brugada pattern, by performing higher intercostal ECG recordings or pharmacological challenge to optimize patient management.