Left Bundle Branch Block: A Reversible Pernicious Effect of Lacosamide.

A 95-year-old male with a medical history of focal epilepsy presented with transient ischemic attack (TIA)/pre-syncope like symptoms. He was on lacosamide (LCM) and levetiracetam. On evaluation, he was found to have left bundle branch block (LBBB), sinus pause of three seconds, and 1st degree atrioventricular (AV) block. After holding LCM, electrocardiogram changes were reversed to baseline (before commencing LCM). In conclusion, to the best of our knowledge, this is the first case of reversible LBBB along with sinoatrial (SA) node and AV node dysfunction in an elderly male on LCM therapy.