TY - JOUR T1 - Intermittent left bundle branch block and acute heart failure in trastuzumab-induced cardiotoxicity JF - BMJ Case Reports JO - BMJ Case Reports DO - 10.1136/bcr-2020-236009 VL - 13 IS - 7 SP - e236009 AU - Ravi Masson AU - Hooman Bakhshi AU - Tariq M Haddad Y1 - 2020/07/01 UR - http://casereports.bmj.com/content/13/7/e236009.abstract N2 - A 70-year-old woman with HER2+/ER+ breast cancer on adjuvant trastuzumab therapy without a history of cardiovascular disease presented with respiratory failure from influenza and was found to have intermittent left bundle branch block (LBBB) with new onset systolic heart failure. Her course was complicated by polymorphic ventricular tachycardia and recurrent chest pain. Significant investigations included a normal cardiac MRI and cardiac catheterisation with unobstructed coronaries. It was determined that the aetiology of her heart failure was trastuzumab-induced cardiotoxicity after comprehensive workup. This case highlights an uncommon presentation of LBBB and the steps taken to diagnose a rare cardiomyopathy. ER -