Ventricular arrhythmias and sudden death in patients taking ibrutinib

To the editor: Ibrutinib, approved by the US Food and Drug Administration (FDA), is an inhibitor of Bruton tyrosine kinase (BTK).[1][1][⇓][2][⇓][3][⇓][4]-[5][5] Ibrutinib use is associated with atrial fibrillation (AF), with an incidence of 5% to 6% after 18 months on therapy[4][4][⇓][5]-[6