Concealed His extrasystoles are a well-known masquerader of AV block. It
is therefore necessary to consider pseudo AV block in patients who
develop unexpected AV block without a clear etiology. In this report, we
present a case of a 46-year-old female who was found to have
pseudo-Mobitz II AV block secondary to His extrasystoles diagnosed on
surface ECG without requiring invasive electrophysiology study. We also
demonstrated in this patient that flecainide can be an effective
treatment for His extrasystoles.