Concealed His Extrasystoles: A Masquerader of AV Block

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.