Prolonged Ventricular Pauses in an Asymptomatic Athlete with "Apparent Mobitz Type II Second-Degree Atrioventricular Block"

We report the case of a 30-year-old basketball player with asymptomatic, nocturnal ventricular pauses of >3,000 ms, the longest being similar to 12,000 ms, who was misdiagnosed with Mobitz type II second-degree atrioventricular (AV) block. Conversely, the tracings were characteristic of a vagally mediated AV block, a phenomenon first described by Massie and called apparent Mobitz type II AV block. Although the patient was asymptomatic with ventricular pauses occurring only at night, it was decided to implant a permanent pacemaker to prevent neurological damage or life-threatening ventricular arrhythmias resulting from repeated, abnormally prolonged ventricular pauses. The persistence of AV block after a 3-month detraining period led us to believe that our decision was reasonable. (PACE 2011; 14)