Prolonged ventricular pauses in an asymptomatic athlete with "apparent Mobitz type II second-degree atrioventricular...

We report the case of a 30-year-old basketball player with asymptomatic, nocturnal ventricular pauses of >3,000 ms, the longest being ∼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.