An example of the deleterious effects of right ventricular apical pacing.

Pacemaker implantation remains the mainstay of treatment in patients with symptomatic sinus node disease or severe heart block. Despite the dramatic benefits of this therapy, a high burden of ventricular pacing is known to have its disadvantages. Reported is the case of an 85-year-old woman with a history of sick sinus syndrome who presented with congestive heart failure after her atrioventricular sequential pacemaker defaulted to ventricular pacing mode as a result of battery depletion. After replacement of her generator and reinstitution of atrial pacing, dramatic improvements in her symptoms and echocardiographic findings were observed. Although it is difficult to predict which patients will ultimately develop cardiac decompensation as a result of ventricular pacing, closer follow-up and early recognition of these complications is essential to prevent adverse outcomes.