Single chamber ventricular compared with dual chamber pacing: a review.

Since its introduction in the 1950s, the cardiac pacemaker has become increasingly sophisticated in an attempt to mimic normal cardiac physiology. Rapidly evolving pacing technology has seen pacemakers evolve from crude, fixed-rate, single chamber ventricular devices to dual chamber rate-adaptive units. While there is indirect evidence that supports the use of dual chamber pacing in the vast majority of patients, it is still unclear whether these newer, more expensive devices afford a significant morbidity and mortality benefit over single-chamber, ventricular, rate-adaptive pacemakers. A review of three large, randomized trials failed to demonstrate a clear benefit of dual chamber or atrial-based pacing over single chamber ventricular pacing for the majority of cardiovascular outcomes (heart failure, stroke and mortality), with the possible exception of atrial fibrillation. Information is also needed on the potential protective effects of atrial-based pacing over dual chamber pacing in elderly patients with sinus node dysfunction. Longer follow-up periods may be necessary to determine whether there are any mortality benefits associated with dual chamber pacing. Additional confirmation of benefits of dual chamber pacing may be provided by other ongoing prospective trials.