Comparative Evaluation of Rate Modulated Dual Chamber and VVIR Pacing

Abstract

While dual chamber pacing is considered superior to VVI pacing at rest, there is a continuing debate as to the relative benefit of AV synchrony versus rate increase with exercise. To evaluate this question and to correlate different methods of evaluation, 14 patients with DDDR pacemakers were studied using serial treadmill exercise test with a CAEP protocol. Patients were exercised in DDD, DDDR, and VVIR modes. Echo-Doppler cardiac outputs were determined and pulmonary gas exchange was measured during exercise. There was a significant improvement in cardiac output with exercise in the DDDR versus VVIR modes, and in DDDR versus DDD modes in patients with chronotropic incompetence. There were small increases in exercise duration in DDDR versus VVIR modes, and small but consistent increases in VO2 at all levels of exercise, though not statistically significant. In this group of patients, DDDR pacing was superior to VVIR pacing, and superior to DDD pacing when chronotropic incompetence was present.

Chronotropic Incompetence in Patients with an Implantable Cardioverter Defibrillator: Prevalence and Predicting Factors

“…Regardless of the definition applied, however, published findings have demonstrated for pacemaker patients that they profit from rate‐adaptive pacing, especially in confirmed cases of CI 17–19 …”

Quality of Life and Clinical Outcomes in Elderly Patients Treated with Ventricular Pacing as Compared with Dual-Chamber Pacing

“…the reported failure to find a clear difference in exercise duration in patients with atrioventricular block with rate-adaptive pacing, ventricular pacing, or dualchamber pacing. [27][28][29][30] The design of the study did not permit maintenance of an accurate registry to compare the screened and enrolled populations. However, the demographic and clinical characteristics of the participants were very similar to those of recipients of dual-chamber pacemakers in the Medicare data base.…”

Have the Results of Randomized Clinical Trials of Pacing Altered the Practice of Cardiac Pacing?

“…DDDR pacing is expected to produce a clinically meaningful improvement compared to DDD pacing by having the patient reach higher heart rates during exertion. Clinical investigators, however, have found an inconsistent improvement in the exercise capacity of DDDR‐paced patients compared to DDD patients 27–30 . This inconsistent improvement in peak exercise capacity with DDDR mode compared with DDD pacing may reflect patient selection bias in small studies, noncardiac limitations to exercise in others, the specific ability of the rate‐modulation sensors to mimic sinus node function in patients with noncardiac physical limitations, and the variability of DDDR programming.…”