Quality of life and exercise capacity in patients with prolonged PQ interval and dual chamber pacemakers: a randomized comparison of permanent ventricular stimulation vs intrinsic AV conduction.

Aims: The aim of this study was to assess quality of life (QoL) and exercise capacity during permanent ventricular stimulation (PVS) compared with intrinsic atrioventricular conduction (IAVC) in patients with dual chamber pacemakers (PMs) and an intrinsic PQ interval >210 ms. Dual chamber PMs in patients with atrioventricular (AV) block are usually programmed to PVS in VDD or DDD mode, although IAVC is preserved, but prolonged. This results in PVS, although long periods of IAVC may occur.

Methods And Results: Fourteen consecutive patients (age 76 +/- 6 years; intermittent high degree AV block in six patients, binodal disease in eight patients) were enroled in a prospective, randomized, single blind, crossover study of IAVC vs PVC. To permit IAVC, programmed AV delays were prolonged. At the end of each phase, QoL scores were assessed using a questionnaire and echocardiography and cardiopulmonary stress tests were performed. During the study period with IAVC, 95 +/- 10% of the beats were conducted intrinsically. QoL scores (28.3 +/- 11 vs 29.3 +/- 13; P = 0.68), peak exercise capacity (5.4 +/- 2.4 vs 5.2 +/- 2.9 METs; P = 0.35) and peak oxygen uptake (19.8 +/- 4.5 vs 18.8 +/- 5.2 ml/kg/min; P = 0.16) were comparable during IAVC and PVS, respectively. Similar echocardiographic values were found for left ventricular (LV) ejection fraction (50 +/- 9% vs 51 +/- 10%; P = 0.67) and velocity time integral at the left ventricular outflow tract (24 +/- 5 vs 22 +/- 6 cm; P = 0.20), respectively.

Conclusions: We conclude that in patients with dual chamber PMs and intermittent high degree AV block neither PVS nor IAVC is superior with respect to QoL or exercise capacity. Therefore, pulse generators may be programmed to IAVC to extend their longevity.