An intrapatient comparison of adaptation to aerobic and anaerobic exertion during 3 types of physiological cardiac stimulation in chronotropic failure of the sinus node: DDD, VVIR and DDDR

In sick sinus syndrome with chronotropic incompetence, dual-demand rate responsive pacing (DDDR) may be better than ventricular-inhibited rate responsive pacing (VVIR) and dual-demand pacing without rate responsive function (DDD). In order to compare exercise performance during different activity-driven pacing modes, 15 patients (9 males, 6 females; mean age 59 +/- 13 years), implanted with Synchrony 2020T pacemaker (Siemens-Pacesetter Inc, USA, activity sensor) for sick sinus syndrome, randomly performed 3 treadmill tests (modified Bruce protocol) during DDD, VVIR and DDDR pacing, with pacing heart rate, oxygen consumption (Q-Plex 5000, Quinton), work time, anaerobic threshold and human atrial natriuretic peptide level monitoring. Four patients were excluded from the data results (3 for normalization of chronotropic incompetence, 1 for angina pectoris during rate responsive pacing). Heart rate at the end of exercise was significantly higher during VVIR pacing mode (131 +/- 21 b/min) and DDDR (136 +/- 14 b/min) than during DDD pacing mode (105 +/- 21 b/min), p < 0.05. During DDDR we obtained a significantly higher work tolerance (652 +/- 161 s) and a higher oxygen uptake (22.7 +/- 7.1 ml/kg/min) than during DDD (565 +/- 106 s; 20.1 +/- 6.5 ml/kg/min) and VVIR (599 +/- 155 s; 18.8 +/- 6.5 ml/kg/min), p < 0.05. Also the work time and the oxygen uptake at anaerobic threshold were better during DDDR stimulation (350 +/- 119 s; 14.2 +/- 4.9 ml/kg/min) than during DDD (280 +/- 101 s; 12.2 +/- 4.6 ml/kg/min) and VVIR pacing mode (306 +/- 122 s; 11.6 +/- 4.60 ml/kg/min), p < 0.05. On the contrary, human atrial natriuretic factor values at the maximum exercise were lower during DDD (139 +/- 100 pg/ml) than VVIR (256 +/- 182 pg/ml) and DDDR (209 +/- 195 pg/ml) pacing mode, p < 0.05. In conclusion, DDDR pacing proved to be better than VVIR and DDD in patients with sick sinus disease and chronotropic incompetence.