Benefit of single setting rate responsive ventricular pacing compared with fixed rate demand pacing in elderly...

In order to assess the value of a simple, single setting rate response option to VVI pacing, 12 patients (mean age 75.1 +/- 6.2, range 62-83 years, seven males, five females) with symptomatic complete heart block were entered into a double-blind, randomized crossover trial of VVI versus VVIR (single setting rate responsive) pacing using Medtronic Activitrax pacemakers. Assessment was by time taken in seconds (sec) and Borg scale symptom score (6-20) for simple activities (standing from chair x 30; walking 800 meters; 52 steps on stairs [slow and fast pace], and incremental, noninclined maximal treadmill exercise), performed after a 4-week period with the patient in each pacing mode. Times were significantly improved in VVIR mode for standing from chair [mean +/- SD] (78.7 +/- 22.5 vs 70.7 +/- 19.5 sec; P less than 0.05), for 800 m walk (1032 +/- 80 vs 885 +/- 59 sec; P less than 0.05), fast ascent of stairs (29.5 +/- 7.7 vs 26.5 +/- 5.6 sec; P less than 0.02), and treadmill exercise (626.7 +/- 189.5 vs 741.0 +/- 170.2 sec, P less than 0.005) although no difference in time for slow stair ascent was demonstrated. Symptom scores were significantly less in VVIR for standing from chair (12.7 +/- 2.8 vs 10.3 +/- 1.8; P less than 0.01), 800 m walk (10.9 +/- 2.7 vs 9.0 +/- 2.4; P less than 0.01), slow ascent of stairs (11.6 +/- 2.1 vs 10.0 +/- 2.0; P less than 0.01), and fast ascent of stairs (13.0 +/- 2.0 vs 11.7 +/- 1.9; P less than 0.02) but unchanged for treadmill exercise.(ABSTRACT TRUNCATED AT 250 WORDS)